10 GHz ATV Transmission
Mt Macedon to Sydenham ( 43 Km )
( Pictures taken both on and off air )
On 20 Feb 2000 a 10 GHz FM ATV test transmission was made by Jose VK3TMS from Mt Macedon to Geoff VK3GE (ex VK3JDG) in Sydenham, a distance of approximately 43 Km.
VK3TMS transmitted using 10 mW from a gunn diode with a small horn feed into a 60cm offset TVRO dish. Video was processed and fed to a varactor diode placed near the gunn diode. Problems were experienced with the video quality during the test as the transmitter head had fallen against some metal work in the rear of the transport vehicle on the way up the hill and along a very bumpy dirt road. With tolerances being very small at 10 GHz this had the effect of altering things to the point of upsetting the alignment between varactor and gunn diodes.
The receive system was set up on the veranda roof at the QTH of VK3GE (ex VK3JDG) in Sydenham, which gave good views of Mt Macedon ( see photo below ). Receive consisted of a modified Ku TVRO LNC fed from a 60 cm prime focus terrestrial dish with a penny feed at the focal point. The I.F. out of the LNC was fed to a standard satellite receiver to produce composite video.
No audio was transmitted on 10 GHz. Actual frequency used was 10.360 GHz with 10 mW on the TX end and approx 30db of gain in the dish's at each end. Signal strengths received were approx 25db above the noise. The width of the transmission beam caused a few problems for alignment as a movement of either dish 1.5 to 2 degree's in any direction would cause the signal to drop into the noise. The received video was retransmitted to the VK3RTV repeater on 1250 MHz for all to see. Liaison was on 147.400 MHz FM.
Test Card received by VK3GE from VK3TMS using 10 GHz from Mt Macedon to Sydenham ( Approx 43 Km )
|10 GHz Transmit Dish ( 60cm diameter offset , horn feed )|
|10 GHz Transmitter ( 10 mw )|
|Jose VK3TMS adjusting transmitting dish at Mt Macedon|
|10 GHz Receive Dish ( 60 cm diameter, penny feed )|
|10 GHz Receive set-up ( modified LNB on rear of dish fed to satellite receiver)|
|Mt Macedon as seen from the receive dish at Sydenham|