Experiments In Modern Radio
I developed an interest in radio whilst at school in the early 1980s. With the support of my physics teacher I studied for the amateur radio exam and became licensed to transmit on the 'ham radio' bands in around 1982. I was an active amateur for a while, and a member of the Radio Society of Great Britain, but by the end of the eighties my interests were more focused on computing and computer networks rather than amateur radio.
A few years ago I decided to take a look at what amateur radio was now up to and found it had changed considerably over the past 20+ years. There were lots of new digital modes for sending computer data over radio, imported Chinese handsets had brought the costs of transmitting down and Software Defined Radio had shifted a lot of what had been the preserve of analogue hardware into computer software. I also found that my qualifications were still valid and I could re-apply for an amateur radio license through OFCOM. I couldn't remember my old call sign, so I was allocated the new one M0JPP.
Most of experiments are based around low-cost, low-power, radio transceivers (such as those made by Baofeng and found on eBay for £20-£30) and make use of various types of digital communications. I normally operate on the 2m and 70cm amateur radio bands. I have also been making use of the short-range license free frequencies around 433MHz and 860MHz for Arduino and digital arts projects.
Automatic Packet Reporting System (APRS)
Automatic Packet Reporting System (APRS) is a way of sending small 'packets' of status information over a radio connection. It is typically used for location tracking, getting data from weather stations and other sensors, messaging and for digital communications in emergency situations. In the UK it operates on 144.800MHz, which means you need an amateur radio license to use it.
APRS can messages can be passed between radio stations through a 'digipeater' and forwarded over the internet using an 'iGate'. This greatly increases the range of your transmissions. The status of the entire APRS network can be seen on the aprs.fi website.
I'm experimenting with a range of APRS technologies at the moment - testing range and reliability - and operate a number of test stations. It's unlikely that more than a couple of them will be live at any one time.
My current APRS stations are:
Windows PC with TNC-X, free APRSIS32 software, Baofeng UV-5R handheld transceiver (8W), Comet GP-3 vertical antenna. Configured to run as a base station iGate. The station is on most of the time and has a 10/15 mile TX/RX radius.
Raspberry Pi with TNC-Pi, free APRX software, Baofeng UV-5R handheld transceiver (8W), home-brew Slim Jim J-Pole antenna. Configured to run as a portable iGate and digipeater. Sometimes located at Interact Labs or Leicester Hackspace.
Yaesu FT1DR handheld transceiver (5W) with built-in GPS and APRS terminal.
AP510/AVRT5 handheld APRS transceiver (1W) with built-in GPS. Occasionally operates as a digipeater and a tracker for my bike. The AP510 is a very handiy testing device with a 1 mile range.
M0JPP-11 / M0JPP-12
Various Arduino projects based around the Argent Data Systems Radio Shield.