Email Over High-Frequency Radio in West Africa

Guillaume Filion writes "LinuxJournal has a fascinating article about Radio Email in West Africa over HF links. 'Deep inside the warm green interior of Guinea, centered in the frontal lobe of West Africa, field personnel in the widely scattered village-towns of Dabola, Kissidougou and Nzerekore now enjoy access to regular internet e-mail, directly from their desktops. Here we have bridged the digital divide, and there isn't a telephone line or satellite dish in sight.' Talk about Wireless Fidelity!"

Comments

Reminds me of Packet Radio

[ackthpt]

Amature radio buffs were into packet radio years ago, I don't know if it's still alive, but some I knew were sending the usual* chit-chat over 2M.

* "Hi", "How's the weather at your house", "Are you going to Dayton?", "Can I ride with you?"

Re:Reminds me of Packet Radio

[HeelToe]

This isn't quite HAM packet radio. Packet radio on HAM frequencies disallows gatewaying content to/from the internet at large.

Re:Reminds me of Packet Radio

[lucifuge31337]

This is EXACTLY packet radio, without FCC-imposed limitations of what one can or can't do with it. While the article is deatiled and pretty interesting, that obligatory /. "is this news?" is still in order. HF packet radio has been around for a long time.

If I can find out what freq they're on, all their mail are belong to us.

Re:Reminds me of Packet Radio

[Chanc_Gorkon]

Pretty funny since there are gateways all over the net for this! You just have to be verfied by the operator of the gateway as a ham. Simple phone call, or e-mail would get initial verification. The next would be monitoring your use and making sure you don't use it for what it's not intended for (ie sending porn to other ham friends). This is the act of being a conrtol point operator. You are responsible for everything your station sends as the control point operator. When using a HT you are both the radio operator and control point operator, but sometimes you are not the one talking. Hence repeaters using volunteer control ops that listen to the local repeater via base station or handheld radio. There IS NO FCC Law or restrictiong regarding the use of packet radio except Part 97. Basically you can do whatever you want with it so long as you don't make money(have a pecuniary interest), and you don't send questionable content such as porn, music or other stuff otherwise against Part 97. Transfering MP3's over packet radio would be illegal as MP3 is music. Only way you could do that was if your the space shuttle (only exception to music in part 97 and this is because of the rebroadcasts of shuttle missions. Part 97 does not have the word internet in it and the word network only comes up once and that's in the line stating that a frequency band in the 220 MHz range is to be used for digital packet backbones. Other then that, this is NOT news. I transmitted a packet e-mail cross country before I ever sent a e-mail across country. HF so far has been limited to about 300 baud. I think the most you can do wirelessly using amateur radio is 14.4k(on 2m and maybe 440). The reason for this is because the faster you want to go, the wider your signal gets(hence the term bandwidth..). That's why there's a restriction for 300 baud on HF Frequencies. This may have changed as I don't really have all that much time to keep up on the digital modes. I don't think much has changed though with the excpetion of a couple guys were expermenting with using lasers for voice and possibly data (Would be THz range for RF I think).

picking nits

[Faggot]

The term 'baud' refers to 'lever transitions per second', not 'bits per second'. Baud and bps coincide at 2400bps and lower; however above 2400bps each baud carries more than one bit of data. Therefore, the term 'baud' becomes incorrect.

'bps' is faster to type anyhow.

Re:picking nits

[BLBishop]

And it isn't really "levels," it's "symbols." A symbol represents multiple bits in modems from 1200 bps up, and some of these symbols have identical levels. Instead, they differ in phase.

SailMail

[linuxwrangler]

This setup is very similar to SailMail which I have used on several crossings of the Pacific. Yes, it's really slow but that's not a big deal when you are just sending a few paragraphs of text around.

The last time I sailed across the ocean last July (in the Pacific Cup Race) we used an Iridium phone with the data option. We were able to send back a couple of digital pictures but the phone bill for the week was something like $200. Next time we'll save the pix till we hit land.

Careful, folks

[PhysicsScholar]

The range of frequencies over which the electromagnetic spectrum is used in radio transmission is between about 3 kHz and 300 GHz.

What the article doesn't talk much about is how these waves are actually transmitted. And as science buffs, we're all probably intelligent and curious enough to read a bit about the details of such a feat as this. It may seem complex at first, but it's nothing but physics, which is nothing more than a few algebra rules that most of you learned back in 9th grade.

The simplest approach to describing radio wave propagation is to solve for the index of refraction h = (m e)1/2, where m is the magnetic permeability (1.25664 x 10-6 H m-1) and e is the dielectric constant.

The index of refraction, in turn, describes the relationship between the angles of incidence and refraction through Snell's Law.

To put it simply, all that that mumbo-jumbo really shows is that there's a finite maximum usable frequency (MUF) that will reflect off the ionosphere and allow still higher frequencies to pass through relatively unchanged.

Bottom line -- email rocks.

You thought email was insecure BEFORE.....

[FuryG3]

...now anyone in the world can dial in and see your messages.

Seriously though, hams have been doing this kind of stuff for a while, on various bands. BBSes and email are commonly used (and tied together). There are TCP/IP networks (granted, most of them on bands like 2m which have higher throughput) with internet gateways. As a matter of fact, amateur radio operators have their own Class A (i belive it's 44.x.x.x)

PSK31 is used on the HF bands and gives you a real matrix feel. You can see the information coming down throughout the band, and click on the stream to see the text moving through it. Here's a screenshot: http://users.skynet.be/on1dht/media/rxpsk_scrn1.gi f

definitly cool stuff.

73, k6gnu

For those actually interested in this topic...

[DaoudaW]

Volunteers in Technical Assistance (VITA) have been doing packet radio in the third world for years. Here is their page on communication technology.

The page also describes their LEO satellite system which is just now coming on line.

Re:Speed?

[kbielefe]

I communicate quite happily on my HF radio on PSK31. In case any of you didn't know, the 31 stands for 31 baud, which happens to coincide fairly closely with an average person's typing speed. PSK31 gives a rather robust connection even with my paltry rig and antenna. More importantly, it is extremely narrow band. You can fit at least 10 connections in the space of a normal SSB voice signal. When you set up a wireless LAN in your house, you only have to worry about interfering with other LANs on your street. When you set up a wireless connection on HF, you have to share your bandwidth with the entire planet. On HF, the narrower the better. Why do you need a connection that's 1000 times faster than you can type if all you are doing is sending email?

73, KD7KME

Re:Clover Digital HF

[dark&stormynight]

Clover is still around. Check out Clover 2000 at: http://www.halcomm.com/clover2000.htm

Re:Hams have done this for years

[mla_anderson]

Well the no-code-tech license is fairly easy. I think the youngest to obtain it was a 7 year old girl. A friend's son got his at 8. Basic math and a half-way decent memory is all that's required.

I however took four years of university for mine. (got my BSEE first)

Re:encryption and ham packet

[kbielefe]

Yes, using SSL or SSH is illegal on the ham bands. The purpose of the "private codes" rule is to ensure that the other rules are being followed. If your transmission is encrypted, how can they know if you are discussing business or downloading obscene material?

Bottom line is, if you want secure transmissions don't use the amateur radio service. If you really want secure transmissions, don't use wireless at all.

However, I don't think the FCC will come after you for encrypting a password, like how hotmail uses ssl for login and then drops it afterward. They've always supported the right of private access codes for repeater control, etc.

I think hams are accustomed to a certain lack of privacy. It's the price we pay for free bandwidth.

73 de KD7KME

AX.25, TCP/IP, Linux and HAM radio

[N3GQF]

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.

We've been doing this for 3 or so years already

[dperik]

We're out here in Papua New Guinea (near Australia). We started using Lotus cc:Mail running over the Codan 9002 modems. Then we switched to use a Linux machine as the "router". The "problem" with using PPP is that you can't use Windows on the client side, since there's no way to increase the timeouts, so we're using (C)SLIP. Most of our field workers are less than computer techies, so Linux hasn't been an option on the other end (yet).

It is excruciatingly slow, so only e-mail is realistically usable.

We have an ISP here that we helped set up. They've got the radio modems plugged straight into a Cisco router.