Transmitting ATV Pictures
Overview
The basic components of an ATV transmitter system are: A camera or camcorder, a suitable ATV transmitter and a high gain antenna, typically a Yagi, with horizontal polarization being used on all frequencies in the Melbourne area.
Cameras
Just about any camera that produces video that your transmitter will accept will work as your video source. If you don't have a camera then the video out of a computer or recording device can be used. The most common video camera is of the camcorder variety as a majority of people have one of these already. There are older cameras that can be acquired very cheaply but they usually need more light and are physically larger than the modern equivalent. If cost is a factor then the older cameras work well and can be picked up at places like cash converters for next to nothing. The audio out of the camera microphone is fine for the audio to your transmitter but most stations are using external microphone's.
Frequency Selection
At present, there are 3 video inputs to the VK3RTV ATV repeater: 1244MHz, 1256MHz, and 1278MHz which are all DVB-S2 or DVB-S inputs. The 1278 MHz antenna is pointed NW, the 1255 MHz antenna is pointed NE, and the 1255 MHz antenna is pointed SE. See the VK3RTV & Melbourne ATV frequency plan for more specifics.
From most areas of Melbourne, stations are having great success getting full quieting digital signals into the repeater with modest yagi's ( 1m - 2m boom ) or small gridpac dishes, good low loss feed lines, and 1 (some down to 100mW) to 10W of power.
Transmitters and Antennas
On 23cm, all that seems to be needed from most areas of Melbourne with line of site to Mount View is 1 - 10 Watts of power and an antenna of 10dB gain or more. The antenna should be horizontally polarized and should be mounted such that it has as line of site view of VK3RTV on Mount View. It should be fed with low loss coax such as Times Microwave LMR400 or similar.
Transmitters, both analogue and digital are normally constructed at home rather than ready made. Some items can be bought as kits or others as boards that are wired together.
For ideas on where to get transmitters, kits or parts see ATV equipment sources.