That works well for transponders with o LY one signal. On commercial satellites, each transponder is shared among multiple signals, so that would not work.
Didier Jim Lux <[email protected]> wrote: >On 7/3/13 2:21 PM, Dennis Ferguson wrote: >> >> On 3 Jul, 2013, at 11:47 , Bob Camp <[email protected]> wrote: >>> The pipe in this case is up on one frequency and down on another. >The conversion oscillator on satellite that's the weak link, no matter >how good the signal from the ground happens to be. >> >> That's certainly true but it doesn't seem like a problem that the >> presence of a high stability free-running oscillator, like a >rubidium, >> would help. The oscillator on a geostationary satellite has a >> continuous frequency reference to lock to (the uplink carrier) and >> hence only needs short term stability sufficient to track this and >> transfer it accurately to the downlink. It seems like this is the >> kind of problem that quartz excels at. >> > >Kind of depends on what the transponder on the satellite looks like. > >For deep space, we use a very narrow band loop filter to recover the >received carrier. The synthesis approach for the downlink is designed >to cancel any variations in the local crystal oscillator (e.g. it's >typically a ratio.. for X band, 880/749) > > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. -- Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
