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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!"
More African Spam!
Did you know you can fertilize your lawn with used motor oil?
* "Hi", "How's the weather at your house", "Are you going to Dayton?", "Can I ride with you?"
A feeling of having made the same mistake before: Deja Foobar
No longer just a Ham toy.
:)
Life at 9600baud is more fun anyhow
West Africans now can order Domino's over the internet.
Drivers carry less than 20 shiny rocks and buttons on them.
If you think about it, much of the last 2 decades' innovations and progress have had the effect (deliberate or not) of making life (at least for those who could afford it) more open and footloose. The company I work for used to have a Chicago address, just because nobody would believe that a large, international, reputable organization would be based in Salt Lake City. Nowadays nobody even thinks about that sort of thing. Even now, with telecommuting technologies, it's not necessary to have all your employees come to the office every day. Maybe in the future, the term "headquarters" will be obsolete, because organizations can be so distributed.
Okay, it's a little off-topic, but the article makes me think about the steps we're taking, technologically, and where they're leading.
Any sufficiently simple magic can be passed off as mere advanced technology.
to use this service, you need to send them 2500 which will be reimbursed when they transfer the rest of the money out of their respective repressed country!
This is my sig. Its pathetic.
. ....Bushmeat Pizza!
.
"A microprocessor... is a terrible thing to waste." --
GeneralEmergency
I think that this is fantastic and has lots and lots of world applications. But why do I get the sense that what these people really need isnt wireless email to their laptops. How many africans benifit from this? Do they now when hungry email their american counterpart and ask him to describe the BigMac?
"The International Rescue Committee (IRC) has one of their largest operations in Guinea, providing services and support to a population of up to 200,000 refugees quartered in many camps established throughout the country." I applaud their efforts with refugees and truely do think Guinea is an island of peace in a otherwise bleak sea. But seriously do these 200,000 refugees need google?
Well enough with this rant.. I do believe that this is a great tech and email is something that I use everyday. Now when on vay-k I will rest assured that i will have email in Guinea!!
Go ahead and mod me down i know its kinda offtopic but I just needed to say it.
If I were only smart enough to accomplish the things I dream about.. Or maybe too dumb to care.
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.
But what do I know. I'm just looking for anonymous gay sex.
This isn't really anything new. The first successor to long copper lines in the US were microwave links. Plenty of other developing nations have been using wireless links to reach far flung small villages for a while now. One of the big examples of this has been Chile.It is especially useful in mountainous areas. In rough terrain it becomes cheaper to put up two expensive microwave towers that it is to pay for the labor of stringing copper or fiber.
The opinions expressed above are those off one side of my brain, the other side and my employer may not agree.
Nuts. As an American, I now have to put Guinea on my "can not visit" list. Thanks, /.
-DDT
So long, michael. Don't let the door hit you...
And now if they can just get running water, electricity, and roads they'll be set.
The radio modems we are using here are speced at an anorexic 2400 baud! And wait, it gets worse. Two-way radio is the classic half-duplex medium of communication; that is, you are either transmitting--push to talk--or receiving, not both at the same time. This, plus the robust error-checking protocols implemented by the modem hardware itself, means the actual link experience is more on the order of 300 baud. Does anyone remember 300 baud? Unless you measure your patience with radio-carbon, your dreams of remote login sessions will be dashed and splattered. As for on-line browsing, chat, video-conferencing and the like, well, best to not even think about it.
Cool technology, but its still years behind...
Maybe they've got some of those old BBS programs running. 300 baud + BBS would be great to reminisce to...
Good quote, too many chars. Seriously, the slashdot 120 char limit sucks!
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.
~~~~~~~
"You are not remembered for doing what is expected of you." - Atul Chitnis
So does anybody know how secure this likely to be?
Rake Free + Mac Poker: CardCrusade
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.
Department of Physics and Atmospheric Science, Dalhousie University, Halifax, N.S., Canada, B3H 3J5
Before this, they were using carrier pigeon to transmit email. Just establishing a connnection to the mail server was a bitch.
It's pretty damn obvious you missed the critical point: "centered in the frontal lobe of West Africa". This technology is plugged into the executive control centre of the psyche of the African continent and promises to generate a go-go hi-tech culture. Pay attention!
Tiny bandwidth, monstrous lag, and packet loss caused by German machine guns.
Slashdotter are stupid and biased.
African packet radio users will notice faster downloads and less net traffic over the next several years, as half the adults on the continent die of AIDS.
But what do I know. I'm just looking for anonymous gay sex.
I would assume that nigeria could easily fund getting the whole country high speed bandwidth. I cannot begin to tell you how many emails I get a day from nigerians that wish to send me millions of dollars just for doing a simple bank transfer.
Got Code?
Talk about needing PGP!
A doctor could email a hospital of some symptoms in the field and get a reply of what the illness and proper care for it is. Although the individuals wouldn't get a benefit directly there would be an indirect benefit.
If you think education is expensive, you should try ignorance -- Derek Bok, president of Harvard
...now anyone in the world can dial in and see your messages.
i f
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.g
definitly cool stuff.
73, k6gnu
How does this system organize the data streams? What if two people miles apart transmit their message at the same time on the same frequency? How does it handle contention issues? They have an awful lot of bandwidth to transmit so the messages should be pretty "bursty" and fast unless they're downloading entire web pages and such.
It's like that time I kept bitching at the moderators... basically creating a one-sided dialog where the only thing I got in response was (-1 troll) , etc. Neat, in a sort of meta-fictional way.
Infact I got ALMOST every negative moderation, except for redundant...
This was a discussion where I also got a 5 and a 4, so it balanced out my one-man tirade.
In the future, I would want to not be isolated from my friends in the Space Station.
subj. sez all.
Good call!
In the future, I would want to not be isolated from my friends in the Space Station.
supports this already through the ax25 modules?
This ties amateur ax.25 protocols directly to the Linux kernel. Works great, lasts a long time.
I suspect the "commercial" modems in use were transmitting in something other than ax.25, probably sitor/amtor/pactor, but it's all about the same at 300 baud.
The advantage with Linux is that you have to configure one driver for tcp/ip as opposed to dealing with the mgetty and ppp nonsense in the article.
be effectively written in text? I would never have guessed.
or way too slow ...
can someone put the contents on the forum,
This is really the core of the train of thought in Africa. Most of the central African governments are looking at 802.11 type net access as a cheap alternative to putting in expensive infrastructure like telephone lines.
In South Africa it's even more interesting: there is a definite shove in getting broadband net access working - and working well. In fact, the recent de-monopolising of the Telecoms Company Telkom has finally opened the door for broadband.
The key advantage, however, is somewhat ironic - in fact, the reason is simply that Africa does not have any decent infrastructure to begin with, this makes it easier to climb in with the leading pack and use leading technology from the start.
The problem with 802.11 is however that it is unreliable. I've had the opportunity of working with a few wireles net-frastructures using 802.11 to connect a multitude of willing volunteers to various wireless wans and lans. Unfortunately, the best uptime stats we had was around 89%, comparable to the 99.9% uptime we enjoyed with one of Africa's biggest ISPs namely iAfrica.
African countries have been connecting rather well to the net over the last few years, and doing so beneath the radar for the most part. It however will most likely not become the multi-million dollar industry like it is in the western world, but the key importance of connectivity in remote African cities and Towns is not to establish capitalistic approaches, but rather bring vital services to poverty stricken people, and offer them the opportunities that many dream the Internet still carry.
Recently I visited a very poor school where the classrooms were the great outdoors and they had one blackboard to share with several teachers. Some students were older than the teachers. The amazing thing was when I saw these kids faces when they saw a pictures of Africa and the rest of the planet we downloaded off the net via Satellite shown onto a makeshift projector screen.
Stories like this should not surprise people. What surprises me is that people in the western world still think us Africans ride lions and chase each other with spears. Africa is poor, but their is a lot of technological knowledge about. And we have that one advantage...
"Diplomacy --- the art of saying "Nice doggie" 'til you can find a stick." Wynn Catlin
I used to dabble in Amateur Radio, mainly 2 meter packet. In those days, about 8 years ago, there were a number of digital HF schemes. About the best of them was Clover -- an AT-compatible board that used its own modulation scheme and protocols.
One problem with HF is that the ionosphere has a large, time-dependant phase dispersion. It really procludes wide-band schemes unless someone can come up with something very clever.
The Clover board claimed 500 characters per second, under good band conditions, through a 25 Hz cw filter. At the time, there was no HF scheme that came close.
I have no idea if Clover still exists -- maybe someone on Slashdot can enlighten us.
Their webservers on their HF connection...
radio modems we are using here are speced at an anorexic 2400 baud!
And wait, it gets worse. Two-way radio is the classic half-duplex medium of communication; that is, you are either transmitting--push to talk--or receiving, not both at the same time. This, plus the robust error-checking protocols implemented by the modem hardware itself, means the actual link experience is more on the order of 300 baud.
-=Lothsahn=-
Anyone notice how the author spends the bulk of the article talking about a mail setup using the prorpietary qmail MTA (which has a look-but-don't-touch license that's in many ways more restrictive than Microsoft's Shared Source) and then goes ahead and praises it as being Open Source in the last paragraph?
It's funny the LinuxJournal editors didn't pick up on this (the article has already been published in print). I mean, there's nothing wrong with using proprietary software where it's the best option, but calling it Open Source is a bit unfair to both the original author of the software (Dan Bernstein), and the developers of actual Open Source MTAs like postfix, exim and sendmail.
1/2 to world should be on your "can not visit" list. Given that you'll be shot rather quickly.
Go America
hahaha
The whole reason that the Internet was created stemmed from the need for a communications system that's global in scale and dependable and durable enought to withstand any natural or not-so-natural (read: nuclear) disaster that takes place.
In the case of sending and receiving email via radio waves, one must be aware that the electric fields from the equipment can be so high that spontaneous glow discharges can be produced by any metal object within six inches of the routers, and fluorescent tubes can be lit up anywhere in the surrounding room without being contacted.
The RF energy being generated is probably so immense and so poorly defined in frequency that probably all air-traffic communications must be jammed for a few miles around when this news system is operating.
Department of Physics and Atmospheric Science, Dalhousie University, Halifax, N.S., Canada, B3H 3J5
maybe they should change the dept to the were-running-out-of-ideas dept
/., you can do better than that!!
i mean "connections dept" ? come on
Psssst! I thought the digital divide mostly concerns those (and the majority) of people who live in these developing countries. Unfortunately the article seems slashdotted - but from that clip it seems like analogy to saying : "Here we have bridged the hunger problem, by taking 42 quality JUST for us". The fact that a few techno geeks can do this really means nothing - even if you describe the surroundings with words " the warm green interior of Guinea". Or do you mean this solution can be easily accessed by those who really are on the other side of the digital divide. (well, have to wait until that article gets back online, but really that clip sounds like example of black humor).
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.
With internet access becoming more common, it'll only be a matter of time before viruses start to propagate across the airwaves. Never fear though, all you need to do is put a floppy into an machine that isn't online yet and the virus will be cured! Honest!
Am I the only one who heard Roxette to sing "I'm gonna get blitzed for some sex"?
Wow.. For a comment that I thought would go unread alot of people have expressed some strong feelings.
Let me explain then.. I realize that my posting this comment didnt help out any refugees but im sure that my yearly, tax deductable ( so why doesnt everyone do it ) contributions to different agencies does. And as someone pointed out Guinea isnt as repressed as I let on. The thing that does concern me is the fact that most people, me included, know nothing about what these people are going through but as soon as LinuxJournal covers some tech people care. No that doesnt quite fit what I want to say either. I guess it is just a sense of frustration. I do realize the benifits of this on a medical and humanatarian level and think it is awsome.
Like I said everyones posts on this lame ass thread I started I would have moded up yesterday when I still had the points.
Thanks all for a great enlightening discussion.
(and please dont mind the spelling mistakes..im awful)
as of right now:
Moderation Totals: Offtopic=1, Flamebait=1, Insightful=3, Interesting=2, Overrated=3, Underrated=2, Total=12
If I were only smart enough to accomplish the things I dream about.. Or maybe too dumb to care.
Not just for sending mail. In this case, you could probably also use this for a telnet-type terminal. Depending on the cost (yes, what's the cost) of a typical setup, this could be convenient for sending telnet-type command strings to remote hardware,etc.
I always thought Guinea was located in it's occipital lobe. :-)
14.4 is definately not the fastest you can go.
The GRAPES and WA4DSY modems are (I believe) 56k units, designed for 440 and above. (One of those might be a G3RUH-compatible 9600 design...)
In Europe, 76k on 440 is common, and the Baycom folks have quite a bit of hardware for this.
Some guys in Slovenia are doing 1.1 Mbps in the 1.2 GHz band.
retrorocket.o not found, launch anyway?
How does this system organize the data streams? What if two people miles apart transmit their message at the same time on the same frequency? How does it handle contention issues? They have an awful lot of bandwidth to transmit so the messages should be pretty "bursty" and fast unless they're downloading entire web pages and such.
From my reading of the article they use an ad-hoc token method, of stations rotating who connects via RF and sessions are limited to 15 minutes.
As far I gathered from the article, they send/receive email, not randomly browse web pages. The qmail server is configured to accepts messages up to 8,000 bytes, to prevent huge messages (like HTML email with images attached spam).
With RF, contention means errors, the weaker signal is wiped out and the stronger signal suffers interference. This is really bad when two remote stations trying to connect to the central hub cannot hear each other and you end up with what is called the hidden transmitter problem.
Sounds like lots of propagation delay, especially with throughput of 300 baud. Interesting options for OpenBSD's pf and pfctl.conf that could help: high-latency A high-latency environment (such as a satellite connection) satellite Alias for high-latency Otherwise, interactive terminals (such as ssh and telnet) would be almost unusable.
At last check, you COULD send MIDI data over packet radio. This was in one of the ARRL's guidebooks. The MIDI data (and hence MP3) was considered data. I think the example given was one of controlling a musical keyboard remotely.
Then again, the ARRL has changed their mind about things a few times. I have a 10-year-old "Now You're Talking" that said you could call mayday over a broken down car, since motorists have been killed alongside highways. Newer editions state that you cannot.
So is any encryption planned? There are some sections of West Africa that are still politically volitile. I can see where field workers, such as Doctors Without Borders and/or missionaries and/or UN Officials might not want their information intercepted.
... but I'd hate to see the same technology triangulated against them.
I realize that sending and receiving individual messages should be strongly encrypted, but that still doesn't necessarily obfuscate the sender or the receiver. I mean I'm glad to see such email used as the article says " the radio equipment, providing an essential lifeline for the safety and security of field office and mobile unit personnel"
--- have you healed your church website?
HF can propagate a heck of a lot farther than most VHF or UHF signals. All you have to get is one dirty transmitter, and Lord only knows how many ham, commercial marine, or aircraft HF frequencies it could mess up. Remember the 'Russian Woodpecker?'
Has anyone considered the question of interference to other services from this 'service?'
For that matter, has anyone considered the value of 'net connectivity as opposed to food, medical care, housing, and decent schools? Don't even get me started on the potential for cultural impact.
Bruce Lane, KC7GR,
Blue Feather Technologies
Except it requires rather difficult to obtain ( for the no- techie ) licenses here in the US
/me ducks as all the amateurs start throwing rocks for such a suggestion. )
Opening that up to the masses here would help solve that 'last mile' problem,
among other things.
(
---- Booth was a patriot ----
Faster than tape, too :-) Maybe I'm mixing up C64 and TRS80, but some of the tape drives for the early home computers were basically doing 300 baud modem codecs on cheap consumer audio tape. (Also, of course, the ham packet radio might not have been that fast when you were using your C64...)
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Yep, the name of the Ethernet (as in "transmitting over the aether") protocol is a subtle salute to the pioneering work that went into building the original ALOHANET.
I don't think that its impossible that wireless "hubs" will get cheap enough that they're equivalent in cost and practicality to plain wires.
We think of wires as being 'free', but they're not. You have to wire up some kind of connector between the board and the "transmission device", be it wires or wireless or a carrier pigeon gate or whatever.
An especially good possibility is that the hubs will be practically required equipment. If, in this case, the hubs are multi-purpose, the wire-based connection will be an additional cost. Why pay more for wires when you've already bought wireless?
I guess the case I'm specifically thinking about is computer to keyboard/mouse/monitor/peripherals.
What wire-based communications can you think of that are not particularly suited to wireless?
$.02
-Zipwow
I don't know which is more depressing, that 2/3 didn't care enough to vote, or that 1/2 of those that did are crazy.
Or does this refer to the rule against hams using private codes or language to communicate with (voice, CW, or whatever). I can't believe the FCC would mandate insecure data communications. Perhaps the rule is a throwback to the days when data security wasn't as big an issue (and there wasn't a public internet to gateway to, etc.)?
Do you have a URL to the rules, perhaps? Also, knowing what paragraph, etc., in the rules would be handy.
Arrggh. My ticket just lapsed a few days ago, I just realized (I'm KD4TFF).
Anyway, I'm wanting to get into packet, and was discussing this very topic with another ham last week.
Need a Linux consultant in New Orleans?
Wireless is fine for low-speed connections, or medium-speed connections that don't have to go very far, and can either interoperate between multiple users in the same space or else do some non-interference trick like spread spectrum. And it's really nice to have freedom of movement and ability to get some kind of service wherever you are, which means wireless in the most general case (though LANs with DHCP and VPNs are a good start.)
But fundamentally, wire-like technologies (including fiber as well as copper) are much more practical for high-speed connections, and can fit arbitrarily large capacity in a given area because separate wires don't interfere with each other, unlike multiple sets of radio waves. For high-speed connections over non-short distances, wireless needs line-of-sight, while wires don't need to be in straight lines, can leap under tall buildings at a single bound, wrap around mountains and curved planets, etc. Also, the physics for devices that mess with wires make it easy to put huge bandwidths on a fiber, limited by the cost of the high-tech equipment on the ends (which gets Moore's Law kinds of price/performance effects) - practical bandwidths get into the gigabit range for cheap short-distance equipment ($59 at Fry's) and into the terabit range per fiber for long-distance telco-quality equipment.
There is some relatively high-speed line-of-site equipment that can fit multiple separate connections in nearly the same space - free-space optics is the most focused, and there are microwave systems that are pretty tight. They can't do long distances, because of weather as well as because of the earth's curvature, but some of them are in the half-gigabit speed range over a few kilometers. They're really nice as a backup for building data feeds - they get rain fade, but they don't get backhoe fade, don't usually need permits to cross highways, and are surprisingly tolerant of earthquakes.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Since they're using SMTP, a *really* simple thing to do is to enable STARTTLS, which does encryption on SMTP connections if both sides support it, which doesn't have the user-visibility that PGP does and is simpler than IPSEC.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
so when is subspace comms going to be out...sure beats 2400 baud (or even the effective 300)
THE WORLD IS GOING TO END!!!! eventually.
They're using PPP to establish a TCP/IP connection over HF. While it's a solution, it's not the best solution - using UUCP and eliminating the overhead of PPP and TCP/IP is a much better, more robust, and higher throughput solution for store-and-forward applications. Been there, done that.
-- Ed Carp, N7EKG erc@pobox.com PGP KeyID: 0x0BD32C9B What I'm up to: http://intuitives.mine.nu
How many birds did you need? I presume 1 bird per 1 packet...
They have an awful lot of bandwidth to transmit so the messages should be pretty "bursty" and fast unless they're downloading entire web pages and such.
They're using HF, which is often used for CW (morse code), they have a very narrow bandwidth.
When flying across oceans or remote parts of the world (many parts of Asia, Africa, South America, Australia), pilots are not under radar coverage, and conventional VHF radio that they use to talk to air traffic controllers and their own airline don't work, and satellite usage is expensive, so they have developed technology called (Airccraft and Crew Reporting System) and closely related CPDLC (Controller/Pilot Data Link Communication) for communications between a plane and airline operations or ATC respectively. These are basically text messaging links carried over HF radio. It's not Internet email, but the concept is very much the same.
:)
These days, an airliner on a transoceanic flight may very well be doing all its communications overwater by HF text messaging, and the pilots will not actually speak to anyone for the entire ocean crossing. While it might seem strange, ACARS and CPDLC communications frees up a lot of frequency congestion for non-routine emergency messages that would otherwise be taken up by traffic such as routine status reports, etc. Think about that next time you cross the pond.
There's 10 types of people in this world, those who understand binary and those who don't.
Water, electricity, and roads would be great.
But these do not just get installed by gnomes.
They require a functioning goverment and decent civil institutions.
These do not survive in countries where power and politics are aligned with tribal sympathies.
The best way to get around that is to create middle classes who do not care what tribe you are from.
But middle classes need access to information and markets, and email is one of the best tools for this in West Africa.
So this kind of infrastructure is not redundant - it is very important and possibly one of the keys to creating better-functioning societies in much of Africa.
Sig for sale or rent. One previous user. Inquire within.
Yes... But can they use the radios to crush nuts like the IBM Global Uplink Modems?
the network serves relief workers for their internal communication + communication with family outside the country
that being said, I'm sure the ability to e-mail out of a remote location is still very useful (as pointed out earlier, e-mailing for medical help, etc.)
Is this good for Africa? Ok, so I saw the argument that doctors could send for a diagnoses, etc. Ok, sounds good.... But, why do we feel that we must westernize everyone? I visited Malawi (SE Africa) this summer and they have signs that say "24 hours" at the gas station, yet they are definetely not open all day/night. When I asked the attendant why they weren't open at midnight the night before when they had this sign and he replied "not in a row." My point is this... Africans do things just because they think that by doing this they will become rich like the white people... they don't really understand things.
Why must we feel that our form of progress is the ultimate form of progress? I mean, look at us. We spend too much time eating and behind the TV... We can't survive without broadband... etc. Well, enough of my rant
I think my principles are reachin' an all time low
Very Low Frequency, used by Elephants for long-distance communication, and copied by natives using drums. Imagine: Ancient E-mail of "What's for Dinner". Content: "Barbequed Elephant"
I was reading this until I got to the description of the PPP link and remembered the days of UUCP over serial lines. Since the modem took care of the error correction they could send much more data more quickly by using straight serial UUCP instead of trying to get a PPP handshake to get TCP/IP working. A UUCP chat script was always faster than PPP in my experience.
Kris
Kriston
Umm... the original ARRL book did indeed call being on the side of the road broken down life threatening, as "motorists have been killed waiting for aid alongside the road." The obvious (idiot) case would be opening your door into traffic. I need to find my pre-no-code-Tech copy again; it's actually quite interesting how quite a few paragraphs throughout the ARRL's "Now You're Talking" have reversed their positions.
But yes, the FCC is indeed the final authority on this. I have not seen a ruling for music over digital mediums; I just know what the ARRL has said historically -- the new voice codes some HTs have (that could code music digitially) might change things.
And as an aside, were you at the COARES (Centrol Ohio ARES) meeting this past night? If not, you should join ( www.qsl.net/coares ). Just going by your email address :)
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.
Radio Amateurs have done this for years, since at least 1984. The protocols at that time were 300 baud with perhaps 100 bps throughput. The situation now is more robust protocols (CLOVER,
CLOVER2000, PACTOR-II, PACTOR-III) with throughput as high as 750 bps in 500 Hz bandwidth or more than 2000 bps in 2.5 KHz bandwidth. That is data throughput not counting protocol overheads.
There is a large use of this kind of HF store and forward in Africa, for the reasons pointed out in the article. I'm a bit surprised the authors are not aware of (and/or failed to comment on) the existing "email over HF radio" networks.
The Amateur Radio store and forward HF radio network has covered most of the world since 1985, and commercial and military spin-offs from it have been in use nearly as long.
These networks do not use tcp/ip due to the large overhead and requirement for frequent link turnaround. Instead, protocols similar to FIDO or the original uucp based usenet batch are used.
I still run such a system on HF, have done so since early 1984.
believe it or not, oil companies have been there and done all that ages ago, if you go hunting around old junk stores you will find all kinds of HF transmission gear, and almost all with encryption packages tacked on top, those guys have always been paranoid about each others plays! The entry of crytpo into the banking sector seems quite recent by comparison, I recall talking to a friend about all the data the firms (banks) that he worked for was routinely fired through the air waves totally un-encrypted.
By the way, about 2 yrs ago I was still sending my LAS data to Saana in Yemen over a HF set with some old dos package driving it. It worked, often took hours to get less than 1 MB over, and of course, for the drillers, we also had to hook up the fax and fax the squiggly lines too - all over the same HF connection. This connection could barely support audio, so I think we did OK.
And of course we all know that with the correct conditions, you can transmit all the way around the world with HF - it's great stuff when you get into it!!! That probably why most places require you to be licensed to run it.
An interesting aside, way out in Eastern Indonesia (beyond Bali, etc), HF is a normal means of communication, telephones requiring major infra-structure, one interesting thing I observed, radio call signs are displayed on the houses, like mail box numbers, I thought that it was a nice idea!
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.
Dude. I believe this is a hoax. Nice try.
Any coding scheme other than straight ASCII (or one or two other represemtations) is also not permitted. Modulation methods are also somewhat restricted, so forget about bandwidth enhancing techniques such as Digital Radio unless you are in the experimental bands.
Sure, no tel. lines, & satellite dishes, but it needs beaucoup wires, antennae, transmitting and receiving equipment and required paraphanalia. I have worked around packet radio and there are currently very good reasons that it is not a big hit in the US, such as low baud rate, high maintenance, and weird people everywhere. Then again, most of that sounds like us! (Maybe we need a Amateur Engineer Club. AARL is a very successful org.) :{)||
amateur radio operators have been exchanging notes to each other in this fashion since the 80's. Before computers the idea was the same but they used Fax or teletype machines (since the 20's)
why should this change anything since it really isnt breaking into any new technology?
I used to offer a bridge to vhf frequencies via what is called packet radio.
took about 20 minutes to setup the software, node was under linux so all the packages involved were in current distributions.. (regular mail packages with ax-25 protocals loaded)
no big deal
A scientific truth does not triumph by convincing its opponents and
making them see the light, but rather because its opponents eventually
die and a new generation grows up that is familiar with it.
-- Max Planck
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