Digital ham radio communication with BS2
achilles03
Posts: 247
Has anyone else ever programmed a BS2 to transmit digital information over long distances (more than a few miles)? More specifically, has anyone ever hooked up a BS2 to a transmitter (through a voltage divider) and written code using the "freqout" command to communicate with a recieving station far away? I managed to get a BS2 to transmit to a handheld scanner, which was hooked up to my soundcard. A program called MixW (ham radio software) decodes the incoming signal and prints the incoming text to a screen. The format I used was called RTTY (Radio TeleTYpe) at 45.45 baud. I've sent and recieved over 1000 characters without error so far. Although RTTY is one of the older, slower modes, I think it'd be easy to modify the code to transmit at 100 baud or even use a faster, error-correcting mode like AMTOR-B, ASCII, etc. Heck, you could even just use high-speed CW (morse code).
It looks like the waveform at higher frequencies (1000Hz and up) is FAR from a sine wave, but apparently it's good enough for the software to decode... ?
The only distance limitation I can see is based on the transmitter power, frequency, and antenna. You could easily communicate to a receiving station over 1,000 miles away with a BS2 and decent transmitter on the right frequency.
I don't think this would be one for the "customer applications", but proper documentation could open up a new niche for the BS2.
Dave
It looks like the waveform at higher frequencies (1000Hz and up) is FAR from a sine wave, but apparently it's good enough for the software to decode... ?
The only distance limitation I can see is based on the transmitter power, frequency, and antenna. You could easily communicate to a receiving station over 1,000 miles away with a BS2 and decent transmitter on the right frequency.
I don't think this would be one for the "customer applications", but proper documentation could open up a new niche for the BS2.
Dave
Comments
Dave
I assume you do have a HAM license, or you wouldn't have the equipment you've mentioned. Also note that if you do this once, there's no problem. If 100 people do this, you may start saturating the bandwidth. Just a thought.
145.61-63-65-67-69. If you use these you may be able to connect via or node connect a existing relay and get coverage for hundreds of miles as long as you are not doing commercial. Also then you would not be interfering with anyone. My node coule handel hundreds of stampers with no trouble.
1200 baud but that can handel a lot of data and cheaply.
A alternative is the murs channels at about 2 watts just above 2 meters. No licence required but you have to use approved equipment. There are 5 channels there and data is allowed.
Use one of al williams's real ttl to rs-232 adapters between your stamp and the tnc..
Oh i forgot. I think the mfj tnc, one of the cheeper units has ttl stamp compatable i/o connectors.
73
spence
k4kep
packet since 1981(i think)
HOWEVER, you could use FMS or GPRS (I think I got the acronyms right), one of which you can buy off the shelf at Walmart (no license needed). Mic one to the BS2, and speaker the other one out to your computer, and you should be up and running.
As far as spectrum saturation goes, unless you have lots of people transmitting on powerful transmitters when they don't have anything to say (which is a no-no in the ham world), you shouldn't have to worry about saturating the spectrum. There are tens of thousands of people in the US communicating via RTTY, PACTOR, and packet radio right now. These communications aren't continuous, and are more burst oriented (you're only transmitting when you have something to say). Hundreds of people are using 144.39 MHz (a common APRS frequency) right now to communicate via packet. Collisions at 144.39 can and do occur, but periodic retransmission overcomes this. Also, path loss and line of sight limitation prevent your signal from going too far, unless you're on the lower HF frequencies.
I would upload the wav of it transmitting, but apparently I can't upload audio files here... oh well.
Dave
145.61-63-65-67-69."
Because the stamp isn't fast enough to encode packet radio, atleast not at 1200 baud. 1200 baud FSK (frequency shift keying) is way too fast for the BS2 to be able to time accurately. And TNC's cost money. This is a "no additional equipment needed" solution.
"OH I FORGOT. I THINK THE MFJ TNC, ONE OF THE CHEEPER UNITS HAS TTL STAMP COMPATABLE I/O CONNECTORS."
My point is why would you need a TNC when you can communicate on RTTY or AMTOR adequately without one?
Thanks for the feedback.
73,
Dave
it is frs (family radio service) and gmrs which does require a license...
I don't believe you are alowed data on frs but as i said. Murs
multi user radio service does allow data.
73
spence
k4kep
do you have nim or aim. (my callsign)
packet has a input buffer of about 256 bytes usable. And end with a cr/lf.
Packet is error checking with a error rate of something like 4 out of severl million characters.
You can set paclen as little as 3 to 5 charaters. For short messages.
73
spence
All repeaters are usually set up so that they transmit their station IDs every 10minutes or so and during so many 'keys'.
Depending where you live, you'll find FRS might be congested.· Went with the famille to Disney this past year with these radios for our group.· Well, it was pretty hard finding a channel not being used!
Also, up here, you are not allowed to encrypt data.· Being that these are international activities, Canada does copycat most everyone else....so your laws may be similar.· Of course, I've lived in the new digs for a year and can still see the base station sitting in the corner collecting dust....so the laws may have changed in the last few years.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·
Steve
http://members.rogers.com/steve.brady
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
Can't encrypt down here either. I believe it is an agreement by international treaty.
On the bands allowing digital traffic you id yourself digitally via whatever protocol you are using. On the boat we do email via pactor. The data stream includes our call sign. We've also configured our system to send our call sign in morse when the modem signs off. But that is optional.
Jim
A couple suggestions...
Do you know about the TinyTrak?· It's a one-way TNC for APRS.· It works great.· You hook it up to a GPS and it transmits posits according to the configuration you download to it.
Second, the TinyTrak Yahoo group has an open source version of the TinyTrak.· You could buy a TT and then modify this firmware to suit your own needs.
Third, there is a drop-in firmware replacement for the TT called DataTrak (http://www.ringolake.com/pic_proj/t_trak/data_trak.html).· This is also open source.· You program a new PIC with this firmware and put it in the TT.· It will transmit packets of anything you send to it via the serial connection.· I've used this too and it works.· This is what I'll be using for telemetry for my balloon project.
Fourth, there is OpenTracker.· Also open source.
All of these transmit at the standard packet rate of 1200baud.
-Mike
·
Just as a matter of interest I went to the FCC web site to try and do some investigating into the Multi User Radio Service (MURS) which SPENCE suggested. There is a good deal of valuable information in just a few web pages, located at the link below. It turns out that MURS is essentially nothing more or less than Citizen's Band Radio at VHF frequencies. Here is the FCC web site link:
http://wireless.fcc.gov/services/personal/murs/
At the risk of repeating what SPENCE has said about MURS, data transmission and remote control usage is permitted, call sign transmission is NOT required, frequencies are limited to five "color dot" frequencies, specific emission requirements must be met, transmitter power is limited to 2 watts, all channels are shared cooperatively, and continuous carrier is prohibited. Repeaters are prohibited, as well at packet switching and store-and-forward systems. There are other conditions and restrictions which are not included in this brief paragaph, and the FCC documention should be consulted for additional information.
Regards,
Bruce Bates
IF YOU DON'T WANT TO SPEND THAT MUCH. YOU CAN GET A PC BOARD XTAL AND A MX-614 FROM FARCIRCUITS FOR 15$ + S&H ABOUT 1.85;
http://www.farcircuits.net/modem2.htm
THIS IS BASIC 202 BELL STANDARD MODEM TONES SAME AS THE TNC'S USE BUT "NOT" COMPATABLE BECAUSE OF THEIR DATA FORMAT.
WITH BARE BOARD YOU HAVE TO USE CRC OR CHECKSUM & LRC TO INSURE DATA INTEGRITY WHICH THE TNC'S HAVE BUILT IN.
73
SPENCE
K4KEP