Mastering Precision: 10MHz Reference Testing & Analysis (TM4313 GPSDO)
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- เผยแพร่เมื่อ 8 พ.ค. 2024
- EEVblog forum link to the post containing the Excel Document - www.eevblog.com/forum/metrolo...
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In this video we take a look at an offering from the great auction site in the sky for a GPSDO. I have been asked a few time what I think about GPS units and given that we have a lab available to us here and gear that can DO the testing It was time to get it going. So here is the first GPSDO that we are testing! I am starting to build a table for some stability references to aid in picking the GPSDO that is right for you!
** Repair exposes the Tech to mains electric and should only be done by trained personnel. Errors can be fatal. ** - วิทยาศาสตร์และเทคโนโลยี
It is arguably AMAZING what is now available to the "Hobbyist" Tech. I also have a Rubidium and GPSDO. Though I built my Rubidium oscillator at a time when ebay sellers haven't lost their minds yet.... the modules sold for $79 all day long. They are "good enough for me". 👍
I would buy the ones with LCDs to read the status. Whoever did the design tried to save a dollar on this one. I bought one from AliExpress and I'm very happy.
When my old HP GPS time and frequency reference receiver finally kicked the bucket I got a new Stanford Research Systems GPSDO and frequency counter with optional rubidium time base. Best of both worlds, GPS and rubidium. However, you could probably buy a rather large pile of those little GPSDO's for what I paid for the SRS one new. If I only worked on HF/VHF/UHF transceivers one of those little things would probably be fine. In my case I also work on SHF and EHF transceivers. A tiny error in the 10MHz reference to one of the EHF radios can cause a frequency error of hundreds if not thousands of Hertz error.
I have a similar set up here. I have a GPS unit steering a FS725. It is the same physics package but I do have have the associated frequency counter.
You should test the holdover as well. Sometimes you loose GPS for solar flares and weather events, how well does it hold frequency.
I can defiantly add that to the Spread Sheet.
I just got a fleabay gpsdo and a name brand distribution amplifier this week and I am pumped to have a stable frequency standard! Its pretty awesome to see how close to spec my gear is without being calibrated in who knows how long.
No mention of your Leo Bodnar unit or how it compares to this unit. ?
That is a really good point I should do the same testing with the Leo. I do have one of his 2 port units that I could test.
@@ZenwizardStudios I have connected the one- port Bodnar unit to a $65 amplifier/ splitter I found on epay. It seems to work very well.
👍👍👍
Does your unit ever lock? Mine doesn't. Check the NMEA output from the USB serial port - you might be surprised to see it never locks. Without the GPS, it's just a glorified OCXO.
It seemed to based on the LED patterns as well as the stability. I have a active GPS antenna outside that is shared between my bench GPSDO, a 2 port Leo GPSDO, and Leo's GPS NTP server. All seem to lock quite well. Usually this is due to signal level at the patch antenna. I have had units struggle with the patch antenna at the bench especially because the lab is below ground
All very interesting as a hobby , but without having been authorised as a calibration lab and having all trhe associated paperwork like UKAS accreditation , in the uk .............. it is just that a hobby .
In this cases as this analysis was only on frequency this one is traceable back to NIST cesium through the GPS network as far as my understanding goes.