Empathy List Archives

DI

David I. Emery

Fri, Jan 26, 2007 10:23 PM

I snagged (for $150 BIN, which might have been too much) a

Datum/Austron PRR-10 Stratum 1 Timing receiver complete with a LPRO
Rb... and two channels of GPS receiver/timing board (redundant, hot
swappable).

These things use the Motorola Oncore family timing receivers

(the latest version (rev G firmware) can support the M12M+) and are
primarily intended to supply precise timing for telco networks as DS1 or
E1 output signals with all the right bits set for timing purposes.

There is a 4 channel "analog" output board available that can

supply 10 mhz, 5 mhz and 1 mhz (I found one of those too), but the
primary outputs in usual units one finds in the field/surplus are the
DS1 or E1 variety.

The interesting thing about these units (which ceased production

in July 2005 - possibly because of the abandonment of the Oncore
receiver family by Motorola) is that they are the second kind of GPS
disciplined clocks - namely phase microstepper based designs which
accept a reference 10 mhz input and use a DDS chip to create a phase
rotated and frequency corrected version which is used to phase lock a 20
mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in
distinction to the Lucent RFTGs which adjust the C field of the LPRO RB
to phase lock it to the 1 PPS input.

Apparently the firmware measures the frequency offset of the 10

Mhz reference input (in my unit generated by a LPRO 101) and its
behavior over time and temperature and uses this to generate a phase
step correction for the DDS which results in a precise 10 mhz output and
1 PPS used to compare with the GPS timing receiver 1 PPS and adjust the
correction and its derivatives over time for optimum tracking.

This means they can take a slightly off frequency but stable 10

mhz and make a precisely on frequency and even more stable 10 mhz locked
to GPS when GPS is available and open loop corrected to the last GPS
offset values when GPS is not using both measured frequency offset and
change of frequency offset with time (and I think temperature).

I have a users manual (circa 2001) in .pdf format, but would dearly

love to find a source of more detailed documentation - the things are full
of jumpers and stuffed/not stuffed options and it would be nice to know
much more about them.

They do, however, provide some ADEV data on the quality of the

input source as one of their data outputs available from the RS-232
port and as such are kind of neat...

--
Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."

I snagged (for $150 BIN, which might have been too much) a Datum/Austron PRR-10 Stratum 1 Timing receiver complete with a LPRO Rb... and two channels of GPS receiver/timing board (redundant, hot swappable). These things use the Motorola Oncore family timing receivers (the latest version (rev G firmware) can support the M12M+) and are primarily intended to supply precise timing for telco networks as DS1 or E1 output signals with all the right bits set for timing purposes. There is a 4 channel "analog" output board available that can supply 10 mhz, 5 mhz and 1 mhz (I found one of those too), but the primary outputs in usual units one finds in the field/surplus are the DS1 or E1 variety. The interesting thing about these units (which ceased production in July 2005 - possibly because of the abandonment of the Oncore receiver family by Motorola) is that they are the second kind of GPS disciplined clocks - namely phase microstepper based designs which accept a reference 10 mhz input and use a DDS chip to create a phase rotated and frequency corrected version which is used to phase lock a 20 mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in distinction to the Lucent RFTGs which adjust the C field of the LPRO RB to phase lock it to the 1 PPS input. Apparently the firmware measures the frequency offset of the 10 Mhz reference input (in my unit generated by a LPRO 101) and its behavior over time and temperature and uses this to generate a phase step correction for the DDS which results in a precise 10 mhz output and 1 PPS used to compare with the GPS timing receiver 1 PPS and adjust the correction and its derivatives over time for optimum tracking. This means they can take a slightly off frequency but stable 10 mhz and make a precisely on frequency and even more stable 10 mhz locked to GPS when GPS is available and open loop corrected to the last GPS offset values when GPS is not using both measured frequency offset and change of frequency offset with time (and I think temperature). I have a users manual (circa 2001) in .pdf format, but would dearly love to find a source of more detailed documentation - the things are full of jumpers and stuffed/not stuffed options and it would be nice to know much more about them. They do, however, provide some ADEV data on the quality of the input source as one of their data outputs available from the RS-232 port and as such are kind of neat... -- Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493 "An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either."

DB

Dr Bruce Griffiths

Sat, Jan 27, 2007 12:58 AM

David
David I. Emery wrote:

The interesting thing about these units (which ceased production

in July 2005 - possibly because of the abandonment of the Oncore
receiver family by Motorola) is that they are the second kind of GPS
disciplined clocks - namely phase microstepper based designs which
accept a reference 10 mhz input and use a DDS chip to create a phase
rotated and frequency corrected version which is used to phase lock a 20
mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in
distinction to the Lucent RFTGs which adjust the C field of the LPRO RB
to phase lock it to the 1 PPS input.

Apparently the firmware measures the frequency offset of the 10

Mhz reference input (in my unit generated by a LPRO 101) and its
behavior over time and temperature and uses this to generate a phase
step correction for the DDS which results in a precise 10 mhz output and
1 PPS used to compare with the GPS timing receiver 1 PPS and adjust the
correction and its derivatives over time for optimum tracking.

This means they can take a slightly off frequency but stable 10

mhz and make a precisely on frequency and even more stable 10 mhz locked
to GPS when GPS is available and open loop corrected to the last GPS
offset values when GPS is not using both measured frequency offset and
change of frequency offset with time (and I think temperature).

This technique is suitable for use with any of the ultrastable oscillators on the surplus market whose frequency has drifted outside the efc and manual adjustment range. Since 48 bit DDS chips are readily available, adequate adjustment range and resolution is available to discipline oscillators that are 100ppm or more off frequency. If a mix and divide technique like that in:

http://www.karlquist.com/FCS95.pdf

is used then the residual phase noise floor and spurs from the DDS output can be significantly attenuated, particularly if a regenerative divider is used in the last stage of the mix and divide chain.

Another option is to use a low noise reference OCXO that has no frequency adjustments using either varactors or trimmer capacitors, perhaps enhancing the oscillators stability somewhat.

Bruce

David David I. Emery wrote: > The interesting thing about these units (which ceased production > in July 2005 - possibly because of the abandonment of the Oncore > receiver family by Motorola) is that they are the second kind of GPS > disciplined clocks - namely phase microstepper based designs which > accept a reference 10 mhz input and use a DDS chip to create a phase > rotated and frequency corrected version which is used to phase lock a 20 > mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in > distinction to the Lucent RFTGs which adjust the C field of the LPRO RB > to phase lock it to the 1 PPS input. > > Apparently the firmware measures the frequency offset of the 10 > Mhz reference input (in my unit generated by a LPRO 101) and its > behavior over time and temperature and uses this to generate a phase > step correction for the DDS which results in a precise 10 mhz output and > 1 PPS used to compare with the GPS timing receiver 1 PPS and adjust the > correction and its derivatives over time for optimum tracking. > > This means they can take a slightly off frequency but stable 10 > mhz and make a precisely on frequency and even more stable 10 mhz locked > to GPS when GPS is available and open loop corrected to the last GPS > offset values when GPS is not using both measured frequency offset and > change of frequency offset with time (and I think temperature). > > This technique is suitable for use with any of the ultrastable oscillators on the surplus market whose frequency has drifted outside the efc and manual adjustment range. Since 48 bit DDS chips are readily available, adequate adjustment range and resolution is available to discipline oscillators that are 100ppm or more off frequency. If a mix and divide technique like that in: http://www.karlquist.com/FCS95.pdf is used then the residual phase noise floor and spurs from the DDS output can be significantly attenuated, particularly if a regenerative divider is used in the last stage of the mix and divide chain. Another option is to use a low noise reference OCXO that has no frequency adjustments using either varactors or trimmer capacitors, perhaps enhancing the oscillators stability somewhat. Bruce

DI

David I. Emery

Sat, Jan 27, 2007 4:21 AM

On Sat, Jan 27, 2007 at 01:58:58PM +1300, Dr Bruce Griffiths wrote:

This means they can take a slightly off frequency but stable 10

mhz and make a precisely on frequency and even more stable 10 mhz locked
to GPS when GPS is available and open loop corrected to the last GPS
offset values when GPS is not using both measured frequency offset and
change of frequency offset with time (and I think temperature).

This technique is suitable for use with any of the ultrastable
oscillators on the surplus market whose frequency has drifted outside
the efc and manual adjustment range. Since 48 bit DDS chips are readily
available, adequate adjustment range and resolution is available to
discipline oscillators that are 100ppm or more off frequency.

Apparently the Austron/Datum versions (they held a patent on

this) have adjustment in the better than 10^12 area but the PRR-10 is a
pretty old design and one could certainly do better with a modern NCO
chip.

The PRR-10 and other Austron designs I am vaguely familiar with

apparently use a 20 MHz VCXO to clean up after the DDS chip. Given the
right choice of loop parameters (and the inherently narrow bandwidth of
the VCXO EFC) this should knock down DDS spurs a lot I should think. I'd
imagine spurs and phase noise out beyond a few hertz would be based
entirely on the VCXO phase noise performance and of course EMI issues in
the board design, not the DDS. And most DDS's don't have all close in
spurs, though their close in phase noise I guess depends on analog
issues in the DAC and clock jitter.

Another option is to use a low noise reference OCXO that has no
frequency adjustments using either varactors or trimmer capacitors,
perhaps enhancing the oscillators stability somewhat.

I think that is what the Austron folks claimed is the big win

with the technique. And indeed I imagine that various materials
effects in the magnetics of a Rb might well mean that is more stable if
left alone than tweaked with EFC changes to the C field coil current (I
am only speculating, and someone on this group probably knows much much
more than I do about such issues).

And there is little doubt that the Telcos used PRR-10s with

cesiums as 10 MHz input on occasion or other standards which provided no
EFC ability to complete the loop.

The PRR-10s (which have sometimes gone pretty cheap on Ebay) are

a kind of amusing surplus toy, however... they will take an external
input 10 MHz and tell you how far off GPS it is and what kind of Allan
deviation it exhibits. I first met one (from Ebay) in 2003 that was a
casualty of the Enron collapse (no kidding, the GPS location in the
EEPROM was the Enron building in Houston according to Google Earth) and
played with it then to monitor another disciplined Rb here for a while.

--
Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."

On Sat, Jan 27, 2007 at 01:58:58PM +1300, Dr Bruce Griffiths wrote: > > This means they can take a slightly off frequency but stable 10 > > mhz and make a precisely on frequency and even more stable 10 mhz locked > > to GPS when GPS is available and open loop corrected to the last GPS > > offset values when GPS is not using both measured frequency offset and > > change of frequency offset with time (and I think temperature). > This technique is suitable for use with any of the ultrastable > oscillators on the surplus market whose frequency has drifted outside > the efc and manual adjustment range. Since 48 bit DDS chips are readily > available, adequate adjustment range and resolution is available to > discipline oscillators that are 100ppm or more off frequency. Apparently the Austron/Datum versions (they held a patent on this) have adjustment in the better than 10^12 area but the PRR-10 is a pretty old design and one could certainly do better with a modern NCO chip. The PRR-10 and other Austron designs I am vaguely familiar with apparently use a 20 MHz VCXO to clean up after the DDS chip. Given the right choice of loop parameters (and the inherently narrow bandwidth of the VCXO EFC) this should knock down DDS spurs a lot I should think. I'd imagine spurs and phase noise out beyond a few hertz would be based entirely on the VCXO phase noise performance and of course EMI issues in the board design, not the DDS. And most DDS's don't have all close in spurs, though their close in phase noise I guess depends on analog issues in the DAC and clock jitter. > Another option is to use a low noise reference OCXO that has no > frequency adjustments using either varactors or trimmer capacitors, > perhaps enhancing the oscillators stability somewhat. I think that is what the Austron folks claimed is the big win with the technique. And indeed I imagine that various materials effects in the magnetics of a Rb might well mean that is more stable if left alone than tweaked with EFC changes to the C field coil current (I am only speculating, and someone on this group probably knows much much more than I do about such issues). And there is little doubt that the Telcos used PRR-10s with cesiums as 10 MHz input on occasion or other standards which provided no EFC ability to complete the loop. The PRR-10s (which have sometimes gone pretty cheap on Ebay) are a kind of amusing surplus toy, however... they will take an external input 10 MHz and tell you how far off GPS it is and what kind of Allan deviation it exhibits. I first met one (from Ebay) in 2003 that was a casualty of the Enron collapse (no kidding, the GPS location in the EEPROM was the Enron building in Houston according to Google Earth) and played with it then to monitor another disciplined Rb here for a while. -- Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493 "An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either."

RK

Rob Kimberley

Sat, Jan 27, 2007 8:39 AM

I remember them well...

Have sold them and installed them for Telco customers in Europe when I
worked for Datum in the mid 90's. Novel design, and as you say they don't
attempt to correct the Rubidium, but compare its output against GPS and use
DDS to make the correction. In practise they worked very well and provided
excellent Stratum 1 references.

Unfortunately I don't have any documentation, but have some of the blanking
panels and other bits of hardware lurking in the store room here. Will have
a hunt around, and see exactly what's available to anyone interested.

You got yourself an excellent bargain!

Rob Kimberley

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of David I. Emery
Sent: 26 January 2007 22:23
To: time-nuts@febo.com
Subject: [time-nuts] Austron PRR-10 GPS discliplined Rb...

I snagged (for $150 BIN, which might have been too much) a

Datum/Austron PRR-10 Stratum 1 Timing receiver complete with a LPRO Rb...
and two channels of GPS receiver/timing board (redundant, hot swappable).

These things use the Motorola Oncore family timing receivers (the

latest version (rev G firmware) can support the M12M+) and are primarily
intended to supply precise timing for telco networks as DS1 or
E1 output signals with all the right bits set for timing purposes.

There is a 4 channel "analog" output board available that can supply

10 mhz, 5 mhz and 1 mhz (I found one of those too), but the primary outputs
in usual units one finds in the field/surplus are the
DS1 or E1 variety.

The interesting thing about these units (which ceased production in

July 2005 - possibly because of the abandonment of the Oncore receiver
family by Motorola) is that they are the second kind of GPS disciplined
clocks - namely phase microstepper based designs which accept a reference 10
mhz input and use a DDS chip to create a phase rotated and frequency
corrected version which is used to phase lock a 20
mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in
distinction to the Lucent RFTGs which adjust the C field of the LPRO RB to
phase lock it to the 1 PPS input.

Apparently the firmware measures the frequency offset of the 10 Mhz

reference input (in my unit generated by a LPRO 101) and its behavior over
time and temperature and uses this to generate a phase step correction for
the DDS which results in a precise 10 mhz output and
1 PPS used to compare with the GPS timing receiver 1 PPS and adjust the
correction and its derivatives over time for optimum tracking.

This means they can take a slightly off frequency but stable 10 mhz

and make a precisely on frequency and even more stable 10 mhz locked to GPS
when GPS is available and open loop corrected to the last GPS offset values
when GPS is not using both measured frequency offset and change of
frequency offset with time (and I think temperature).

I have a users manual (circa 2001) in .pdf format, but would dearly

love to find a source of more detailed documentation - the things are full
of jumpers and stuffed/not stuffed options and it would be nice to know much
more about them.

They do, however, provide some ADEV data on the quality of the input

source as one of their data outputs available from the RS-232 port and as
such are kind of neat...

--
Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, Weston, Mass
02493 "An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole -
in celebration of what could have been, but wasn't and is not to be now
either."

time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

I remember them well... Have sold them and installed them for Telco customers in Europe when I worked for Datum in the mid 90's. Novel design, and as you say they don't attempt to correct the Rubidium, but compare its output against GPS and use DDS to make the correction. In practise they worked very well and provided excellent Stratum 1 references. Unfortunately I don't have any documentation, but have some of the blanking panels and other bits of hardware lurking in the store room here. Will have a hunt around, and see exactly what's available to anyone interested. You got yourself an excellent bargain! Rob Kimberley -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of David I. Emery Sent: 26 January 2007 22:23 To: time-nuts@febo.com Subject: [time-nuts] Austron PRR-10 GPS discliplined Rb... I snagged (for $150 BIN, which might have been too much) a Datum/Austron PRR-10 Stratum 1 Timing receiver complete with a LPRO Rb... and two channels of GPS receiver/timing board (redundant, hot swappable). These things use the Motorola Oncore family timing receivers (the latest version (rev G firmware) can support the M12M+) and are primarily intended to supply precise timing for telco networks as DS1 or E1 output signals with all the right bits set for timing purposes. There is a 4 channel "analog" output board available that can supply 10 mhz, 5 mhz and 1 mhz (I found one of those too), but the primary outputs in usual units one finds in the field/surplus are the DS1 or E1 variety. The interesting thing about these units (which ceased production in July 2005 - possibly because of the abandonment of the Oncore receiver family by Motorola) is that they are the second kind of GPS disciplined clocks - namely phase microstepper based designs which accept a reference 10 mhz input and use a DDS chip to create a phase rotated and frequency corrected version which is used to phase lock a 20 mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in distinction to the Lucent RFTGs which adjust the C field of the LPRO RB to phase lock it to the 1 PPS input. Apparently the firmware measures the frequency offset of the 10 Mhz reference input (in my unit generated by a LPRO 101) and its behavior over time and temperature and uses this to generate a phase step correction for the DDS which results in a precise 10 mhz output and 1 PPS used to compare with the GPS timing receiver 1 PPS and adjust the correction and its derivatives over time for optimum tracking. This means they can take a slightly off frequency but stable 10 mhz and make a precisely on frequency and even more stable 10 mhz locked to GPS when GPS is available and open loop corrected to the last GPS offset values when GPS is not using both measured frequency offset and change of frequency offset with time (and I think temperature). I have a users manual (circa 2001) in .pdf format, but would dearly love to find a source of more detailed documentation - the things are full of jumpers and stuffed/not stuffed options and it would be nice to know much more about them. They do, however, provide some ADEV data on the quality of the input source as one of their data outputs available from the RS-232 port and as such are kind of neat... -- Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493 "An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either." _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

DB

Dr Bruce Griffiths

Sat, Jan 27, 2007 11:23 AM

David I. Emery wrote:

Apparently the Austron/Datum versions (they held a patent on

this) have adjustment in the better than 10^12 area but the PRR-10 is a
pretty old design and one could certainly do better with a modern NCO
chip.

The PRR-10 and other Austron designs I am vaguely familiar with

apparently use a 20 MHz VCXO to clean up after the DDS chip. Given the
right choice of loop parameters (and the inherently narrow bandwidth of
the VCXO EFC) this should knock down DDS spurs a lot I should think. I'd
imagine spurs and phase noise out beyond a few hertz would be based
entirely on the VCXO phase noise performance and of course EMI issues in
the board design, not the DDS. And most DDS's don't have all close in
spurs, though their close in phase noise I guess depends on analog
issues in the DAC and clock jitter.

The mix and divide technique (at the cost of increased complexity) also
reduces the close in phase noise, which for a DDS at 10Hz offset from
the carrier can be 20-30dB worse than a low phase noise crystal
oscillator of the same frequency as the DDS output. Even for ultrastable
OCXOs (and other frequency stable sources) that have drifted out of the
adjustment range only require a DDS correction range of a few ppm to
make them usable as frequency standards. Consequently it is relatively
easy to significantly reduce the close in phase noise by 40dB or more
with a well designed mix and divide technique whilst allowing a
frequency adjustment range of 10ppm or more. Eventually the close in
phase noise is limited by the dividers used. Regenerative dividers have
far lower noise than digital dividers so they can be useful for the last
mix and divide stage when the ultimate phase noise performance is desired.

Combining this with GPS carrier phase tracking techniques to discipline
the frequency reference should result in near hydrogen maser
performance, at least for short observation times.

Bruce

David I. Emery wrote: > Apparently the Austron/Datum versions (they held a patent on > this) have adjustment in the better than 10^12 area but the PRR-10 is a > pretty old design and one could certainly do better with a modern NCO > chip. > > The PRR-10 and other Austron designs I am vaguely familiar with > apparently use a 20 MHz VCXO to clean up after the DDS chip. Given the > right choice of loop parameters (and the inherently narrow bandwidth of > the VCXO EFC) this should knock down DDS spurs a lot I should think. I'd > imagine spurs and phase noise out beyond a few hertz would be based > entirely on the VCXO phase noise performance and of course EMI issues in > the board design, not the DDS. And most DDS's don't have all close in > spurs, though their close in phase noise I guess depends on analog > issues in the DAC and clock jitter. > The mix and divide technique (at the cost of increased complexity) also reduces the close in phase noise, which for a DDS at 10Hz offset from the carrier can be 20-30dB worse than a low phase noise crystal oscillator of the same frequency as the DDS output. Even for ultrastable OCXOs (and other frequency stable sources) that have drifted out of the adjustment range only require a DDS correction range of a few ppm to make them usable as frequency standards. Consequently it is relatively easy to significantly reduce the close in phase noise by 40dB or more with a well designed mix and divide technique whilst allowing a frequency adjustment range of 10ppm or more. Eventually the close in phase noise is limited by the dividers used. Regenerative dividers have far lower noise than digital dividers so they can be useful for the last mix and divide stage when the ultimate phase noise performance is desired. Combining this with GPS carrier phase tracking techniques to discipline the frequency reference should result in near hydrogen maser performance, at least for short observation times. Bruce

MD

Magnus Danielson

Sat, Jan 27, 2007 11:35 AM

Hi!

Those interested in micro-steppers might want to look at the Symmetricom
AOG-110 manual. They have a local 5 MHz OCXO locked through a interesting
gear with the incomming 5 MHz and a DDS to result in a 10 kHz comparision
frequency for the phase detector in the loop. The gear acheives a 512000
increase in gain (1024 from gear-works as such and 500 from the ratio of 5 MHz
and 10 kHz). To acheive the 1E-19 stepsize it then takes the DDS a few bits,
but what is 56 bits among friends? Since we don't need to waste too much on
this, there is a 8 bit CPU processing it all in there and it uses a 56 bit
fixed point format.

I'd naturally love a few comments on that one.

Cheers,
Magnus

Hi! Those interested in micro-steppers might want to look at the Symmetricom AOG-110 manual. They have a local 5 MHz OCXO locked through a interesting gear with the incomming 5 MHz and a DDS to result in a 10 kHz comparision frequency for the phase detector in the loop. The gear acheives a 512000 increase in gain (1024 from gear-works as such and 500 from the ratio of 5 MHz and 10 kHz). To acheive the 1E-19 stepsize it then takes the DDS a few bits, but what is 56 bits among friends? Since we don't need to waste too much on this, there is a 8 bit CPU processing it all in there and it uses a 56 bit fixed point format. I'd naturally love a few comments on that one. Cheers, Magnus

UB

Ulrich Bangert

Sat, Jan 27, 2007 12:24 PM

Hi Magnus,

can you supply this manual???

Ulrich Bangert, DF6JB

-----Ursprüngliche Nachricht-----
Von: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] Im Auftrag von Magnus Danielson
Gesendet: Samstag, 27. Januar 2007 12:36
An: time-nuts@febo.com; bruce.griffiths@xtra.co.nz
Betreff: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb...

Hi!

Those interested in micro-steppers might want to look at the
Symmetricom AOG-110 manual. They have a local 5 MHz OCXO
locked through a interesting gear with the incomming 5 MHz
and a DDS to result in a 10 kHz comparision frequency for the
phase detector in the loop. The gear acheives a 512000
increase in gain (1024 from gear-works as such and 500 from
the ratio of 5 MHz and 10 kHz). To acheive the 1E-19 stepsize
it then takes the DDS a few bits, but what is 56 bits among
friends? Since we don't need to waste too much on this, there
is a 8 bit CPU processing it all in there and it uses a 56
bit fixed point format.

I'd naturally love a few comments on that one.

Cheers,
Magnus

time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts

Hi Magnus, can you supply this manual??? Ulrich Bangert, DF6JB > -----Ursprüngliche Nachricht----- > Von: time-nuts-bounces@febo.com > [mailto:time-nuts-bounces@febo.com] Im Auftrag von Magnus Danielson > Gesendet: Samstag, 27. Januar 2007 12:36 > An: time-nuts@febo.com; bruce.griffiths@xtra.co.nz > Betreff: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb... > > > Hi! > > Those interested in micro-steppers might want to look at the > Symmetricom AOG-110 manual. They have a local 5 MHz OCXO > locked through a interesting gear with the incomming 5 MHz > and a DDS to result in a 10 kHz comparision frequency for the > phase detector in the loop. The gear acheives a 512000 > increase in gain (1024 from gear-works as such and 500 from > the ratio of 5 MHz and 10 kHz). To acheive the 1E-19 stepsize > it then takes the DDS a few bits, but what is 56 bits among > friends? Since we don't need to waste too much on this, there > is a 8 bit CPU processing it all in there and it uses a 56 > bit fixed point format. > > I'd naturally love a few comments on that one. > > Cheers, > Magnus > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts >

UB

Ulrich Bangert

Sat, Jan 27, 2007 12:32 PM

Rob,

are you absolutely sure it works this way? I experimented a lot with a
48 bit dds chip from analog devices for a GPSDO just to learn that THIS
way worked not good. What however works good is to imagine the
combination of OCXO and dds as kind of 'pure digital efc'. That is: The
output of the DDS (and not the RB's) is divided doen to a 1 pps which is
phase compared to the gps receiver. This makes the system an overall PLL
closed loop as seen with conventional efc circuits, however without the
need for precise analogue circuitry, which is why i use it!

Best regards
Ulrich Bangert, DF6JB

-----Ursprüngliche Nachricht-----
Von: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] Im Auftrag von Rob Kimberley
Gesendet: Samstag, 27. Januar 2007 09:39
An: 'Discussion of precise time and frequency measurement'
Betreff: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb...

I remember them well...

Have sold them and installed them for Telco customers in
Europe when I worked for Datum in the mid 90's. Novel design,
and as you say they don't attempt to correct the Rubidium,
but compare its output against GPS and use DDS to make the
correction. In practise they worked very well and provided
excellent Stratum 1 references.

Unfortunately I don't have any documentation, but have some
of the blanking panels and other bits of hardware lurking in
the store room here. Will have a hunt around, and see exactly
what's available to anyone interested.

You got yourself an excellent bargain!

Rob Kimberley

-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of David I. Emery
Sent: 26 January 2007 22:23
To: time-nuts@febo.com
Subject: [time-nuts] Austron PRR-10 GPS discliplined Rb...

I snagged (for $150 BIN, which might have been too

much) a Datum/Austron PRR-10 Stratum 1 Timing receiver
complete with a LPRO Rb... and two channels of GPS
receiver/timing board (redundant, hot swappable).

These things use the Motorola Oncore family timing

receivers (the latest version (rev G firmware) can support
the M12M+) and are primarily intended to supply precise
timing for telco networks as DS1 or E1 output signals with
all the right bits set for timing purposes.

There is a 4 channel "analog" output board available

that can supply 10 mhz, 5 mhz and 1 mhz (I found one of those
too), but the primary outputs in usual units one finds in the
field/surplus are the DS1 or E1 variety.

The interesting thing about these units (which ceased

production in July 2005 - possibly because of the abandonment
of the Oncore receiver family by Motorola) is that they are
the second kind of GPS disciplined clocks - namely phase
microstepper based designs which accept a reference 10 mhz
input and use a DDS chip to create a phase rotated and
frequency corrected version which is used to phase lock a 20
mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in
distinction to the Lucent RFTGs which adjust the C field of
the LPRO RB to phase lock it to the 1 PPS input.

Apparently the firmware measures the frequency offset

of the 10 Mhz reference input (in my unit generated by a LPRO
101) and its behavior over time and temperature and uses this
to generate a phase step correction for the DDS which results
in a precise 10 mhz output and 1 PPS used to compare with the
GPS timing receiver 1 PPS and adjust the correction and its
derivatives over time for optimum tracking.

This means they can take a slightly off frequency but

stable 10 mhz and make a precisely on frequency and even more
stable 10 mhz locked to GPS when GPS is available and open
loop corrected to the last GPS offset values when GPS is not
using both measured frequency offset and change of frequency
offset with time (and I think temperature).

I have a users manual (circa 2001) in .pdf format, but

would dearly love to find a source of more detailed
documentation - the things are full of jumpers and
stuffed/not stuffed options and it would be nice to know much
more about them.

They do, however, provide some ADEV data on the quality

of the input source as one of their data outputs available
from the RS-232 port and as such are kind of neat...

--
Dave Emery N1PRE, die@dieconsulting.com DIE Consulting,
Weston, Mass 02493 "An empty zombie mind with a forlorn
barely readable weatherbeaten 'For Rent' sign still vainly
flapping outside on the weed encrusted pole - in celebration
of what could have been, but wasn't and is not to be now either."

time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts

Rob, are you absolutely sure it works this way? I experimented a lot with a 48 bit dds chip from analog devices for a GPSDO just to learn that THIS way worked not good. What however works good is to imagine the combination of OCXO and dds as kind of 'pure digital efc'. That is: The output of the DDS (and not the RB's) is divided doen to a 1 pps which is phase compared to the gps receiver. This makes the system an overall PLL closed loop as seen with conventional efc circuits, however without the need for precise analogue circuitry, which is why i use it! Best regards Ulrich Bangert, DF6JB > -----Ursprüngliche Nachricht----- > Von: time-nuts-bounces@febo.com > [mailto:time-nuts-bounces@febo.com] Im Auftrag von Rob Kimberley > Gesendet: Samstag, 27. Januar 2007 09:39 > An: 'Discussion of precise time and frequency measurement' > Betreff: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb... > > > I remember them well... > > Have sold them and installed them for Telco customers in > Europe when I worked for Datum in the mid 90's. Novel design, > and as you say they don't attempt to correct the Rubidium, > but compare its output against GPS and use DDS to make the > correction. In practise they worked very well and provided > excellent Stratum 1 references. > > Unfortunately I don't have any documentation, but have some > of the blanking panels and other bits of hardware lurking in > the store room here. Will have a hunt around, and see exactly > what's available to anyone interested. > > You got yourself an excellent bargain! > > Rob Kimberley > > -----Original Message----- > From: time-nuts-bounces@febo.com > [mailto:time-nuts-bounces@febo.com] On Behalf Of David I. Emery > Sent: 26 January 2007 22:23 > To: time-nuts@febo.com > Subject: [time-nuts] Austron PRR-10 GPS discliplined Rb... > > I snagged (for $150 BIN, which might have been too > much) a Datum/Austron PRR-10 Stratum 1 Timing receiver > complete with a LPRO Rb... and two channels of GPS > receiver/timing board (redundant, hot swappable). > > These things use the Motorola Oncore family timing > receivers (the latest version (rev G firmware) can support > the M12M+) and are primarily intended to supply precise > timing for telco networks as DS1 or E1 output signals with > all the right bits set for timing purposes. > > There is a 4 channel "analog" output board available > that can supply 10 mhz, 5 mhz and 1 mhz (I found one of those > too), but the primary outputs in usual units one finds in the > field/surplus are the DS1 or E1 variety. > > The interesting thing about these units (which ceased > production in July 2005 - possibly because of the abandonment > of the Oncore receiver family by Motorola) is that they are > the second kind of GPS disciplined clocks - namely phase > microstepper based designs which accept a reference 10 mhz > input and use a DDS chip to create a phase rotated and > frequency corrected version which is used to phase lock a 20 > mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in > distinction to the Lucent RFTGs which adjust the C field of > the LPRO RB to phase lock it to the 1 PPS input. > > Apparently the firmware measures the frequency offset > of the 10 Mhz reference input (in my unit generated by a LPRO > 101) and its behavior over time and temperature and uses this > to generate a phase step correction for the DDS which results > in a precise 10 mhz output and 1 PPS used to compare with the > GPS timing receiver 1 PPS and adjust the correction and its > derivatives over time for optimum tracking. > > This means they can take a slightly off frequency but > stable 10 mhz and make a precisely on frequency and even more > stable 10 mhz locked to GPS when GPS is available and open > loop corrected to the last GPS offset values when GPS is not > using both measured frequency offset and change of frequency > offset with time (and I think temperature). > > I have a users manual (circa 2001) in .pdf format, but > would dearly love to find a source of more detailed > documentation - the things are full of jumpers and > stuffed/not stuffed options and it would be nice to know much > more about them. > > They do, however, provide some ADEV data on the quality > of the input source as one of their data outputs available > from the RS-232 port and as such are kind of neat... > > > -- > Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, > Weston, Mass 02493 "An empty zombie mind with a forlorn > barely readable weatherbeaten 'For Rent' sign still vainly > flapping outside on the weed encrusted pole - in celebration > of what could have been, but wasn't and is not to be now either." > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts > > > > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts >

RK

Rob Kimberley

Sat, Jan 27, 2007 6:20 PM

Sold by Symmetricom, but actually manufactured by Kvarz in Russia...

Rob K

----- Original Message -----
From: "Magnus Danielson" cfmd@bredband.net
To: time-nuts@febo.com; bruce.griffiths@xtra.co.nz
Sent: Saturday, January 27, 2007 11:35 AM
Subject: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb...

Hi!

Those interested in micro-steppers might want to look at the Symmetricom
AOG-110 manual. They have a local 5 MHz OCXO locked through a interesting
gear with the incomming 5 MHz and a DDS to result in a 10 kHz comparision
frequency for the phase detector in the loop. The gear acheives a 512000
increase in gain (1024 from gear-works as such and 500 from the ratio of 5
MHz
and 10 kHz). To acheive the 1E-19 stepsize it then takes the DDS a few
bits,
but what is 56 bits among friends? Since we don't need to waste too much
on
this, there is a 8 bit CPU processing it all in there and it uses a 56 bit
fixed point format.

I'd naturally love a few comments on that one.

Cheers,
Magnus

time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

Sold by Symmetricom, but actually manufactured by Kvarz in Russia... Rob K ----- Original Message ----- From: "Magnus Danielson" <cfmd@bredband.net> To: <time-nuts@febo.com>; <bruce.griffiths@xtra.co.nz> Sent: Saturday, January 27, 2007 11:35 AM Subject: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb... > Hi! > > Those interested in micro-steppers might want to look at the Symmetricom > AOG-110 manual. They have a local 5 MHz OCXO locked through a interesting > gear with the incomming 5 MHz and a DDS to result in a 10 kHz comparision > frequency for the phase detector in the loop. The gear acheives a 512000 > increase in gain (1024 from gear-works as such and 500 from the ratio of 5 > MHz > and 10 kHz). To acheive the 1E-19 stepsize it then takes the DDS a few > bits, > but what is 56 bits among friends? Since we don't need to waste too much > on > this, there is a 8 bit CPU processing it all in there and it uses a 56 bit > fixed point format. > > I'd naturally love a few comments on that one. > > Cheers, > Magnus > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >

RK

Rob Kimberley

Sat, Jan 27, 2007 6:25 PM

Ulrich,

I'm absolutely certain that this is how they did it. My old boss the late
Bob Ellis made a big point about this being a new way forward that didn't
involve any direct tuning of the Rb. You let it free run and correct using
the DDS technique mentioned. The rational was that this way you got on the
desired frequency quicker than the traditional PLL methods, which was a big
plus when installing these in Telco sites, as time was at a premium when
installing and testing the systems.

Rob

----- Original Message -----
From: "Ulrich Bangert" df6jb@ulrich-bangert.de
To: "'Discussion of precise time and frequency measurement'"
time-nuts@febo.com
Sent: Saturday, January 27, 2007 12:32 PM
Subject: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb...

Rob,

are you absolutely sure it works this way? I experimented a lot with a
48 bit dds chip from analog devices for a GPSDO just to learn that THIS
way worked not good. What however works good is to imagine the
combination of OCXO and dds as kind of 'pure digital efc'. That is: The
output of the DDS (and not the RB's) is divided doen to a 1 pps which is
phase compared to the gps receiver. This makes the system an overall PLL
closed loop as seen with conventional efc circuits, however without the
need for precise analogue circuitry, which is why i use it!

Best regards
Ulrich Bangert, DF6JB

-----Ursprüngliche Nachricht-----
Von: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] Im Auftrag von Rob Kimberley
Gesendet: Samstag, 27. Januar 2007 09:39
An: 'Discussion of precise time and frequency measurement'
Betreff: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb...

I remember them well...

Have sold them and installed them for Telco customers in
Europe when I worked for Datum in the mid 90's. Novel design,
and as you say they don't attempt to correct the Rubidium,
but compare its output against GPS and use DDS to make the
correction. In practise they worked very well and provided
excellent Stratum 1 references.

Unfortunately I don't have any documentation, but have some
of the blanking panels and other bits of hardware lurking in
the store room here. Will have a hunt around, and see exactly
what's available to anyone interested.

You got yourself an excellent bargain!

Rob Kimberley

-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of David I. Emery
Sent: 26 January 2007 22:23
To: time-nuts@febo.com
Subject: [time-nuts] Austron PRR-10 GPS discliplined Rb...

I snagged (for $150 BIN, which might have been too
much) a Datum/Austron PRR-10 Stratum 1 Timing receiver
complete with a LPRO Rb... and two channels of GPS
receiver/timing board (redundant, hot swappable).

These things use the Motorola Oncore family timing
receivers (the latest version (rev G firmware) can support
the M12M+) and are primarily intended to supply precise
timing for telco networks as DS1 or E1 output signals with
all the right bits set for timing purposes.

There is a 4 channel "analog" output board available
that can supply 10 mhz, 5 mhz and 1 mhz (I found one of those
too), but the primary outputs in usual units one finds in the
field/surplus are the DS1 or E1 variety.

The interesting thing about these units (which ceased
production in July 2005 - possibly because of the abandonment
of the Oncore receiver family by Motorola) is that they are
the second kind of GPS disciplined clocks - namely phase
microstepper based designs which accept a reference 10 mhz
input and use a DDS chip to create a phase rotated and
frequency corrected version which is used to phase lock a 20
mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in
distinction to the Lucent RFTGs which adjust the C field of
the LPRO RB to phase lock it to the 1 PPS input.

Apparently the firmware measures the frequency offset
of the 10 Mhz reference input (in my unit generated by a LPRO
101) and its behavior over time and temperature and uses this
to generate a phase step correction for the DDS which results
in a precise 10 mhz output and 1 PPS used to compare with the
GPS timing receiver 1 PPS and adjust the correction and its
derivatives over time for optimum tracking.

This means they can take a slightly off frequency but
stable 10 mhz and make a precisely on frequency and even more
stable 10 mhz locked to GPS when GPS is available and open
loop corrected to the last GPS offset values when GPS is not
using both measured frequency offset and change of frequency
offset with time (and I think temperature).

I have a users manual (circa 2001) in .pdf format, but
would dearly love to find a source of more detailed
documentation - the things are full of jumpers and
stuffed/not stuffed options and it would be nice to know much
more about them.

They do, however, provide some ADEV data on the quality
of the input source as one of their data outputs available
from the RS-232 port and as such are kind of neat...

--
Dave Emery N1PRE, die@dieconsulting.com DIE Consulting,
Weston, Mass 02493 "An empty zombie mind with a forlorn
barely readable weatherbeaten 'For Rent' sign still vainly
flapping outside on the weed encrusted pole - in celebration
of what could have been, but wasn't and is not to be now either."

time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts

time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

Ulrich, I'm absolutely certain that this is how they did it. My old boss the late Bob Ellis made a big point about this being a new way forward that didn't involve any direct tuning of the Rb. You let it free run and correct using the DDS technique mentioned. The rational was that this way you got on the desired frequency quicker than the traditional PLL methods, which was a big plus when installing these in Telco sites, as time was at a premium when installing and testing the systems. Rob ----- Original Message ----- From: "Ulrich Bangert" <df6jb@ulrich-bangert.de> To: "'Discussion of precise time and frequency measurement'" <time-nuts@febo.com> Sent: Saturday, January 27, 2007 12:32 PM Subject: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb... Rob, are you absolutely sure it works this way? I experimented a lot with a 48 bit dds chip from analog devices for a GPSDO just to learn that THIS way worked not good. What however works good is to imagine the combination of OCXO and dds as kind of 'pure digital efc'. That is: The output of the DDS (and not the RB's) is divided doen to a 1 pps which is phase compared to the gps receiver. This makes the system an overall PLL closed loop as seen with conventional efc circuits, however without the need for precise analogue circuitry, which is why i use it! Best regards Ulrich Bangert, DF6JB > -----Ursprüngliche Nachricht----- > Von: time-nuts-bounces@febo.com > [mailto:time-nuts-bounces@febo.com] Im Auftrag von Rob Kimberley > Gesendet: Samstag, 27. Januar 2007 09:39 > An: 'Discussion of precise time and frequency measurement' > Betreff: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb... > > > I remember them well... > > Have sold them and installed them for Telco customers in > Europe when I worked for Datum in the mid 90's. Novel design, > and as you say they don't attempt to correct the Rubidium, > but compare its output against GPS and use DDS to make the > correction. In practise they worked very well and provided > excellent Stratum 1 references. > > Unfortunately I don't have any documentation, but have some > of the blanking panels and other bits of hardware lurking in > the store room here. Will have a hunt around, and see exactly > what's available to anyone interested. > > You got yourself an excellent bargain! > > Rob Kimberley > > -----Original Message----- > From: time-nuts-bounces@febo.com > [mailto:time-nuts-bounces@febo.com] On Behalf Of David I. Emery > Sent: 26 January 2007 22:23 > To: time-nuts@febo.com > Subject: [time-nuts] Austron PRR-10 GPS discliplined Rb... > > I snagged (for $150 BIN, which might have been too > much) a Datum/Austron PRR-10 Stratum 1 Timing receiver > complete with a LPRO Rb... and two channels of GPS > receiver/timing board (redundant, hot swappable). > > These things use the Motorola Oncore family timing > receivers (the latest version (rev G firmware) can support > the M12M+) and are primarily intended to supply precise > timing for telco networks as DS1 or E1 output signals with > all the right bits set for timing purposes. > > There is a 4 channel "analog" output board available > that can supply 10 mhz, 5 mhz and 1 mhz (I found one of those > too), but the primary outputs in usual units one finds in the > field/surplus are the DS1 or E1 variety. > > The interesting thing about these units (which ceased > production in July 2005 - possibly because of the abandonment > of the Oncore receiver family by Motorola) is that they are > the second kind of GPS disciplined clocks - namely phase > microstepper based designs which accept a reference 10 mhz > input and use a DDS chip to create a phase rotated and > frequency corrected version which is used to phase lock a 20 > mhz VCXO and from that generate a new 10 mhz and 1 PPS. This is in > distinction to the Lucent RFTGs which adjust the C field of > the LPRO RB to phase lock it to the 1 PPS input. > > Apparently the firmware measures the frequency offset > of the 10 Mhz reference input (in my unit generated by a LPRO > 101) and its behavior over time and temperature and uses this > to generate a phase step correction for the DDS which results > in a precise 10 mhz output and 1 PPS used to compare with the > GPS timing receiver 1 PPS and adjust the correction and its > derivatives over time for optimum tracking. > > This means they can take a slightly off frequency but > stable 10 mhz and make a precisely on frequency and even more > stable 10 mhz locked to GPS when GPS is available and open > loop corrected to the last GPS offset values when GPS is not > using both measured frequency offset and change of frequency > offset with time (and I think temperature). > > I have a users manual (circa 2001) in .pdf format, but > would dearly love to find a source of more detailed > documentation - the things are full of jumpers and > stuffed/not stuffed options and it would be nice to know much > more about them. > > They do, however, provide some ADEV data on the quality > of the input source as one of their data outputs available > from the RS-232 port and as such are kind of neat... > > > -- > Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, > Weston, Mass 02493 "An empty zombie mind with a forlorn > barely readable weatherbeaten 'For Rent' sign still vainly > flapping outside on the weed encrusted pole - in celebration > of what could have been, but wasn't and is not to be now either." > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts > > > > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

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Austron PRR-10 GPS discliplined Rb...