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Getting Started With GNU Radio (hackaday.com)
An anonymous reader writes: Software Defined Radio must be hard to create, right? Tools like GNU Radio and GNU Radio Companion make it much easier to build radios that can tune AM, FM, and even many digital modes. Of course, you need some kind of radio hardware, right? Not exactly. Hackaday has one of their video hands on tutorials about how to use GNU Radio with no extra hardware (or, optionally, a sound card that you probably already have). The catch? Well, you can't do real radio that way, but you can learn the basics and do audio DSP. The next installment promises to use some real SDR hardware and build an actual radio. But if you ever wanted to see if it was worth buying SDR hardware, this is a good way to see how you like working with GNU Radio before you spend any money.
Entry level, about $12. I think I'll just go ahead and risk it.
Have gnu, will travel.
Back in the day, I could blame crippling hardware costs for my ignorance of signal processing. Now what am I going to do?
Where I live, radar detectors are illegal.
Naturally, police have Radar detector-detector built into their radars, and I know of one confirmed case where a friend visiting out of state got caught with his radar detector.
So, can a radar detector built out of SDR/GNU Radio be detected? Hypothetically of coarse.
In the summary, "hands on" should be hyphenated. Otherwise, the sentence might be about Hackaday's video-hands.
Yes, it probably will detect it, at least for inexpensive SDR hardware. Most modern receivers are the superheterodyne type, in which an oscillator within the receiver is set to a frequency near the frequency you wish to detect. This simplifies the circuitry and software because you're only processing the DIFFERENCE between the received signal and the reference, rather than directly processing the source waveform at some sample-rate multiple of the frequency of interest.
The detector-detector picks up the oscillation of this reference frequency.
A non-superheterodyne type could be used, but it would be significantly more expensive.
Shielding MIGHT be an option, though one would have to be sure that the reference frequency doesn't leak out through the cabling and antenna, while allowing the input signal (at the same frequency) to come in.
iirc the lowest band police radar transmit in is 10ghz, with some of the other bands being as high as 24ghz. The SDR dongles generally have a response frequency of around double digit MHZ to a bit over 2.4 ghz. That's almost an order of magnitude lower than what you'd need to detect a radar gun. From what I know of radar detector detectors, they work based on listening for the detector to emit slight echos whenever its oscillator is oscillated by an incoming beam. As such, I doubt there's any interaction between one of these SDRs and a police radar gun since they're not even communicating in the same frequency ranges.
For transmitting there's the HackRF which is a few mW output and is the one I've played with. Also another supplier that has cheaper, transmit only versions; the HackRF Blue
For quite a bit more, there's MIMO capable devices such as the Ettus USRP that lets you run your own GSM basestation among other things.
And for a more stand alone device, there's always the PortableSDR
I've got a HackRF and am having fun with it trying to make a network analyzer. The others, I've just heard about.
Red to red, black to black. Switch it on, but stand well back.
can GNURadio-companion incorporate hamlib as a library to run the radio and basically use gnuradio-companion to build some simple front ends for hamlib? i have a Ten-Tec RX320 and Grig is not much as a front end, i was hoping to build a nicer front end that was more specific to this HF receiver and include a waterfall feature to get a good look at a few KCs of spectrum, i use Linux exclussively so there is not a windows PC for me to do this in, if i get good and skilled at this i would love to build a FOSS HamRadioDeluxe clone for Linux with ease of use and feature rich to include all the radios both hamlib and gnuradio will run,
Politics is Treachery, Religion is Brainwashing
For the most part, yes, it can be detected.
That is because when processing the radar signal in order to alert you, it emits another frequency signal and there would be no real way around it without a bunch of larger equipment like antennas and amplifiers or shielding. A radar detector's receiver called a superheterodyne receiver. It emits a frequency that interferes with the radar frequency which in turn allows reception on lower frequencies that are easier amplified.
To get around this, you would need a large antenna or even a couple of them for the variations of different frequency ranges used as well as large amplifiers and large power requirements and such. It would probably make it too cumbersome and expensive to be practical (although I have never thought it through enough to say for certain)
Your car radio works similarly although I don't think it is a "super" heterodyne receiver. I remember a while back a friend experimenting with signals detection was able to use a receiver similar to a detector-detector and tell which radio channels someone was listening to in their car. He got the idea from some concept where electronic billboards would change advertisements presented based on the average of stations passing by every 30 minutes due to the demographics who typically listen to them.
My favorite SDR platforms. I have a cheap RTL dongle that I use for just about everything outside the ham bands. I use soundmodem along with aprx to run my digipeater/igate. fldigi takes care of PSK and other modes on HF. GNURadio and SDR# for listening to what is going on around town.
Fun stuff.
>There's no way to shield that form of RF leakage through the antenna without shielding the antenna... which would make it unable to detect anything to begin with.
Yeah I mean to add it would not be easy, if it's possible at all.
"There's no way" to do it, much like we used to say "there's no way" to alter a file without changing it's MD5 hash, and we said "there's no way" to install 3rd-party software on an iPhone, etc. Impossible, until some clever person figures out how to do it.
I was a professional magician before I was a locksmith, which was before I was a "vulnerability assessment engineer" (hacker). My my entire career has been doing what can't be done - you -can't- open a good safe without the combination, you -can't- tell which card someone looked at before shuffling it back into the deck, and you -can't- install software on a computer without being logged in to the machine. Of course I do these things all day, every day.
So much rubbish being written here about receivers.
It is perfectly possible to design a super-hets which hardly emit any interfering signals. The front stage LNA can give you 30ish dB of rejection, the mixer another 20dB or so (or more). But that's beside the point. The super-het mixes down to a separate IF frequency, so the locally generated signal is not at the same frequency you are interested in. So you can place a filter on the antenna input which passes the signal you want and reject any leakage you might create. Any leakage will be so small that no police detector would ever see it. Think power emitted by a few hundred human cells as the amount of leakage.
The reason I suspect most cheap radar detects are easy to detect is that they are probably direct conversion receivers, as these can be made cheaply. Your locally generated signal is therefore in your band of interest, so you cant filter it out and the only thing stopping it radiating is the reverse isolation of your receiver. This is typically crap in cheap and nasty receivers. They might not even have a front end LNA and mix directly with a passive mixer (it is 10GHz after all). If that is the case then the leakage will be terrible.
It is quite possible to design a radar detector which can't be easily detected, whether they be a super-het or a direct conversion. It just costs more.
So, can a radar detector built out of SDR/GNU Radio be detected? Hypothetically of coarse.
Yes, because the radar-detector detector looks for oscillator leakage at radar frequencies which would be present on the SDR tuned to the radar band.
Where I live, radar detectors are illegal.
Naturally, police have Radar detector-detector built into their radars, and I know of one confirmed case where a friend visiting out of state got caught with his radar detector.
Yes, but are radar detector-detector-detectors illegal?
Well, you certainly sound like you know more about it than I do. The information I have is third hand from someone probably along the same level as you or maybe a little more advanced. The question is, can you do all that with software defined radio?
I decided to look to see if anyone is offering an undetectable radar detector and it appears Escort is in their redline series and claimed to have patented some "TotalShield Technology". So it is able to be done.
Where I live, radar detectors are illegal.
Naturally, police have Radar detector-detector built into their radars, and I know of one confirmed case where a friend visiting out of state got caught with his radar detector.
Yes, but are radar detector-detector-detectors illegal?
Not yet, but I've detected that the idea of making laws to screen radar detector-detector-detectors certainly is on lawmakers' radar screens.
I too was attracted by the allure of "approachable" radio communication system design....
I've been working on my Masters thesis involving GNU Radio. I have an RTL-SDR (a Terratec Elonics E4000) and more importantly 2 bladeRF x40 SDRs. Observing/listening/decoding certain transmissions with pre-existing standards is fairly easy. Building a complete digital data transmitter and receiver in GNURadio Companion has a bit of a learning curve. And by "learning curve" I mean "like free climbing the Dawn Wall".
Totally correct
The cheap radar detectors use a simple Direct Conversion receiver with a primitive diode mixer, so the Local Oscillator is radiated back through the antenna and hence is easily detected.
Adding an RF stage would fix the L.O. radiation, or by changing to a (slightly more complex) Superhet design.
You can download my SdrDx for either Windows or OS X, download a saved RF file, and start receiving from a recording of, for instance, a ham band during a contest, or a SW band with some interesting stations on it. No SDR required to fool around, and the software is free.
You can tune around, play with bandwidths, demodulation modes, noise blanking, peak tracking, notch and other filtering, the analysis scope, etc. WIth a recording, you get the span of the spectrum that was recorded (for instance, 200 khz of spectrum) but within that, you can do pretty much whatever you want.
screenshot
Works with OS X 10.6.8 and up, XP and up.
If you want to use an actual SDR, SdrDx leans decidedly towards the middle and high end, but supports anything using the RFSPACE protocols, so (obviously) pretty much any RFSPACE SDR model, the Andrus MK 1.5, and the AFDRI. Also supports the Funcube. No one has written an RFSPACE compatible server for the RTL sticks, but perhaps someday they will. :)
I've fallen off your lawn, and I can't get up.
GNU Radio, only 80-some years after radio was new and exciting. I see the blazing relevance of GNU Hurd has struck again! What's next, GNU Black & White TV? GNU Bakelite? GNU Impressionist paintings? GNU Art Deco jewelry?
No amount of "software defined" pixie dust, or "Open Source" hype can hide the technological and societal irrelevance.
I am a proud owner of a pro 2006 with a optoscan 456.
I have no real software for this, though I have reaction tuned this reciever with my scout (also from opto). Now a question to the community if I may, witch interface may be best the civ or rs 232? I don't know if the serial will take a usb dongle or not, the civ will need an adapter also. I still want to keep the reaction tune capability with the scout and do the signal processing on the computer the audio part...
I also have the detector output witch has better bandwith then the audio out, though I have never used it.
I have several tv dongles have yet to get any of them working.
Any help/advice is appreciated...
Napervillian
"No amount of _____ pixie dust or _____ hype can hide the technological and societal irrelevance.
Well done! I'm going to clip this word-puppy and spice a bunch with some ugly Pando type illustrations, where crudely drawn cartoon figures are fondling little blobs of 'techy' things with ludicrous expressions of awe, disgust or blank stares. Then spray the Ad networks with variations of it... selling everything from Cadillacs to Cialis to Catpoop scoops.
Socio-irrelevance-slackers will click on it expecting to land on some obtusely erudite scathing commentary on how things, especially these things, really really suck, and what's the use anyway. They seek articles that trigger a little endorphin release they get when smarty-people tear a popular or noble idea apart and trash it in front of them --- and due to a bit of faulty brain wiring --- the mere act of reading triggers in them the same wave of satisfaction as a difficult obstacle overcome or job well done. Just as if they had thought of and written it themselves.
But it is a conditioned response and the mere anticipation of reward begins the endorphin release. So by the time they actually load the sell-page and are staring at the Product the joy juices are already flowing. They'll rationalize away the appearance of simple advertising, thinking that the Author is fronting some edifice by 'reproducing' the object of scorn first on the page. By the time they navigate the spiel and reach the buy/commit links at the bottom, they'll think they're participating in an elaborate multi-page dismemberment of said Product that is so well done, and Author so courageous and hip that the commentary if on... the next page! Or even omitted entirely, since the Point is so Obvious and you are so Clever. In the presence of such greatness, one can only proceed to the end so one can boast about the experience.
Actually, they'll just keep clicking and agreeing until the endorphins stop.
Proud owners of a Catpoop scoop to place on their coffee table as a symbol of capatalist-anarchy-agression.
And I'll be affiliate-rich!
<blink>down the rabbit hole</blink>