Empathy List Archives

BC

Brooke Clarke

Sun, Dec 25, 2022 9:51 PM

Hi Matthias:

Here's a hardware GPS sawtooth corrector I made some time ago:
https://prc68.com/I/timefreq.shtml#Sawtoooth
Although it did not work on the Motorola GPS it would give you some idea of what parts are needed.
https://prc68.com/I/PRS10.shtml

--
Have Fun,

Brooke Clarke
https://www.PRC68.com
axioms:

The extent to which you can fix or improve something will be limited by how well you understand how it works.
Everybody, with no exceptions, holds false beliefs.

-------- Original Message --------

On Donnerstag, 22. Dezember 2022 00:22:37 CET James Wilson via time-nuts
wrote:

After running in many of the familiar problems of connecting a GPS timing
module 1PPS signal to a PRS-10, I want try building a software sawtooth
correction board. I’ve seen previous discussion of some of the commands to
use for adjusting the PLL and PPS control on the PRS-10 and getting the
sawtooth error from ublox GNSS modules, but not a start-to-finish
description of how to put everything together.

My idea to use a microcontroller with multiple UART ports; one connected to
the ublox module and the other connected to the PRS-10, with level shifters
as needed. The microcontroller sits between the two devices, and gets the
PPS sawtooth correction info from the ublox (specifically via the
UBX-TIM-TP message and its qErr field), and then adjusts the PRS-10’s PPS
time offset by this value to null out the sawtooth for the next pulse.

I suggest you try correcting the 1PPS pulse of the timing module itself, using
a variable delay line. I don't have a particular part in mind, Maxim might
have something.

There was a very elaborate GPSDO project discussed last year on this list that
used this technique.

BR,
Matthias

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Matthias: Here's a hardware GPS sawtooth corrector I made some time ago: https://prc68.com/I/timefreq.shtml#Sawtoooth Although it did not work on the Motorola GPS it would give you some idea of what parts are needed. https://prc68.com/I/PRS10.shtml -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. -------- Original Message -------- > On Donnerstag, 22. Dezember 2022 00:22:37 CET James Wilson via time-nuts > wrote: >> After running in many of the familiar problems of connecting a GPS timing >> module 1PPS signal to a PRS-10, I want try building a software sawtooth >> correction board. I’ve seen previous discussion of some of the commands to >> use for adjusting the PLL and PPS control on the PRS-10 and getting the >> sawtooth error from ublox GNSS modules, but not a start-to-finish >> description of how to put everything together. > >> My idea to use a microcontroller with multiple UART ports; one connected to >> the ublox module and the other connected to the PRS-10, with level shifters >> as needed. The microcontroller sits between the two devices, and gets the >> PPS sawtooth correction info from the ublox (specifically via the >> UBX-TIM-TP message and its qErr field), and then adjusts the PRS-10’s PPS >> time offset by this value to null out the sawtooth for the next pulse. > I suggest you try correcting the 1PPS pulse of the timing module itself, using > a variable delay line. I don't have a particular part in mind, Maxim might > have something. > > There was a very elaborate GPSDO project discussed last year on this list that > used this technique. > > BR, > Matthias > >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

BC

Bob Camp

Sun, Dec 25, 2022 11:46 PM

Hi

Just a note for anybody headed down this path:

There are several cases for sawtooth correction:

Message applies to previous PPS / message applies to next PPS
Sawtooth is added / sawtooth is subtracted

It seems like this would be easy to just read out of the doc’s on the device and put into action.
From doing it on several dozen devices over the years … not so much. You have four cases.
Testing them all is not super tough to do. Implement each of them and note if the 1 second ADEV
gets better or worse. One of the four should stand out as the winner …..

Bob

On Dec 25, 2022, at 4:51 PM, Brooke Clarke via time-nuts time-nuts@lists.febo.com wrote:

Hi Matthias:

Here's a hardware GPS sawtooth corrector I made some time ago:
https://prc68.com/I/timefreq.shtml#Sawtoooth
Although it did not work on the Motorola GPS it would give you some idea of what parts are needed.
https://prc68.com/I/PRS10.shtml

--
Have Fun,

Brooke Clarke
https://www.PRC68.com
axioms:

The extent to which you can fix or improve something will be limited by how well you understand how it works.
Everybody, with no exceptions, holds false beliefs.

-------- Original Message --------

On Donnerstag, 22. Dezember 2022 00:22:37 CET James Wilson via time-nuts
wrote:

After running in many of the familiar problems of connecting a GPS timing
module 1PPS signal to a PRS-10, I want try building a software sawtooth
correction board. I’ve seen previous discussion of some of the commands to
use for adjusting the PLL and PPS control on the PRS-10 and getting the
sawtooth error from ublox GNSS modules, but not a start-to-finish
description of how to put everything together.

My idea to use a microcontroller with multiple UART ports; one connected to
the ublox module and the other connected to the PRS-10, with level shifters
as needed. The microcontroller sits between the two devices, and gets the
PPS sawtooth correction info from the ublox (specifically via the
UBX-TIM-TP message and its qErr field), and then adjusts the PRS-10’s PPS
time offset by this value to null out the sawtooth for the next pulse.

I suggest you try correcting the 1PPS pulse of the timing module itself, using
a variable delay line. I don't have a particular part in mind, Maxim might
have something.

There was a very elaborate GPSDO project discussed last year on this list that
used this technique.

BR,
Matthias

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Just a note for anybody headed down this path: There are several cases for sawtooth correction: Message applies to previous PPS / message applies to next PPS Sawtooth is added / sawtooth is subtracted It *seems* like this would be easy to just read out of the doc’s on the device and put into action. From doing it on several dozen devices over the years … not so much. You have four cases. Testing them all is not super tough to do. Implement each of them and note if the 1 second ADEV gets better or worse. One of the four *should* stand out as the winner ….. Bob > On Dec 25, 2022, at 4:51 PM, Brooke Clarke via time-nuts <time-nuts@lists.febo.com> wrote: > > Hi Matthias: > > Here's a hardware GPS sawtooth corrector I made some time ago: > https://prc68.com/I/timefreq.shtml#Sawtoooth > Although it did not work on the Motorola GPS it would give you some idea of what parts are needed. > https://prc68.com/I/PRS10.shtml > > -- > Have Fun, > > Brooke Clarke > https://www.PRC68.com > axioms: > 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. > 2. Everybody, with no exceptions, holds false beliefs. > > -------- Original Message -------- >> On Donnerstag, 22. Dezember 2022 00:22:37 CET James Wilson via time-nuts >> wrote: >>> After running in many of the familiar problems of connecting a GPS timing >>> module 1PPS signal to a PRS-10, I want try building a software sawtooth >>> correction board. I’ve seen previous discussion of some of the commands to >>> use for adjusting the PLL and PPS control on the PRS-10 and getting the >>> sawtooth error from ublox GNSS modules, but not a start-to-finish >>> description of how to put everything together. >> >>> My idea to use a microcontroller with multiple UART ports; one connected to >>> the ublox module and the other connected to the PRS-10, with level shifters >>> as needed. The microcontroller sits between the two devices, and gets the >>> PPS sawtooth correction info from the ublox (specifically via the >>> UBX-TIM-TP message and its qErr field), and then adjusts the PRS-10’s PPS >>> time offset by this value to null out the sawtooth for the next pulse. >> I suggest you try correcting the 1PPS pulse of the timing module itself, using >> a variable delay line. I don't have a particular part in mind, Maxim might >> have something. >> >> There was a very elaborate GPSDO project discussed last year on this list that >> used this technique. >> >> BR, >> Matthias >> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe send an email to time-nuts-leave@lists.febo.com >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

E

ew

Sun, Dec 25, 2022 11:56 PM

This is all it takes. I would leave the GPS unit separate since so many choices are available including a 9T and 250 and 500 psec chips are readily available now Analog Devices. At the time I did publish it there was no interest today I am to old but be glad to help off list
Bert Kehren
In a message dated 12/25/2022 6:32:49 PM Eastern Standard Time, time-nuts@lists.febo.com writes:
Hi Matthias:

Here's a hardware GPS sawtooth corrector I made some time ago:
https://prc68.com/I/timefreq.shtml#Sawtoooth
Although it did not work on the Motorola GPS it would give you some idea of what parts are needed.
https://prc68.com/I/PRS10.shtml

--
Have Fun,

Brooke Clarke
https://www.PRC68.com
axioms:

The extent to which you can fix or improve something will be limited by how well you understand how it works.
Everybody, with no exceptions, holds false beliefs.

-------- Original Message --------

On Donnerstag, 22. Dezember 2022 00:22:37 CET James Wilson via time-nuts
wrote:

After running in many of the familiar problems of connecting a GPS timing
module 1PPS signal to a PRS-10, I want try building a software sawtooth
correction board. I’ve seen previous discussion of some of the commands to
use for adjusting the PLL and PPS control on the PRS-10 and getting the
sawtooth error from ublox GNSS modules, but not a start-to-finish
description of how to put everything together.

My idea to use a microcontroller with multiple UART ports; one connected to
the ublox module and the other connected to the PRS-10, with level shifters
as needed. The microcontroller sits between the two devices, and gets the
PPS sawtooth correction info from the ublox (specifically via the
UBX-TIM-TP message and its qErr field), and then adjusts the PRS-10’s PPS
time offset by this value to null out the sawtooth for the next pulse.

I suggest you try correcting the 1PPS pulse of the timing module itself, using
a variable delay line. I don't have a particular part in mind, Maxim might
have something.

There was a very elaborate GPSDO project discussed last year on this list that
used this technique.

BR,
Matthias

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com

This is all it takes. I would leave the GPS unit separate since so many choices are available including a 9T and 250 and 500 psec chips are readily available now Analog Devices. At the time I did publish it there was no interest today I am to old but be glad to help off list Bert Kehren In a message dated 12/25/2022 6:32:49 PM Eastern Standard Time, time-nuts@lists.febo.com writes: Hi Matthias: Here's a hardware GPS sawtooth corrector I made some time ago: https://prc68.com/I/timefreq.shtml#Sawtoooth Although it did not work on the Motorola GPS it would give you some idea of what parts are needed. https://prc68.com/I/PRS10.shtml -- Have Fun, Brooke Clarke https://www.PRC68.com axioms: 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. 2. Everybody, with no exceptions, holds false beliefs. -------- Original Message -------- > On Donnerstag, 22. Dezember 2022 00:22:37 CET James Wilson via time-nuts > wrote: >> After running in many of the familiar problems of connecting a GPS timing >> module 1PPS signal to a PRS-10, I want try building a software sawtooth >> correction board. I’ve seen previous discussion of some of the commands to >> use for adjusting the PLL and PPS control on the PRS-10 and getting the >> sawtooth error from ublox GNSS modules, but not a start-to-finish >> description of how to put everything together. > >> My idea to use a microcontroller with multiple UART ports; one connected to >> the ublox module and the other connected to the PRS-10, with level shifters >> as needed. The microcontroller sits between the two devices, and gets the >> PPS sawtooth correction info from the ublox (specifically via the >> UBX-TIM-TP message and its qErr field), and then adjusts the PRS-10’s PPS >> time offset by this value to null out the sawtooth for the next pulse. > I suggest you try correcting the 1PPS pulse of the timing module itself, using > a variable delay line. I don't have a particular part in mind, Maxim might > have something. > > There was a very elaborate GPSDO project discussed last year on this list that > used this technique. > > BR, > Matthias > >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com

MW

Matthias Welwarsky

Tue, Dec 27, 2022 9:15 AM

On Montag, 26. Dezember 2022 00:56:08 CET ew via time-nuts wrote:

This is all it takes. I would leave the GPS unit separate since so many
choices are available including a 9T and 250 and 500 psec chips are readily
available now Analog Devices. At the time I did publish it there was no
interest today I am to old but be glad to help off list
Bert Kehren

Indeed the Maxim DS102x series of programmable delay lines was what I found,
too, and it seemed to fit the bill after a cursory look. Good to see that it
can actually be used.

BR,
Matthias

On Montag, 26. Dezember 2022 00:56:08 CET ew via time-nuts wrote: > This is all it takes. I would leave the GPS unit separate since so many > choices are available including a 9T and 250 and 500 psec chips are readily > available now Analog Devices. At the time I did publish it there was no > interest today I am to old but be glad to help off list > Bert Kehren Indeed the Maxim DS102x series of programmable delay lines was what I found, too, and it seemed to fit the bill after a cursory look. Good to see that it can actually be used. BR, Matthias

JW

James Wilson

Wed, Dec 28, 2022 12:38 AM

On 2022-12-27 01:15, Matthias Welwarsky via time-nuts wrote:

On Montag, 26. Dezember 2022 00:56:08 CET ew via time-nuts wrote:

This is all it takes. I would leave the GPS unit separate since so many
choices are available including a 9T and 250 and 500 psec chips are readily
available now Analog Devices. At the time I did publish it there was no
interest today I am to old but be glad to help off list
Bert Kehren

Indeed the Maxim DS102x series of programmable delay lines was what I found,
too, and it seemed to fit the bill after a cursory look. Good to see that it
can actually be used.

I can't see what the other ICs on Bert's board are, but I gather it is
using the timing module's sawtooth error data to set the programmable
delay line. This seems to be a good option if the receiver of the PPS
signal cannot accept adjustment data, but what can it do if the qErr
data indicates the next pulse is going to be late instead of early?

On 2022-12-27 01:15, Matthias Welwarsky via time-nuts wrote: > On Montag, 26. Dezember 2022 00:56:08 CET ew via time-nuts wrote: >> This is all it takes. I would leave the GPS unit separate since so many >> choices are available including a 9T and 250 and 500 psec chips are readily >> available now Analog Devices. At the time I did publish it there was no >> interest today I am to old but be glad to help off list >> Bert Kehren > > Indeed the Maxim DS102x series of programmable delay lines was what I found, > too, and it seemed to fit the bill after a cursory look. Good to see that it > can actually be used. I can't see what the other ICs on Bert's board are, but I gather it is using the timing module's sawtooth error data to set the programmable delay line. This seems to be a good option if the receiver of the PPS signal cannot accept adjustment data, but what can it do if the qErr data indicates the next pulse is going to be late instead of early?

E

ew

Wed, Dec 28, 2022 1:23 AM

There are 3 IC's. A PIC, a HEX inverter chip and the delay chip. Today I would use a Arduino 114 pin DIL more software experts.and socket.
Bert Kehren
In a message dated 12/27/2022 7:43:12 PM Eastern Standard Time, time-nuts@lists.febo.com writes:
On 2022-12-27 01:15, Matthias Welwarsky via time-nuts wrote:

On Montag, 26. Dezember 2022 00:56:08 CET ew via time-nuts wrote:

This is all it takes. I would leave the GPS unit separate since so many
choices are available including a 9T and 250 and 500 psec chips are readily
available now Analog Devices. At the time I did publish it there was no
interest today I am to old but be glad to help off list
Bert Kehren

Indeed the Maxim DS102x series of programmable delay lines was what I found,
too, and it seemed to fit the bill after a cursory look. Good to see that it
can actually be used.

I can't see what the other ICs on Bert's board are, but I gather it is
using the timing module's sawtooth error data to set the programmable
delay line. This seems to be a good option if the receiver of the PPS
signal cannot accept adjustment data, but what can it do if the qErr
data indicates the next pulse is going to be late instead of early?

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com

There are 3 IC's. A PIC, a HEX inverter chip and the delay chip. Today I would use a Arduino 114 pin DIL more software experts.and socket. Bert Kehren In a message dated 12/27/2022 7:43:12 PM Eastern Standard Time, time-nuts@lists.febo.com writes: On 2022-12-27 01:15, Matthias Welwarsky via time-nuts wrote: > On Montag, 26. Dezember 2022 00:56:08 CET ew via time-nuts wrote: >> This is all it takes. I would leave the GPS unit separate since so many >> choices are available including a 9T and 250 and 500 psec chips are readily >> available now Analog Devices. At the time I did publish it there was no >> interest today I am to old but be glad to help off list >> Bert Kehren > > Indeed the Maxim DS102x series of programmable delay lines was what I found, > too, and it seemed to fit the bill after a cursory look. Good to see that it > can actually be used. I can't see what the other ICs on Bert's board are, but I gather it is using the timing module's sawtooth error data to set the programmable delay line. This seems to be a good option if the receiver of the PPS signal cannot accept adjustment data, but what can it do if the qErr data indicates the next pulse is going to be late instead of early? _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com

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PRS-10 sawtooth correction with microcontroller