More likely it multiplies up to something useful. For instance, for deep space communications, older radios multiplied up something around 5 MHz to get the 2.x GHz or 8.X GHz transmit frequencies.. 9.5625 MHz * 880 gives 8415 MHz, which is in the middle of the Deep Space "space to earth" band. The corresponding earth to space frequency would be 749/880 times that. Similarly in the 2 GHz band, the ratio is 221/240.
The entire system is based on the crystal frequency chosen for your channel and stuff is divided up and down. Until very recently, you got an allocation for your mission (many years in advance) and you'd order your crystals, wait a couple years for them to be delivered, then install them in your radio and tune it up. If your mission happened to use a spare radio from a previous mission, you'd hope you could use the same channel so you didn't have to get a new crystal. More at deepspace.jpl.nasa.gov/dsndocs/810-005/201/201A.pdf Not that your OCXO was used for that, but there are a remarkable number of fixed frequency systems around with oddball frequencies. I'll bet there's a lot of terrestrial microwave systems that multiplied a ovenized oscillator up to the frequency of use, and since they're on fixed allocated channels, there's no particular reason why one frequency is any better than another... They're all custom. On 11/19/09 10:48 AM, "Don Latham" <[email protected]> wrote: > I just found in my dusty junk, a couple of ovenized frequency sources at > 5.199155 MHz, part# EROS-750-MA111 Dunno why I got these. Is this a magic > frequency? It does not seem to divide down to a baudrate... > Don > _______________________________________________ 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.
