Re: [time-nuts] Absolute phase

[Dana Whitlow]

Hello Arthur,

Might be interesting to try the same experiment both with the two
receivers on the same antenna and on the two different antennas.
In an ideal world I'd expect the time output(s) to track as well
either way, but it would be interesting to know how well this works
out in practice.

Dana  K8YUM


On Fri, Nov 17, 2017 at 4:15 PM, Arthur Dent 
wrote:

> I have 2 antennas mounted on opposite ends of a roof and both of them feed
> commercial GPS DA/splitters and I can have as many as 10 receivers running
> at one time for testing. I have also used one of the high frequency type F
> TV passive splitters with one D.C. feed through and added 200-300 ohm
> resistors from the other outputs to ground. All this has seemed to work
> just fine but one of the older receivers apparently radiated its L.O. out
> the antenna coax and would interfere with a couple of other receivers I
> connected to the same DA.
>
>
>
> Connecting one 10 Mhz references to the external trigger on my scope and
> feeding 2 other GPS receivers to the input channels (all from the same
> antenna DA), I can watch the slow drift at 2 ns/div with respect to the
> trigger and sometimes one receiver drift one way as the other receiver
> drifts in the opposite direction and sometimes they drift the same way.
> The
> drift is generally less than 2 ns but it is there and I assume it depends
> on what the internal ‘housekeeping’ of the receiver is doing and what birds
> they are using. So bottom line, they aren’t ‘locked’ to each other but are
> generally close.
>
>
> -Arthur
> ___
> 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 instructions there.
>
___
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 instructions there.

Re: [time-nuts] Absolute phase

[Jerry Hancock]

When I first powered them on together, they seemed to drift all over the place 
with regards to relative phase.  For the past hour now, they are keeping around 
7 degrees and sometimes dropping to around 4.  I think that is pretty amazing 
given all the stuff between the source and final display.  I have the cursors 
on them now and they are sitting at 2ns difference.  I am going to figure out 
how to plot this possibly using Timelab and my HP 5371a.


> On Nov 17, 2017, at 2:29 PM, Bob kb8tq  wrote:
> 
> Hi
> 
> As the “filter” (or control loop) in some GPSDO’s scales, it impacts the 
> degree 
> of “agreement” between the GPSDO’s. Not all GPSDO’s scale filters so not all 
> exhibit the behavior. The HP / Symmetricom  Z38xx units are one family that 
> do this kind of scaling. 
> 
> As the scale moves longer (time) or narrower (frequency) the ADEV improves.
> This also depends a bit on the quality of the OCXO you have and the 
> environment
> the GPSDO is in. Somewhat counter intuitively, the level of agreement gets 
> worse
> as the ADEV improves. As the time agreement gets worse and ADEV gets better, 
> the frequency accuracy (in the frequency nut sense) gets better. 
> 
> Again - not all GPSDO’s do this sort of thing. 
> 
> Bob
> 
>> On Nov 17, 2017, at 5:15 PM, Arthur Dent  wrote:
>> 
>> I have 2 antennas mounted on opposite ends of a roof and both of them feed
>> commercial GPS DA/splitters and I can have as many as 10 receivers running
>> at one time for testing. I have also used one of the high frequency type F
>> TV passive splitters with one D.C. feed through and added 200-300 ohm
>> resistors from the other outputs to ground. All this has seemed to work
>> just fine but one of the older receivers apparently radiated its L.O. out
>> the antenna coax and would interfere with a couple of other receivers I
>> connected to the same DA.
>> 
>> 
>> 
>> Connecting one 10 Mhz references to the external trigger on my scope and
>> feeding 2 other GPS receivers to the input channels (all from the same
>> antenna DA), I can watch the slow drift at 2 ns/div with respect to the
>> trigger and sometimes one receiver drift one way as the other receiver
>> drifts in the opposite direction and sometimes they drift the same way.  The
>> drift is generally less than 2 ns but it is there and I assume it depends
>> on what the internal ‘housekeeping’ of the receiver is doing and what birds
>> they are using. So bottom line, they aren’t ‘locked’ to each other but are
>> generally close.
>> 
>> 
>> -Arthur
>> ___
>> 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 instructions there.
> 
> ___
> 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 instructions there.

___
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 instructions there.

Re: [time-nuts] Absolute phase

[Bob kb8tq]

Hi

As the “filter” (or control loop) in some GPSDO’s scales, it impacts the degree 
of “agreement” between the GPSDO’s. Not all GPSDO’s scale filters so not all 
exhibit the behavior. The HP / Symmetricom  Z38xx units are one family that 
do this kind of scaling. 

As the scale moves longer (time) or narrower (frequency) the ADEV improves.
This also depends a bit on the quality of the OCXO you have and the environment
the GPSDO is in. Somewhat counter intuitively, the level of agreement gets worse
as the ADEV improves. As the time agreement gets worse and ADEV gets better, 
the frequency accuracy (in the frequency nut sense) gets better. 

Again - not all GPSDO’s do this sort of thing. 

Bob

> On Nov 17, 2017, at 5:15 PM, Arthur Dent  wrote:
> 
> I have 2 antennas mounted on opposite ends of a roof and both of them feed
> commercial GPS DA/splitters and I can have as many as 10 receivers running
> at one time for testing. I have also used one of the high frequency type F
> TV passive splitters with one D.C. feed through and added 200-300 ohm
> resistors from the other outputs to ground. All this has seemed to work
> just fine but one of the older receivers apparently radiated its L.O. out
> the antenna coax and would interfere with a couple of other receivers I
> connected to the same DA.
> 
> 
> 
> Connecting one 10 Mhz references to the external trigger on my scope and
> feeding 2 other GPS receivers to the input channels (all from the same
> antenna DA), I can watch the slow drift at 2 ns/div with respect to the
> trigger and sometimes one receiver drift one way as the other receiver
> drifts in the opposite direction and sometimes they drift the same way.  The
> drift is generally less than 2 ns but it is there and I assume it depends
> on what the internal ‘housekeeping’ of the receiver is doing and what birds
> they are using. So bottom line, they aren’t ‘locked’ to each other but are
> generally close.
> 
> 
> -Arthur
> ___
> 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 instructions there.

___
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 instructions there.

[time-nuts] Absolute phase

[Arthur Dent]

I have 2 antennas mounted on opposite ends of a roof and both of them feed
commercial GPS DA/splitters and I can have as many as 10 receivers running
at one time for testing. I have also used one of the high frequency type F
TV passive splitters with one D.C. feed through and added 200-300 ohm
resistors from the other outputs to ground. All this has seemed to work
just fine but one of the older receivers apparently radiated its L.O. out
the antenna coax and would interfere with a couple of other receivers I
connected to the same DA.



Connecting one 10 Mhz references to the external trigger on my scope and
feeding 2 other GPS receivers to the input channels (all from the same
antenna DA), I can watch the slow drift at 2 ns/div with respect to the
trigger and sometimes one receiver drift one way as the other receiver
drifts in the opposite direction and sometimes they drift the same way.  The
drift is generally less than 2 ns but it is there and I assume it depends
on what the internal ‘housekeeping’ of the receiver is doing and what birds
they are using. So bottom line, they aren’t ‘locked’ to each other but are
generally close.


-Arthur
___
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 instructions there.

Re: [time-nuts] Absolute phase

[Leo Bodnar]

I don't know how power feed for active antenna is designed in your equipment.
Sometimes equipment can be back-powered through its GPS antenna port.  This 
might be benign or not.
Get at least an RF DC block for one unit (fancy name for a cap stuck between 
two BNC ports.)

Leo

On 17 Nov 2017, at 20:38, time-nuts-requ...@febo.com wrote:

> From: Jerry Hancock <je...@hanler.com>
> Subject: Re: [time-nuts] Absolute phase
> 
> I figured, what the heck, and just used a BNC T and it’s working.

___
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 instructions there.

Re: [time-nuts] Absolute phase

[Jerry Hancock]

I agree.  I disconnected it after wondering about the active antenna bias.


> On Nov 17, 2017, at 12:35 PM, Magnus Danielson  wrote:
> 
> Can work, can go wrong.
> 
> One should be careful and think it though.
> 
> Cheers,
> Magnus
> 
> On 11/17/2017 09:25 PM, Jerry Hancock wrote:
>> I figured, what the heck, and just used a BNC T and it’s working.
>>> On Nov 17, 2017, at 12:20 PM, Magnus Danielson  wrote:
>>> 
>>> Hi,
>>> 
>>> The reason I mention sharing antenna is that it takes out the difference 
>>> that is natural from having different antennas and the difference in 
>>> multipath.
>>> 
>>> Sharing antenna has its own set of problems, so a suitable antenna splitter 
>>> was assumed. Effectively you need to bypass DC to power the antenna, you 
>>> need to amplify the signal to compensate for the loss due to the splitter, 
>>> and it needs to look like an antenna to the GPS receiver, so the antenna 
>>> alarm does not goes off.
>>> 
>>> Cheers,
>>> Magnus
>>> 
>>> On 11/17/2017 09:01 PM, Jerry Hancock wrote:
 Thanks, understand completely.
 You mention “sharing an antenna”.  Is there a problem with connecting the 
 same antenna to two units?  I am referring to my REF0/REF1 pair.
 Thanks
> On Nov 17, 2017, at 11:39 AM, Magnus Danielson 
>  wrote:
> 
> Hi,
> 
> First of all, the receiver varies around some average phase.
> The average of two receivers may not be the same, even if sharing antenna.
> Their average can be offset from "absolute phase" because of offsets in 
> the receiver, antenna cables and antenna.
> 
> If you are not to careful, a GPSDO will do nicely for many applications. 
> The more you care, the more hassle.
> 
> Oh, and two GPSDOs next to each other can have significant common mode 
> disturbance, so you can't really evaluate a GPSDO by measuring up to 
> another GPSDO.
> 
> Cheers,
> Magnus
> 
> On 11/17/2017 08:05 PM, Jerry Hancock wrote:
>> Granted I expect someone on this list to reply with something that makes 
>> me feel stupid, if you have two GPSDO units running side by side, should 
>> the phase delta on the 10Mhz output be zero (ideally)?  Is there an 
>> absolute phase standard kept between GPSDO units as all it would take is 
>> one extra inverter in the chain to flip the phase, no?
>> Thanks
>> Jerry
>> ___
>> 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 instructions there.
> ___
> 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 instructions there.

___
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 instructions there.

Re: [time-nuts] Absolute phase

[Magnus Danielson]

Can work, can go wrong.

One should be careful and think it though.

Cheers,
Magnus

On 11/17/2017 09:25 PM, Jerry Hancock wrote:

I figured, what the heck, and just used a BNC T and it’s working.



On Nov 17, 2017, at 12:20 PM, Magnus Danielson  wrote:

Hi,

The reason I mention sharing antenna is that it takes out the difference that 
is natural from having different antennas and the difference in multipath.

Sharing antenna has its own set of problems, so a suitable antenna splitter was 
assumed. Effectively you need to bypass DC to power the antenna, you need to 
amplify the signal to compensate for the loss due to the splitter, and it needs 
to look like an antenna to the GPS receiver, so the antenna alarm does not goes 
off.

Cheers,
Magnus

On 11/17/2017 09:01 PM, Jerry Hancock wrote:

Thanks, understand completely.
You mention “sharing an antenna”.  Is there a problem with connecting the same 
antenna to two units?  I am referring to my REF0/REF1 pair.
Thanks

On Nov 17, 2017, at 11:39 AM, Magnus Danielson  
wrote:

Hi,

First of all, the receiver varies around some average phase.
The average of two receivers may not be the same, even if sharing antenna.
Their average can be offset from "absolute phase" because of offsets in the 
receiver, antenna cables and antenna.

If you are not to careful, a GPSDO will do nicely for many applications. The 
more you care, the more hassle.

Oh, and two GPSDOs next to each other can have significant common mode 
disturbance, so you can't really evaluate a GPSDO by measuring up to another 
GPSDO.

Cheers,
Magnus

On 11/17/2017 08:05 PM, Jerry Hancock wrote:

Granted I expect someone on this list to reply with something that makes me 
feel stupid, if you have two GPSDO units running side by side, should the phase 
delta on the 10Mhz output be zero (ideally)?  Is there an absolute phase 
standard kept between GPSDO units as all it would take is one extra inverter in 
the chain to flip the phase, no?
Thanks
Jerry
___
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 instructions there.

___
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 instructions there.



___
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 instructions there.

Re: [time-nuts] Absolute phase

[Jerry Hancock]

I figured, what the heck, and just used a BNC T and it’s working.


> On Nov 17, 2017, at 12:20 PM, Magnus Danielson  wrote:
> 
> Hi,
> 
> The reason I mention sharing antenna is that it takes out the difference that 
> is natural from having different antennas and the difference in multipath.
> 
> Sharing antenna has its own set of problems, so a suitable antenna splitter 
> was assumed. Effectively you need to bypass DC to power the antenna, you need 
> to amplify the signal to compensate for the loss due to the splitter, and it 
> needs to look like an antenna to the GPS receiver, so the antenna alarm does 
> not goes off.
> 
> Cheers,
> Magnus
> 
> On 11/17/2017 09:01 PM, Jerry Hancock wrote:
>> Thanks, understand completely.
>> You mention “sharing an antenna”.  Is there a problem with connecting the 
>> same antenna to two units?  I am referring to my REF0/REF1 pair.
>> Thanks
>>> On Nov 17, 2017, at 11:39 AM, Magnus Danielson  
>>> wrote:
>>> 
>>> Hi,
>>> 
>>> First of all, the receiver varies around some average phase.
>>> The average of two receivers may not be the same, even if sharing antenna.
>>> Their average can be offset from "absolute phase" because of offsets in the 
>>> receiver, antenna cables and antenna.
>>> 
>>> If you are not to careful, a GPSDO will do nicely for many applications. 
>>> The more you care, the more hassle.
>>> 
>>> Oh, and two GPSDOs next to each other can have significant common mode 
>>> disturbance, so you can't really evaluate a GPSDO by measuring up to 
>>> another GPSDO.
>>> 
>>> Cheers,
>>> Magnus
>>> 
>>> On 11/17/2017 08:05 PM, Jerry Hancock wrote:
 Granted I expect someone on this list to reply with something that makes 
 me feel stupid, if you have two GPSDO units running side by side, should 
 the phase delta on the 10Mhz output be zero (ideally)?  Is there an 
 absolute phase standard kept between GPSDO units as all it would take is 
 one extra inverter in the chain to flip the phase, no?
 Thanks
 Jerry
 ___
 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 instructions there.
>>> ___
>>> 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 instructions there.

___
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 instructions there.

Re: [time-nuts] Absolute phase

[Magnus Danielson]

Hi,

The reason I mention sharing antenna is that it takes out the difference 
that is natural from having different antennas and the difference in 
multipath.


Sharing antenna has its own set of problems, so a suitable antenna 
splitter was assumed. Effectively you need to bypass DC to power the 
antenna, you need to amplify the signal to compensate for the loss due 
to the splitter, and it needs to look like an antenna to the GPS 
receiver, so the antenna alarm does not goes off.


Cheers,
Magnus

On 11/17/2017 09:01 PM, Jerry Hancock wrote:

Thanks, understand completely.

You mention “sharing an antenna”.  Is there a problem with connecting the same 
antenna to two units?  I am referring to my REF0/REF1 pair.

Thanks


On Nov 17, 2017, at 11:39 AM, Magnus Danielson  
wrote:

Hi,

First of all, the receiver varies around some average phase.
The average of two receivers may not be the same, even if sharing antenna.
Their average can be offset from "absolute phase" because of offsets in the 
receiver, antenna cables and antenna.

If you are not to careful, a GPSDO will do nicely for many applications. The 
more you care, the more hassle.

Oh, and two GPSDOs next to each other can have significant common mode 
disturbance, so you can't really evaluate a GPSDO by measuring up to another 
GPSDO.

Cheers,
Magnus

On 11/17/2017 08:05 PM, Jerry Hancock wrote:

Granted I expect someone on this list to reply with something that makes me 
feel stupid, if you have two GPSDO units running side by side, should the phase 
delta on the 10Mhz output be zero (ideally)?  Is there an absolute phase 
standard kept between GPSDO units as all it would take is one extra inverter in 
the chain to flip the phase, no?
Thanks
Jerry
___
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 instructions there.

___
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 instructions there.



___
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 instructions there.

Re: [time-nuts] Absolute phase

[Jerry Hancock]

Thanks, understand completely.  

You mention “sharing an antenna”.  Is there a problem with connecting the same 
antenna to two units?  I am referring to my REF0/REF1 pair.

Thanks

> On Nov 17, 2017, at 11:39 AM, Magnus Danielson  
> wrote:
> 
> Hi,
> 
> First of all, the receiver varies around some average phase.
> The average of two receivers may not be the same, even if sharing antenna.
> Their average can be offset from "absolute phase" because of offsets in the 
> receiver, antenna cables and antenna.
> 
> If you are not to careful, a GPSDO will do nicely for many applications. The 
> more you care, the more hassle.
> 
> Oh, and two GPSDOs next to each other can have significant common mode 
> disturbance, so you can't really evaluate a GPSDO by measuring up to another 
> GPSDO.
> 
> Cheers,
> Magnus
> 
> On 11/17/2017 08:05 PM, Jerry Hancock wrote:
>> Granted I expect someone on this list to reply with something that makes me 
>> feel stupid, if you have two GPSDO units running side by side, should the 
>> phase delta on the 10Mhz output be zero (ideally)?  Is there an absolute 
>> phase standard kept between GPSDO units as all it would take is one extra 
>> inverter in the chain to flip the phase, no?
>> Thanks
>> Jerry
>> ___
>> 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 instructions there.
> ___
> 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 instructions there.

___
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 instructions there.

Re: [time-nuts] Absolute phase

[Magnus Danielson]

Hi,

First of all, the receiver varies around some average phase.
The average of two receivers may not be the same, even if sharing antenna.
Their average can be offset from "absolute phase" because of offsets in 
the receiver, antenna cables and antenna.


If you are not to careful, a GPSDO will do nicely for many applications. 
The more you care, the more hassle.


Oh, and two GPSDOs next to each other can have significant common mode 
disturbance, so you can't really evaluate a GPSDO by measuring up to 
another GPSDO.


Cheers,
Magnus

On 11/17/2017 08:05 PM, Jerry Hancock wrote:

Granted I expect someone on this list to reply with something that makes me 
feel stupid, if you have two GPSDO units running side by side, should the phase 
delta on the 10Mhz output be zero (ideally)?  Is there an absolute phase 
standard kept between GPSDO units as all it would take is one extra inverter in 
the chain to flip the phase, no?

Thanks

Jerry


___
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 instructions there.


___
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 instructions there.

Re: [time-nuts] Absolute phase

[Bob kb8tq]

Hi

Most GPSDO’s use a divider to get straight from the 10 MHz to the PPS. There 
are some that 
derive both the PPS and the 10 MHz off a higher frequency, they are not common 
in the eBay
world (yet). The divider is going to have a fixed delay based on it’s design. 
That might be 35 ns,
it might be 3.5 ns. It all depends on how they did this or that. There easily 
could be an inversion 
that moves everything 50 ns. 

If the GPSDO wanders around over a 30 ns range, that’s a pretty big phase shift 
at 10 MHz. If
they both are doing this you are up to (maybe) half a cycle or more. 

Now toss in devices that “skip” a 10 MHz cycle to keep the PPS aligned. This is 
pretty uncommon 
in normal operation. Uncommon does not mean that it never happens. 

So, if you have two of the same model / same firmware GPSDO’s, the 10 MHz phase 
is probably
“in the ballpark”. It’s certainly not close in terms of < 1 degree or something 
like that. If you have
GPSDO’s from multiple outfits …. who knows what you will see.

Bob

> On Nov 17, 2017, at 2:05 PM, Jerry Hancock  wrote:
> 
> Granted I expect someone on this list to reply with something that makes me 
> feel stupid, if you have two GPSDO units running side by side, should the 
> phase delta on the 10Mhz output be zero (ideally)?  Is there an absolute 
> phase standard kept between GPSDO units as all it would take is one extra 
> inverter in the chain to flip the phase, no?
> 
> Thanks
> 
> Jerry
> 
> 
> ___
> 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 instructions there.

___
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 instructions there.

Re: [time-nuts] Absolute phase

[jimlux]

On 11/17/17 11:05 AM, Jerry Hancock wrote:

Granted I expect someone on this list to reply with something that makes me 
feel stupid, if you have two GPSDO units running side by side, should the phase 
delta on the 10Mhz output be zero (ideally)?  Is there an absolute phase 
standard kept between GPSDO units as all it would take is one extra inverter in 
the chain to flip the phase, no?



I don't think so..
GPSDOs are really more of a syntonization (same frequency) rather than a 
synchronization (same phase) box.


You might have two boxes of the same kind that have some well defined 
and stable phase relationship between, say, the 10 MHz sine and the 1pps 
(if the 1pps is derived by dividing the 10 MHz, for instance)



___
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 instructions there.

[time-nuts] Absolute phase

[Jerry Hancock]

Granted I expect someone on this list to reply with something that makes me 
feel stupid, if you have two GPSDO units running side by side, should the phase 
delta on the 10Mhz output be zero (ideally)?  Is there an absolute phase 
standard kept between GPSDO units as all it would take is one extra inverter in 
the chain to flip the phase, no?

Thanks

Jerry


___
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 instructions there.