At 04:51 PM 11/16/2008, Hal Murray wrote... >So why did cell phone towers switch to 15 MHz? Or is it just Lucent >that switched?
Ultimately, CDMA base stations need a precise 1.2288 MHz clock, as that is the chip clock rate. A PLL locked to a 10 MHz GPSDO (like the Tribles and HP Z3801s, which came out of Nortel BSC/BTS CDMA base stations and were known as GPSRs) were probably used originally simply because of easy commercial availability. Some newer units (Nortel GPSTM, used in their newer Metrocell base stations) output 9.8304 MHz, which is an 8X multiple of the chip rate. These also put out 10 MHz and 0.5 Hz (even-second) signals. Did Lucent switch, or have they always locked to a 15 MHz source? I've only seen the 15 MHz units. Any Timenuts have an Endrun Tycho CDMA-derived frequency reference? http://www.endruntechnologies.com/pdf/TychoCDMA.pdf http://www.endruntechnologies.com/pdf/PTTI2001_WhitePaper.pdf _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.