The Vital Sounds KU-Band Satellite Power Controller

When you go out to lease a channel on a satellite, one of the most important decisions is how much power you will need. Satellites only have so much power available, and if you need a lot, you will pay dearly for it. So you tend to buy as little as you need to get the signal to all the places you need to receive it.

One problem with KU-Band satellites is that the signal level is severely cut down by rain. Historically, you protected against rain fade being a problem by buying more power than you needed, and hoping the extra power would 'blast through' the rain clouds. This usually worked, but you could easily end up buying (and paying for) 10 times the signal you needed when it wasn't raining.

In 1991, a system was developed that would correct for this problem. Basically, it was a computer program that measured the level of the signal coming back from the satellite, and if rain started to make it drop, the power being sent up to the satellite would be increased. It sounds simple until you realize that when the signal is being measured at the uplink, it will have passed through the rain TWICE; once on the way up and again on the way down. The problem, then, is not to keep the received signal constant at the uplink; rather, to keep it constant at the output of the satellite transponder. The Satellite Power Control program does this. It samples the received signal and adjusts the power either every two seconds for the newer satellite terminals, or as needed for the older ones. (Which can only have the power adjusted 100,000 times before a memory chip expires and has to be replaced)

The Power Controller was developed with assistance from Alan Walker of Walker/Weiss in Pasadena, who did the machine code COM port routines .

The program was distributed exclusively through California Digital Audio Systems. Although it was admittedly expensive to buy, it paid for itself in the first two months of operation. Typical savings of $ 3,000 a month are common when the power required for a 'SCPC' channel can be cut by 70 %.


Copyright 2005 by Vital Sounds - ALL RIGHTS RESERVED