I have found my Trimble units to be very good at power on even without a GPS lock. However if you're storing them for several months unpowered I think you'd want to power them on for several hours with a solid GPS lock before using them to calibrate other equipment.
I have found my Trimble units to be very good at power on even without a GPS lock. However if you're storing them for several months unpowered I think you'd want to power them on for several hours with a solid GPS lock before using them to calibrate other equipment.
I assume they feed a control voltage to the OCXO PLL based on the GPS info. Do you know if that control voltage is stored between boots? Or is power on today the exact same as power on last year? (Rather than the same as the last power off?)
I assume they feed a control voltage to the OCXO PLL based on the GPS info. Do you know if that control voltage is stored between boots? Or is power on today the exact same as power on last year? (Rather than the same as the last power off?)
It's not just a matter of preserving the control voltage in non-volatile memory, it's physical changes to the crystal that happen when it sits powered off - the longer it sits that way, the worse. There's some good info on that on the thread (may be the other thread I started on this topic). That said, I think all those issues have to do with phase noise, not the overall usefulness of the frequency standard for 99.999% of the use cases.
I see. So with the GPS whipping the OCXO into shape it can account for phase noise as well?
I have a 5 port video amp on order. I was going to convert that to 50ohm.
Do you think this eBay item is comparable to the ones you guys use:
http://www.ebay.com/itm/121530825744?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
EDIT: This seller looks better:
http://www.ebay.com/itm/10MHZ-Output-Sine-Wave-GPS-Disciplined-Clock-GPSDO-Antenna-Power-Supply-USA/281802105734?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D35851%26meid%3Dbd3ea62677a64cec9b16b74b0a4ecc33%26pid%3D100011%26rk%3D1%26rkt%3D7%26sd%3D281701995263
I see a few out there, and want to make sure I get the "good one."
Yeah, I found the other thread. I don't seem to be able to find one of the STAR4 models. Grrr.... Anyone?
I have been running my BG7TBL / 2014-12-09 for quite a while now and it is working fine. I have been trying to get it working as a source for an NTP server using the instructions at: http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html
I cannot get the receiver t change its settings to match the requirements to work at 4800 baud and use only $GPRMC sentences. I am using the u-center software but none of the settings I send take hold. With the default settings the NTP server software does not use the GPS as the clock.
Any suggestions?
You can buy surplus Trimble units for less then 60 USD shipped on ebay, tough to beat the performance per dollar.