Amateur Radio Data Communication

Amateur Radio Data Communication was really the start of what we today know as WIFI, GPRS and 3G.

Where does amateur radio data communication come from?

Since the earliest days of radio communication - Marconi and his spark transmitter - the first basic communication techniques required operators to transmit alphanumeric characters in an audio form that was not spoken. The first development was of the Morse code as the means of transmitting alphanumeric data. Over the years the developments was that ham operators devised procedures and technology to send and receive these Morse code signals know in ham radio as CW (an acronym for Continuous Wave). The signals are done by keying a continuous wave on and off in pure CW. The receiver then hear it as a signal on his side and by careful determination and later by using computer sound card technology the signals are decoded.

How did the true data modes of today develop?

Now with all these attempts to get the information sent faster and faster the developers devised other ways that pure on and of switching of a carrier wave and the process of building more and more complex modulation developed to a point where at first the signal was coded by on-off keying of a signal at a rate of approximately 5 to 65 words per minute to an effective data rate of several megabits per second on the latest microwave links. It was all a matter of refining the traditional systems to near perfect and then changing some small aspect to get a new mode to refine.

How does data communication work?

There are basically 2 basic modes of data transmission Analogue that means a piece of data like this page on the web is changed in a modem (where MOD- in modem means modulator) from a digital electronic signal on a computer disk to a analogue audible signal that is transmitted via a normal voice channel on either a telephone line or via a radio link. These have severe penalties due to attenuation (also known as the degradation of the signal). The modem will often use different tones for different digital signals. The normal limit for analogue modems on either radio or telephone lines is about 57 kbps. At the receiver the sound signal that was modulated at the origin is demodulated to become a digital signal again. The DEM in modem is for demodulator.

Recent developments in digital technology brought the data rates on digital links like GPRS, 3G and WIFI up to several gigabits.

Data communications in less than favourable conditions.

What often happens is that when the 1st world are working at improving their systems in 2nd and 3rd world countries they need to use the technologies that is often seen as redundant in the 1st world except in emergencies. The recent Tsunami (2 years ago in South East Asia), and the Hurricane that hit New Orleans took out all the state of the art communications and fixed installations. The area was literally cut off from the world in terms of communications and the data communications was only possible via satellite or short wave radio - and guess what - Radio Amateurs had the means to provide data communications in cases where the satellite was over stressed due to all the traffic.

In Africa internet connectivity is still seen as a luxury and very expensive. Email is virtually impossible due to poor telephone links so what remains? Short wave radio.

What does the future hold for us on data communication front?

The new developments in this is probably going to change the way we live for ever - internet is already easy to get to via your mobile phone - and that in itself is not even the end. Next is probably going to be wrist watches or designer glasses with a receiver built into the frame and something of a Heads-up-Display on the lenses?

Personally I enjoy playing with radio data communication techniques.

Links with further info about radio data communication:
TAPR
Winlink


Written by JD
22 December 2006
South Africa