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There is even a programming library and some applications available to control various radios.

Hey! I resemble that remark. Ham radio is still alive and kicking. Hams are just as much geeks as any other computer geek. Some of us (like me) enjoy computers and amateur radio. I have spent many thousands of dollars in ham gear and many thousands of dollars in computer gear. The only difference is not only will my ham radio gear work without the internet, but it will hold it's value far longer than any of my computer equipment. DSP radios are not new, our local group here is working on a DSP based data radio. Other groups like TAPR sell a DSP radio kit.

While he may be correct in saying that radio signals, in and of themselves, don't "interfere" with each other he's neglecting to mention a critical point.

It's also true that two radio signals, each of a different frequency, will, when mixed together, produce an entirely different set of signals based on the sum and difference of the two frequencies.

This is the same principle that superheterodyne circuits (the type used in just about any kind of modern RF receiver) are dependent on. Example: You want to receive a signal on a carrier frequency of 146.5200 MHz, and your receiver has a 10.700 MHz IF.

OK, so the local oscillator (LO) in your receiver needs to produce a frequency of its own that will mix with the incoming 146.5200, and produce 10.7MHz as a result. That 10.7 signal will then be demodulated and turned back into audio.

Assuming you use low-side injection, your receiver's LO would need to generate a frequency of 135.8200MHz (this, by the way, is why scanning receivers are not permitted in commercial aircraft. 135.8200 is in the aircraft comm band), which is merely 146.5200MHz minus 10.700MHz.

Anyway... What I'm driving at is this; Think of a mountain top transmitter site that's got a ton of broadcast, public safety, amateur, and other kinds of transmitters on top of it, many of which are producing hundreds, if not thousands, of watts worth of RF.

There's going to be signal mixing. Lots of it. That means tons of the very "interference" that Reed doesn't seem to think exists.

The techniques mentioned in the article, BTW, including software-defined radios, are nothing new. They've been around for decades, and ham radio folk are already experimenting with them. For one example of a purely software-controlled radio, take a look at this radio kit from TAPR.

73 de KC7GR

Basically, the history of radio is the history of our practical ability to coordinate multiple stations. In the beginning, radio signals were generated by spark gaps; the resulting impluse occupied the entire longwave spectrum, propagating by groundwave. Separation was accomplished by time, and stations scheduled their transmissions by the clock. This held sway until the invention of the triode vacuum tube by DeForest, which enabled coherent, narrowband transmission of information, and thus coordiation by wavelength. The government then got involved as a third party coordination body.

As more stations went on the air, technological development was aimed at expanding the useable spectrum beyond longwave -- first medium wave (300 kHz to 3MHz) then shortwave (3-30MHz) then VHF (30-300MHz).

WWII advanced the pace of development in UHF (300-900 MHz) and microwaves (above 900 MHz). With those developments came the ability to use polar and spatial diversity. But the latter really took off with the development of microprocessor controlled radios, which enabled spatial diversity by cell -- cellular radio.

However, even with all of the spectrum that these techniques have enabled, the fact remains that, owing to propagation differences, some parts of the spectrum are inherently more valuable than others, a scarcity that leads to economic realities that agencies like the ITU and FCC have been exploiting for decades.

Quietly, however, which these developments were taking place in wavelength coordination, our ability to coordinate transmissions in time has caught up -- first with spread spectrum (not that funny frequency hopping junk) and now individual pulse trains for Ultra Wide Band. UWB in particular holds the promise of ending the economics of scarcity found in wireless. Aside from a thousandfold increase in spectral efficiency, it also maps well to the bursty nature of information -- you don't need a channel all the time, but thanks to coordination by wavelength, you sit on it anyway.

Needless to say, when you challenge the economics of the status quo, you're not going to be too popular in certain political circles.

Of course, this assumes that the machine has enough memory for this. I wonder how small you could get that? I'm thinking you might be able to write to a CD-RW using as little as 16MB, depending on how the boot process works (ie, figures out the modules needed and loads them before unmounting the CD-RW).

There's also a bootable Compact Flash reader. Compact Flash cards are rewritable, standard, and far more expensive than CD-Rs ($80 for a 128MB card...), but the 8MB ones are fairly cheap and might be useful. There are bootable CF IDE drives available. It costs $60, but allows booting off CF cards, which are fairly standard. You can get USB and PCMCIA cards that can read them as well, and several of the newer PDAs also have adapters that allow them to be used.

Mind you, I think that the 88mm CD-Rs are the perfect "bootable" replacement for floppies. The Gentoo LiveCD makes for perfect "rescue" CDs for almost all Linux distros, and the stage-1 Live CD fits on an 88mm CD-R.

It's called APRS (or here), and it's free... Get a Ham license!

I'm not sure what radio modems they are using. But, it actually sounds a little archaic if you ask me. I mean you have to work with what you have when you're on a budget (or worse ... don't have one). But, it seems that this could be setup a lot better with some equipment donotions. HAMs (amatuer radio operators) are generally relatively generous people. And, all they would need is a couple HF radios since they have the computers already.

AX.25 is natively supported in Linux, and could easily be leveraged to make this whole thing a lot better. With some donated HF radios, they could have routable RF network up all the time in no time. They might even be able to use APRS instead of AX.25. But, AX.25 is a more proven protocol for this type of thing. See the AX.25 Linux HOWTO for details. Information about the protocol can be found at TAPR's website. They might even be able to get a little bit more speed, though not much, by using 10 Meter (28 MHz) FM. Though 10M can be probmatic sometimes, so I'm not sure I'd recommend that. 20M (14 MHz) and down are much better frequencies if you want something reliable. A DSP based noise filter would certainly help things in regards to speed, but they cost a bit of money.

As far as the modem goes... You can use a sound card and a small "control" box. All the box does is operate the PTT (push to talk) circuit. So, you might be able to do with out that if you wire things up just so. But, I have not played with that as of yet. You can also use a Terminal Node Controller (TNC) to get the signal to the radio. Some of the newer TNCs have a DSP filter built in, so that could be an advantage there. But, the best you can hope for on HF is about 2400 bps at half duplex, and 2400 is pushing it. There's just too much noise on Upper/Lower Side Band, and I'm not sure if you would want to use AM (though that might be an option).

There are a number of sites to check out if anyone is interested in digital commincations over amatuer radio. TAPR is a very good one, as is RATS. RATS works with a protocol known as ROSE. There is another one called NETROM, but I don't have a link readily available for that. TCP/IP is by far the best for this type of thing though. You can also check out the ARRL's site, and the FCC's amatuer radio page, for more information on amatuer radio in general here in the United States. BTW, you don't need to know morse code anymore to get on VHF/UHF. And, to get on HF you only need 5 wpm on the code, which is not all that hard.

Ok, I admit that last paragraph was a sales pitch. But, amatuer radio seems to be a dying hobby; at least here in the US. So, anything that can be done to increase interest is a good thing. :)

I'll step down off my soap box now.

I'm not sure what radio modems they are using. But, it actually sounds a little archaic if you ask me. I mean you have to work with what you have when you're on a budget (or worse ... don't have one). But, it seems that this could be setup a lot better with some equipment donotions. HAMs (amatuer radio operators) are generally relatively generous people. And, all they would need is a couple HF radios since they have the computers already.

AX.25 is natively supported in Linux, and could easily be leveraged to make this whole thing a lot better. With some donated HF radios, they could have routable RF network up all the time in no time. They might even be able to use APRS instead of AX.25. But, AX.25 is a more proven protocol for this type of thing. See the AX.25 Linux HOWTO for details. Information about the protocol can be found at TAPR's website. They might even be able to get a little bit more speed, though not much, by using 10 Meter (28 MHz) FM. Though 10M can be probmatic sometimes, so I'm not sure I'd recommend that. 20M (14 MHz) and down are much better frequencies if you want something reliable. A DSP based noise filter would certainly help things in regards to speed, but they cost a bit of money.

As far as the modem goes... You can use a sound card and a small "control" box. All the box does is operate the PTT (push to talk) circuit. So, you might be able to do with out that if you wire things up just so. But, I have not played with that as of yet. You can also use a Terminal Node Controller (TNC) to get the signal to the radio. Some of the newer TNCs have a DSP filter built in, so that could be an advantage there. But, the best you can hope for on HF is about 2400 bps at half duplex, and 2400 is pushing it. There's just too much noise on Upper/Lower Side Band, and I'm not sure if you would want to use AM (though that might be an option).

There are a number of sites to check out if anyone is interested in digital commincations over amatuer radio. TAPR is a very good one, as is RATS. RATS works with a protocol known as ROSE. There is another one called NETROM, but I don't have a link readily available for that. TCP/IP is by far the best for this type of thing though. You can also check out the ARRL's site, and the FCC's amatuer radio page, for more information on amatuer radio in general here in the United States. BTW, you don't need to know morse code anymore to get on VHF/UHF. And, to get on HF you only need 5 wpm on the code, which is not all that hard.

Ok, I admit that last paragraph was a sales pitch. But, amatuer radio seems to be a dying hobby; at least here in the US. So, anything that can be done to increase interest is a good thing. :)

I'll step down off my soap box now.

I love the fact that a good, Free Software voice codec is out there, and here are my reasons:

1) Ham Radio. The Tucson Amateur Packet Radio organization is working on experimental digitized voice over amateur radio applications, and a couple of venders (mostly Kenwood) are offering radios that have this ability. Right now, TAPR are looking at using DVSI's IMBE vocoder, which is QUITE expensive and VERY not-Free. The availability of a Free codec would greatly improve the availabilty of this protocol.
2) Currently, The Association of Public-Safety Officials (APCO) (the folks who define the specs for the radios used by police, fire, and government) have defined the current digital trunked radio standard, APCO Project 25 as using DVSI's IMBE vocoder. While this is licensed under a Reasonable And Non-Discrimitory license, if you want to license the IMBE vocoder for a P-25 project, you will cough up US$100,000.00 for the privilege (I know firsthand, as the company I work for has done this). Uniden, Radio Shack, and other scanner companies are looking into putting this into their scanners, so they have had to cough it up as well. A Free vocoder would allow anybody to build a product with this capability in it - you could even use a scanner and your sound card to decode the Phase 1 C4FM format signals.

Like so many other things, a Free Software tool to do these things would greatly accelerate the industry. I hope Xiph does well.

Check out the DSP-10 designed by Bob Larkin, W7PUA and offered as a kit by TAPR. It receives and transmits in the 2 meter amateur band (144-148MHz) using a standalone DSP card (that has power similar to a PC sound card). The code to drive it is all open source, and the DSP can not only handle traditional modes, but can also be programmed to do all sorts of neat stuff. New modulation schemes programmed into the DSP-10 have resulted in successful "moonbounce" (that's right, using the moon as a radio signal reflector) contacts with much lower power/smaller antennas than ever before used.

Check out the DSP-10 designed by Bob Larkin, W7PUA and offered as a kit by TAPR. It receives and transmits in the 2 meter amateur band (144-148MHz) using a standalone DSP card (that has power similar to a PC sound card). The code to drive it is all open source, and the DSP can not only handle traditional modes, but can also be programmed to do all sorts of neat stuff. New modulation schemes programmed into the DSP-10 have resulted in successful "moonbounce" (that's right, using the moon as a radio signal reflector) contacts with much lower power/smaller antennas than ever before used.

http://www.arrl.org/arrlletter/audio/

http://www.tapr.org/newsline/

For accurate time you want a 1 PPS output. GPS chipsets and embedded modules (like that $24.95 thing that appears to be sold out) usually have that. The higher quality modules 1 PPS output is good to within a few microseconds, but the cheaper ones can be off by 25-50 microseconds.

Here is the famous W3IWI Totally Accurate Clock available in kit form from TAPR for the princely sum of $139.00 for non-TAPR-members. That's a pretty good deal--that $24.95 module was a stupendous deal and had to be some kind of surplus closeout.

P2P packet radio is an old idea. Check out the old Aloha and AX25 protocols. One of the best sites for amature packet radio is Tucson Amateur Packet Radio or Packet Primer.

But techniques like Spread-Spectrum and Ultra Wide Band are precisely those that will allow radio channels to be utilized most efficiently, almost up to the capacity limit predicted by Claude Shannon and Information Theory over 50 years ago. "Traditional radio technology" does not offer as much room for improvement, certainly not as much as would be required for the kind of "Unlimited Airwaves" that Dan Gillmor predicts could exist.

For example, a proposal for near-infinite frequency reusability based on spread-spectrum techniques, is given by Steve Shepard.

I'm also an amateur licensed operator and I have to disagree. The only time that spread spectrum use in the amateur allocations would have a possibility of interfering would be for the weak signal guys such as the ones that bounce their signals off the moon. Interference for storm chasing or repeater operation, both of which are done on FM, would not be noticed even though the noise floor would be raised (only marginally) since all you would do would be to turn the squelch up or turn on a code squelch such as Motorola's PL (CTCSS in amateur radio) tones. http://www.tapr.org for more info.

Oh, and amateur radio enthusiasts have been homebrewing radio gear for years... all analogue.

What's the advantage in using a DSP? And how do you get rid of all the clock hash?

You must be one of those pro-cw freaks that thinks everyone wanting to use a radio must use, or
at least know cw before obtaining an operator's license.

Amateur radio operators have also been homebrewing radio gear for years in digital too. Have you
ever checked out TAPR (Tucson Amateur Packet Radio) organization and their digital projects?

Or how about the DSP-10 project which is an SDR (software defined radio) that can be built for
less than $400, operates in the VHF range, has a large user base, and all source code/project plans
are freely attainable from http://www.proaxis.com/~boblark/dsp10.htm

Don't want to operate or listen in the VHF range. Build or buy a transverter kit that can downconvert
or upconvert to the frequency range you need. This project is perfect for that. People have already made
two way contacts with 150W or less and single yagi antennas at each station by bouncing their signals off
of the moon. Before this type of hardware it use to take higher power and a small antenna farm to make this
type of contact. These same people have gone back and made a second contact with 5W and 10' dishes on
a higher frequency, again using the moon.

Want a SDR totally made for linux? Try Linrad. The project leader gives very good instructions on setting up
linux and various software packages needed to support Linrad and goes beyond by providing links to plans for
building A/D boards (analog-digital) and interfacing them with the computer or plans for using your sound card
as the interface.

Check out tapr.org and the DSP-10 project. It's a 2 meter ham radio that is defined in software, using the DSP board to handle modulation. I am saving my nickels and dimes to buy a kit, and it seems interesting. Also, since it's all defined in software, it can be connected to a transverter and the output can be SSB, FM, etc and the software for the PC can be programmed to take into account that the transverter is making the 2 meter rig into say a 10 meter or microwave rig.

-RickTheWizKid

The US government already gave the fcc enforcement powers and regulation powers through an Communications Act signed in 1934 - and this has been upheld by the supreme court several times.

There is an option though - work with tapr to develope spread spectrum technology using bandwidth allocated to amateur radio operators - at least those are somewhat protected (part of the 2.4 ghz band is for hams only - the rest is shared).

Those who do not study Amateur radio are doomed to reinvent it.

We've had this "location beaming" capability for some time - it's called
APRS (Automatic Position Reporting System).

We've also had interference problems, a**holes on the bands, and repeaters causing interference. That's why we have licenses and are held accountable by the FCC - so that if somebody starts doing this, they get hit with a $8000 fine.

Just look at Children's Band (CB) - one big heterodyne squeal from end to end. Why did this happen? Because the FCC allowed anybody to use CB without a license, and stopped enforcing the law there. Now Chicken Band is like reading at -1.

If they want to stop this, the FCC needs to enforce the law. Go after anybody causing interference, require radio manufacturers to show their nifty new features don't cause harm, etc.

Otherwise, FRS will be CB at a higher frequency.

(And personally, I'm glad there's a place for these morons to play that isn't where I am trying to communicate.)

(Of course, many BPOFs (brass pounding old farts) will say the same about me, since I am a DSNCT (dirty stinking no-code tech).)

Here's some text snagged from The FAQ at TAPR.ORG

TNC (terminal Node Controller)
A TNC contains a modem, a computer processor (CPU), and the associated circuitry required to convert communications between your computer (RS-232) and the packet radio protocol in use. A TNC assembles a packet from data received from the computer, computes an error check (CRC) for the packet, modulates it into audio frequencies, and puts out appropriate signals to transmit the packet over the connected radio. It also reverses the process, translating the audio that the connected radio receives into a byte stream that is then sent to the computer.

Most amateurs currently use 1200 bps (bits per second) for local VHF and UHF packet, and 300 bps for longer distance, lower bandwidth HF communication. Higher speeds are available for use in the VHF, UHF, and especially microwave region, but they often require special (not plug-and-play) hardware and drivers.

Computer or Terminal
This is the user interface. A computer running a terminal emulator program, a packet-specific program, or just a dumb terminal can be used. For computers, almost any phone modem communications program (i.e. Procomm+, Bitcom, X-Talk) can be adapted for packet use, but there are also customized packet radio programs available. A dumb terminal, while possibly the cheapest option, does have several limitations. Most dumb terminals do not allow you to scroll backwards, store information, upload, or download files.

A radio

For 1200/2400 bps UHF/VHF packet, commonly available narrow band FM voice radios are used. For HF packet, 300 BPS data is used over single side band (SSB) modulation. For high speed packet (starting at 9600 bps), special radios or modified FM radios must be used. 1200 bps AFSK TNCs used on 2-meters (144-148Mhz) is the most commonly found packet radio.

http://wireless.oldcolo.com and http://www.tapr.org/

Don't give up.. the solution to your problem is out there.. If they could wire Mongolia to the net using SS, they can certainly do the same for you..

maybe you could get an NSF grant to do this...

For some interesting historical background on spread-spectrum, check out http://www.ncafe.com/chris/pat2/index.html

I'll forward your post on to some other people who might have some answers..

Chris

Ok, I didn't read all the replies... So, I apologize in advance if this is a repeat. This solotion uses a combination of HAM and Commercial pieces. The commercial part of it is you'll need to license frequencies from the government. The HAM part of it is packet radio. There is a college in Italy that is using this. They have connection speeds ranging from 2Mb to 34Mb. Check out their web site here. The theoretical limit is 155Mb according to the site. If your interested in reading more about packet radio you can check out The Tucson Amateur Packet Radio Club. I'm not sure what is entailed in licensing frequencies from the government. But, it can't be that much trouble.

The TAPR offers a card that makes a Compact Flash card act like a hard drive. Plugs right into a ATA-HD plug.CF is pretty cheap now as well.

1) Get:
- 1U 4bays rack mountable chassis from Sliger Designs
- 3WARE 6410 Escalade IDE controller (Choice of 0/1/0+1/5 Raid) on a 90 PCI riser card
- 4 x 75/100GB ATA100 drives (maybe DiamondMax)
- MicroATX mainboard with NIC and Video integrated on board (invest in RAM not in processing power - 750/850MHZ should be more than sufficient)
- Minimum Linux/*BSD OS booting from a read-only 16 to 64MB flash IDE device, loading kernel and a customised Ramdisk root filesystem, mounting Raid devices in R/W mode, starting SAMBA (and/or Netatalk).
A good starting point is Linux Bootdisk HOWTO

2) Choose 0+1 Raid and you get quick and completely redundant 150/200GB storage that can survive the full failure of one disk.

3) Want remote grafical managment from a standard web browser? Go for Webmin or SWAT.

It's still very expensive to do a true SDR that can suck in DC to daylight (or any reasonable subset thereof) and digitize it. However, you can take beginning steps by using traditional methods for the "front end" of the radio, and using DSP techniques at the back end. Hams are doing that now, and we're seeing some very interesting results.

Bob Larkin, W7PUA, developed a DSP radio called the DSP-10 that works at the ham 2M (144-148MHz) band, with a DSP board that's essentially a souped-up sound card. In addition to handling normal communication modes, Bob programmed the DSP for several unique modes that involve extremely narrow bandwidths (easy for DSP, virtually impossible to do in analog) and very long data integration times.

The result is that a pair of these radios were able to talk to each other via "moonbounce" (yes, bouncing signals off the moon) with power levels and antennas far below the macho amplifiers and antennas normally required.

The DSP-10 software is fully open source, so it's wide open for experimenters to work with. The radio itself is being sold as a kit by TAPR (http://www.tapr.org), a ham radio R&D organization. Details on the DSP-10 are at http://www.tapr.org/tapr/html/Fdsp10.html.

It's still very expensive to do a true SDR that can suck in DC to daylight (or any reasonable subset thereof) and digitize it. However, you can take beginning steps by using traditional methods for the "front end" of the radio, and using DSP techniques at the back end. Hams are doing that now, and we're seeing some very interesting results.

Bob Larkin, W7PUA, developed a DSP radio called the DSP-10 that works at the ham 2M (144-148MHz) band, with a DSP board that's essentially a souped-up sound card. In addition to handling normal communication modes, Bob programmed the DSP for several unique modes that involve extremely narrow bandwidths (easy for DSP, virtually impossible to do in analog) and very long data integration times.

The result is that a pair of these radios were able to talk to each other via "moonbounce" (yes, bouncing signals off the moon) with power levels and antennas far below the macho amplifiers and antennas normally required.

The DSP-10 software is fully open source, so it's wide open for experimenters to work with. The radio itself is being sold as a kit by TAPR (http://www.tapr.org), a ham radio R&D organization. Details on the DSP-10 are at http://www.tapr.org/tapr/html/Fdsp10.html.

Well, I am not directly involved with SDR tech yet in ham radio, but I understand the tech, and when I have the time, I will get involved. Anyway, here is the link: http://www.tapr.org/sdr/

So, any hams that want to get involved, there is a start, I know I will be some time in the next 12 months, I'm really hanging out for a HF version, or maybe even a 6m one, maybe I should design one...

VK3TST

Tuscon Amateur Radio Society has one.


...phil

1994. I was just out of graduate school and teaching physical science in my hometown. I had made friends with an officer from the Naval Postgraduate School who was also an Amateur Radio operator (N7HPR). It would be a year before Netcom would provide dialup for a 14.4 modem, so his ability to dial-in from home with a "secure" line to a Linux box he set up at NPS was novel. He used Trumpet WinSock and NCSA Mosaic, and we stayed up all night playing. It blew my mind, and we both knew what we wanted to do with it: Educate. I never thought anybody would pay me to play that way. The Web was going to be an avocation; they're fools to pay us to do what we do.

This was on the heals of learning about email. I had an account in grad school, but not enough peers in my field had one, so it was rarely used. It wasn't until I had to build a packet radio station while living in Hawaii for two years that I really appreciated digital communications. A letter to my Dad would take a couple of days to hop from the islands to California, no better than the pony express but saving us a great deal in phone bills. Sure helped my Dad understand the concept when I convinced him to get one of those Netcom accounts years later.

Stopping stupid patents is something that individuals can do. As an example, several years ago a company obtained a patent on a channel access method for digital radio systems. It turns out that Phil Karn, a ham radio operator/networking guru/author/coder extrordinaire had published an article about this same concept -- even using the same name and acronym for it -- several years earlier.

The patent office hadn't seen it because the article was published in the ARRL/TAPR Computer Networking Conference/Digital Communications Conference Proceedings, a journal fairly well known to hams who do digital radio, but not to the outside world.

Phil filed an objection to the patent based on his published prior art, and the patent was invalidated. Had the patent office known about the CNC/DCC Proceedings, the patent would never have issued in the first place.

The moral is that sometimes, the little guy can win!

3 grand??? Good Grief... I bought a differential kit for my Oncore from www.tapr.org for around $200. This thing works great and is fun to play with as well.

I don't see anything new in this. It is basically just a modified APRS setup designed to fit in airplanes, and to be approved by the FAA. Technically, it would be very easy to implement. It could just use standard packet radio operating on aircraft frequencies.

The only realistic way that someone could try to crack the system would be to report an additional plane, or to be actually on a plane and crack the hardware to make it report the wrong position. The system probably wouldn't be used to replace the current system, but to make it more accurate. GPS data at altitude should be very accurate. Most of the inaccuracy of the GPS system is caused by the atmosphere. A mile or two up there is a whole lot less atmosphere to worry about.

Now, what we really need is for the standard ELT's (Emergency Locator Transmitter, one of the black boxes, it is a beacon that goes of when a plane crashes) to include a GPS receiver with a transmitter to report the location of the accident.

Phaser777:
Would the Microdrive be any slower than the normal hard drive?

The new Microdrive is much faster than the old Microdrive (despite spinning at a lower RPM -- it has 3x+ the data density) but not as fast as the latest 2.5" hard drives.

And would there be any problems booting from the PCMCIA slot?

If it isn't a bootable slot then there would be major problems. Thanks for pointing that out.

Hey! Anyone out there booting off the PCMCIA slot on their Picturebooks?

Another option would be to use an adapter to let you plug the Microdrive in the IDE interface. It has been speculated, but not yet proven, that you could use the tapr.org flash-to-IDE adapter for this if you bent the rails up to fit the larger Microdrive.

Currently further along than XAPRS.

You can also run numerous DOS APRS programs under DOSEMU; maybe WINE will support the windows-based stuff (haven't tried it myself).

More APRS info at TAPR

ka1lm

TAPR has a PC board that will let you use a CompactFlash memory card as a replacement for an IDE disk drive. You plug the memory card into the PC board and attach the IDE drive cable to the connector on the PC board. It looks ideal for Linux based controllers, routers and firewalls. Flash memory cards are getting cheaper. I've seen 16 MB flash cards selling for about $50.

TAPR has a PC board that will let you use a CompactFlash memory card as a replacement for an IDE disk drive. You plug the memory card into the PC board and attach the IDE drive cable to the connector on the PC board. It looks ideal for Linux based controllers, routers and firewalls. Flash memory cards are getting cheaper. I've seen 16 MB flash cards selling for about $50.

Amateur radio is a possibility. Currently she would need to pass a 5 word per minute code test, but that shouldn't be to hard and a written exam (the license fee is $6-7). Then you need a radio, a multi mode controller (a modem for radio), and a computer. You might not need a multi mode controller, you might be able to use the sound card in the computer. This would give her email from just about anywhere, almost all of the time. She would be using a collection of pactor to email gateways located around the world. The drawbacks would be no busuiness communications (illegal), and no encryption (illegal, but shouldn't be a problem). For more information use a search engine and check out www.tapr.org and www.arrl.org.

Additionally, they would have to learn to understand Morse Code at a rate of 5 words per minute (in order to get Shortwave privileges, which would probably be necessary for getting email in the middle of the ocean).

If you are interested in getting more information about becoming an amateur, go to:
http://www.arrl.org/hamradio.html

For information about digital wireless communication over amateur radio go to:
http://www.tapr.org/tapr/html/pktf.html

Amateur Radio has done IP on it's frequencies for years.

We have our own domain: ampr.org.

We have our own IP space: 44/8.

Phil Karn, KA9Q who posted earlier developed one of the first freely available Network Operating Systems (KA9Q NOS) which made it possible to use IP from your DOS machine either over modems, LAN or Amateur Radio AX.25 over the radio. (Hi Phil. Very cool that you read /.)

Admittedly the data speed has been rather slow, 56k probably being the high-end, but folks over at TAPR are working on a 900Mhz FHSS radio that would go to 128k or above.

There's plenty of bandwidth available to do what you want, provided you have the technical know-how and the desire. You want a 2mbit point-to-point wireless link? Do it up around 2.4ghz.

Anything's possible if you want to do it badly enough.

N8USK - http://ohioaprs.net

This is just another pie in the sky thing that will never fly. The author seems to want something that will 'save' Ham Radio. Well, I'll give him two, both of which have already happened:

Kill the "Old Geezer" Licensing System

Tie Amateur Radio and the New Geekdom together

The first happened April 15th when the FCC (in the United States) decided to eliminate for all practical purposes the testing of Morse code proficiency. (N.B., other countries have done it already.) All you need now to get 99.99995% of the frequencies is knowlege of radio theory and electronics. And, people responded--the FCC was deluged with 20,000 applications for new licenses and upgrades.

The second, which is FAR more important, is the leverage of the Internet savvy, /.-reading, computer-programming, gizmo-hacking crowd into amateur radio. A new mode of Ham Radio operating, the Automatic Packet Reporting System (APRS) ties HF, VHF, UHF, and microwave radio, satellites, the Internet, Palm Pilots, GPS, real-time mapping, and nomadness into one juggernaut of technology. Interested? Check out www.aprs.net and www.tapr.org

/rant QuantumHack, alias KA9MVA, Ham radio guy

The error randomly rotates, so the solution you mention would not work.

Actually, it works almost exactly that way. It's call DGPS (for Differential GPS). For example, checkout a tutorial here.

In fact, DGPS can give better accuracy than even military non-DGPS receivers because it can correct for ionospheric delays. Interesting stuff.

You can get the data for yourself from the government, or by looking for APRS maps (a ham radio application). The format of APRS is published, so the data should be transportable. Start with TAPR - they have a very good set of APRS files.

The GPS units themselves output the data in a format called NMEA. You can get some info here, though I don't know if the GPS spec is published for free through this site. I have seen it on line, though, so it wouldn't be hard to find. Another good site would be here.


...phil

It sounds like you are looking for something like spread spectrum technology. In terms of transmission via radio, traditionally we use narrowband methods. FM 102.1 has a big bunch of energy that is easily visible around 102.1 MHz. Even if you encrypt it you know something is there.

Spread spectrum disperses the signal across a larger bandwidth so unless you know where to look, it appears that there is only background noise. It appears there is no data at all. The receiver needs a code that matches the transmitter so the receiver can know where to find the transmitted signal.

This is the technology that is used in CDMA - Code division multiple access. The method that Qualcomm uses for PCS. There are a lot of interesting advantages that this method has over TDMA and FDMA (Time, Frequency).

I wrote a paper on this topic for the 7th ARRL Networking Conference (available from TAPR). Briefly, at frequencies above 1 GHz, it begins to make a great deal of sense to take advantage of gain antennas and spatial diversity. With omnidirectional antennas, you're spewing RF everywhere, causing your network to extend over a larger than necessary area. Directional antennas reduce the spatial occupancy. If you're worried about interfering with omnidirectional networks, take advantage of the polar diversity and separation available to you at these wavelengths: omnis vertical, directionals horizontal.
-=paulf, N9FZX

No offense, but, you're obviously not familiar with radio.

Usually, with ham radio at least, you'd use a TNC to convert from serial data to RF for a radio to transmit. The faster the data rate, the higher the bandwidth. Why do you think they call cable "High Bandwidth"? 'Cause you can't do 6 megabits over 560kHz (AM Broadcast), you need Higher Bandwidth.

Ask youreself: What kind of line quality do you need for voice? To answer this, think in terms of an MP3. A radio recording of a talk show only needs Mono/22kHz/8bit/96bps. That is fine for radio, but for data (especially for full-duplex) you're gonna need some serious improvement. You may be asking "But doesn't the audio get digitized first?" Yes (probably) but it still only requires a 14.4-class data rate to transfer.

References...
TAPR: These guys are the IETF of packet radio.
Guerilla.net: An underground alternative to the wired Internet.

P.S. TNC is a "Terminal Node Controller". Could be described as a radio-modem.

1 2 3 4 5 6 7

There's a few to start you off.

Try posing your question to the group on the HTAPRS mailing list. It is a discussion list created for the Kenwood TH-D7A, and the question you have would fit right in. :) Subscription information can be found at www.tapr.org.

Good luck! If I had a palm, I would definately be attempting to do what you are doing using my D7A (coolest little durn radio I've found).

Right now I use my D7A with a Tripmate GPS unit as a standalone tracker in my vehicle (and backpack once in a while).

73 and good luck!

--Joseph

Check out TAPR . Some people are even sending their email to their Palm Pilots this way.

KD5AMB