WarrenS wrote:
> ...
>
>
>> Also if you would, I'd like to have a better understand of
>> what seems like an over obsessions with Low Noise GPSDO.
>> I do understand the need (or at least the desire)
>> to have low noise oscillators when using them directly for high
>> frequency and/or short t
...
> Also if you would, I'd like to have a better understand of
> what seems like an over obsessions with Low Noise GPSDO.
> I do understand the need (or at least the desire)
> to have low noise oscillators when using them directly for high
> frequency and/or short time scale data taking applic
Bruce Griffiths wrote:
> 4) Obsession
>
> Bruce
Bruce,
I think you are confused. #4 is the name of a perfume !
BillWB6BNQ
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l subject; I've cleaned up things and added my
> responses in the text below)
>
>
> Re: [time-nuts] GPSDO using 100Hz
> from Tom Van Baak
> Mon, 24 Nov 2008 17:17:34 -0800
>
>
> by WarrenS
>
>>> Besides asking if anyone is using the 100Hz outpu
d added my
responses in the text below)
Re: [time-nuts] GPSDO using 100Hz
from Tom Van Baak
Mon, 24 Nov 2008 17:17:34 -0800
by WarrenS
>> Besides asking if anyone is using the 100Hz output,
>> I would like to know why it is that the generally available
>> GPSDO don't use
[EMAIL PROTECTED] wrote on 11/24/2008 08:31:22 PM:
> Bruce wrote:
> > Analog time constants of several hours are generally considered
> > impractical due to the lack of suitable low noise components
> > principally high value resistors and capacitors.
> > So how do you propose to get arou
Tom Van Baak wrote:
>> This raises some questions on the interpreatation of the M12+T and
>> Jupiter-T receiver specs.
>>
>> Some measurements are required in order to settle the questions once and
>> for all.
>>
>> Can anyone that has either or both of these receivers make the required
>> measurem
Warren Answers and comments to /tvb below in the text.
Besides asking if anyone is using the 100Hz output, I would like to ask
>> why don't the generally available GPSDO use the 100Hz, which can give
>> about 1 ns of certainly with a simple PLL and analog RC filter, instead of
>> the using th
Tom Van Baak wrote:
>> This raises some questions on the interpreatation of the M12+T and
>> Jupiter-T receiver specs.
>>
>> Some measurements are required in order to settle the questions once and
>> for all.
>>
>> Can anyone that has either or both of these receivers make the required
>> measurem
4, 2008 6:48 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] GPSDO using 100Hz
Bruce
My Oncore's phase is definitely different on each 100Hz cycle. A digital
storage scope shows it very well.
Some things that come to mine:
1) Not all Oncores are the same, mine is
riginal Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of WarrenS
Sent: Monday, November 24, 2008 6:48 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] GPSDO using 100Hz
Bruce
My Oncore's phase is definitely different on each 100Hz cycle.
> This raises some questions on the interpreatation of the M12+T and
> Jupiter-T receiver specs.
>
> Some measurements are required in order to settle the questions once and
> for all.
>
> Can anyone that has either or both of these receivers make the required
> measurements?
We know the sawtoot
Bruce wrote:
> Analog time constants of several hours are generally considered
> impractical due to the lack of suitable low noise components
> principally high value resistors and capacitors.
> So how do you propose to get around this with an analog control loop?
Not too many years ago,
WarrenS wrote:
> Bruce
>
> My Oncore's phase is definitely different on each 100Hz cycle. A digital
> storage scope shows it very well.
>
> Some things that come to mine:
>
> 1) Not all Oncores are the same, mine is an old 8 channel one. (Don't
> remember the number, it is the one with the sawto
> Besides asking if anyone is using the 100Hz output, I would like to ask
> why don't the generally available GPSDO use the 100Hz, which can give
> about 1 ns of certainly with a simple PLL and analog RC filter, instead of
> the using the 1 sec which has more like 100 ns of uncorrected uncertain
Bruce
My Oncore's phase is definitely different on each 100Hz cycle. A digital
storage scope shows it very well.
Some things that come to mine:
1) Not all Oncores are the same, mine is an old 8 channel one. (Don't remember
the number, it is the one with the sawtooth capability)
2) The actual
Peter Vince wrote:
>>> B) The variable pulse width of the 100Hz (and 10kHz) outputs do no favours
>>>
>> to an XOR phase detector, its better to use the leading edges of these
>> signals.
>> We agree again, That is why they MUST be divided by two first, using the
>>
> correct edge.
>
>
Mike Monett wrote:
> Warren
>
> Ok, it seems they are calculating the best time for each 100Hz pulse
> individually. That makes life a bit easier for a PLL.
>
>
Not according to the datasheets which imply the phase of the 100Hz (or
10kHz) burst is adjusted once per second.
This should be ve
> Mike
> Note: I gave you a simple example of why it is not possible to
> just buffer the High Freq osc . The actual working get a bit more
> complicated.
> In short when it is time to give out the next pulse whether it is
> 1 Hz or 100 Hz It sends it outs as close as poss
> >B) The variable pulse width of the 100Hz (and 10kHz) outputs do no favours
> to an XOR phase detector, its better to use the leading edges of these
> signals.
> We agree again, That is why they MUST be divided by two first, using the
correct edge.
I'm not convinced that would cure the problem.
Bruce wrote:
> Analog time constants of several hours are generally considered
> impractical due to the lack of suitable low noise components
> principally high value resistors and capacitors.
> So how do you propose to get around this with an analog control loop?
> Bruce
WarrenS wrote:
> Bruce
> It would seem we are now in agreement and on the same track in most areas.
>
>
We probably always have been, but this certainly wasn't clear from the
original posting.
>>B) A time constant of several hours is only useful with a very high
> quality OCXO.
> Agree, a H
Warren
The optimum loop time constant depends on the quality of the local
oscillator and the GPS timing receiver timing signals.
A time constant of several hours is only useful with a very high quality OCXO.
The 100Hz output of an M12+T is phase jerked into alignment with the the
second once ever
> Mike
> Neither do I, know how to reply to a post that is. This may be the
> blind leading the blind and end up in some unknown place.
> True it would be simpler to use the High freq Osc directly but it
> would not be accurate.
> The problem with just using the High freq as you sugge
> Mike
> Neither do I, know how to reply to a post that is. This may be the
> blind leading the blind and end up in some unknown place.
> True it would be simpler to use the High freq Osc directly but it
> would not be accurate.
> The problem with just using the High freq as you sug
WarrenS Email wrote:
>
> Bruce, Thanks for the feedback, Good information to know,
> but you seemed to missed my point and question.
> in it and must use a processor?
>
> Also I should comment that on LeapSecond.com
> http://www.leapsecond.com/pages/gpsdo/
> you stated "where the ADEV for variou
WarrenS Email wrote:
>
> Bruce, Thanks for the feedback, Good information to know,
> but you seemed to missed my point and question.
> in it and must use a processor?
>
> Also I should comment that on LeapSecond.com
> http://www.leapsecond.com/pages/gpsdo/
> you stated "where the ADEV for variou
Sorry my example should of said skip 126 cycles every 500 seconds (500/4 +1)
- Original Message -
From: "WarrenS" <[EMAIL PROTECTED]>
To:
Sent: Monday, November 24, 2008 10:27 AM
Subject: Re: [time-nuts] GPSDO using 100Hz
> Mike
>
> Neither do I, know how t
WarrenS Email wrote:
> Bruce Griffiths answered:
>
> Its difficult to make much useful comment as you provide few measured
> results.
>
> With an M12+T or equivalent the ADEV of the PPS output (without sawtooth
> correction) goes below 1E-10 at Tau > 200 sec or so.
> Thus with an optimized GPSDO i
Mike Monett wrote:
> Hi,
>
> Sorry, I don't know how to reply to a post using the digest. But my
> question is if 100Hz or 10KHz are available from a GPS unit, where do they
> come from? Does that mean there is a 10MHz oscillator somewhere on the pcb
> that is just divided down?
>
> If so, then add
,
therefore skipping 11 divides every 500 seconds.
Regards,
Warren
- Original Message -
From: "Mike Monett" <[EMAIL PROTECTED]>
To:
Sent: Monday, November 24, 2008 9:02 AM
Subject: Re: [time-nuts] GPSDO using 100Hz
> Hi,
>
> Sorry, I don'
Hi,
Sorry, I don't know how to reply to a post using the digest. But my
question is if 100Hz or 10KHz are available from a GPS unit, where do they
come from? Does that mean there is a 10MHz oscillator somewhere on the pcb
that is just divided down?
If so, then adding another PLL loop to control a
---
> From: WarrenS Email <[EMAIL PROTECTED]>
> To: Discussion of precise time and frequency measurement
>
> Sent: Mon, 24 Nov 2008 12:49 pm
> Subject: [time-nuts] GPSDO using 100Hz
>
>
> Ulrich Bangert
>
> Thanks for the great Information.
>
>>UR) James
[time-nuts] GPSDO using 100Hz
Ulrich Bangert
Thanks for the great Information.
>UR) James Miller, G3RUH, also uses the 100 Hz signal
Thanks, that is what I was asking for, other people that were using the
100Hz.
Now if I could just figure out how to post a response under an existing
thread
Ulrich Bangert
Thanks for the great Information.
>UR) James Miller, G3RUH, also uses the 100 Hz signal
Thanks, that is what I was asking for, other people that were using the 100Hz.
Now if I could just figure out how to post a response under an existing
thread, and not have it start a new one
] Im Auftrag von WarrenS Email
> Gesendet: Montag, 24. November 2008 10:48
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] GPSDO using 100Hz
>
>
> Bruce Griffiths answered:
>
> Its difficult to make much useful comment as you provid
Bruce Griffiths answered:
Its difficult to make much useful comment as you provide few measured
results.
With an M12+T or equivalent the ADEV of the PPS output (without sawtooth
correction) goes below 1E-10 at Tau > 200 sec or so.
Thus with an optimized GPSDO it wont take an hour or so to achiev
WarrenS Email wrote:
> This is my first listing so don't know if I'm doing correctly.
>
> Question is: Has anyone done any work using the 100Hz GPS output, instead of
> the 1 Hz output?
> The reason I ask is because I am in the process of cleaning up my SIMPLE GPS
> Freq Phase lock tracker breadb
I have a design based on the Motorola MT12+ receiver that uses a CMOS
XOR-based PLL. I will send you the file with write up and schematic.
Bob Q.
- Original Message -
From: "WarrenS Email" <[EMAIL PROTECTED]>
To:
Sent: Sunday, November 23, 2008 2:18 PM
Subject: [time-n
This is my first listing so don't know if I'm doing correctly.
Question is: Has anyone done any work using the 100Hz GPS output, instead of
the 1 Hz output?
The reason I ask is because I am in the process of cleaning up my SIMPLE GPS
Freq Phase lock tracker breadboard that does about the same as
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