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 wa
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
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
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 ve
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 c
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 7.15 GHz. It's how we m
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
> distance and velocity
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 track
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 app
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 oscillat
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 similari
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
> PLLâing one oscillator to the other u
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 f
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 fundament
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 d
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 you can
lock to. That l
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 pos
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_ requirement.
It's like
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 been reported to d
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 post process all of the data to give
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 the stability o
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 you
> 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 a
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
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 degre
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 degree, would be acc
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 c
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