Software-Defined Radio For $11

Malvineous writes "Don't have $1500 to drop on a USRP? A Linux kernel developer has discovered that a Realtek digital TV tuner chip has an undocumented mode that turns it into a software-defined radio, with a frequency range of 64-1700MHz. The going rate for one of these USB devices can be as low as US$11. If you're unfamiliar with software-defined radio and have 20 minutes to spare, Balint Seeber has a great video introduction."

Comments

receive only?

[Anonymous Coward]

If it's a TV tuner it probably just has a receiver, no transmitter, right?

/.'d - google cache

[Anonymous Coward]

http://webcache.googleusercontent.com/search?q=cache:fRixFRVwNjoJ:sdr.osmocom.org/trac/wiki/rtl-sdr+sdr.osmocom.org/trac/wiki/rtl-sdr&cd=1&hl=en&ct=clnk

(which is also slow as zark. anyone manage a mirror?)

Were they running their website on an $11 dongle?

[Anonymous Coward]

Because now it's an $0.11 smoking heap of slag...

Getcha google cache here!

Too long

[ebcdic]

I'm unfamiliar with software-defined radio, and I don't want to spent 20 minutes watching a video. I hate this trend of using a video for something that could be explained in text that I could read in a fraction of the time.

Re:Too long

[Bananana]

yep. and the trend is not limited to April fools' pranks.

Re:Too long

[hardie]

Just assume you've used Google to read about software defined radio and aren't interested.

Re:Too long

[shish]

Watching the video now, it appears to be "dump ALL the radio signals to disk, for later analysis", so you can then use software to pick out audio / text / morse code / etc signals

Re:Too long

[trout007]

I found this great new site you may be unaware of. It's called Wikipedia. It is kinda of like an online encyclopedia that has brief summaries of almost anything. Check it out I'm sure you will like it.

http://en.wikipedia.org/wiki/Software-defined_radio

Re:Too long

[bill_mcgonigle]

I'm unfamiliar with software-defined radio, and I don't want to spent 20 minutes watching a video.

http://lmgtfy.com/?q=software+defined+radio

Re:Too long

[MinusOne]

Would it really have been that hard to embed the Wikipedia link in the article? Sure I can look this some up, but someone is trying to explain it to me and its just one stupid link.

Re:Too long

[Anonymous Coward]

There is a Wiki link in there, if you're too lazy to read the text that you could read in a fraction of the time, don't complain if the video isn't edited to your likeing...

Re:Too long

[swalve]

It is easier to think about in the transmit mode of operation, and then receive is just the opposite. Alright, you know how you can take digital data on your computer and convert it into sounds coming out of your sound card? Same thing but with higher (faster) radio frequencies. Reversing it for receive means that you hook up your "microphone" (antenna) to the line-in, and tell it to record. Using the raw "wave" file, you can filter out the signal you want, and then process that signal to get the data out.

Re:Too long

[Alsee]

In a "normal" radio-using device you have an electronic circuit to detect or create an exact sort of signal at a particular frequency range. For example you have one sort of circuit to detect FM tpy signals and a completely different circuit to detect AM radio signals, and a TV has circuitry that transforms exact-TV-format signals into the needed picture and sound signals. The advantage of these specific electronics is that they are cheaper and use less power.

A software defined radio picks up (or transmits) radio waves basically as a graph. A digitized wave form. A software defined radio uses a CPU to examine (or create) the radio wave. This means that simply by loading in the right software you can detect (or create) absolutely any sort of signal at all. You have one circuit that can handle up AM, FM, TV, cellphone signals, wifi signals, or anything. They can also use advanced digital methods to eliminate various kinds of noise.

The downside of software defined radio is that the circuitry needs to be bigger, faster, and more power-hungry to handle fast computation.

Software defined radio has the government worried and paralyzed. The government is used to individually regulating the frequencies and power levels and signal characteristics of each kind of radio-using device. An AM/FM radio specifically does not pick up police or cell phone frequencies, and things like CBs and walkie-talkies and cellphones and baby monitors all have specific power levels and specific frequencies they can broadcast on, and they only broadcast in specific radio formats. And those limits are hard-baked into the devices by their exact circuitry. Software defined radio throws that entire idea out the window. A software defined radio is going to have some inherent power limit based on the exact hardware, and some minimum and maximum frequency range based on the hardware, but generally it can handle a very broad range from low frequency bands to high frequency bands, and they can send/detect absolutely any radio format over that entire range, and they can do it at full power. There's no way to regulate "don't detect police/cell frequencies", and no way to regulate "don't broadcast FM on what is supposed to be an AM band", and there is no way to regulate different power levels on different bands. Once you sell a software defined radio, the end user can load in any software they want.

Software defined radio is revolutionary. It is incredibly flexible. And that flexibility is exactly the "problem" for government regulators.

-

Re:Too long

[Anonymous Coward]

Jesus all kinds of increasingly lazy people around here go to wikipedia

Re:Too long

[Polo]

I found this particular video showed me what you could do in a visual way I wouldn't have picked up by reading about it.

Yes, I agree that sometimes you can't watch a video where you could read text though.

Re:Too long

[Auroch]

Actually, I think the point the OP was trying to make was something like ... "Why not just explain it in a sentence or two IN THE F*SKING ARTICLE instead of linking a video or an external source".

Re:Too long

[jimmerz28]

As accustomed to ultra-consumption as we are 20 minutes to learn something new in an area you're (at least I was) totally unfamiliar with isn't all that much time.

Plus the video is rather well done and informative.

Re:Too long

[nurb432]

Just using logic alone should explain what a 'software defined radio' might be.

A radio, defined in software instead of hardware..

Re:Too long

[bmo]

Software defined radio has the government worried and paralyzed. The government is used to individually regulating the frequencies and power levels and signal characteristics of each kind of radio-using device. An AM/FM radio specifically does not pick up police or cell phone frequencies, and things like CBs and walkie-talkies and cellphones and baby monitors all have specific power levels and specific frequencies they can broadcast on, and they only broadcast in specific radio formats. And those limits are hard-baked into the devices by their exact circuitry. Software defined radio throws that entire idea out the window. A software defined radio is going to have some inherent power limit based on the exact hardware, and some minimum and maximum frequency range based on the hardware, but generally it can handle a very broad range from low frequency bands to high frequency bands, and they can send/detect absolutely any radio format over that entire range, and they can do it at full power. There's no way to regulate "don't detect police/cell frequencies", and no way to regulate "don't broadcast FM on what is supposed to be an AM band", and there is no way to regulate different power levels on different bands. Once you sell a software defined radio, the end user can load in any software they want.

Anyone with the technical knowledge can do any of these tasks in hardware, for not a lot of money. There are entire libraries of books and technical articles on how to broadcast/receive on any band, even "forbidden" ones like 800MHz cellular. I remember an article in Popular Communications for a down-converter you could build to listen to 800MHz back in the early 90s that simply screwed into the BNC of your scanner in line with the antenna.

BFD.

>implying it's somehow illegal to listen to bands outside of AM/FM

What the hell are you talking about? Beyond the Cellular legislation, any and all bands are open for reception. It's your right to intercept radio waves on whatever spectrum and you don't need a license to do so. You only need a license to transmit on licensed spectrum.

>cannot regulate power levels and bands

As if they weren't able to regulate for the past 80 years?

Protip: If you are transmitting 1kw, and transmitting in a band you shouldn't be in, it won't be the feds who track you down, it will be the licensed operators who will find you and turn your ass in to the feds and they'll be happy to do so.

The only reason why Joe Trucker doesn't get turned in with his 1kw linear on CB is because he's a moving target. Anyone else sitting in his basement throwing shitty harmonics up and down the bands can be found.

Also, software defined radios are not amplifiers. You are conflating one technology with another.

The amount of wrong in your post is staggering.

--
BMO

Re:Too long

[Anonymous Coward]

Yeah, everyone follows laws regarding CB modifications and power limits. And no one uses off the shelf scanners to listen to police traffic. I don't feel like this is a problem for the government for a couple reasons:

1) SDR can't do much that a large amalgamation of current radios can do. Just easier, nothing new here.
2) Most SDRs have wimpy TX power
3) Most amateur and commercial radios can be modified to go out of band or over power, depending on what band you're in, none of this is new.

SDR is just an easier more flexible way to do things we've already been doing for years, and soon enough, more cheaply. I say bring it on.

Re:Too long

[Anonymous Coward]

What the hell are you talking about?

1) The hard bit of any radio, especially important for transmission, is low noise band filtering, precise tuning and mixing to convert to/from AF. This all involves a lot of careful analog design and cannot be replaced by the S of SDR. Sure, the oscillator can use DDS, but that's not going to be done by wasting your computer's CPU cycles and it wouldn't make any difference anyway;

2) For analog modes, it's arguably easier to build a circuit than write decoding software. For digital modes, you're either running software on your desktop/laptop or you're running software on the radio's CPU. The only relevant questions are a) whether the modulation is documented - the answer is usually "yes" except for military; b) the keys for any encryption are available to you - if not, being able to implement an SDR makes not a hoot of difference;

3) Yes, you can do some fine DSP with a modern CPU but only an idiot thinks this is a substitute for a good antenna and (per 1) front-end.

SDR is the e-m equivalent of the "winmodem" in dial-up days: yes, you have the opportunity for a lot more versatility, but only by creating something dumb and offloading the work to a less power-efficient general purpose computer which may or may not have something better to do.

Re:Too long

[girlintraining]

The only reason why Joe Trucker doesn't get turned in with his 1kw linear on CB is because he's a moving target

Actually, it's because the government just doesn't give a sh*t about CB radio frequencies. But given that it uses an incredibly simple modulation scheme, it can easily be traced and tracked in realtime. All you need to catch "Joe Trucker" is three antennas spaced one wavelength or more apart and you can get a fix on their position. They may be a moving target, but they're moving along a fixed path: The road. Find a guy heading northwest in the same direction as the highway and you just hop on the road a few exits up and join the flow of traffic. He'll talk again, and when he does... oh look, it's the guy 50 feet in front of you in the left lane... *flips on lights* Goodbye 1kW transmitter, goodbye trucker.

Be more concerned about frequency hopping mobile devices that use a PRNG to communicate with another device over a range of frequencies and encoding techniques... That requires a LOT more equipment to sort out where the signal is coming from. Actually, that's pretty much what the military does... o_o

Re:Too long

[Anonymous Coward]

"There's no way to regulate "don't detect police/cell frequencies",

Because it's perfectly legal to listen in on any frequency. Getting around the encryption used to obscure the content (law enforcement comms) might be a different issue.

"and no way to regulate "don't broadcast FM on what is supposed to be an AM band"

Really. Then how come there -is- such regulation, and how come it is in fact being enforced?

Re:Too long

[Anonymous Coward]

God damn. Mod parent up!!!

Re:Too long

[LWATCDR]

Sorry but why complain because someone didn't know you knew what software radio was? This is Slashdot News For Nerds not CNN. If someone posted a story about AMD would you complain that they didn't include a wikipedia link to AMD?
I just don't think that it is outside of reason to expect someone reading slashdot to google something they do not understand.

Re:Too long

[hairyfeet]

I have a good question....why? Are radio chips REALLY expensive or something now? hell all the old analog TV tuners had radios built in and they ended up dropping the feature because nobody used the damned things, so why would you want to do it much more inefficiently in software? this is one of those things like that cassette deck for PCs where i sit there with a serious "WTF?" look on my face because i honestly don't get it. I mean all you are picking up is standard radio, right? no police bands or anything cool like that? hell there are a bazillion free radio station on the net and unlike the clearchannel crapola they play music that doesn't suck.

So I'm sorry if I'm missing something but i really don't get it. Radio is all but dead now anyway, you have tons of free streams, so why care about adding a dying format to your PC?

Re:Too long

[Gothmolly]

No kidding. Are people too illiterate to read a 1 page article?

Re:Too long

[Grieviant]

The modern definition of 'radio' refers to any device that uses wireless to transmit / receive an electromagnetic signal. Your wifi modem, bluetooth device, smartphone, TV, etc., are all radios. It's not limited to traditional FM radio from 88-108 MHz. Pretty much all radios are using some form of digital communications these days, as opposed to analog modulation with FM radio. Software defined radio really isn't anything special - the low frequency part of the radio (from IF down to baseband) is handled with a digital signal processor that can be programmed to handle many different formats. It's a natural evolution of digital communications that gets tossed around as a buzzword.

Re:Too long

[Anonymous Coward]

Just assume you've used Google to read about software defined radio and aren't interested.

What are the chances that assumption was true for this particular person? :)

Re:Too long

[superdave80]

So you've managed to deduce that software defined radio is a radio defined in software? Awesome.

Re:Too long

[Goaway]

This has nothing to do with April fools', Slashdot is just late on the uptake as usual.

Re:Too long

[nurb432]

The point was that the OP couldn't figure it out without asking, Not that i didn't know what it was.

But thanks for being an ass, i would hate to think that there were still respectable humans out there.

Re:Too long

[DrVomact]

I'm unfamiliar with software-defined radio, and I don't want to spent 20 minutes watching a video. I hate this trend of using a video for something that could be explained in text that I could read in a fraction of the time.

Amen, brother. I figured that my aversion to video "tutorials" or "reviews" or whatever was just cranky old me being out of touch with the rest of the world again, so I wasn't going to say anything. But yeah, I am very sick of people talking and mugging for the camera instead of just writing a couple of clear concise paragraphs. The written word is random access. I can quickly skim a few paragraphs to see if this is what I'm looking for, I can read a lot faster than some fool can talk, and I if I just need one particular piece of information I can find it much more quickly in a written document than a video. I reserve particular disgust for people who try to demonstrate complex procedures, but have no idea about lighting or camera angle, so that the critical stuff is always done either in murky darkness or hidden behind the guy's hand.

Videos suck time. You have to sit in front of the monitor and watch while some guy natters on about whatever the subject is. Even if the video truly contains important reference information, you can't just watch it once, then later quickly go back to the critical part that you forgot. You have to try to find the right place to start playing the video. Again. You can't search a video for key-words. You can't print a video for later reference, or print a page to give to a friend who has a similar problem, and needs just a bit of key information. You can just send him the link, and invite him to waste his time.

What I truly fear is that the trend to videos is just another sign of cultural degeneration: it is part of the decline of literacy, of regard for the written word, and of the analytical thought that is possible only by means of the written word. So I don't look for a reversal of this trend any time soon. It's just going to get worse, along with everything else.

Re:Too long

[Anonymous Coward]

Actually, I think the point the OP was trying to make was something like ... "Why not just explain it in a sentence or two IN THE F*SKING ARTICLE instead of linking a video or an external source".

Because saying "an approach to move radio functionality from hardware to software" a) doesn't cut it, and b) doesn't say anything that "software-defined radio" doesn't stand for already. Why rehashing something anyone self-proclaimed geek can find with a quick google or wikipedia search, specially rehashing it poorly? Might as well just copy/paste the first two sentences off wikipedia, and for that you might as well *gasp* not do that at all and instead opt to link to the external source. If you look hard enough for something to bitch about, you'll be bound to find it, even if it is inane.

Re:Too long

[Anonymous Coward]

> I'm unfamiliar with software-defined radio, and I don't want to spent 20 minutes watching a video. I hate this trend of using a video for something that could be explained in text that I could read in a fraction of the time.

I chose to reply here instead of one reply to all the morons that pass by and say "Google it!".

First, what's the big idea about opening a tech site and having to google the subject? What kind of tech site is this?

Second, it's okay being unfamiliar with something. If someone understands SDR what are the chances the guys groks Biology? We have lots of kinds of smart dudes over here but you cannot assume everyone has to know what you happen to know...

Moreover, after that insanely basic video about TVs a few days ago, what is the deal with an "introductory" video talking about kinds of different signals? wtf?

And finally, I'd like to have great sound quality and online digital is more than enough... sorry for those without fiber at home, but there's still internet on radio. So what really is SDR useful for? For the common user -- and I understand this would require some bureaucracy -- mp3/ogg streaming over normal SW might be enough.

Re:Too long

[foniksonik]

I highly recommend the video. You could not describe it effectively with words even combined with static images.

Re:Too long

[illtud]

Be more concerned about frequency hopping mobile devices that use a PRNG to communicate with another device over a range of frequencies and encoding techniques... That requires a LOT more equipment to sort out where the signal is coming from. Actually, that's pretty much what the military does... o_o

Yes, thanks in no small part to Heady Lamarr. Now that's a factoid.

Re:Too long

[Anonymous Coward]

What I truly fear is that the trend to videos is just another sign of cultural degeneration: it is part of the decline of literacy, of regard for the written word, and of the analytical thought that is possible only by means of the written word. So I don't look for a reversal of this trend any time soon. It's just going to get worse, along with everything else.

Page views and ad revenue. The average viewer wants to passively receive information from an audiovisual medium. This has worked well for movies, music, and TV since the time they were invented/perfected/mass distributed.

The 'fringe element' know their time is valuable and opt for text based solutions to get the information they want or need. They uses all sorts of adblock to speed up their browsing to increase their 'mental bandwidth'. It is all but impossible for advertisers to make money from this group of people so they focus on the other, larger group who aren't inclined to shift themselves to the other group because it is 'too complicated'.

CAPTCHA: stuffed (the advertising that fills commercial television. :P [about 20 minutes/hour in 2012 (>_); )

Re:Too long

[Anonymous Coward]

"...goodbye trucker..."

OMG I don't want them to kill him! Just take his amp!!!

Re:Too long

[ChrisMaple]

SDR makes possible "brick wall" filters that aren't practical with analog circuits, and that are more stable over temperature and time than is possible with analog circuits. Software doesn't drift. Physical inductors have limited "Q", crystals and mechanical resonators have "spurs", and so forth and do on.

Re:Too long

[BobNET]

That's Hedley!

Re:Too long

[squiggleslash]

It's a radio that instead of being tunable to the bit of spectrum you want to receive (eg. "200KHz at 88.9MHz, encoded using FM" - that's what your (analog) car radio's tuner is designed to do) , instead receives and digitally encodes an extremely large, fixed, block of spectrum. You then use software to extract the signal(s) you're actually interested in.

The major advantage of the system is that it's highly configurable - in theory, the same receiver can be used to receive and decode FM radio, ATSC TV, Wi-fi, GSM, UMTS, etc, as long as the receiver covers the part of the spectrum those signals are transmitted on.

Disclaimer: I'm not an expert, but I figured what I know to be more useful than being required to plow through a Wikipedia article on the subject.

Re:Too long

[illtud]

We're both wrong, that's Hedy!

Re:Too long

[currently_awake]

A modern radio consists of a radio frequency amplifier, a frequency converter to an intermediate frequency, and a converter to audio or data. The third part comes in many different and incompatible forms (am, fm, pm...). A software defined radio uses a computer (software) for the third part and therefore can be reprogrammed to handle all the different varieties without hardware changes.

Re:Too long

[pz]

Software-defined filters can be arbitrarily good. Hardware filters are much more severely cost-limited. Sofware filters can be a-causal (assuming you are doing post-hoc processing) with characteristics impossible to build in hardware, like zero phase delay for all input frequencies. You can build 100-pole filters in software; sure you can do that in hardware, but it's going to get very expensive, large, and potentially noisy. You can build filters with frequency characteristics that *exactly* match the design parameters, not merely to within the tolerances of the components you use. Software filters *add* *no* *noise*. They have *zero* temperature drift. They have *zero* aging effects. They have essentially infinte power supply rejection. They don't suffer from interference. They can be re-programmed on the fly. They can be crazy non-linear (eg., if you watched the linked video, you can create a softare filter to detect and block whistlers only when they're happening and only affecting the frequencies where the whistlers are, removing only the whistler signal and nothing else, including the background; good luck doing that in analog). You can get close to all of these characteristics in pure analog hardware, but it is far more difficult and far more expensive than doing it digitally.

Given how inexpensive digital hardware has become, most of the assumptions that go into creating standard analog reciever and transmitter hardware need to be re-examined. On the reciever side, for example, the only reason you have an IF stage is because it's prohibitively expensive to use a non-superhet design and get the same performance ... unless the signals are processed digitally.

Have you seen the amazing (and highly non-linear) filters available in Photoshop for processing images? Imagine applying the same sort of technology to radio: difficult things become easy, and radical things become possible.

Re:Too long

[hairyfeet]

Then they REALLY need to change the wording because it is REALLY confusing. I mean i'm sure that when 99.999% of the population hears the word "radio' they automatically think of AM/FM, after all that word has been pretty much the sole property of those bands for over a century. Hell we don't say "Sell me a Wifi radio" do we? Or a bluetooth radio? of course not.

So they should really change the name to "wireless signal processing' or something like that. When you see wireless signal processing you automatically think of ALL the different wireless signals, like BT and Wifi, cell phones, its just a better descriptor. I'm a firm believer in what George Carlin would say about words mattering, and in this case the language is VERY misleading as to what the thing actually does. If they were to start using WSP they would probably get more buzz and people interested in helping as THAT does sound interesting and neat, but software radio makes me think of some crystal radio kinda thing using a PC, not very interesting at all.

Re:Too long

[SQLGuru]

The problem is that they went to the trouble to provide an "if you don't know what it is" link that was to a rather lengthy video and their audience is part of the tl;dw; crowd. I'm not saying they are right or wrong, just summarizing the complaint.

Re:Too long

[Anonymous Coward]

> it's arguably easier to build a circuit than write decoding software

Yes, but you can't download a circuit.

Re:Too long

[Prune]

Holy crap, she's stunning! Could give Audrey Hepburn a run for her money. *Goes off to invent a time machine.*

Re:Too long

[Anonymous Coward]

Software defined radio has the government worried and paralyzed.

What are you smoking? Only the government can afford SDR, for crying out loud. It's an expensive approach to radio.

Re:Too long

[Anonymous Coward]

Yes you can do a whole lot of neat things in software but you have to digitize the signal first. Good luck getting an A2D that can receive the 700MHz public safety band at -120dBm and while standing next to a 800MHz cell tower without using a front end filter. There's also this little thing called power and high speed A2D eat a whole lot of it without even accounting for the power you need for processing. There is a reason the military abandoned their JTRS radio program. Even given 6 Billion dollars there weren't able to come up with a SDR that was any practical value.

Re:Too long

[serbanp]

I agree that the GP was an ass. Totally offtopic, but related to your sig, why was Booth a patriot?

Re:Too long

[wagnerrp]

I'm sure 99.999% of the population who thinks "radios" are something they're listening to music on have exactly zero reason to know what a software defined radio is. The rest remainder of us who actually understand technology can use whatever terminology we see fit.

Re:Too long

[Malvineous]

Just for the record, I too dislike the trend of explanations being posted as videos, but the reason why I linked to a video in this case was because of the nature of the topic. Reading about software defined radio is one thing, but actually seeing the analysis take place in real time is far more interesting in video form. Watching what the radio waves do, and how they sound different as you tune in and out of different signals is something you can only get by watching a video.

Had it been just about anything else I would have gladly omitted a video link.

Re:Too long

[Anonymous Coward]

How does it compare to my Encyclopedia Britannica volumes?

Re:Too long

[Technician]

All you need to catch "Joe Trucker" is three antennas spaced one wavelength or more apart and you can get a fix on their position

My rabbit hunting days was done with 4 antennas only 1/4 wave apart. Working in pairs, they were added with a 1/4 wave delay switched in and out of each antenna. If the signal was inline with an antenna pair, one direction added in phase and the other added out of phase. This modulated the carrier based on direction. Signals from the side of one pair remained un modulated, while the pair 90 degrees to the first pair provided maximum modulation. An XY scope display showed the relative modulation and phase info to give a decent relative bearing for mobile turkey hunting. Working with an active partner to flamebait a turkey, the silent DF partner usualy had little trouble finding a mobile or base target.

Re:Too long

[perryizgr8]

some one should put up a let-me-wiki-that-for-you.com website.

Re:Too long

[Anonymous Coward]

His post is very wrong in ways and misleading in others, but

Anyone with the technical knowledge can do any of these tasks in hardware, for not a lot of money. There are entire libraries of books and technical articles on how to broadcast/receive on any band, even "forbidden" ones like 800MHz cellular. I remember an article in Popular Communications for a down-converter you could build to listen to 800MHz back in the early 90s that simply screwed into the BNC of your scanner in line with the antenna.

The point isn't the different frequencies you can pick up, it's the modes of transmission. A software-defined radio can pick up FM or AM or what-have-you without new hardware or hardware tricks.

Re:Too long

[Anonymous Coward]

You're a knob.

Re:Too long

[Guy Harris]

That's Hedley!

...who uses his tongue prettier than a twenty dollar whore.

(And, since it's 1874, he'll be able to sue her.)

Re:Too long

[tlhIngan]

Software defined radio has the government worried and paralyzed. The government is used to individually regulating the frequencies and power levels and signal characteristics of each kind of radio-using device. An AM/FM radio specifically does not pick up police or cell phone frequencies, and things like CBs and walkie-talkies and cellphones and baby monitors all have specific power levels and specific frequencies they can broadcast on, and they only broadcast in specific radio formats. And those limits are hard-baked into the devices by their exact circuitry. Software defined radio throws that entire idea out the window. A software defined radio is going to have some inherent power limit based on the exact hardware, and some minimum and maximum frequency range based on the hardware, but generally it can handle a very broad range from low frequency bands to high frequency bands, and they can send/detect absolutely any radio format over that entire range, and they can do it at full power. There's no way to regulate "don't detect police/cell frequencies", and no way to regulate "don't broadcast FM on what is supposed to be an AM band", and there is no way to regulate different power levels on different bands. Once you sell a software defined radio, the end user can load in any software they want.

Not really. You can receive any frequency you want - you can buy equipment that very easily receives 100kHz-3GHz, legally.

The only trouble is with transmit, and the FCC controls intentional radiators. And no, government is not worried about it because there are some Very Nasty Fines for transmitting illegally. And they're levied on you, the operator, not the equipment manufacturer (though they can be found liable for making the equipment as well if its sole purpose was to do it, or even lose FCC certification). Pirate radio? That's really small potatoes.

Heck, the government has allowed many people to build their own radio transmitters legally and encourages people to do so legitimately - for the cost of obtaining the appropriate license (which is really quite minimal - if you can build your own transmitter, you can afford the license). It's called amateur radio and it really gives people full flexibility in building intentional radiators.

But receiving is always free. And the 800MHz cell law is hopelessly obsolete since no one uses AMPS anymore. Decoding digital transmissions is a lot harder, especially since there are now over a dozen frequency bands to which a cell call can be transmitted

And transmitters also have the limitation that they're fairly narrowband devices because the amplifiers tend to not have huge bandwidths. At least if you don't want to generate such crappy output that makes it even easier for people to find you.

SDR is revolutionary, yes. Even the government is using SDR technology as part of their SIGINT programs because they're very effective at scanning huge swaths of frequencies at once and isolating signals. And they're quite cheap - a whole bank of SDRs packed into a rackable unit isn't that expensive and can gather easily 24+ different freqeuncies at once (at 192kHz bandwidth each - using cheap-ass 192kHz/24bit audio ADCs used for consumer electronics). The beauty of this is as long as the signal you're looking at is less than 192kHz wide, you can pick it up. And TV's pretty much one of the few signals that requires a bit more bandwidth (6MHz).

Re:Too long

[guitardood]

Couldn't agree more.

Who do I see about getting my freaking 20 minutes back and the fee for my dogs' vet visit for their hearing being bugged by this moron listening to digital data that sounds like my old CoCo tapes. The point could have been made in a two paragraph article. The only thing viral about this video is the effect on the viewer.....headache, earache, chills.

What a waste of time, brain cells and bandwidth.

Re:Too long

[Anonymous Coward]

Software-defined filters can be arbitrarily good.

Only for sufficiently small bandwidth and sufficiently small variation in signal power.

Ideally we'd plug an antenna straight into an ADC of infinite resolution to simultaneously pick up everyone from the broadcaster across the street to the QRP Siberian ham, sample at twice the highest frequency desired, and have infinitely cheap CPU cycles to deal with the 600 million samples a second which result up to VHF (good luck with UHF and beyond!).

In practice, like I said in my first post:

The hard bit of any radio, especially important for transmission, is low noise band filtering, precise tuning and mixing to convert to/from AF.

For receiver-only applications, an imprecise tune could be mitigated against with more CPU-wasting software processing.

If you wanted to go wild you could try to transmit by connecting a DAC directly to your matched antenna. Explaining why this isn't done is left as an exercise for the reader.

On the reciever side, for example, the only reason you have an IF stage is because it's prohibitively expensive to use a non-superhet design and get the same performance ... unless the signals are processed digitally.

Yeah, and the reason my DAB receiver costs ten times as much and sucks up at least ten times the power of my FM broadcast receiver is because simple analog circuitry is insufficient. Meanwhile good IF filters may still allow you to reject a loud adjacent channel and crank up the gain to give a better amplitude on the signal of interest for your ADC.

Imagine applying the same sort of technology to radio: difficult things become easy, and radical things become possible.

Yes, I'm a ham with a math background and last year I had a bit of an obsession with writing DSP filters, motivated by some horrible local use of PLT. A good frontend and especially a good antenna remain your primary aims - no amount of DSP with a bad front-end will give you a comparable output and we're back to the theoretical ADC of infinite resolution to pick up those minute changes in the presence of overwhelming noise.

Moving to the digital domain for AF filtering and demodulation is fine, but an FPGA is a better option than stressing a generic CPU, making it less an "S"DR anyway.

tl;dr no.

Re:Too long

[Anonymous Coward]

The modern definition of 'radio' refers to any device that uses wireless to transmit / receive an electromagnetic signal. Your wifi modem, bluetooth device, smartphone, TV, etc., are all radios.

Except that's always been the definition of "radio", no "modern" about it. Hairyfeet is just plain wrong in his definition, as he is when he estimates all but 3000 people in the US share his delusion. (c.f. 700,000 ham radio licensees,,, most of whom surely realize their radio(s) is/are in fact radio(s).)

Re:Too long

[Frank T. Lofaro Jr.]

Links to Wikipedia are lazy.

Make links to the real information. not to an i-cyclopedia.

Re:Too long

[MiG82au]

You pretty much missed everything. I would have thought that somebody that's prepared to spend 5 minutes writing a post would have some clue about the topic.

Re:Too long

[jovius]

#define radio ...

Re:Too long

[Anonymous Coward]

Or, alternatively, people who have interest in a topic can learn the correct terms. There's nothing misleading about the terminology; you simply don't know it, evidently. You can learn them.

People don't usually ask to buy a bluetooth radio or a wifi radio because that's not actually what they want. They ask to buy a wifi card or a bluetooth dongle or a phone with bluetooth capability because that's what they actually want. The wifi card they buy will have lots of components: a radio, an antenna, a connector for your computer, some non-radio-related electronics, etc. If I wanted to talk about the quality of the wifi radios shipped by some laptop manufacturer or the quality of the bluetooth or GSM/CDMA radios shipped by some cell phone manufacturer, I would/do use the word "radio", as do other people who discuss things that specifically. (Most people don't need or want that level of specificity.)

As for the marketing benefits of throwing out the current terminology and adopting "wireless signal processing", I don't seem any reason to think it would have the effect you suggest. Maybe we need some focus groups?

Re:Too long

[nurb432]

Its just designed to make people think.

Booth was willing to do a drastic act and sacrifice himself for his country, but he was seen as a terrorist. While someone like Washington who also did terrible acts against the enemy is applauded as a hero.

Its all about which side who wins if we ignore what was done, and how hypocritical we are all at our core. Just as long as 'our side' wins.

Re:Too long

[Anonymous Coward]

Im sorry but the hard bit of a radio depends on its architecture. For example, the hard bit of a rake receiver is in the digital processing, not analog. This digital processing is usually a combination of hardware and software. Don't generalize. I've done a seprad spectrum sdr in dsp code. The physical layer software sections required the most work on the project. The RF guy was only half time on the project.

Re:Too long

[Anonymous Coward]

How do you think that a modern mobile phone works? Look at the radios in them. They are all SDR: a saw filter, an I/Q mixer and an analog to digital converter. Then it goes into a DSP. There are billions of mobile phones using SDR today.

Re:Too long

[drwho]

There I was, working at Radio Shack, and the customer says "No, I wanted a WIRELESS USB hub!". So I ripped out all the cables and gave it to him.

Re:Too long

[Anonymous Coward]

Something like that. In a conventional radio receiver, the incoming analog signal is amplified, then shifted in frequency (usually more than once) and fed through a series of bandpass filters before it's digitised and the computer starts to look at it directly. In a software-defined radio, the incoming analog signal is amplified, then digitised: all the subsequent signal-processing steps happen in the computer itself. This has a couple of advantages: it's much easier to reconfigure the radio to do different things (because you only have to change software, not hardware), and it's becoming cheaper (because digital electronics get cheaper faster than analog electronics).

I'm a radio astronomy student, and this is quite a big deal for us: the next generation of radio receivers will mostly work like this. We don't call it "software-defined", because the signal processing is implemented in FPGAs, so it's configured by changing firmware rather than software - but this isn't a very firm distinction, compared to the distinction between doing analog vs digital signal processing.

Incidentally - you might have seen a couple of stories on Slashdot recently about the Square Kilometre Array telescopes. There's a prototype for it in Australia, called ASKAP, that provides a good example of this change of approach: they built the first six antennas with old-style analog receivers, but they're building the other thirty with new-style digital receivers (and presumably retrofitting the first six when they can).

Re:Too long

[Anonymous Coward]

Wow, you're definitely a ham (like me). The most important part is the bloody antenna. Without it, you ain't
gonna receive squat, and if you're a ham into DXing, the old adage still applies - "If you can't *HEAR* them,
you can't *WORK* them". I don't care if you're trying to do some fancy, esoteric SDR DSP *stuff* on your
bench, because if the signals ain't coming down the transmission line from the antenna, it won't matter at all.

It's relatively trivial to build a receiver for any given frequency and modulation scheme.

Doing so in a practical way is the key. Just because SDR exists, doesn't necessarily mean it's a practical
solution to all of your receiver requirements. I've also found that sometimes various DSP filters and the like
are a PITA, what with ringing, desensitization, etc., and have been able to work weak DX stations on CW
simply by opening up the electronic filters (to 2.4 or 3.0 kHz) and let my ears and brain do the filtering by
consciously ignoring the idiot 150Hz away who has no clue that there's a rare DX station in his passband.

Re:Too long

[serbanp]

Thank you, this is really (+1 Insightful).

Cheers!

Re:Too long

[Lucractius]

For the very geeky gamers. A little bit of trivia. Half Life 2's Dr Kleiner keeps in a headcrab called Lamarr as an allusion to this very Hedy Lamarr of spread spectrum fame.

Re:Too long

[Anonymous Coward]

Are you trolling or what?

There are no thinkable proposition that can't also be written. It all depends on the thought and care (+creativity) of the author. In fact video will never include such a wide range of expression, from undefined to narrow, because it relies on (2D) images.

Get off my lawn and go to school!

Love, Sigg3 .net

Re:Too long

[superdave80]

Well, I never said that you didn't know what it was. It was just that you didn't explain anything. Your response was a little like saying a clock radio is a radio with a clock. It doesn't offer any new information. Yet you acted like you offered some great insight, when you clearly didn't.

Re:Too long

[hairyfeet]

So its "lets be a douche because we can!" and people wonder why so many geeks are looked down upon as maladjusted assholes? this is the same "logic" which brings so much hate to the Linux community thanks to the "Linux is just a kernel" douchebags, and yes we DO hate you if you say that lame shit and hope you DIAF.

Is it REALLY so fucking hard to just be, oh I don't know...NICE to others? maybe be considerate? shit like this is frankly what is wrong with this country, if given a choice between being considerate or being a flaming dickhole too damned many choose being a flaming prick.

Re:Too long

[wagnerrp]

No. There's just not a whole lot of point to dumbing down rather simple concepts for people who really don't care in the first place.

Re:Too long

[AdamWill]

preach it, brother. Is there some sort of pressure group we can join? every time I go to CNN, see an interesting headline, click on it, and see the bloody video player load up, I reach for my revolver...

Re:Too long

[Anonymous Coward]

I would imagine if Joe Trucker is improperly using amplifiers on CB they would begin to splatter on nearby bands which would then start attracting some negative attention.

Re:Too long

[Anonymous Coward]

"A software defined radio is going to have some inherent power limit based on the exact hardware, and some minimum and maximum frequency range based on the hardware, but generally it can handle a very broad range from low frequency bands to high frequency bands, and they can send/detect absolutely any radio format over that entire range, and they can do it at full power."

This also means that it can be used to create radio "networks" that ignore physical infrastructure(like the internet--imagine a P2P network that never touched a backbone). Encrypt the whole thing and the only way to shut it down is to start kicking in doors after triangulating every station. If the stations are close enough to each other, and use a low enough transmission power, most people would never even know it was there....

WTF is that Acronym?

[Anonymous Coward]

How difficult would it have been to type Universal Software Radio Peripheral to avoid the obvious confusion with the Ukrainian Socialist-Revolutionary Party?

quantity

[nten]

I use USRPs, I like USRPs. There are many, many things you can do with a USRP that you could never do with one of these (if you spent some extra and got a daughterboard, otherwise its a brick). However, there are some things you could do with 100 of these that you could never do with a single, similarly priced USRP. I did not order 100, but I did get some. I'm thinking a beagle bone, might make a nice friend for it.

Re:quantity

[Auroch]

Beagle bone + USRPs? I'd google that, but it sounds like I'd find some nasty rule 34 images out there... Unless you mean beagle BOARD ...

Re:quantity

[Anonymous Coward]

I haven't played w/ this setup, but the openHPSDR setup is slick!

Re:quantity

[Anonymous Coward]

Yep, this is very true.

I assume the 3.2 M/s limit comes from the chipset's design being centered around a TV channel (and presumably there's a bandpass filter in there as well), but lost samples suggests it's saturating the USB bus or something. In any case, a series of USB 3.x hubs would certainly permit connecting a farm of these to one PC.

I'm a ham (albeit one with no real SDR experience... yet), so I can see loads of applications, but a lot of them really want a fairly sophisticated tx setup to go with. One good application might be the gnarliest FM broadcast receiver setup ever -- it's receive-only, and decent antennas are dead-simple and dirt-cheap to make, so it's easy to throw, say, 28 receiver/antenna modules up, and use it as 7 arrays (88 to 108 =20MHz, so 7x 3MHz subbands) to receive the entire FM broadcast band, and phase the 4 antennas in each array (in software) to get directional selectivity. Then you can stream any or all stations over your LAN to various speakers around the house. Perfect for NYC or such places, where the band is jampacked...

A smaller version might be suitable for mobile applications -- 3 antennas fit easily enough on your average car (stock antenna plus two mag-base whips on the trunk), and while you'd "only" get all the stations in one 3MHz strip, you could easily follow a single station (or, y'know, several stations in that 3MHz band, if cacophony's your thing), even on a highway commute crossing the centerline between two transmitters on the same channel.

Naturally, there's less-legal (GSM snooping) options, and maybe some nifty tricks for the scanner guys listening to trunked (yay software radio!) or multiple systems.

Of course the bandwidth just covers the 1.25m/222MHz band, and there's certainly nothing wrong with a SDR receiver to monitor various frequencies while using a hardware radio to transmit (maybe routing the frequency your transmitter's on to the right channel, and mixing the others to the left).

Re:quantity

[Anonymous Coward]

a series of USB 3.x hubs would certainly permit connecting a farm of these to of PCs

Sadly, USB 2.0 (or 1.1 ...) over USB 3.0 doesn't work like that. For 100% backward compatibility, a USB 2.0 device opens a complete point to point channel talking only USB 2.0 all the way to the root hub. I'm not certain if a single 2.0 device hugging the entire bandwidth will practically prevent USB 3.0 traffic from flowing at full speed, but I suspect so.

Re:quantity

[Anonymous Coward]

It's the DAB out that ia 3.2M/s, the TV out runs thru a seperate demod. And the dongles are good for GPS, ADS-B, ACARS,polar WX sats......... the frquency range (on some) is from 64MHz to 1700MHz..

Re:better get

[Anonymous Coward]

not if they're receiving only. doubtful the thing can transmit.

google cache link

[Nyder]

https://webcache.googleusercontent.com/search?q=cache:fRixFRVwNjoJ:sdr.osmocom.org/trac/wiki/rtl-sdr+&cd=1&hl=en&ct=clnk&gl=us

funny thing about this google cache link though, it's trying to load stuff from sdr.osmocom.org, which is currently slashdotted, so not sure if google knows what cache means anymore...

yes, sorry, https because that's how i roll baby...

Re:google cache link

[Malvineous]

Google only caches the page text, it still loads the images from the original source. If you click on the 'text-only version' link at the top right then it skips any external content and loads almost instantly.

Some info from the page

[Nyder]

rtl-sdr

DVB-T sticks based on the Realtek RTL2832U can be used as a cheap SDR, since the chip allows transferring the raw I/Q samples to the host, which is officially used for DAB/DAB+/FM demodulation. The possibility of this has been discovered by the V4L/DVB kernel developer Antti Palosaari.
Specifications

The RTL2832U outputs 8-bit I/Q-samples, and the highest theoretically possible sample-rate is 3.2 MS/s, however, the highest sample-rate without lost samples that has been tested so far is 2.8 MS/s. The frequency range is highly dependent of the used tuner, sticks that use the Elonics E4000 offer the best range (64 - 1700 MHz).
Supported Hardware

So far, the following devices are supported:

        ezcap EzTV668 USB 2.0 DVB-T/DAB/FM stick (Elonics E4000 tuner) (sources: AliExpress, Dealextreme)
        ezcap EzTV666 USB 2.0 DVB-T/DAB/FM stick (Elonics E4000 tuner, picture Download)
        Hama nano DVB-T stick (Elonics E4000 tuner)
        Terratec NOXON DAB/DAB+ USB-Stick (Fitipower FC0013 tuner)

People over at reddit are collecting a list of other devices that are compatible.

Other sticks based on the RTL2832U might be added in the future as well.

Re:Some info from the page

[Anonymous Coward]

CDN cache

http://sdr.osmocom.org.nyud.net/trac/wiki/rtl-sdr

Re:Some info from the page

[Formalin]

The only one from the page with a link is $19.50 (dealextreme).

Where is the $11 one the summary refers to?

Re:Some info from the page

[Anonymous Coward]

Go to Ebay. Search for "DVB-T P160". If there any left.

Re:Some info from the page

[Anonymous Coward]

It's cool to see a SDR for sub-$20, but to compare a 3.2 Msamp/sec with the USRP's 64+ Msamp/sec (or my home-grown SDR's 125 MSamp/sec) is really disingenuous. That's like saying "you can get an OWON scope for $500 compared to a $50k Agilent scope." Yeah... but the baseband bandwidth and sampling rates differ by an order of magnitude!

That said... there is some really cool low-cost microwave test equipment coming available. Mr. Vacuum Tube (who teaches the MIT DIY radar course) recently pointed out these "cheap" (sub-$500, "usb stick") multi-GHz RF synthesizers from Quonset Microwave. (Note: no affiliation, I just think they're pretty cool).

Not Searchable.

[solios]

Time isn't the issue for me. The issue for me is the fact that video "tutorials" feature voices that frequently grate on my nerves. Worse, the video tutorial cannot be quickly searched for the relevant information.

Seriously. I can find out if a text tutorial is relevant to the issue at hand in seconds. With video tutorials, I've typically closed the tab before the "host" finishes talking about how great he is, how great the software is, and what the tutorial is going to cover.

Re:Not Searchable.

[ColdWetDog]

I agree and feel like complaining this morning.

Come on, world. Shaky, unedited cell phone cam 'videos' are only slightly worse than slick, over prepared 'tuts' with dippy techo music in the background and pointless transitions (yeah, the ones on the very bottom of the picklist that nobody has used since 1981).

Just write it down. Show a static picture if you need to. Video is for things that move, not talking heads, not pointing fingers.

Now, if you don't mind. I shall take a nap. That was exhausting.

Re:Not Searchable.

[Anonymous Coward]

This was my big problem with Joomla too - you need 2 hours and goddamn popcorn and soda just to get through the basic how to's.

A video may be worth a thousand words, but technical video documentation is only worth one click.

Re:Not Searchable.

[Anonymous Coward]

...over prepared 'tuts' with dippy techo music in the background...

Could be worse. Could be Creed.

Re:Not Searchable.

[Anonymous Coward]

videos suck ass, the MTV / stupid passive-participation crowd have won out.

but how did you NOT see that coming?

Re:Not Searchable.

[Anonymous Coward]

Right on!

Fucking tired of where I work saying "Oh, that was covered in the 2 hour video of the meeting, did you not watch it?" No, I fucking didn't. The first 10 minutes were worthless and I have work to do, I don't have 2 hours to watch that worthless video for one little piece of information. I'd be happy to do it the stupid way if I weren't on salary...

Last time they forced me to do it, I took notes and wrote a nice text document on the presentation.

Re:Not Searchable.

[jamesh]

Time isn't the issue for me. The issue for me is the fact that video "tutorials" feature voices that frequently grate on my nerves. Worse, the video tutorial cannot be quickly searched for the relevant information.

Seriously. I can find out if a text tutorial is relevant to the issue at hand in seconds. With video tutorials, I've typically closed the tab before the "host" finishes talking about how great he is, how great the software is, and what the tutorial is going to cover.

Is the term "tl;dw" in common use? It would apply to any video over about 30 seconds (or any porn video over 60 minutes).

Re:better get

[Anonymous Coward]

Don't be a retard.

It's a TV receiver, it has no transmit capability. No FCC license is required to receive (almost) anything with a Class 15 device, which these are. The exception would be cellular telephony, but AFAIK there is no FCC license permitting eavesdropping on those -- you're either the (licensed) carrier who's actually handling the call, or you can't listen.

If you add a transmitter, well, the fact that you're listening via TV dongle obviously doesn't eliminate the licensing and equipment requirements for whatever radio service you're operating in, so a warning specific to this case is unneeded. Anyone "freebanding" or otherwise operating illegally probably knows exactly what they're doing, and if they don't care about what the law says, I very much doubt they care what you say either.

Re:better get

[fuzzyfuzzyfungus]

The widgets with this chip are all designed as TV-receiver USB widgets. I'm sure that there are some $11 electronics out there that are... um... totally FCC part 15 compliant; but no intentional radiating is going on.

Jerri Elsworth on FPGA-based SDR

[Anonymous Coward]

FYI

http://www.youtube.com/watch?v=0UBKw7F9Mck

Challenge Accepted

[Gordonjcp]

In a conventional radio receiver, you start by filtering off the wanted signal with a broad filter, mixing it with another locally-generated signal (the Local Oscillator) to make a lower Intermediate Frequency (IF), then filtering the IF to extract a single "channel" of information. Then you demodulate this, possibly after mixing it down to an even lower IF.

In a software-defined radio, you convert directly down to a much lower frequency (audio frequency, even), but - and this is the clever bit - you do it with two local oscillators, 90 degrees out of phase. This gives you a complex sample, a pair of samples representing In-phase and Quadrature, or the real and imaginary components of your signal.

From there you can apply digital signal processing techniques to extract the wanted signal, show an FFT of the chunk of band you're capturing, and so on. This lets you do very sharp filtering, because you're no longer constrained by the physical realities of trying to implement electronic filters with practical components.

Shameless plug - if you want to try SDR out, go here:
https://github.com/gordonjcp/lysdr
Follow the instructions in the README, then either post a reply or bug me in irc.freenode.net ##electronics for further instructions.

Re:Challenge Accepted

[YoopDaDum]

What you described is the difference between an old two stages RF architecture going from the target frequency to a base band signal through an intermediate frequency and a direct conversion / zero IF RF architecture. All recent RF chips for wireless are zero IF nowadays.

But SDR usually refers to the digital processing part. Some modem implementations use custom digital logic to do the processing. A SDR approach will use a big DSP (vector DSP even) to do the processing in software. Although typically some heavy parts like the FEC and FFT (for OFDM/OFDMA) can still be done with custom hardware for better efficiency.

In any case, the dream of a purely generic hardware is still only a dream. We can have flexible software modem (if you're not too concerned about die size and power efficiency), we have also wide band radios. But in front of that you still require a RF front-end (FE), comprising filters (not to be blinded by adjacent channels in Rx, or not to kill adjacent channels in Tx) and power amplifier in the transmission side. And there's no much flexibility there. You can have wide-band PAs, but it's limited and efficiency will suffer (so burn more power, heat more than a narrow band PA). And filters are not configurable. If you want to support many bands combinations, you end up with many different filters and a switch.

So the post is too optimistic. You may be able to toy a bit with this hardware, but don't expect making anything solid (product quality) based on that. Still for hacking and the fun / learning value, why not?

Re:Challenge Accepted

[pakar]

You should probably do a bit more fact-checking before saying stuff like that..

http://www.linuxfordevices.com/c/a/News/Embedded-Linux-powers-first-handheld-software-radio/
http://www.electronicsweekly.com/Articles/17/12/2007/42781/intel-targets-wimax-with-software-radio-device.htm

There are already chips that do direct-if conversion for DVB-T.. It's not a generic chip they use but a specialized that will have a high-speed ADC and then have hardware that do the 'tuning' to the wanted frequency...

So... There is stuff already doing this on a large scale...

If you want something that works with any type of protocol then you need some type of generic CPU that can be loaded with software that can be reprogrammed, and this is probable something that don't exist outside some specific circles, but it do exist and is available commercially. This stuff is usually done on FPGA's to reduce the powerusage and get good performance....

Re:Challenge Accepted

[colsandurz45]

You're just talking about different receiver structures (super heterodyne and direct conversion respectively). There's no receiver structure that's specific to SDR (in fact the USRP, which is an SDR, has a super heterodyne structure). IQ sampling doesn't have anything do with receiver structure either, super heterodyne receivers and direct conversion receivers can have IQ sampling (the USRP, a super heterodyne as I mentioned, implements IQ sampling). Also, implementing a filter with a sharp transition band is due to using a digital system, there's nothing special about SDR that let's you implement a 500 tap FIR filter, there *is* something special about digital system (FPGA, ASIC, DSP, GPP) that let's you implement a 500 tap FIR filter.

Re:Challenge Accepted

[colsandurz45]

All recent RF chips for wireless are zero IF nowadays.

Not true, super heterodyne is still very popular.

A SDR approach will use a big DSP (vector DSP even) to do the processing in software.

Not really. Depending on your platform the industry trend is actually going away from DSPs. DSP operations are being implemented in FPGAs these days (since they're faster and the newer Virtex 6 or 7s (and whatever Stratix whatever) are really huge).

Re:Challenge Accepted

[Gordonjcp]

I think you're rather missing the point. The fact that SDR *is* software-defined is what allows you to use an FIR filter.

What sort of hardware you implement this on is irrelevant. Even supposing you use a pair of ADCs hooked to an FPGA and implement the whole thing in the FPGA, it's still software.

Re:Challenge Accepted

[YoopDaDum]

I should have clarified that I was talking about the device side, and particularly handsets. There, as far as I can see, it's zero IF and SoC embedded DSP cores as FPGA as not sufficiently power, size and cost efficient for a handset. On the network side the situation is very different. I have no knowledge of the RF architectures there, but indeed FPGAs are very popular.

Re:Challenge Accepted

[YoopDaDum]

You should probably do a bit more fact-checking before saying stuff like that..

There's nothing below that invalidate what I've said, on the contrary. So let's go for some fact checking...

http://www.linuxfordevices.com/c/a/News/Embedded-Linux-powers-first-handheld-software-radio/

An old prototype from 2003 handling low bands. Nothing commercial seem to have followed.
Yes, for low frequency systems you could do direct sampling. With a big badass A/D converter you just sample a huge band, filter out in software (DSP) the channel of interest and decode it also in software. The problem with this approach is that it's not necessarily the most efficient (many DVB-T systems still use a RF) although this may change, and doesn't address the part I mentioned about filtering.

Because in real life, you can have adjacent systems transmitting at high power while you receive a low power. This is called the near/far effect. For example, a close GSM phone transmitting at 900 MHz while you try to receive a far base station in a close band. You will have a HUGE power difference. There are only two ways to deal with this:

1. 1) Use a RF filter to extract all power but the channel of interest. Then you're not blinded by adjacent interferers anymore and can use a reasonable A/D with a lower dynamic;
2. 2) Have a very high dynamic on the A/D converter. The problem there is that there's a trade-off between speed (and how much band you can handle) and dynamic. There's no magic converter that can offer both at reasonable price and power consumption for mobile devices, if at all.

That's why we're still living with RF front-ends which are band specific, and SDR is in most cases restricted to the baseband processing.

That won't prevent people from dreaming of a universal wireless device anyway, because it's a very sexy idea. It's been a very sexy idea for more than 20 years actually. It's made significant progress. But plenty ignored the fine details to their detriment. My point here by the way is not to ridicule the idea or kill the dream. Just to instill some doze of hard nosed practical sense.
For a truly universal practical radio modem, we would need programmable filters and wide-band or programmable power amplifiers, with acceptable cost / size / power consumption. I'm sorry to say I don't know of anything practical there, not even on the radar. But with LTE huge amount of bands (40+, and increasing) there would definitely be a use for that. So we'll see, the big carrot may lead to a breakthrough one day?

http://www.electronicsweekly.com/Articles/17/12/2007/42781/intel-targets-wimax-with-software-radio-device.htm

Well, in this very article it says:

The test chip [...] links to three RF chips for the different networks.

So it doesn't even have a wide band RF, which is something available nowadays (the article dates back from 2007, which can explains this). So expect different network specific RF FEs too. It's really exactly as I described: SDR here purely refers to the digital processing part.

There are already chips that do direct-if conversion for DVB-T.. It's not a generic chip they use but a specialized that will have a high-speed ADC and then have hardware that do the 'tuning' to the wanted frequency...

For VHF TV this could be doable indeed. It's low enough for a high-speed ADC, and you can have a front-end protecting the TV band too. And the power consumption may not be a problem in many use-cases (even mobile possibly: when the screen is on, a bit more power on the modem may not be so significant). Still, this is not applicable to many domains

subreddit dedicated to the RTL-SDR project

[citizenr]

http://www.reddit.com/r/RTLSDR

has all the info, list of tuners that work, tutorials and more.

Cool!...only

[Anonymous Coward]

...has anyone found any ATSC tuners with a similar mode? (writing from USA).

Re:Cool!...only

[Jimbookis]

No but what do you care if you are in the USA? You won't be using this dongle for TV, just SDR. There are plenty of Chinese sites and eBay vendors who will sell you this from China and have it at your door within 2 weeks.

Been there, done that

[ctrl-alt-canc]

A few years ago, together with a friend, we reverse engineered a DVB-T usb pen by Hauppauge, and we were able to extract the raw data stream skipping the demodulation process. We did it since we wanted to test if it the device could be used as a DSP IF strip in a homemade spectrum analyzer. The device worked, but the analog IF strip we wanted to replace was actually drawing circles around its digital replacement, so we abandoned the project. 8 bit of resolution and an hardware designed for a very specific purpose couldn't bring us too far, as we feared.
It is nice to see that somebody else was capable to reverse engineer these devices, but as you can see from their results, they aren't actually that good. I saw somewhere that a USB pen for DVB had to hit the market, and its ADC has been announced to be 12 bit wide.This could be an interesting device to hack for SDR applications, hoping it isn't vaporware...

Re:Been there, done that

[citizenr]

A few years ago, together with a friend, we reverse engineered a DVB-T usb pen by Hauppauge

link?

It is nice to see that somebody else was capable to reverse engineer these devices, but as you can see from their results, they aren't actually that good.

WAT?
It works, someone already posted YT clip decoding APRS. Osmo guys decoded GMR that uses 1634 to 1656 MHz, far above DVB-Ts spec.

Re:Been there, done that

[Anonymous Coward]

A few years ago, together with a friend, we reverse engineered a DVB-T usb pen by Hauppauge

Does the DMCA stop *ALL* forms of 'reversing' in the USA since copyrighted content can travel through any technological device capable of accessing them?

Re:better get

[Anonymous Coward]

The FCC put rules into place a long time ago forcing manufacturers of receivers to block analog cellular frequencies from being received by the tuner. I don't see why this gear would be exempted from that.

Granted there are very few analog cell phones out there now days, so it may be a moot point. Maybe the FCC has since rescinded that rule.

Links Slashdotted

[utkonos]

Here is a link to the GNU Radio site in Google's cache. And here is the link to osmocom, also from Google's cache.

That would be a *receive-only* SDR

[Anonymous Coward]

And a USRP has a reconfigurable FPGA, which provides a whole lot more processing horsepower than your PC streaming samples over USB.

But cool none-the-less.

This isn't nearly supercillious enough

[Colin Smith]

You should of course have used LMGTFY. Let me show you.

http://lmgtfy.com/?q=software+defined+radio

Reality check

[Anonymous Coward]

Your cell phone and modem are basically software defined radios.

The idea with modern radio is to get the RF signal down to a frequency where it can be digitized and then do everything else in software. I have often said that, if you tried to implement a 3G cell phone in circuitry rather than software, it would occupy a rather large room.

Is the government really having a fit over sdr? Not so much. For one thing, they can't do much about it. The hardware isn't too hard, as long as you aren't trying to stuff it in a small package. You don't even need high speed a/d converters for the most part. The gnuradio system uses the sound card in your computer. http://www.ettus.com/

The other thing is that most interesting signals are encrypted.

If you want to play, gnuradio-companion is great. You don't need to mess with code because you can drag and drop blocks in an interactive gui. Check out Sharlene Katz's sdr project page. You don't need hardware because you can run the software with files. http://www.csun.edu/~skatz/katzpage/sdr_project/sdrproject.html

Slashdot

[Higgins_Boson]

Has become a haven for cowards who think that "I disagree" and "troll" are the same thing.

This site has gone so far down hill that it's now underground and slowly suffocating to death.

Let it die off already... especially if this is how it is allowed to run.

Re:better get

[Gordonjcp]

Your old analogue mobile phone frequencies are in analogue TV frequencies in the rest of the world.

I break FCC regulations all day, every day. Why should I care about the "cell phone hole"?

Government is paralyzed?

[Anonymous Coward]

SDR has the *paralyzed the government*? Really?

I would think if anything has paralyzed the government is the inability of our two political parties to come to consensus on more mundane issues such as budgeting and taxation.

Missing the point?

[lpt1]

What everybody seems to be missing that worries regulators/spectrum enforcers is that this opens the way for the radio equivalent of script kiddies.

Sure, you could disassemble your Radio Shack scanner, desolder this, resolder that, jumper the other, and receive whatever you wanted.

Now, you download this, dbl click that, agree to a EULA, and you're done. Better yet, a fairly simple data wipe of that directory, and there's no evidence.

Consider if this hack did apply to a transmit capable device:
Would you be comfortable with script kiddies being able to transmit on your local fire dept/ambulance freqs?
Do you really think a script kiddie will respect freq allocations? Even emergency ones?

Now, consider trying to track down every l33t teen kid who runs the software. Make enforcement a nightmare when you go from a couple of thousand complaints a year to tens of thousands a month.

Re:Missing the point?

[razvan784]

Would you be comfortable with script kiddies being able to transmit on your local fire dept/ambulance freqs?

Yes, I would. Are you suggesting we ban all TX-capable SDRs because they can be misused by kids? While we're at it, let's also stop any research and abandon all technology because, you know, it can be misused. Law enforcement is paid to enforce the law: if someone is transmitting illegally, triangulate them out and make them stop. Do this a few times and I'm sure kids will quickly get the idea that it's not OK to use their WiFi in undocumented modes to transmit in ambulance bands or whatever. Keep your hands off my equipment!

knowing he did that with an 11 dollar TV card

[FudRucker]

makes me mad at companies like WinRadio and RF_Limited and Icom etc... that charge damn near 1000 bucks and more for a computer controlled shortwave radio or wideband radio when i know they probably have maybe 50 to 150 bucks in hardware

i wont ever buy one of those high dollar software defined radios or software controlled radios knowing they are not worth what they are asking, i will sooner buy a cheap portable like a sangean for about a hundred bucks

Re:knowing he did that with an 11 dollar TV card

[Jimbookis]

Steady on - those companies have been making SDR since last century. No, what they do isn't so novel anymore since commodity widgets that are repurposed came out in the last year or so. You'll find though that they make hardware that is mature and is intended to be parts of larger systems that are reliable and have a long working life. They do need to get their skates on and make something comparable to RealtekDSR for price and performance. Anyway I have my ezyTV dongle sitting here waiting to get a big aerial attached.

Re:knowing he did that with an 11 dollar TV card

[Anonymous Coward]

You realize that if a significantly-sized company is selling you a radio for $1K that has $150 worth of parts in it, for an item that isn't mass-market consumer
    (and ICOM/Kenwood/Yaesu radios intended for the HAM market aren't "mass market", compared to, for example, cell phones), that they are on the edge of
    *losing money*. I've run two different manufacturing businesses in the last 20 years, and really, if you only look at the raw BOM costs of something, and don't
    factor in all the other costs of bringing a reliable product to market, you'll go out of business.

Many of the so-called "high dollar" SDRs out there are "high dollar" for fairly good reasons. They are typically sold into markets where economies of manufacturing scale don't really apply, they often have feature sets that are *vastly* larger than what we're seeing in these "rtl-sdr" devices, and they tend to use higher-quality components. These DVB-T devices, for example, use a master clock that is good to about 100PPM--which for radios is rather seriously crappy. They won't have features like a DDC (usually FPGA resident) for fine-tuning the RX signal. The 8-bit resolution may be fine for some applications, but for others requiring higher dynamic range, that 8-bit resolution will be a killer. Plus many of the "high dollar" SDR devices offer TX chains as well as RX chains, and all the other comments apply for the TX chain as well.

But one of the big things about "high dollar" SDR devices is that they're primarily designed as *development platforms* for developing SDR applications across a wide "spectrum" of fields of endeavour. So they include large FPGAs, those FPGAs allow you to perform part/all of your DSP algorithms at insane speeds inside the FPGA--speeds/sample-rates that would be impractical for a host-software implementation. Large/fast FPGAs are expensive, and that cost has to be passed on. Further, the "high dollar" SDRs typically offer bandwidths into/out-of the host at much higher sample rates than 3.2Msps. Yes, 3.2Msps, RX-only, 8-bit resolution, no-fancy features is entirely-adequate for a lot of different hobbyist work. But it's inadequate for a lot of other types of work for which the so-called "high dollar" SDRs are supremely-well suited.

Re:knowing he did that with an 11 dollar TV card

[Anonymous Coward]

Jesus tapdancing christ, a finished product is more than the sum of its parts - you sound like the people who whine because Apple's making $x "profit" based on $sale_price - $parts_price.

1) Much higher quality hardware filters for the band and for the particular AF signal required, giving the sort of selectivity needed for amateur levels of power;
2) Low noise amps, again essential for amateur levels;
3) DDS or PLL tuners accurate to a few Hz at worst, not ones which vary by at least 100Hz on the tuned frequency;
4) Well-documented open or semi-open RS232/USB interface;
5) Higher resolution ADC;
6) DSP running on-board rather than wasting the CPU cycles of your far hotter desktop/laptop;
7) Good, local vendor support for a small market keen to get the most use out of a well-built product, rather than zero vendor support for a consumer market buying a throwaway item;
8) Sometimes an on-board UI.

Finally, you're ignoring that "Icom etc" make transceivers, whereas this is firmly receiver-only. And a shitty receiver is one thing, but someone operating a transmitter with shitty parts isn't only being a dick to fellow spectrum users but may be breaking the law.

Re:knowing he did that with an 11 dollar TV card

[Anonymous Coward]

Same people who whine about price also complain about the movement of domestic engineering jobs to cheaper parts of the world. They want their cheap electronics, *and* they want their jobs to stay here. Hmmmm.

Re:knowing he did that with an 11 dollar TV card

[drwho]

Thank yoy, Anonymous Cow-herd, for your comments on the ham electronics market. Yes, many ham radios seem to have cheap parts in them and expensive price tags, but like you say, the companies are barely making money. Hams are notoriously cheap. They also love their old radios. And now, the only segment that is large, which is UHF/VHF HTs, is being invaded by cheap chinese stuff. That's going to hurt the japanese manufacturers quite a bit.

And yes, crappy SDR sucks. Even the expensive USRP doesn't have high enough resolution for many tasks, though I am hoping that the USRp N210 is better. I hope to afford one some day. What's amazing to me is that no one has cloned the USRP and offered it for less money - the plans are right there, open source. What does that say? That even though the price of the USRP is high that there's not a lot of profit in it for Matt Ettus.

Re:better get

[MichaelSmith]

> The FCC put rules into place a long time ago forcing manufacturers of receivers to block analog cellular frequencies from being received by the tuner

Do those frequencies seriously exist where you live? They were closed ten years ago here in Australia.

LOL

[ArchieBunker]

You really think it happens like that?

Re:Too long - come on!

[bdabautcb]

Would it really be that hard to hit ctrl-t and type software defined radio? If you are that lazy, in about two mouse clicks more than it would take to hit the link to copy, then paste and search. Sometimes I do not wonder how much influence Snooki has on the 'give me everything now' culture.

eBay

[ArchieBunker]

But the sellers have sold out days ago along with all the other retailers. Looks like one is left and they ship direct from Hong Kong so expect a few weeks wait. I'm kinda pissed about only finding out now.

I've been toying with the idea of getting an entry level SDR for a while just to see what all is out there on the airwaves. This USB tuner chip appears to do the same thing as the $100+ Funcube Dongle.

Re:eBay

[NekoHunter]

Reddit users have confirmed that the model P160 tuners, still available on eBay, are compatible. Just search for P160 Tuner and you should find some.

Ask Slashdot: Mesh Networks?

[Bob9113]

Help a noob out; I'm just poking around on Wikipedia reading about SDRs and software defined antennas. These sound kind of like a magic pill to solve decentralized mesh networking. Stick an SDA on the roof, wire it up to an SDR, seek some marker signal identifying a freenet mesh node, focus in directional point-to-point comm to anyone in range who is running a compatible sda/sdr/router.

Does that about sum it up, or am I just being an over-excited noob?

Re:Ask Slashdot: Mesh Networks?

[Anonymous Coward]

AMPRnet has been around since the late '70s, various forms of packet radio existing before and after. The first TCP/IP stack I ever used was KA9Q.

1) lack of bandwidth;
2) legality of high power transmissions for non-hams;
3) legality of encrypted transmissions for hams.

Re:Ask Slashdot: Mesh Networks?

[Anonymous Coward]

The RTLSDR powered receivers can only receive. It's not illegal to listen to transmissions and otherwise inaccessible broadcasts, but if you want to transmit you'll need a lot more equipment, licence for the band and agreement from others. The radio spectrum is already crowed as it is (look up "frequency allocation chart"), and the unallocated are for a reason (Not enough bandwidth, power requirements for a usable transmission, effort required).

Re:Ask Slashdot: Mesh Networks?

[vandamme]

The 3 cm band has 500 MHz of bandwidth, and it's pretty easy to homebrew. Well, better than EHF. And a ham license is pretty easy to get (for nerds).

Wikipedia the online encyclopedia

[dgharmon]

"I found this great new site you may be unaware of. It's called Wikipedia. It is kinda of like an online encyclopedia that has brief summaries of almost anything", trout007

Is this the same Wikipedia that says Windows NT wasn't designed for the Internet?

Re:Wikipedia the online encyclopedia

[Guy Harris]

"I found this great new site you may be unaware of. It's called Wikipedia. It is kinda of like an online encyclopedia that has brief summaries of almost anything", trout007 Is this the same Wikipedia that says Windows NT wasn't designed for the Internet?

No, it's the same Wikipedia that says

Consumer versions of Windows were originally designed for ease-of-use on a single-user PC without a network connection, and did not have security features built in from the outset. However, Windows NT and its successors are designed for security (including on a network) and multi-user PCs, but were not initially designed with Internet security in mind as much, since, when it was first developed in the early 1990s, Internet use was less prevalent.

which is not the same as "Windows NT wasn't designed for the Internet".

beaglebone

[nten]

http://beagleboard.org/static/beaglebone/latest/README.htm

YouTube pays $$$

[Anonymous Coward]

The poster makes $$$ every time his video is viewed. This is the reason his info is in the video.

"Radio" defined

[tepples]

there's still internet on radio. So what really is SDR useful for? For the common user -- and I understand this would require some bureaucracy -- mp3/ogg streaming over normal SW might be enough.

Perhaps you misunderstand what "radio" means. It's much broader than just "transmissions of popular music using frequency modulation in the 88.0 to 108.0 MHz band". See Grieviant's comment.

Re:"Radio" defined

[Anonymous Coward]

Thanks for helping but a few views of mine are in order, FWIW.

> Perhaps you misunderstand what "radio" means.

A possibility, but not in the present case... radio has a plethora of meanings to me (e.g. quasar).

> It's much broader than just "transmissions of popular music using frequency modulation in the 88.0 to 108.0 MHz band".

Actually, we didn't have FM when I was young over here... and I'm quite disappointed at FM's sound quality.

> See Grieviant's comment [slashdot.org].

From Grieviant's comment:

> Pretty much all radios are using some form of digital communications these days, as opposed to analog modulation with FM radio.

Not where I live. Besides my interest is getting digital content with no extra hardware if at all possible.

> Software defined radio really isn't anything special - the low frequency part of the radio (from IF down to baseband) is handled with a digital signal processor that can be programmed to handle many different formats.

Here is the part I don't understand very well. Maybe different formats mean some kind of low level next-to-metal layer (like Ethernet), otherwise what kind of "software defined" would we be talking about?

I also happen to disagree with the "Software defined radio really isn't anything special" part. I think huge gains can be made with software replacing hardware implementations.

Again, thanks for replying.

PS: Regarding radio being more than just an instrument for communication, I acknowledge others who have different interests. But I got mine, too. It just appears SDR is about a much greater scope -- and not of any use to me atm.

Re:better get

[pla]

Don't worry, friend - I only broadcast using 45KV sparkgap, not some wussy soft-tunable USB dongle.

GNU Source block code and ExtIO plugin for Windows

[balint256]

Hi folks,

If you want to start using the USB stick for SDR, please check out the follow options:

GNU Radio Source block 'rtl_source_c' in 'gr-baz' module: http://wiki.spench.net/wiki/gr-baz#rtl_source_c
Demo video: http://www.youtube.com/watch?v=FUQd9HOVTk8

ExtIO plugin for Winrad/HDSDR/WRplus: http://wiki.spench.net/wiki/USRP_Interfaces (grab the beta)
Demo video/install guide: http://www.youtube.com/watch?v=Z0hEquzLsWU

Let me know how you go!

Wrong link?

[Ozoner]

I think he posted the wrong link.

Perhaps he meant this one
"$20 ultra-cheap Software Defined Radio with RTL2832 DVB-T USB stick"

at http://www.youtube.com/watch?v=Z0hEquzLsWU

The original article is at
http://sdr.osmocom.org/trac/wiki/rtl-sdr

Re:Wrong link?

[balint256]

I uploaded two videos, one for GNU Radio and the other for Windows - the one you linked to is the Windows one, the first one in my OP is the GNU Radio one. The accompanying links to the GNU Radio Source block code, so you can use it as a capture device in GNU Radio, and the second is the Windows installer so you can use it out-of-the-box on Windows.

Re:better get

[wagnerrp]

Good thing it's a European tuner then...

Re:better get

[PatPending]

And it's hackable, too: Slashdot submission or the original article, Dot-dash-diss: The gentleman hacker's 1903 lulz

Where the $11 chips might be hiding...

[ivi]

They just may the $19.95 chips, purchased in OEM quantities (eg, 100 or 1999) ;-)

Re:Where the $11 chips might be hiding... typo fix

[ivi]

'meant 1000, NOT 1999

Re:better get

[maxwell demon]

Some interesting quotes from that article:

Four days later a gleeful letter confessing to the hack was printed by The Times. The writer justified his actions on the grounds of the security holes it revealed for the public good.

But, as author Sungook Hong relates in the book Wireless, his ambitions were frustrated by Marconi's broad patents, leaving him embittered towards the Italian.

Hackers disclosing security flaws, people hampered by broad patents ... seems the times haven't changed as much as we might believe!

OpenBTS

[minutetraders]

does it work with OpenBTS? http://openbts.sourceforge.net/

Woot

[Bitgod]

Nice, definitely will plan to pick up one of these babies.