Tom Been following the thread with interest. I think several years ago it was mentioned that LadyHeather could produce results by using a external 10 MHz into a GPS reciver for its main oscillator. Always seemed like a great just over the horizon project. With respect to the uBlox F9. Lost me on that part. I think your suggesting to obtain the sawtooth? It will not take in an external 10 MHz. Thanks for you thoughts. Paul WB8TSL
On Mon, Mar 7, 2022 at 6:57 PM Tom Wallace <[email protected]> wrote: > I've been using the NetRS for timing for a couple of years now. They are > inexpensive and work well when properly configured, but they do have > their quirks. Some notes I've found useful: > > 1. The NetRS needs a dongle to provide primary power and the Ethernet > interface. Approximately 100% of the ex-USCG receivers on the well-known > auction site come without the dongle, so plan to locate one elsewhere or > build one (pinouts are in the manual). > > 2. UNAVCO's resource page on the NetRS > (https://kb.unavco.org/kb/article/trimble-netrs-resource-page-471.html) > is a trove of useful information (manuals, FAQ, etc.) If that page > didn't exist, it would be a major undertaking to get a NetRS working well. > > 3. The latest firmware (1.3.2) is available from UNAVCO > (https://kb.unavco.org/kb/article.php?id=770). It adds the ability to > receive the L2C signal in addition to the L2P(Y), and corrects some > security vulnerabilities. It can be applied no matter what the unit's > warranty status (all the surplus ones are out of warranty). > > 4. For timing use, clock steering on the NetRS must be turned off. > Otherwise, the clock values are smeared by the steering and don't > reflect the state of the 10 MHz input. > > 5. Converting the binary output of the NetRS to RINEX is a multistep > process: use runpkr > ( > https://kb.unavco.org/kb/article/trimble-runpkr00-latest-versions-744.html) > > to convert to .tgd format, then teqc > (https://www.unavco.org/software/data-processing/teqc/teqc.html) to > convert to RINEX. > > 6. Computing clock stability from PPP data can be done over the net > using NRCan (https://webapp.geod.nrcan.gc.ca/geod/tools-outils/ppp.php) > or locally using gLAB (https://gage.upc.edu/gLAB/). Comparison of these > results gives good agreement (~1 ns) in the magnitude of the clock > variations. > > 7. The absolute offset of a clock from the reference source is not > easily determined using the NetRS; there is no consistency in the clock > offsets computed by 2 NetRS systems using the same antenna and fed by > the same 10 MHz reference. Interestingly, the differences are not even > the same modulo 100 ns (the period of the 10 MHz signal). > > 8. The NetRS handled the last WNRO with no problem. However, I have been > unable to find information on whether the system uses a pivot point to > handle WNRO. If it does, and the pivot is the date of the last software > release (October 2012), then the systems are good for another decade. > However, I have no information on this, and would be interested to hear > from anyone who does. > > 9. The sawtooth in the NetRS PPS output is very large (+/- 30 ns), and > the output voltage is over 5V (it may have been designed to deliver 5V > into 50 Ohms). If you want to discipline the oscillator you're > measuring, I'd suggest checking the input level it can tolerate, or > using a modern receiver like the uBlox F9 (which has around 1/8 the > sawtooth variation). > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send > an email to [email protected] > To unsubscribe, go to and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
