Bruce Griffiths wrote: > Data delay devices (http://www.datadelay.com) also do programmable delay > lines their minimum order is $US75 which isnt too bad particularly if > more than one sawtooth corrector is to be built. > They even do ECL programmable delays as do Micrel (http://www.micrel.com). > However these ECL programmable delay devices dont have enough range for > this application. > There is also a good programmable delay line from Dallas/MAXIM that is less expensive (see http://www.maxim-ic.com/appnotes.cfm/an_pk/107). Rick Hambly uses the DS1020-015 in his CNS Clock (see http://www.cnssys.com). See slides 20, 26, 29 & 30 at http://gpstime.com/files/tow-time2007.ppt for some details.
One comment on the Dallas/MAXIM DS1020 parts: we (Rick & I) found that Motorola (in the M12 GPS receiver) and Dallas (in the delay line chip) have a slightly different (~10%) definition for the nanosecond; it appears to us that the Dallas/MAXIM definition is wrong, and the same error shows up in many samples. Rick now uses the 150 psec/step Dallas chip after finding that the ½ & 1 nsec versions had a scale error (see slides 16-18 in ftp://ftp.cnssys.com/pub/PTTI/PTTI_2006.ppt which represents slightly earlier work than presented at the 2007 TOW). The "true" scale factor with the ~10% correction is contained in a look-up table that converts the M12M binary sawtooth error output into the value sent to the delay line. Season's Greetings to all -- Tom _______________________________________________ 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.
