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Experiments In Modern Radio

I developed an interest in radio whilst at school in the 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 radio 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 my 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 art 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 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 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:

Microsat WX3in1 APRS Advanced Digipeater/I-Gate, Baofeng UV-5R handheld transceiver (8W), Comet GP-3 vertical antenna. Used as a base station iGate. The station is on most of the time and has a 10/15 mile TX/RX radius.


Pi-Star Digital Node. Operating on 438.800MHz.

Yaesu FT2D handheld transceiver (5W) with built-in GPS and APRS terminal.

Android phone with the iGate2 app and an RTL-SDR dongle. Used as a portable iGate and sometimes as a Software Defined Radio with SDR Touch.

M0JPP-11 / M0JPP-12
Various Arduino projects based around the Argent Data Systems Radio Shield.

Other equipment used: TNC-X, Moblinkd TNC2, APRSIS32 software.

Automatic Dependent Surveillance – Broadcast (ADS-B)

People are often surprised to hear that all aircraft transmit an unencrypted beacon on 1090MHz that contains information about their current speed, location and altitude. What more, you can receive these beacons using a cheap digital TV RTL-SDR dongle.

These ADS-B signals can then be plotted on a map using free software such as ADSBScope. Using a short 15cm antenna I have picked up signals from across the East Midlands and as far as the North Sea and Wales. If I tune my radio into the East Midlands Airport control tower on 124MHz I can also hear communications between air traffic control and the aircraft.

Even if you don't have a radio received and decoder, you can see the data collected from ADS-B beacons on the FlightRadar24 website.


Coming soon.

Updated 20th April 2020