BS
Bob Stewart
Sun, Dec 18, 2016 11:16 PM
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
-----------------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
-----------------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
ES
Eric Scace
Mon, Dec 19, 2016 12:13 AM
Speaking as an owner of a well-behaved mechanical clock:
Clock rate performance over time can be done based on time interval measurements anchored to a solid frequency standard. No 1pps needed per se.
Bring a clock to time is simplified with a timescale-accurate 1pps source.
On 2016 Dec 18, at 18:16 , Bob Stewart bob@evoria.net wrote:
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
Speaking as an owner of a well-behaved mechanical clock:
Clock rate performance over time can be done based on time interval measurements anchored to a solid frequency standard. No 1pps needed per se.
Bring a clock to time is simplified with a timescale-accurate 1pps source.
> On 2016 Dec 18, at 18:16 , Bob Stewart <bob@evoria.net> wrote:
>
> One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
> Bob - AE6RV
BC
Bob Camp
Mon, Dec 19, 2016 12:16 AM
Hi
Roughly 99% of all GPSDO’s are only used for the PPS output. They go into cell sites and the reason
they exist is to sync up the Gold Codes on CDMA. That’s also why you see a lot of PPS only Rb’s
on the surplus market. The ones that don’t get used for cell towers, mostly go into other com systems
that for some reason need to have accurate time (also involves codes …).
Bob
On Dec 18, 2016, at 6:16 PM, Bob Stewart bob@evoria.net wrote:
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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.
Hi
Roughly 99% of all GPSDO’s are only used for the PPS output. They go into cell sites and the reason
they exist is to sync up the Gold Codes on CDMA. That’s also why you see a *lot* of PPS only Rb’s
on the surplus market. The ones that don’t get used for cell towers, mostly go into other com systems
that for some reason need to have accurate time (also involves codes …).
Bob
> On Dec 18, 2016, at 6:16 PM, Bob Stewart <bob@evoria.net> wrote:
>
> One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
> Bob - AE6RV
> -----------------------------------------------------------------
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> _______________________________________________
> 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.
J
jimlux
Mon, Dec 19, 2016 12:56 AM
On 12/18/16 3:16 PM, Bob Stewart wrote:
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Anyone who needs to trigger events at a precise time or log the
occurrence of an event uses the 1 pps - the serial port (or other
interface) gives you the "at the tone the time will be" message, and the
edge of the 1pps is the "tone".
I've got several systems flying in space (or soon to fly in space) that
use the 1pps from GPS to calibrate their internal clocks and/or to
provide an absolute time reference (along with the aforesaid time message).
For example, one needs to have your carrier frequency within a certain
tolerance for communications with the ground stations: you can either
fly a precision oscillator with an oven (big, heavy, high power) or you
can measure a not-so-precision oscillator (small, cheap, low power)
against a 1pps, and adjust your frequency that way.
I grant you that this is really more like building a GPSDO than
using a GPSDO.
I've used the 1pps from a GPSDO as a common trigger to synchronize
timing and timestamping for separate systems.
On 12/18/16 3:16 PM, Bob Stewart wrote:
> One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Anyone who needs to trigger events at a precise time or log the
occurrence of an event uses the 1 pps - the serial port (or other
interface) gives you the "at the tone the time will be" message, and the
edge of the 1pps is the "tone".
I've got several systems flying in space (or soon to fly in space) that
use the 1pps from GPS to calibrate their internal clocks and/or to
provide an absolute time reference (along with the aforesaid time message).
For example, one needs to have your carrier frequency within a certain
tolerance for communications with the ground stations: you can either
fly a precision oscillator with an oven (big, heavy, high power) or you
can measure a not-so-precision oscillator (small, cheap, low power)
against a 1pps, and adjust your frequency that way.
I grant you that this is really more like *building* a GPSDO than
*using* a GPSDO.
I've used the 1pps from a GPSDO as a common trigger to synchronize
timing and timestamping for separate systems.
BS
Bob Stewart
Mon, Dec 19, 2016 1:33 AM
Hi Jim,
Thanks Jim,
So, what I'm seeing so far, assuming I'm interpreting it correctly, is big budget commercial and government applications, generally clustering around time-controlled multiplexing, as well as the niche that is the space industry. Then there's the hobbyist, such as Eric who wants to control a Fedchenko clock, or similar type of application, such as whatever sort of spread spectrum that ham radio may morph into, or perhaps the low S/N EME guys. Any others?
Bob
From: jimlux <jimlux@earthlink.net>
To: time-nuts@febo.com
Sent: Sunday, December 18, 2016 6:56 PM
Subject: Re: [time-nuts] 1PPS users?
On 12/18/16 3:16 PM, Bob Stewart wrote:
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Anyone who needs to trigger events at a precise time or log the
occurrence of an event uses the 1 pps - the serial port (or other
interface) gives you the "at the tone the time will be" message, and the
edge of the 1pps is the "tone".
I've got several systems flying in space (or soon to fly in space) that
use the 1pps from GPS to calibrate their internal clocks and/or to
provide an absolute time reference (along with the aforesaid time message).
For example, one needs to have your carrier frequency within a certain
tolerance for communications with the ground stations: you can either
fly a precision oscillator with an oven (big, heavy, high power) or you
can measure a not-so-precision oscillator (small, cheap, low power)
against a 1pps, and adjust your frequency that way.
I grant you that this is really more like building a GPSDO than
using a GPSDO.
I've used the 1pps from a GPSDO as a common trigger to synchronize
timing and timestamping for separate systems.
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.
Hi Jim,
Thanks Jim,
So, what I'm seeing so far, assuming I'm interpreting it correctly, is big budget commercial and government applications, generally clustering around time-controlled multiplexing, as well as the niche that is the space industry. Then there's the hobbyist, such as Eric who wants to control a Fedchenko clock, or similar type of application, such as whatever sort of spread spectrum that ham radio may morph into, or perhaps the low S/N EME guys. Any others?
Bob
From: jimlux <jimlux@earthlink.net>
To: time-nuts@febo.com
Sent: Sunday, December 18, 2016 6:56 PM
Subject: Re: [time-nuts] 1PPS users?
On 12/18/16 3:16 PM, Bob Stewart wrote:
> One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Anyone who needs to trigger events at a precise time or log the
occurrence of an event uses the 1 pps - the serial port (or other
interface) gives you the "at the tone the time will be" message, and the
edge of the 1pps is the "tone".
I've got several systems flying in space (or soon to fly in space) that
use the 1pps from GPS to calibrate their internal clocks and/or to
provide an absolute time reference (along with the aforesaid time message).
For example, one needs to have your carrier frequency within a certain
tolerance for communications with the ground stations: you can either
fly a precision oscillator with an oven (big, heavy, high power) or you
can measure a not-so-precision oscillator (small, cheap, low power)
against a 1pps, and adjust your frequency that way.
I grant you that this is really more like *building* a GPSDO than
*using* a GPSDO.
I've used the 1pps from a GPSDO as a common trigger to synchronize
timing and timestamping for separate systems.
_______________________________________________
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.
CA
Chris Albertson
Mon, Dec 19, 2016 1:35 AM
Who uses 1PPS? In industry they are used to phase lock various
oscillators. I would bet most of those oscillators are used in the
telecommunications industry both for bit rate clocks and for carrier
frequency synthesis.
We also see a lot of 1 PPS used for NTP servers that in turn are used to
keep computer internal time of day clocks running at the correct rate.
On Sun, Dec 18, 2016 at 3:16 PM, Bob Stewart bob@evoria.net wrote:
One thing I've never really understood is who actually uses the
high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort,
and money on developing my GPSDO without a whole of thought to the user
base. It was just a quest for the best result I could obtain with a
particular technology. The frequency standard users was a no brainer.
Everyone who wants a frequency standard eventually understands they need to
get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good
frequency standard. And then Tom prodded me a bit and showed me the
shortcomings of what I was doing, and I did something about it. So, if an
NTP user can get his time fix directly from a noisy receiver, who actually
needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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.
--
Chris Albertson
Redondo Beach, California
Who uses 1PPS? In industry they are used to phase lock various
oscillators. I would bet most of those oscillators are used in the
telecommunications industry both for bit rate clocks and for carrier
frequency synthesis.
We also see a lot of 1 PPS used for NTP servers that in turn are used to
keep computer internal time of day clocks running at the correct rate.
On Sun, Dec 18, 2016 at 3:16 PM, Bob Stewart <bob@evoria.net> wrote:
> One thing I've never really understood is who actually uses the
> high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort,
> and money on developing my GPSDO without a whole of thought to the user
> base. It was just a quest for the best result I could obtain with a
> particular technology. The frequency standard users was a no brainer.
> Everyone who wants a frequency standard eventually understands they need to
> get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good
> frequency standard. And then Tom prodded me a bit and showed me the
> shortcomings of what I was doing, and I did something about it. So, if an
> NTP user can get his time fix directly from a noisy receiver, who actually
> needs a time-accurate, low jitter 1PPS pulse?
> Bob - AE6RV
> -----------------------------------------------------------------
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> _______________________________________________
> 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.
>
--
Chris Albertson
Redondo Beach, California
JA
John Ackermann N8UR
Mon, Dec 19, 2016 1:54 AM
For amateur use, PPS comparison requires less equipment and can be more
accurate than trying to measure RF rates like 10 MHz.
When comparing two PPS signals, phase slips are very infrequent so you
can observe drift rate over minutes/hours/days with an oscilloscope or
simple time interval counter to get much better resolution than most
frequency counters can provide. (Of course, a GPS works as well for
this as a GPSDO, albeit with more short term jitter.)
John
On 12/18/2016 08:33 PM, Bob Stewart wrote:
Hi Jim,
Thanks Jim,
So, what I'm seeing so far, assuming I'm interpreting it correctly, is big budget commercial and government applications, generally clustering around time-controlled multiplexing, as well as the niche that is the space industry. Then there's the hobbyist, such as Eric who wants to control a Fedchenko clock, or similar type of application, such as whatever sort of spread spectrum that ham radio may morph into, or perhaps the low S/N EME guys. Any others?
Bob
From: jimlux <jimlux@earthlink.net>
To: time-nuts@febo.com
Sent: Sunday, December 18, 2016 6:56 PM
Subject: Re: [time-nuts] 1PPS users?
On 12/18/16 3:16 PM, Bob Stewart wrote:
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Anyone who needs to trigger events at a precise time or log the
occurrence of an event uses the 1 pps - the serial port (or other
interface) gives you the "at the tone the time will be" message, and the
edge of the 1pps is the "tone".
I've got several systems flying in space (or soon to fly in space) that
use the 1pps from GPS to calibrate their internal clocks and/or to
provide an absolute time reference (along with the aforesaid time message).
For example, one needs to have your carrier frequency within a certain
tolerance for communications with the ground stations: you can either
fly a precision oscillator with an oven (big, heavy, high power) or you
can measure a not-so-precision oscillator (small, cheap, low power)
against a 1pps, and adjust your frequency that way.
I grant you that this is really more like building a GPSDO than
using a GPSDO.
I've used the 1pps from a GPSDO as a common trigger to synchronize
timing and timestamping for separate systems.
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.
For amateur use, PPS comparison requires less equipment and can be more
accurate than trying to measure RF rates like 10 MHz.
When comparing two PPS signals, phase slips are very infrequent so you
can observe drift rate over minutes/hours/days with an oscilloscope or
simple time interval counter to get much better resolution than most
frequency counters can provide. (Of course, a GPS works as well for
this as a GPSDO, albeit with more short term jitter.)
John
----
On 12/18/2016 08:33 PM, Bob Stewart wrote:
> Hi Jim,
> Thanks Jim,
>
> So, what I'm seeing so far, assuming I'm interpreting it correctly, is big budget commercial and government applications, generally clustering around time-controlled multiplexing, as well as the niche that is the space industry. Then there's the hobbyist, such as Eric who wants to control a Fedchenko clock, or similar type of application, such as whatever sort of spread spectrum that ham radio may morph into, or perhaps the low S/N EME guys. Any others?
> Bob
>
> From: jimlux <jimlux@earthlink.net>
> To: time-nuts@febo.com
> Sent: Sunday, December 18, 2016 6:56 PM
> Subject: Re: [time-nuts] 1PPS users?
>
> On 12/18/16 3:16 PM, Bob Stewart wrote:
>> One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
>
> Anyone who needs to trigger events at a precise time or log the
> occurrence of an event uses the 1 pps - the serial port (or other
> interface) gives you the "at the tone the time will be" message, and the
> edge of the 1pps is the "tone".
>
>
> I've got several systems flying in space (or soon to fly in space) that
> use the 1pps from GPS to calibrate their internal clocks and/or to
> provide an absolute time reference (along with the aforesaid time message).
>
> For example, one needs to have your carrier frequency within a certain
> tolerance for communications with the ground stations: you can either
> fly a precision oscillator with an oven (big, heavy, high power) or you
> can measure a not-so-precision oscillator (small, cheap, low power)
> against a 1pps, and adjust your frequency that way.
>
> I grant you that this is really more like *building* a GPSDO than
> *using* a GPSDO.
>
> I've used the 1pps from a GPSDO as a common trigger to synchronize
> timing and timestamping for separate systems.
>
>
>
> _______________________________________________
> 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.
>
PR
Peter Reilley
Mon, Dec 19, 2016 1:59 AM
There was a discussion here a while ago about synchronizing radio
telescopes that
were separated by some miles. The 1PPS from GPS was suggested as a
possibility.
I am working on a project to do location by triangulation that uses the
1PPS signal.
I would like to get better than the +-10 nS that the better receivers
provide.
Pete.
On 12/18/2016 6:16 PM, Bob Stewart wrote:
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
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.
There was a discussion here a while ago about synchronizing radio
telescopes that
were separated by some miles. The 1PPS from GPS was suggested as a
possibility.
I am working on a project to do location by triangulation that uses the
1PPS signal.
I would like to get better than the +-10 nS that the better receivers
provide.
Pete.
On 12/18/2016 6:16 PM, Bob Stewart wrote:
> One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
> Bob - AE6RV
> -----------------------------------------------------------------
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> _______________________________________________
> 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.
>
SS
Scott Stobbe
Mon, Dec 19, 2016 2:22 AM
Part of the reason 1PPS needs to be so clean is because you are
continuously integrating phase noise of the LO (hopefully an OCXO). While
10 uS is pretty trivial off a gps receiver. Without gps, 10 us over 24 hrs
with a plane jane AT-cut crystal subject environmental dynamics becomes
ludicrous. More than likely the short term stability of GPSDO is cleaner
than it needs to be for many applications, but that is so holdover over an
hour or day remains reasonable.
On Sun, Dec 18, 2016 at 6:16 PM, Bob Stewart bob@evoria.net wrote:
One thing I've never really understood is who actually uses the
high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort,
and money on developing my GPSDO without a whole of thought to the user
base. It was just a quest for the best result I could obtain with a
particular technology. The frequency standard users was a no brainer.
Everyone who wants a frequency standard eventually understands they need to
get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good
frequency standard. And then Tom prodded me a bit and showed me the
shortcomings of what I was doing, and I did something about it. So, if an
NTP user can get his time fix directly from a noisy receiver, who actually
needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
AE6RV.com
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Part of the reason 1PPS needs to be so clean is because you are
continuously integrating phase noise of the LO (hopefully an OCXO). While
10 uS is pretty trivial off a gps receiver. Without gps, 10 us over 24 hrs
with a plane jane AT-cut crystal subject environmental dynamics becomes
ludicrous. More than likely the short term stability of GPSDO is cleaner
than it needs to be for many applications, but that is so holdover over an
hour or day remains reasonable.
On Sun, Dec 18, 2016 at 6:16 PM, Bob Stewart <bob@evoria.net> wrote:
> One thing I've never really understood is who actually uses the
> high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort,
> and money on developing my GPSDO without a whole of thought to the user
> base. It was just a quest for the best result I could obtain with a
> particular technology. The frequency standard users was a no brainer.
> Everyone who wants a frequency standard eventually understands they need to
> get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good
> frequency standard. And then Tom prodded me a bit and showed me the
> shortcomings of what I was doing, and I did something about it. So, if an
> NTP user can get his time fix directly from a noisy receiver, who actually
> needs a time-accurate, low jitter 1PPS pulse?
> Bob - AE6RV
> -----------------------------------------------------------------
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> _______________________________________________
> 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.
>
BS
Bob Stewart
Mon, Dec 19, 2016 4:20 AM
Hi Scott,
I do understand the reasons that these users want this quality of output. It's who these users are, what fields, industries, etc, that I didn't quite understand.
Bob -----------------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
From: Scott Stobbe <scott.j.stobbe@gmail.com>
To: Bob Stewart bob@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sunday, December 18, 2016 8:22 PM
Subject: Re: [time-nuts] 1PPS users?
Part of the reason 1PPS needs to be so clean is because you are continuously integrating phase noise of the LO (hopefully an OCXO). While 10 uS is pretty trivial off a gps receiver. Without gps, 10 us over 24 hrs with a plane jane AT-cut crystal subject environmental dynamics becomes ludicrous. More than likely the short term stability of GPSDO is cleaner than it needs to be for many applications, but that is so holdover over an hour or day remains reasonable.
On Sun, Dec 18, 2016 at 6:16 PM, Bob Stewart bob@evoria.net wrote:
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
----------------------------- ------------------------------ ------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/ GFS-GPSDOs/info
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.
Hi Scott,
I do understand the reasons that these users want this quality of output. It's who these users are, what fields, industries, etc, that I didn't quite understand.
Bob -----------------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
From: Scott Stobbe <scott.j.stobbe@gmail.com>
To: Bob Stewart <bob@evoria.net>; Discussion of precise time and frequency measurement <time-nuts@febo.com>
Sent: Sunday, December 18, 2016 8:22 PM
Subject: Re: [time-nuts] 1PPS users?
Part of the reason 1PPS needs to be so clean is because you are continuously integrating phase noise of the LO (hopefully an OCXO). While 10 uS is pretty trivial off a gps receiver. Without gps, 10 us over 24 hrs with a plane jane AT-cut crystal subject environmental dynamics becomes ludicrous. More than likely the short term stability of GPSDO is cleaner than it needs to be for many applications, but that is so holdover over an hour or day remains reasonable.
On Sun, Dec 18, 2016 at 6:16 PM, Bob Stewart <bob@evoria.net> wrote:
One thing I've never really understood is who actually uses the high-quality 1PPS output from a GPSDO. I have spent a lot of time, effort, and money on developing my GPSDO without a whole of thought to the user base. It was just a quest for the best result I could obtain with a particular technology. The frequency standard users was a no brainer. Everyone who wants a frequency standard eventually understands they need to get a GPSDO, or an Rb, or a Cs. And that's all I thought I had: a good frequency standard. And then Tom prodded me a bit and showed me the shortcomings of what I was doing, and I did something about it. So, if an NTP user can get his time fix directly from a noisy receiver, who actually needs a time-accurate, low jitter 1PPS pulse?
Bob - AE6RV
----------------------------- ------------------------------ ------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/ GFS-GPSDOs/info
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