W5VSI ATV System

The small window visible to the left of the antenna connector is the "looking up" window for one video camera. The window on the side or a window on the bottom of the payload can be used by the second camera.

The ATV system was built by Mike Manes, W5VSI. More detailed pictures of the interior components are available here.


This ATV system transmits on 426.250 MHz at 1 watt output. The signal is AM. The FM narrowband audio sub-carrier has a CW ID of AE0SS.

note from Mike Manes: The baseband signal comprises video plus a 4.5 MHz audio sub-carrier (plus a 3.58 MHz color sub-carrier if the camera is color). The baseband signal amplitude modulates a 426.25 MHz RF carrier. The 4.5 MHz audio sub-carrier itself is frequency modulated by the audio at about 25 KHz deviation. The 3.58 color sub-carrier is both amplitude and phase modulated according to chrominance (color saturation) and color, respectively.

The optimum receive system would include an ATV receiver and a gain antenna with some pre-amplification. ATV receivers are much more sensitive than other receivers that might be used, such as cable ready TV sets as discussed below.

There are two cameras aboard this payload. One points up, the other down. A duty cycle is programmed for each mission and may differ from flight to flight. Generally we transmit a minute of video pointed up, a minute pointed down and sometimes we leave a minute "empty" with no transmission in order to open an unobstructed receive window to the input frequency of the Cross Band Repeater. The actual duty cycle will probably be discussed in the Flight Announcement for each flight where this ATV system is incorporated.

Cable Ready TVs

It is possible to receive this transmission on a cable ready TV tuned to channel 58. However, the ATV output is a very weak signal and a good gain antenna and probably a preamp will be needed to see the picture. Cable TV tuners are expecting much stronger signals than that you will receive with just an antenna by itself. But, if you are very close to the payload, who knows. Cable ready TVs have been used in the past as monitors at the launch site to check on ATV operations prior to launch. But, once the payload leaves the ground, a multi element beam (I think it's around 10 elements perhaps 10 to 13 DB of gain) is used in conjunction with a preamp and an ATV receiver to monitor the payload during flight.