'The temperature chip is there to “learn” the TC of the unit while it is in lock.' I think this is news for the group: as of my knowledge, we don't know if the 1620 has an active role in the TBolt other than measuring temperature for the TSIP output.
On Wed, Dec 4, 2019 at 4:04 PM Bob kb8tq <[email protected]> wrote: > > Hi > > The temperature chip is there to “learn” the TC of the unit while it is in > lock. If and when the unit goes into holdover that information is used > to compensate the unit. If the environment does not change much when > you are in holdover this may be a benefit. If the HVAC goes when the > holdover happens …. maybe not so much. > > The DAC and voltage reference on the E-911 TBolts has a pretty > substantial temperature coefficient. On top of the wide tune range of the > OCXO this gives thepart a pretty substantial temperature wander. If holdover > is part of the “plan” the temperature chip probably is worth having. > > The Nortel GPSDO’s have a very different OCXO in them (normally a double > oven) with a narrower tuning range The DAC and voltage reference are > done very differently as well. On top of that, the Nortel spec for holdover > was much tighter than the E-911 requirement . Net is that the temperature > chip in the Nortel versions may not be as important, even in holdover. > > Yes, way more than you wanted to know …... > > Bob > > > On Dec 4, 2019, at 2:52 AM, Christophe Huygens > > <[email protected]> wrote: > > > > Thanks all - if of no consequence, case closed. > > > > On 04/12/19 03:03, Tom Van Baak wrote: > >> Most TBolt measure board temperature to about 1/100th C resolution. > >> This is the correct behavior. Some TBolt report temperatures that seem > >> to step in 1 C increments, or they report a constant -55 C, or they > >> glitch once in a while. These are bugs. > >> > >> You can replace the DS1620 chip if you want. It's perhaps best to > >> locate the 20-year old version of the chip. There are lots of threads > >> about this in the archive. > >> > >> The DS1620, working or not, has no effect on the performance of a > >> running TBolt. So I've never bothered replacing any of mine. It may > >> have a slight effect on extended holdover performance. It's a long > >> story and I'm not sure if anyone has actually verified or quantified > >> this. > >> > >> Here's additional info about the TBolt & DS1620; it's more complex > >> than you think: > >> > >> "Strange temperature peak" > >> https://lists.febo.com/pipermail/time-nuts_lists.febo.com/2011-May/039188.html > >> > >> > >> "Trimble Thunderbolt GPSDO Temperature Sensor Details" > >> http://leapsecond.com/pages/tbolt-1620/ > >> > >> "Dallas state machine glitch" > >> https://www.digitemp.com/docs/ds1820-report.pdf > >> > >> /tvb > >> > >> > >> On 12/3/2019 1:47 AM, Christophe Huygens wrote: > >>> Hi all, > >>> > >>> I am back on time-nuts after many moons. > >>> > >>> Lady heather shows constant -55deg C for my Tbolt. > >>> > >>> all else seems to function fine (is in a constant T environment, sort > >>> of) > >>> > >>> Any thoughts.... > >>> > >>> br and thanks > >>> > >>> Xtof > >>> > >>> _______________________________________________ > >>> time-nuts mailing list -- [email protected] > >>> To unsubscribe, go to > >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >>> and follow the instructions there. > >>> > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > > > > -- > > -- > > http://distrinet.cs.kuleuven.be/people/showMember.do?memberID=u0013167 > > prof. dr. ir. Christophe Huygens iMEC-KULeuven-DistriNet > > > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
