Re: [time-nuts] GPS discipline oscillator vs phase lock

Jim - Your first thread in this post was fascinating to me - stuff I'd never been exposed to. It seems like the 'tricks of the trade' for so much of how things actually get done are so often only accessible to those who work closely with them. I was about to shoot you an email to ask if there

Re: [time-nuts] GPS discipline oscillator vs phase lock

On 6/20/17 4:22 PM, Hal Murray wrote: jim...@earthlink.net said: sequential tone ranging: by putting a "ranging tone" at, say, 1 MHz, on the carrier Thanks. The part that attracted my attention was your "spectrally pure signal" for the VCO. Typically a maser at the ground station - that

Re: [time-nuts] GPS discipline oscillator vs phase lock

jim...@earthlink.net said: > sequential tone ranging: by putting a "ranging tone" at, say, 1 MHz, on the > carrier Thanks. The part that attracted my attention was your "spectrally pure signal" for the VCO. I think the answer I was fishing for is that the modulation has to be easy to filter

Re: [time-nuts] GPS discipline oscillator vs phase lock

On 6/18/17 9:29 PM, Hal Murray wrote: jim...@earthlink.net said: Well, at JPL we regularly lock two crystal oscillators together that are over a billion km apart with added Allan deviation of less than 1E-15 at 1000 seconds with a radio link at 7.15 GHz. It's how we measure the distance and

Re: [time-nuts] GPS discipline oscillator vs phase lock

jim...@earthlink.net said: >> Well, at JPL we regularly lock two crystal oscillators together that are >> over a billion km apart with added Allan deviation of less than 1E-15 at >> 1000 seconds with a radio link at 7.15 GHz. It's how we measure the >> distance and velocity to spacecraft (a few

Re: [time-nuts] GPS discipline oscillator vs phase lock

On 6/18/17 7:10 AM, Attila Kinali wrote: On Sat, 17 Jun 2017 06:29:02 -0700 jimlux wrote: Well, at JPL we regularly lock two crystal oscillators together that are over a billion km apart with added Allan deviation of less than 1E-15 at 1000 seconds with a radio link at

Re: [time-nuts] GPS discipline oscillator vs phase lock

On Sat, 17 Jun 2017 06:29:02 -0700 jimlux wrote: > Well, at JPL we regularly lock two crystal oscillators together that are > over a billion km apart with added Allan deviation of less than 1E-15 at > 1000 seconds with a radio link at 7.15 GHz. It's how we measure the >

Re: [time-nuts] GPS discipline oscillator vs phase lock

sorry about, but who is 'lifespeed', a robot or a real person with a natural name? many thanks, 73, Arnold, DK2WT Am 17.06.2017 um 23:07 schrieb Lifespeed via time-nuts: Yes, one has to lock them at a high reference frequency so as to avoid multiplied-up phase noise. I can manage the

Re: [time-nuts] GPS discipline oscillator vs phase lock

Yes, one has to lock them at a high reference frequency so as to avoid multiplied-up phase noise. I can manage the tracking loop design. Some applications aren't line-of-sight, so the radio link doesn't solve every situation. Fiber optic backup plan, but everybody hates cords. This is my

Re: [time-nuts] GPS discipline oscillator vs phase lock

On 6/16/17 10:55 PM, Lifespeed via time-nuts wrote: Not too surprising to read locking two crystal oscillators together without using a physical cable is difficult to impossible. Essentially what I am looking for is the phase alignment accuracy (and phase noise) one would get PLL’ing one

Re: [time-nuts] GPS discipline oscillator vs phase lock

Hi If you also need the phase noise of the OCXO’s to be quite good when operating, the PLL approach has some issues. If you are after -100 doc / Hz sort of numbers at 1 Hz offset at 100 MHz, then a PLL to GPS is not your friend. At GPS will degrade that by many 10’s of db. If the phase

Re: [time-nuts] GPS discipline oscillator vs phase lock

time-nuts@febo.com said: > Not too surprising to read locking two crystal oscillators together without > using a physical cable is difficult to impossible. Essentially what I am > looking for is the phase alignment accuracy (and phase noise) one would get > PLL’ing one oscillator to the other

Re: [time-nuts] GPS discipline oscillator vs phase lock

I guess that is the obvious answer, and sort of how the problem is currently addressed up to the limits of realistic cable length, which actually cannot be very long for my application. I am trying to come up with a better way. What you describe quickly becomes impractical. Again, apologies

Re: [time-nuts] GPS discipline oscillator vs phase lock

life-sp...@yahoo.com wrote: Perhaps I could implement an ISM band radio link for the purpose of locking the two oscillators. Of course that wouldn't reach a couple miles either. There appears to be some amount of talking past each other going on here. First, I think you may have a

Re: [time-nuts] GPS discipline oscillator vs phase lock

Not too surprising to read locking two crystal oscillators together without using a physical cable is difficult to impossible. Essentially what I am looking for is the phase alignment accuracy (and phase noise) one would get PLL’ing one oscillator to the other using a cable, but over a longer

Re: [time-nuts] GPS discipline oscillator vs phase lock

Hi > On Jun 16, 2017, at 7:24 PM, life speed wrote: > > That sounds like phase-locking the oscillators to a local radio transmitter. > Not sure there is any difference post-processing vs. real time. The advantage is that you capture a much wider bandwidth signal than

Re: [time-nuts] GPS discipline oscillator vs phase lock

That sounds like phase-locking the oscillators to a local radio transmitter.  Not sure there is any difference post-processing vs. real time. - Lifespeed Hi A far more common approach is to let the two oscillators free run and to record something like a local broadcast station. You then

Re: [time-nuts] GPS discipline oscillator vs phase lock

On Fri, 16 Jun 2017 18:29:31 -0400 Bob kb8tq wrote: > > Well, we still don't know what the requirements are. > > > …. well, we do. A requirement of 0.1 degree at 100 MHz was stated earlier on. > That’s where the ps stuff comes in. Yes, that's _a_ requirement. Not _the_

Re: [time-nuts] GPS discipline oscillator vs phase lock

On Sat, 17 Jun 2017 00:21:54 +0200 Attila Kinali wrote: > Another reference value: Time transfer using calibrated GPS receivers > achieves an absolute accuracy of about 1-2ns(RMS) over base lines of > several 10km with single frequency receivers. Dual frequency receivers > have

Re: [time-nuts] GPS discipline oscillator vs phase lock

Hi > On Jun 16, 2017, at 6:21 PM, Attila Kinali wrote: > > On Fri, 16 Jun 2017 17:46:45 -0400 > Bob kb8tq wrote: > >> A far more common approach is to let the two oscillators free run and to >> record something like a local broadcast station. >> You then

Re: [time-nuts] GPS discipline oscillator vs phase lock

On Fri, 16 Jun 2017 17:46:45 -0400 Bob kb8tq wrote: > A far more common approach is to let the two oscillators free run and to > record something like a local broadcast station. > You then post process all of the data to give you the phase accuracy. One of > several gotcha’s is

Re: [time-nuts] GPS discipline oscillator vs phase lock

I was afraid of that, I guess it doesn't hurt to ask.  Perhaps I could implement an ISM band radio link for the purpose of locking the two oscillators.  Of course that wouldn't reach a couple miles either. - Lifespeed Hi A *lot* depends on your definition of “phase locked”.  If indeed

Re: [time-nuts] GPS discipline oscillator vs phase lock

> I suspect the result of a GPSDO is not the same as phase-locking two > oscillators together. Each GPSDO is phase locked to GPS time. In case you didn't catch it in Attila Kinali's reply... > The analysis above is under the assumption that you have good sky view, with > little multi-path and

Re: [time-nuts] GPS discipline oscillator vs phase lock

Hi A far more common approach is to let the two oscillators free run and to record something like a local broadcast station. You then post process all of the data to give you the phase accuracy. One of several gotcha’s is the stability of any radio link at the level you are looking for. Bob

Re: [time-nuts] GPS discipline oscillator vs phase lock

Hi A *lot* depends on your definition of “phase locked”. If indeed you are after 0.1 degree at 100 MHz, that gets into the “no can do” range. To put some numbers on it, 0.1 degree at 100 MHz is 2.7 ps. GPS time as received simply is not stable to that level … If you drop back to about 20

Re: [time-nuts] GPS discipline oscillator vs phase lock

Moin, On Fri, 16 Jun 2017 18:40:26 + (UTC) life speed via time-nuts wrote: > I suspect the result of a GPSDO is not the same as phase-locking two > oscillators together.  Perhaps it is frequency locking?  Which, if the phase > difference were held constant to within 0.1

[time-nuts] GPS discipline oscillator vs phase lock

I may already know the answer to this, but I figured I would ask the time nuts anyway.  I have an application where I would like to phase-lock two oscillators together, probably 10MHz OCXOs as they have particularly good Allen Deviation compared to what I would ultimately like to use, a 100MHz