ATV --- Getting started

IS THERE ANYBODY OUT THERE ?

One of the first things to do if you are interested in getting involved in Amateur TV is to establish whether there are any ATV signals being sent in your area. Monitoring on 2 metres should give you an idea of any local activity.The usual ATV talkback channel on 2 meters band is 144.75 Mhz but if in use 144.725 can be used. Polarity is usually vertical though some stations do use horizontal. This may vary from area to area and on different repeaters.70cms is used for some talkback,especially if a suitable repeater is available.You may only hear one side of the conversation of course until you can receive on 23cms.

RECEIVING ANALOG ATV

If you have a repeater near you then an old Amstrad analogue satellite receiver can be used but normally requires a preamp and they do suffer from being wideband fm rather than the standard ATV fm signal giving a rather weak video. A decent aerial and possibly a pre-amp will also be required.
A far more elegant solution is to use a Comtec receiver . Available from 2 sources in the uk and on Ebay (see links), they give 625 line colour picture from a 23cms signal input. Given a decent yagi up on the chimney etc will work well with local signals even without a preamp.

RECEIVING DIGITAL ATV
The Freeview box is not suitable for receiving digital atv as the format is entirely different. However DVB-S digital satellite boxes might be useable but only if they let you drop the symbol rate from around 22,000 to 4000 . Most of the sat boxes do not let you set this value. The Sky Star2 and Haupage pc cards both allow full range of settings. If there is a digital repeater near you, you should be able to get the settings from their club or website. We currently transmit a symbol rate of 4000 with FEC of 1/2 on 1311Mhz. These details might change with a move to Pokesdown site later this year.