[time-nuts] Cheap jitter measurements

Bob kb8tq wrote: >Hi > >Without the ability to put out a “known good” time pulse there is no quick way >to >check NTP. GPS modules suffer a similar issue. They put out a pulse and a >“correction” (sawtooth error) to tell you what they just told you. Doing the >same >sort of thing with NTP may

[time-nuts] eBay GPS antennas

Javad charges an extra us$1500 for "GLONASS .2mm Dynamic Calibration" of its triple-frequency timing receiver board: http://www.javad.com:80/jgnss/products/options/gclb.html https://www.javad.com/dynamic/Shop/Product/3268 (the TRE-3 appears to be the only triple-frequency part with the "Precise

[time-nuts] eBay GPS antenna test.

It's still extremely rare to see a low-priced used triple-frequency antenna on ebay. For less than US$300 I've only spotted extremely beat-up Zephyr Geodetic Model 2s and a few Leica AX1203+ GNSS (only the "+GNSS" model is triple-frequency) (there is one up right now). I've seen at least one

Re: [time-nuts] Thunderbolt Rollover Testing

On Mon, 6 Mar 2017 00:38:35 +, you wrote: >Does it have a saved/surveyed position? With a saved position you can >reasonable time performance with 1 sat. Without a saved position all bets >are off, there is no way for the receiver to determine the receiver/satellite >clock difference.

Re: [time-nuts] Thunderbolt Rollover Testing

On Sun, 5 Mar 2017 18:35:25 +0100, you wrote: >One thing a 6100 will let you do is to calibrate the PPS out of your “gizmo” >to +/- 5 ns (one sigma). While it’s >not an impressive number by TimeNuts standards, it is one of the few ways to >get that job done. I want to eventually characterize

Re: [time-nuts] Thunderbolt Rollover Testing

On Sat, 4 Mar 2017 20:39:45 -0800, you wrote: >Matthias Jelen did a test on the Trimble Thunderbolt here: > >https://www.febo.com/pipermail/time-nuts/2014-September/086664.html >https://www.febo.com/pipermail/time-nuts/2015-May/091805.html

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPSdecoding cards

On Tue, 21 Feb 2017 07:37:34 -0500, BC wrote: > >Some 1588 chip sets have (or had, I haven’t looked recently) external sync >pins. >This does get into the whole, what’s a motherboard / what’s a peripheral >debate. Plugging in a 1588 card to get that pin probably no longer counts >as a simple

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPSdecoding cards

SA6CID wrote: > >So, I thought actually of the jitter added on the way between our >accurate source (GPS rx), until we can capture our timer. How much can >this be? As far as I see we don't have a capture mode for the HPET. But, >if we have to do it in software, we get more than 100 ns jitter.