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Amateur Radio

Notes are a work in progress and generally quite messy!

I am currently a Foundation Amateur Radio Licensee with the call sign M7GOY. This allows me to transmit on certain bands within the UK to test various radio equipment and gain a bit more of an understanding for radio technologies and propagation.

I have always been interested in radio technologies and how wireless telegraphy can allow us to contact each other or send data without the need for any physical infrastructure. Emerging technologies, such as the latest 802.11 standards, and 5G interest me, but are more suited to people with PhDs in microwave engineering, with the terms 'turbo encoding', 'orthogonal frequency division multiplexing', and 'Zafhoff-Chu sequences' all being very off-putting yet fascinating concepts.

The more measured approach that I think is achievable to me without spending thousands on radio equipment; attaining a degree, and subsequent PhD in microwave engineering; is becoming licensed as a radio amateur so I can understand the basics of modulation and maybe learn how to fix real-world problems with radios.

Technologies

  • Valves

Equipment

I currently own a Baofeng GT-5R, which is suitable for the 2m and 70cm bands. It has a TX power of 4W, which is quite low compared to my licence conditions of 25W.

Handy Frequencies

  • 145.500MHz 2m FM Calling Frequency
    • Call "CQ CQ CQ M7GOY" a few times
    • Once have a contact ask to hold for a free channel
    • Switch to next channel up which is ±12.5kHz within the band
    • Band is 145.2000-145.5935MHz
  • 433.500MHz 70cm FM Calling Frequency
    • Same as above
  • Mere Repeater RX on 145.1875MHz (this is what we TX on), then outputs at 145.7875MHz (this is what everyone listens on)
    • Need to encode CTCSS tone of 103.5Hz

Local Transmitters

Salisbury

Camp Hill

  • Greatest Hits Radio (102.0 FM)
  • DAB multiplex comes from Camp Hill
  • No ownership for this site online, might be able to get it from business rates

Newton Barrow

  • Nearest big tower is the Newton Barrow, owned and operated by Arqiva.

South West

DMR Cluster

  • South west DMR cluster which is networked together
  • Nearest to me seem to be in Wimborne or Mere
  • Website for the cluster here
  • Believe the cluster operates on the 70cm band

Southampton

GB3SH

  • Website
  • 2m/70cm repeaters
  • Located at Meredith Towers or Dumbleton Towers
  • Also APRS internet gateway

Sites

  • Geerling Engineering - lots of radio, mostly KMOX AM
  • tx.mb21.co.uk lots of info about transmitter sites
  • https://www.antenna-theory.com/basics/main.php
  • QRZ for information about different callsigns
  • aprs.fi and aprs.radio for APRS info

Terms

  • LNA: low noise amplifier, which amplify the received signal without adding their own noise. Ideally wants to be located near the signal source
  • DMR: digital mobile radio. Similar to normal networked trunk radio systems. Need to have a radio that can operate on the correct frequency as part of the network
    • Two timeslots, then different channels to talk to
    • Talk to a local repeater, and comms are networked out to the rest of the repeaters
  • Simplex: each channel has one frequency. No repeaters. All users share the same frequency.
  • CTCSS and DCS: continuous tone coded squelch system and digital coded squelch. Repeaters won't work unless this tone is transmitted along with the voice. Have to configure per repeater we want to access.
  • APRS: Amateur Packet Radio Service. Allows licensed hams to transmit beacon information to a network of receivers with current positions? Bit confusing at the moment but could be a good supplement for cellular or LoRa tracking.
    • APRS Site
    • Can be used with satellites somehow?
    • Useful for vehicle tracking but essentially beacons to others that you're available for a call, or to advertise beacons or gateways of presence