At 05:25 PM 7/3/96 -0700, Timothy C. May wrote:
Someone mentioned the Ku-band dishes that are used by PageSat (or whatever it is now called....). My DSS system, which is technically a Ku-band receiver, has a digital i/o connector of some sort on the back, and it is rumored that this will someday be available for PageSat-like uses. (I have a feeling this may be years off, for admin reasons if not technical reasons.)
As I understand it, the DSS broadcast (unlike older C-band units) consists of a single digital stream which contains the highly compressed (MPEG?) data representing all channels. Being compressed, the data rate needed per channel varies with the scene and the rate it changes. Even if you add up a large number of these statistically-varying channels, you'll still get a fairly wide variation in the needed bit rate per second. The system must have a substantial amount of headroom to protect against occasional times when many channels need a lot of bits, headroom that is mostly not being used, most of the time. If this is correct, then most of this headroom should be available to piggybacked data traffic on a "space-available" basis. Probably tens of megabits per second. Jim Bell jimbell@pacifier.com