Television Standards

ATV is a fascinating and powerful hobby. It enables you to exchange pictures with other Radio Amateurs, as well as the more usual conversational QSO's. The pictures that are sent on 23Cms are much the same standard as the professional broadcasters use. This means that we have a 625 line fast scan picture. Colour is of the usual PAL encoded type which a standard UK domestic TV set will decode. Similarly most Amateurs send a sound channel with the pictures, which in combination with a conventional talkback channel on another band (usually 144Mhz) enables full duplex conversation to take place. Thus it is possible with a fairly simple compliment of equipment, to be described later, to run your own ATV station from the spare room of your house. Over 2000 Radio Amateurs throughout the UK are active in this fascinating hobby, and most large centres of population have a group of ATV enthusiasts.

The ATV Talkback channel

One way of finding more out about ATV activity in your area is to listen on 144.750 MHz in FM mode. This is the international ATV calling and working frequency, and tends to be used by ATVers for local talkback. Talkback is the term used for the phone channel which ATVers use to communicate whilst pictures are being exchanged. It is used for calling CQ-TV when someone is looking for a QSO, and for exchanging comments when the QSO is in progress. In busy areas or during contests, it is sensible to vacate the channel once communication has been established with the other station, but at most times the sound of local ATV activity on 144.750 MHz tends to stop other Amateurs from using if for non-ATV purposes.

The ATV Picture Reporting System

You will often hear ATVers exchanging picture reports and using "P" numbers. These P numbers are a simple system of picture quality reporting, similar to the familiar readability scale for phone transmissions. The scale runs from 0 to 5, with a P5 being a top quality picture, and P0 not really being a picture at all. The BATC publishes a reporting chart, which assists newcomers to assign picture reports to signals with some measure of consistency.