Re: [time-nuts] Moving GPSDO

jg...@zianet.com said: > What about this scenario - the GPSDO has a fixed position on initial > powerup, but then it is moved periodically or even continuously, without > updating the GPS coordinates. The distance from the original coordinates > could be anywhere from close by, to across the

Re: [time-nuts] Moving GPSDO

Joe, In T-mode, the location in X, Y and Z is assumed known so those values is used as constants in producing the T difference between a satellite and the GPSDO. As you now move your receiver from the original X, Y and Z those location errors will translate into time errors. The worst of

Re: [time-nuts] Phase-noise through mixer?

Hi Simple answer is yes. More complex answer gets into things like the noise of the mixer (not just it’s floor), the levels of the signals, noise being coherent rather than non-coherent, AM <-> PM conversion and on and on …. Bob > On Oct 17, 2016, at 4:45 PM, Anders Wallin

Re: [time-nuts] Phase-noise through mixer?

Mixers also have the curious phenomenon of non-reciprocity On 10/17/2016 4:13 PM, Bob Camp wrote: Hi Simple answer is yes. More complex answer gets into things like the noise of the mixer (not just it’s floor), the levels of the signals, noise being coherent rather than non-coherent, AM <->

[time-nuts] Atomic Watch

Well I think there's a mistake or two here... https://www.inverse.com/article/20497-john-patterson-atomic-ce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the

Re: [time-nuts] Atomic Watch

"Whereas other clocks fall victim to relativistic effects at high speeds, cesium clocks do not. The frequency remains the same, and so the time remains accurate.” Well, to the wearer, it probably does. :) It’s ironic they said that given that they flew cesium clocks in the Hafele–Keating

Re: [time-nuts] Atomic Watch

It hurts to read this. John K1AE -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Palfreyman Sent: Monday, October 17, 2016 9:46 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Atomic Watch Well I think there's a

[time-nuts] Improved Symmetricom ET-6000...

Erik, For what it may be worth... I have two DATUM 9390-52054 GPS Frequency and Time Standards. A few years ago I had to replace the original Vectron oscillators in one of the units and eventually in the other one. In my case I used a McCoy VCXO that's in an oven. This McCoy

Re: [time-nuts] Moving GPSDO

Hi Survey is pretty much a bad thing while in motion :) Some (but not all) GPS modules allow you to set up in a “mobile / do not survey” mode. This is one area that the newer ( = not 1997 era) devices do much better at. It also is something that SBAS / EGNOS / WAAS may indeed help you out on.

Re: [time-nuts] Moving GPSDO

Speaking for my GPSDOs specifically, you can’t disable the survey mode with the Venus838 receiver (well, you can, but it requires you to talk to the module with SkyTraq’s software, which requires disabling the GPSDO’s controller - possible to do, but annoying). I haven’t attempted to see what

Re: [time-nuts] Moving GPSDO

Bill, My question was more generally about any GPSDO, but it's good to know about the Motorola/Lucent. What about this scenario - the GPSDO has a fixed position on initial powerup, but then it is moved periodically or even continuously, without updating the GPS coordinates. The distance from the

Re: [time-nuts] Moving GPSDO

Hi Is the OCXO in your GPSDO acceleration compensated? If not then the acceleration involved in your “moving around” will get into the OCXO at around 1x10^-9 / g. Some OCXO’s are compensated to the 1x10^-11 / g level. Some low cost crystals are up around 2x10^-8. Often vibration is an issue as

Re: [time-nuts] Moving GPSDO

On Mon, 17 Oct 2016 07:25:34 -0600 "Cube Central" wrote: > I had run across this just yesterday: > https://www.youtube.com/watch?v=zILwgQhjC_Q > > He talks about how crystal oscillators are sensitive to movement and changes > in gravity. An interesting watch! As

Re: [time-nuts] Moving GPSDO

I had run across this just yesterday: https://www.youtube.com/watch?v=zILwgQhjC_Q He talks about how crystal oscillators are sensitive to movement and changes in gravity. An interesting watch! -Randal (at CubeCentral) -Original Message- From: time-nuts

Re: [time-nuts] Moving GPSDO

Hi In addition to TimeNuts, there are actually *are* people who get nutty about measuring changes in gravity. That’s a bit different than what he’s talking about in the video. Local variations in the earth’s mass cause variations in gravity (think mountains or similar…). They also are one of

[time-nuts] Moving GPSDO

A lot of the telecom GPSDOs that speak SCPI have no way of running except in a "position hold" mode. The Trimble Thunderbolt and telecom GPSDOs (like the NTBW, NTPX, etc) units can run in a dynamic environment... how well they do that is left as an exercise for the user to determine. They

[time-nuts] Phase-noise through mixer?

Hi group! Can someone help me with how phase-noise through a mixer is calculated? Let's say I connect a 1 GHz signal with -80 dBc/Hz PN (wrt. 1GHz carrier) at some offset to the RF port. I then connect a 900 MHz signal with also -80dBc/Hz PN (wrt. 900MHz carrier) at the same offset. I'm

Re: [time-nuts] Phase-noise through mixer?

On Mon, 17 Oct 2016 23:45:23 +0300 Anders Wallin wrote: > Can someone help me with how phase-noise through a mixer is calculated? Have you had a look at Enrico Rubiola's mixer tutorial[1]? I think it contains all you need for noise calculation.