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ProgRock not working #progrock

w7qjq
 

ProgRock not working.
I have trying for weeks to get my ProgRock to function properly.  It simply refuses to dicipline the Si5351 clock generator to stay on 10 MHz.
Typical example: From a cold start (power-on), after a few minutes the GPS receiver acquires enough sats to begin the 1PPS.  At that point the (10 MHz) CLK0 freq error will be several KHz. The ATtiny84 controller will begin pulling the freq towards 10 MHz.  The Si5351 Reg 2 can be seen changing the 27,004,xxx MHz as expected.  After another few minutes the Reg 2  value settles and the CLK0 freq will be 10MHz +/-   2 or 3 Hz .  But the CLK0 freq will not remain at any freq for very long...just a degree or two temperature change will start it moving and the Reg 2 value will not change as necessary to correct the error.  The only times that the error is zero (+/-  0.1Hz) is  when the Reg 2 value and the changing temperature
just by chance allow it.  As I type this, the freq is 9,999,9976.

My 10 MHz standard is a Trimble ICM-SMT GPSDO spec'ed at +/- 0.3 x 10-8 but in reality is better as determined by zero-beat with WWV.  The Trimble 10 MHz provides the reference clock for a HP5302A counter and one channel of a 2-channel scope whose second channel is looking at the Si5351 CLK0.

I have attached some photos that illustrate the setup and results.

Photo 1 shows the setup.  I have one pc running Hyperterm to talk to the QRPLabs terminal program.
A  second pc is running u-center.exe to monitor the QLG1 receiver.

********************************************************************************************

Photo 2  shows the CLK0 freq as a fn of the Reg 2 value (with 1PPS disabled only for this test...obviously connected for all other testing/operation).

********************************************************************************************
Photo 3 shows how I compare the two 10 MHz freqs.  The slightly lumpy ProgRock waveform is an artifact of some cable impedance mis-match.  The HP counter (with 10 Sec timebase)  is also measuring the CLK0 signal with a resolution of 0.1 Hz.

********************************************************************************************

Photo 4 shows what the QLG1 is seeing...the excellent  S/N values are a result of the amplified antenna ( $3 USD).

********************************************************************************************
Photo 5 shows the 1PPS

********************************************************************************************

Photo 6 shows the Si5351 27 MHz xtal divided by 8.


********************************************************************************************

Some additional details...
1)  Room temperature varies only a few degrees (F) during the day/night cycle.  If I place the ProgRock in a small cardboard box, the same freq errors occur, just slowed down.
2)  5 Volt supply is clean.
3)  When I load Reg 2 with a value that stops the drift for the temperature at that moment (freq error zero), within several minutes the freq will have wandered off several tenths but the ATtiny84 controller will not have changed the  Reg 2 value to correct the error.  After 15 minutes or so, the error might reach 2 or 3 KHz, Reg 2 may or may not be updated but even if the Reg 2 value has changed, it is still not a value that will bring the freq to zero error (+/-  0.1 or 0.2 Hz).
4)  I have tried different values for Reg 5 with no observable difference. It is otherwise set to 0.
So, I am wondering, is there anyone, anywhere who has built one of these that actually stay on 10 MHz within a few tenths of a Hz?
73,  Sid   W7QJQ
Radio Welling

Alan de G1FXB
 

??my thoughts.....

It would be useful to know What settings other than the defaults have you entered?
for instance the default settings allows for +/- 5Hz inaccuracy before discipline is applied.
Beyond that:-

Perhaps don't loose sight of your statement " If I place the ProgRock in a small cardboard box, the same freq errors occur, just slowed down. "
By the sound of it,you perhaps see?? atleast some drift caused bt temperature variations. You are not using the OCXO version of the synth PCB(?),
any reason not to in applications needing stability
? (an uncased xtal will be sensitive to environmental changes.
Much has already being discussed over the requirements of frequency stability for the synth modules both here & in the Notes & FAQ's
ones that differ from the median spec would be most noticeable in freq standard use such as your desire,
if you still have persistence tendency for drift perhaps substitute the xtal for another and note the affect if any?
(The Xtals used are nothing special, they come from the same bag that are supplied with the other kit's, The OCXO benefit is that it and the accompanying osc components are heated to well above (hopefully) ambient temperature circa 45 degC to achieve greatest stability. It also has an additional buffer stage that further isolates the xtal from loading changes within the Si5351 IC.)


the minute changes in the 27MHz ref measurements are scaled according to the choice of output freq, there was a good discussion thread months back demonstrating this while putting the U3S on VHF....
(If considering one of the many of the "cheaper" self contained TCXO modules exhibit caution as staircase shaped steps to their control and don't necessary play nice with a second level of correction in this application if the ProgRock GPS calibration is also enabled, choose one or the other but not both? )

" So, I am wondering, is there anyone, anywhere who has built one of these that actually stay on 10 MHz within a few tenths of a Hz? "
Regarding your measurements,
How does the Progrock perform when compared against WWV to produce a beat note and measurement using for instance ARGO Or Spectrum Lab App?

In a past thread about "how good" Hans has quoted:-
" The ProgRock when it is properly set up and working properly, should be within +/- 0.5Hz of the desired 10,000,000 Hz. That is, 0.05ppm (50 parts per billion). The frequency "steps" as the algorithm hunts around making corrections, are NOT several Hz, they will be a fraction of a Hz. Theoretically the steps will be sized 0 to 0.3Hz at this output frequency. They depend on the arithmetic with the particular reference clock measurement that is made by the 1pps."

Alan

On 12/07/2019 02:20, w7qjq wrote:

ProgRock not working.
I have trying for weeks to get my ProgRock to function properly.?? It simply refuses to dicipline the Si5351 clock generator to stay on 10 MHz.
Typical example: From a cold start (power-on), after a few minutes the GPS receiver acquires enough sats to begin the 1PPS.?? At that point the (10 MHz) CLK0 freq error will be several KHz. The ATtiny84 controller will begin pulling the freq towards 10 MHz.?? The Si5351 Reg 2 can be seen changing the 27,004,xxx MHz as expected.?? After another few minutes the Reg 2?? value settles and the CLK0 freq will be 10MHz +/-???? 2 or 3 Hz .?? But the CLK0 freq will not remain at any freq for very long...just a degree or two temperature change will start it moving and the Reg 2 value will not change as necessary to correct the error.?? The only times that the error is zero (+/-?? 0.1Hz) is?? when the Reg 2 value and the changing temperature
just by chance allow it.?? As I type this, the freq is 9,999,9976.

My 10 MHz standard is a Trimble ICM-SMT GPSDO spec'ed at +/- 0.3 x 10-8 but in reality is better as determined by zero-beat with WWV.?? The Trimble 10 MHz provides the reference clock for a HP5302A counter and one channel of a 2-channel scope whose second channel is looking at the Si5351 CLK0.

I have attached some photos that illustrate the setup and results.

Photo 1 shows the setup.?? I have one pc running Hyperterm to talk to the QRPLabs terminal program.
A?? second pc is running u-center.exe to monitor the QLG1 receiver.

********************************************************************************************

Photo 2?? shows the CLK0 freq as a fn of the Reg 2 value (with 1PPS disabled only for this test...obviously connected for all other testing/operation).

********************************************************************************************
Photo 3 shows how I compare the two 10 MHz freqs.?? The slightly lumpy ProgRock waveform is an artifact of some cable impedance mis-match.?? The HP counter (with 10 Sec timebase)?? is also measuring the CLK0 signal with a resolution of 0.1 Hz.

********************************************************************************************

Photo 4 shows what the QLG1 is seeing...the excellent?? S/N values are a result of the amplified antenna ( $3 USD).

********************************************************************************************
Photo 5 shows the 1PPS

********************************************************************************************

Photo 6 shows the Si5351 27 MHz xtal divided by 8.


********************************************************************************************

Some additional details...
1)?? Room temperature varies only a few degrees (F) during the day/night cycle.?? If I place the ProgRock in a small cardboard box, the same freq errors occur, just slowed down.
2)?? 5 Volt supply is clean.
3)?? When I load Reg 2 with a value that stops the drift for the temperature at that moment (freq error zero), within several minutes the freq will have wandered off several tenths but the ATtiny84 controller will not have changed the?? Reg 2 value to correct the error.?? After 15 minutes or so, the error might reach 2 or 3 KHz, Reg 2 may or may not be updated but even if the Reg 2 value has changed, it is still not a value that will bring the freq to zero error (+/-?? 0.1 or 0.2 Hz).
4)?? I have tried different values for Reg 5 with no observable difference. It is otherwise set to 0.
So, I am wondering, is there anyone, anywhere who has built one of these that actually stay on 10 MHz within a few tenths of a Hz?
73,?? Sid???? W7QJQ
Radio Welling


Robin Midgett
 

Hello Sid & the group,
Sid, you're not alone. I can't seem to get my ProgRock to be stable with GPS discipline. It is far more stable & accurate without GPS discipline; I have the standard issue crystal, the die cast aluminum housing (Bud 234) for the project & a 5 volt TO-220 regulator thermally bonded together in close proximity. The indoor room temperature is stable within 5°F. When operated in this mode (no GPS discipline), I find the ProgRock to run within 5-10 Hz. of desired frequency. Like your set up, my power supplies are clean.

Presently, I have a solid, clean 11.7mS wide 1PPS at 4.15V going into the 1PPS input of the ProgRock. This is after having level shifted it up from the 3.3V 1PPS output of the Trimble Resolution T GPS, which is noted for it's accurate 1PPS output. The native output pulse width of the GPS is 1mS. Not being able to achieve results even close to expectations, and based on info from Hans, I stretched the 1PPS pulse width from 1mS to 11mS and shifted the level up. Perhaps worth noting is that the unloaded output voltage from the level shifter stage is a solid 5 volts, but when connected to the ProgRock it falls to 4.15V. I don't know if that is proper or not, but I noted from Sid's post that the QLG1 output is a full 5 volts, and his GPSD ProgRock isn't working as expected.

Querying the registers under GPS discipline I find Reg. 2 to be updating, but still the oscillator behaves like a wayward soul on an Australian walkabout; as much as 9kHz off frequency over 8 hours. By comparison, without GPS, the oscillator is usually less than 10 Hz. from the target over a similar time span. Clearly, some of these boards aren't quite ripe for use under GPS discipline. 
I have a second kit presently unbuilt; I'm curious to see if there will be a difference. I also have the QLG1 & OCXO on the way from QRPLabs; perhaps those changes will put this kit on the right track.
My desire for this oscillator is a base for a set of propagation beacons, so frequency accuracy & stability are of high interest & desire.

Thanks,
Robin Midgett K4IDC


On Fri, Jul 12, 2019 at 7:21 AM Alan de G1FXB via Groups.Io <g1fxb=yahoo.co.uk@groups.io> wrote:
??my thoughts.....

It would be useful to know What settings other than the defaults have you entered?
for instance the default settings allows for +/- 5Hz inaccuracy before discipline is applied.
Beyond that:-

Perhaps don't loose sight of your statement " If I place the ProgRock in a small cardboard box, the same freq errors occur, just slowed down. "
By the sound of it,you perhaps see?? atleast some drift caused bt temperature variations. You are not using the OCXO version of the synth PCB(?),
any reason not to in applications needing stability
? (an uncased xtal will be sensitive to environmental changes.
Much has already being discussed over the requirements of frequency stability for the synth modules both here & in the Notes & FAQ's
ones that differ from the median spec would be most noticeable in freq standard use such as your desire,
if you still have persistence tendency for drift perhaps substitute the xtal for another and note the affect if any?
(The Xtals used are nothing special, they come from the same bag that are supplied with the other kit's, The OCXO benefit is that it and the accompanying osc components are heated to well above (hopefully) ambient temperature circa 45 degC to achieve greatest stability. It also has an additional buffer stage that further isolates the xtal from loading changes within the Si5351 IC.)


the minute changes in the 27MHz ref measurements are scaled according to the choice of output freq, there was a good discussion thread months back demonstrating this while putting the U3S on VHF....
(If considering one of the many of the "cheaper" self contained TCXO modules exhibit caution as staircase shaped steps to their control and don't necessary play nice with a second level of correction in this application if the ProgRock GPS calibration is also enabled, choose one or the other but not both? )

" So, I am wondering, is there anyone, anywhere who has built one of these that actually stay on 10 MHz within a few tenths of a Hz? "
Regarding your measurements,
How does the Progrock perform when compared against WWV to produce a beat note and measurement using for instance ARGO Or Spectrum Lab App?

In a past thread about "how good" Hans has quoted:-
" The ProgRock when it is properly set up and working properly, should be within +/- 0.5Hz of the desired 10,000,000 Hz. That is, 0.05ppm (50 parts per billion). The frequency "steps" as the algorithm hunts around making corrections, are NOT several Hz, they will be a fraction of a Hz. Theoretically the steps will be sized 0 to 0.3Hz at this output frequency. They depend on the arithmetic with the particular reference clock measurement that is made by the 1pps."

Alan

On 12/07/2019 02:20, w7qjq wrote:

ProgRock not working.
I have trying for weeks to get my ProgRock to function properly.?? It simply refuses to dicipline the Si5351 clock generator to stay on 10 MHz.
Typical example: From a cold start (power-on), after a few minutes the GPS receiver acquires enough sats to begin the 1PPS.?? At that point the (10 MHz) CLK0 freq error will be several KHz. The ATtiny84 controller will begin pulling the freq towards 10 MHz.?? The Si5351 Reg 2 can be seen changing the 27,004,xxx MHz as expected.?? After another few minutes the Reg 2?? value settles and the CLK0 freq will be 10MHz +/-???? 2 or 3 Hz .?? But the CLK0 freq will not remain at any freq for very long...just a degree or two temperature change will start it moving and the Reg 2 value will not change as necessary to correct the error.?? The only times that the error is zero (+/-?? 0.1Hz) is?? when the Reg 2 value and the changing temperature
just by chance allow it.?? As I type this, the freq is 9,999,9976.

My 10 MHz standard is a Trimble ICM-SMT GPSDO spec'ed at +/- 0.3 x 10-8 but in reality is better as determined by zero-beat with WWV.?? The Trimble 10 MHz provides the reference clock for a HP5302A counter and one channel of a 2-channel scope whose second channel is looking at the Si5351 CLK0.

I have attached some photos that illustrate the setup and results.

Photo 1 shows the setup.?? I have one pc running Hyperterm to talk to the QRPLabs terminal program.
A?? second pc is running u-center.exe to monitor the QLG1 receiver.

********************************************************************************************

Photo 2?? shows the CLK0 freq as a fn of the Reg 2 value (with 1PPS disabled only for this test...obviously connected for all other testing/operation).

********************************************************************************************
Photo 3 shows how I compare the two 10 MHz freqs.?? The slightly lumpy ProgRock waveform is an artifact of some cable impedance mis-match.?? The HP counter (with 10 Sec timebase)?? is also measuring the CLK0 signal with a resolution of 0.1 Hz.

********************************************************************************************

Photo 4 shows what the QLG1 is seeing...the excellent?? S/N values are a result of the amplified antenna ( $3 USD).

********************************************************************************************
Photo 5 shows the 1PPS

********************************************************************************************

Photo 6 shows the Si5351 27 MHz xtal divided by 8.


********************************************************************************************

Some additional details...
1)?? Room temperature varies only a few degrees (F) during the day/night cycle.?? If I place the ProgRock in a small cardboard box, the same freq errors occur, just slowed down.
2)?? 5 Volt supply is clean.
3)?? When I load Reg 2 with a value that stops the drift for the temperature at that moment (freq error zero), within several minutes the freq will have wandered off several tenths but the ATtiny84 controller will not have changed the?? Reg 2 value to correct the error.?? After 15 minutes or so, the error might reach 2 or 3 KHz, Reg 2 may or may not be updated but even if the Reg 2 value has changed, it is still not a value that will bring the freq to zero error (+/-?? 0.1 or 0.2 Hz).
4)?? I have tried different values for Reg 5 with no observable difference. It is otherwise set to 0.
So, I am wondering, is there anyone, anywhere who has built one of these that actually stay on 10 MHz within a few tenths of a Hz?
73,?? Sid???? W7QJQ
Radio Welling


Alan de G1FXB
 

Hi Robin,


"? It is far more stable & accurate without GPS discipline; I have the standard issue crystal, the die cast aluminum housing (Bud 234) for the project & a 5 volt TO-220 regulator thermally bonded together in close proximity. The indoor room temperature is stable within 5?F. When operated in this mode (no GPS discipline), I find the ProgRock to run within 5-10 Hz. of desired frequency. Like your set up, my power supplies are clean. "
the sweet spot for stable operation of cheap xtals tends to be around 45 DegC but needs to be found for each individual xtal by experimentation,
https://groups.io/g/QRPLabs/message/35232
https://groups.io/g/QRPLabs/message/35242
heating
the xtal to some arbitrary level above ambient using the 5V regulator perhaps yields minimal improvements especially as the xtal and improvised heater combo would also be losing heat to the thermally bonded diecast enclosure described??
It very likely could be improved by use of the dedicated OCXO type module (if for no other reason than the Discrete Colpitts Osc, Buffer stage so negating loading changes from within the Si5351
and adj temperature controlled oven.)

Please report back when you have characterised the results once your OCXO & QLG1 arrive.
(Remember you may need to revisit the PSU circuit of the progrock with the OCXO option, depending how you have the power feeds to the synth / 3.3v regulator & noise filter currently configured.)
"? Clearly, some of these boards aren't quite ripe for use under GPS discipline. "
(
There are no particularly frequency conscious components actually on the progrock PCB?
The ATtiny84 AVR uses a RC Oscilator to clock it's program cycles. with no particular requirement for it's Osc frequency accuracy.
If the progrock programs the CLK0-1 outputs correctly on yor build it is perhaps a confidence "pass" to it's functionality.
Beyond the firmware settings, (Like Sid, note that the default settings allow a measure of drift before applying correction) building your second progrock kit is unlikely to provide a cure,
As you already have it to hand and it's socketed, substitute the AVR IC and see if anything changes.)

Hans never seemingly uses any special GPS Types. Timing optimised, or other for his testing.
Just what ever the current QRP-Labs offered at that time, a
double check of your results with the Trimble against the QLG1 is good check to a known GPS RX.
(
although you really shouldn't have to if you have tried it both alone and with a pulse stretcher.....
I
n the past it sold the VK16 GPS module using the then "new kid on the block" SiRF III chipset, and perhaps one that with hindsight gained a reputation for it's rather indifferent PPS signal.
http://qrp-labs.com/ultimate3/u3info/u3hp.html
But still performed adequately with some choice firmware settings.....

Just because GPS discipline is an option, do you need to use it? perhaps that's worth a further trial.
Others have proven a free running OCXO Kit can produce 0.5Hz accuracy over many hours.
I believe the discipline operation and arithmetic accuracy are handled differently in the Progrock to that of the U3S / VFO kits. (other than the obvious different processors...
Only Hans will know the In / out's of that and which has the greatest "on paper" resolution and under what conditions )

Other builders took the commercial SMD style TCXO route seeking accurate HF QRSS or VHF WSPR operation with their U3S,
only to re-discover after a couple of different threads that a correctly set up OCXO was perhaps the best choice,
https://groups.io/g/QRPLabs/message/32058
https://groups.io/g/QRPLabs/message/32062
https://groups.io/g/QRPLabs/message/32083
https://groups.io/g/QRPLabs/message/35214
" I have recently relocate the mept into the summer house (AKA a shed) since that I have noticed a lot more thermal drift over a 24hr period, at night when its cold it drift up in freq and on a hot day it drifts down (about 25hz max over the swing so about +/-? 15 hz or so) "
https://groups.io/g/QRPLabs/message/35310
" I was getting about 15 hz drift over night when the ?summer house? (shed really)? got cool over night, it was also drifting the other way when its hot (high freq drift when cold, low freq drift when hot ) well I recalibrated the OCXO and did find it was past the flat part of the curve and the current was rather high, I reset it and found a lower current setting (about 150mA give or take a bit) which seemed to be on the flat part of the curve. Its been running in the shed since about 4pm yesterday and I have been monitoring it with Argo set to 30 sec dots slow (0.1Hz steps at that speed) .
I am pleased with its performance the worst drift was about 0.5Hz over that time and now back to the point it started
"
or
https://groups.io/g/QRPLabs/message/32396
another free running OCXO build
" On an overnight run, with typical California indoor temperature changes, I occasionally saw beat frequencies ranging from 0.014 to 0.067 Hz, which yields a peak relative drift of about 5 ppb (= 0.005 ppm). That's amazing! "
or
https://groups.io/g/QRPLabs/message/30301
https://groups.io/g/QRPLabs/message/30555


" My desire for this oscillator is a base for a set of propagation beacons, so frequency accuracy & stability are of high interest & desire. "
+/- half a hertz at say 10MHz you will be in good company,
If you are looking for your own "local" signal source with accuracy to traceable to NIST, it may require more than a progrock, even if driven with the best PPS signal.
?You may need need to visit the time nuts forum where a lucky few discuss home labs, and their primary standards and others just make do..... ? :-[

Alan

On 12/07/2019 14:45, Robin Midgett wrote:
Hello Sid & the group,
Sid, you're not alone. I can't seem to get my ProgRock to be stable with GPS discipline. It is far more stable & accurate without GPS discipline; I have the standard issue crystal, the die cast aluminum housing (Bud 234) for the project & a 5 volt TO-220 regulator thermally bonded together in close proximity. The indoor room temperature is stable within 5?F. When operated in this mode (no GPS discipline), I find the ProgRock to run within 5-10 Hz. of desired frequency. Like your set up, my power supplies are clean.

Presently, I have a solid, clean 11.7mS wide 1PPS at 4.15V going into the 1PPS input of the ProgRock. This is after having level shifted it up from the 3.3V 1PPS output of the Trimble Resolution T GPS, which is noted for it's accurate 1PPS output. The native output pulse width of the GPS is 1mS. Not being able to achieve results even close to expectations, and based on info from Hans, I stretched the 1PPS pulse width from 1mS to 11mS and shifted the level up. Perhaps worth noting is that the unloaded output voltage from the level shifter stage is a solid 5 volts, but when connected to the ProgRock it falls to 4.15V. I don't know if that is proper or not, but I noted from Sid's post that the QLG1 output is a full 5 volts, and his GPSD ProgRock isn't working as expected.

Querying the registers under GPS discipline I find Reg. 2 to be updating, but still the oscillator behaves like a wayward soul on an Australian walkabout; as much as 9kHz off frequency over 8 hours. By comparison, without GPS, the oscillator is usually less than 10 Hz. from the target over a similar time span. Clearly, some of these boards aren't quite ripe for use under GPS discipline.?
I have a second kit presently unbuilt; I'm curious to see if there will be a difference. I also have the QLG1 & OCXO on the way from QRPLabs; perhaps those changes will put this kit on the right track.
My desire for this oscillator is a base for a set of propagation beacons, so frequency accuracy & stability are of high interest & desire.

Thanks,
Robin Midgett K4IDC

w7qjq
 

Good evening Alan,
>"It would be useful to know What settings other than the defaults have you entered?
>for instance the default settings allows for +/- 5Hz inaccuracy before discipline is applied."

I answered than in my original post ( line item 4 in "Some additional details...)

Beyond that:-
One of us is unclear as to what a disciplined oscillator is...
To me, and the reason I built this project, was I was led to believe that as the xtal drifted, the CLK2 signal (CLK0 / 8) would be compared is some manner to the 1PPS reference from the GPS and when an error was detected, the controller (ATtiny84) would load a 'better' value to Reg2 (the xtal freq) to bring the CLK0 freq back to 10 MHz.
 This is clearly not happening.  The solution has nothing to do (or SHOULD have nothing to do) with trying to thermally stabilize the xtal.  Either the discipline scheme works and the CLK0 stays on 10 MHz or it doesn't.  If the scheme doesn't work, then why bother with the controller...get rid of it and go with an insulated box, or a temperature-controlled xtal, or picking a different xtal, or........

>Regarding your measurements,
>How does the Progrock perform when compared against WWV to produce a beat note and
>measurement using for instance ARGO Or Spectrum Lab App?

I discussed than in my original post with words and photo.  Again... my frequency standard is a Trimble ICM-SMT GPSDO and my ultimate 'sanity check' is the 10 MHz xmtr at WWV in Colorado.

Sid


Alan G4ZFQ
 

To me, and the reason I built this project, was I was led to believe that as the xtal drifted, the CLK2 signal (CLK0 / 8) would be compared is some manner to the 1PPS reference from the GPS and when an error was detected, the controller (ATtiny84) would load a 'better' value to Reg2 (the xtal freq) to bring the CLK0 freq back to 10 MHz.
Sid,

I've not been following too closely but this is what should happen.
I was not satisfied with my Progrock until I realised the default GPS setting was not correct for really fine adjustment. Then, I forget what frequency, (14.996MHz?) was set to within a few tenths of Hz.

Of course if the 27MHz crystal is abnormally unstable for any reason this will not happen. Too much drift will not be compensated to a fine degree. So is this stable?

73 Alan G4ZFQ

Alan de G1FXB
 

Hi Sid,
Not unclear, but yes we differ in our beliefs.

I stand by a belief a OCXO reference is more preferable than applying correction to a less stable source.
If a normal SI5351 module is used then best case construction applies, give the controller the easiest possible job.
With thermal masses (others use the term heatsinks ;-)) & avoiding draughts....
With GPS correction there needs to be a trade off between the choice of continuous discipline (reloading Reg2 every sec) or allowing an determinable amount of drift but maintaining a stable 50/50 duty cycle in the mean time. Ideally you don't want to have to recalculate Register 2, ever........

I do note(!) Your observations show " Reg 2 can be seen changing the 27,004,xxx MHz as expected.?? After another few minutes the Reg 2?? value settles and the CLK0 freq will be 10MHz +/-???? 2 or 3 Hz .?? But the CLK0 freq will not remain at any freq for very long...just a degree or two temperature change will start it moving and the Reg 2 value will not change as necessary to correct the error.?? The only times that the error is zero (+/-?? 0.1Hz) is?? when the Reg 2 value and the changing temperature just by chance allow it "

In the prog rock ge mastr exec ii thread Hans promises " When all is well you should be well within 0.05ppm. "

Maybe phase disturbance caused in the discipline process has more than an influence in the counter readings than it first appears / more so if clashing with the gate period?
(It's something that often gets omitted in many discussions.... )


Hans has said there are both,? register options and potential to further improve the F/W given time.....
https://groups.io/g/QRPLabs/message/27419

?I'll take a back seat and let the others contribute to their findings.


Alan


On 13/07/2019 06:26, w7qjq wrote:
Good evening Alan,
>"It would be useful to know What settings other than the defaults have you entered?
>for instance the default settings allows for +/- 5Hz inaccuracy before discipline is applied."

I answered than in my original post ( line item 4 in "Some additional details...)

Beyond that:-
One of us is unclear as to what a disciplined oscillator is...
To me, and the reason I built this project, was I was led to believe that as the xtal drifted, the CLK2 signal (CLK0 / 8) would be compared is some manner to the 1PPS reference from the GPS and when an error was detected, the controller (ATtiny84) would load a 'better' value to Reg2 (the xtal freq) to bring the CLK0 freq back?to 10 MHz.
?This is clearly not happening.? The solution has nothing to do (or SHOULD have nothing to do) with trying to thermally stabilize the xtal.? Either the discipline scheme works and the CLK0 stays on 10 MHz or it doesn't.? If the scheme doesn't work, then why bother with the controller...get rid of it and go with an insulated box, or a temperature-controlled xtal, or picking a different xtal, or........

>Regarding your measurements,
>How does the Progrock perform when compared against WWV to produce a beat note and
>measurement using for instance ARGO Or Spectrum Lab App?

I discussed than in my original post with words and photo.? Again... my frequency standard is a Trimble ICM-SMT GPSDO and?my ultimate 'sanity check' is the 10 MHz xmtr at?WWV in Colorado.

Sid



geoff M0ORE
 

I think that it should be borne in mind that some builders are attempting to achieve stability from a unit costing a few dollars, in some cases the cost of a mug of coffee, that professionals spend thousands of dollars to achieve.

The crystals supplied are standard computer grade units which are not intended to be used as a frequency standard, just to give timing signals for a micro-processor.

If you want to measure the stability of anything, you need to have the test equipment better than the unit you are testing to get any meaningful results. In the case of frequency, what standard are you going to use??


On 13/07/2019 08:20, Alan de G1FXB via Groups.Io wrote:
Hi Sid,
Not unclear, but yes we differ in our beliefs.

I stand by a belief a OCXO reference is more preferable than applying correction to a less stable source.
If a normal SI5351 module is used then best case construction applies, give the controller the easiest possible job.
With thermal masses (others use the term heatsinks ;-)) & avoiding draughts....
With GPS correction there needs to be a trade off between the choice of continuous discipline (reloading Reg2 every sec) or allowing an determinable amount of drift but maintaining a stable 50/50 duty cycle in the mean time. Ideally you don't want to have to recalculate Register 2, ever........

I do note(!) Your observations show " Reg 2 can be seen changing the 27,004,xxx MHz as expected.?? After another few minutes the Reg 2?? value settles and the CLK0 freq will be 10MHz +/-???? 2 or 3 Hz .?? But the CLK0 freq will not remain at any freq for very long...just a degree or two temperature change will start it moving and the Reg 2 value will not change as necessary to correct the error.?? The only times that the error is zero (+/-?? 0.1Hz) is?? when the Reg 2 value and the changing temperature just by chance allow it "

In the prog rock ge mastr exec ii thread Hans promises " When all is well you should be well within 0.05ppm. "

Maybe phase disturbance caused in the discipline process has more than an influence in the counter readings than it first appears / more so if clashing with the gate period?
(It's something that often gets omitted in many discussions.... )


Hans has said there are both,? register options and potential to further improve the F/W given time.....
https://groups.io/g/QRPLabs/message/27419

?I'll take a back seat and let the others contribute to their findings.


Alan


On 13/07/2019 06:26, w7qjq wrote:
Good evening Alan,
>"It would be useful to know What settings other than the defaults have you entered?
>for instance the default settings allows for +/- 5Hz inaccuracy before discipline is applied."

I answered than in my original post ( line item 4 in "Some additional details...)

Beyond that:-
One of us is unclear as to what a disciplined oscillator is...
To me, and the reason I built this project, was I was led to believe that as the xtal drifted, the CLK2 signal (CLK0 / 8) would be compared is some manner to the 1PPS reference from the GPS and when an error was detected, the controller (ATtiny84) would load a 'better' value to Reg2 (the xtal freq) to bring the CLK0 freq back?to 10 MHz.
?This is clearly not happening.? The solution has nothing to do (or SHOULD have nothing to do) with trying to thermally stabilize the xtal.? Either the discipline scheme works and the CLK0 stays on 10 MHz or it doesn't.? If the scheme doesn't work, then why bother with the controller...get rid of it and go with an insulated box, or a temperature-controlled xtal, or picking a different xtal, or........

>Regarding your measurements,
>How does the Progrock perform when compared against WWV to produce a beat note and
>measurement using for instance ARGO Or Spectrum Lab App?

I discussed than in my original post with words and photo.? Again... my frequency standard is a Trimble ICM-SMT GPSDO and?my ultimate 'sanity check' is the 10 MHz xmtr at?WWV in Colorado.

Sid



w7qjq
 

for Alan de G1FXB
If you are going to quote my text, please don't edit it to make me sound like an idiot. 
What is the purpose for all the "?????" that you added? 

You said:
"I stand by a belief a OCXO reference is more preferable than applying correction to a less stable source.
 If a normal SI5351 module is used then best case construction applies, give the controller the easiest possible job.
 With thermal masses (others use the term heatsinks ;-)) & avoiding draughts....
 With GPS correction there needs to be a trade off between the choice of continuous discipline (reloading Reg2 every sec) or allowing an determinable amount of drift but maintaining a stable 50/50 duty cycle in the mean time. Ideally you don't want to have to recalculate Register 2, ever........"

I agree that stabilizing the xtal temp would allow for less frequent corrections.  But that is not the issue, the issue to me is that the controller is not making the necessary corrections.  Please look at my Photo 2.  I can  open the loop by removing the 1PPS and insert my self at the keyboard to close the loop by loading Reg 2 with whatever value is required to bring the CLK0 freq back to 10 MHz to within about 0.37 Hz.  (the Reg 2 resolution is 1 Hz at 27 MHz which is     10  / 27  =  0.37 Hz  at 10 MHz).
But I don't have the patience to have to do this every few minutes, or hours, or days depending on how well I am controlling the xtal temp (or using an OCXO or whatever).  I want to let the controller use the 1PPS to do this for me...it's called disciplining an oscillator.
You continue:
"Maybe phase disturbance caused in the discipline process has more than an influence in the counter readings than it first appears / more so if clashing with the gate period?
 (It's something that often gets omitted in many discussions.... )"

Yes, thank you, I am aware that when Reg 2 changes (either from the ATtiny84 or from the keyboard) that the current 10-sec count is to be disregarded.  Further, the visual info given by the technique of Photo 3 is as good or perhaps better than the counter value.

*******************************************************
for geoff M0ORE
you said:

"I think that it should be borne in mind that some builders are attempting to achieve stability from a unit costing a few dollars, in some cases the cost of a mug of coffee, that professionals spend thousands of dollars to achieve."

This builder was/is expecting to "...achieve stability from a unit costing a few dollars..." that was given on the web site.

and:

"The crystals supplied are standard computer grade units which are not intended to be used as a frequency standard, just to give timing signals for a micro-processor."

Nowhere in the ProgRock description does is say, nor do I expect,  that the 27 MHz xtal is a "frequency standard".  The Si5351 does not measure the xtal freq.  It wants only two numbers (aside from some house-keeping stuff) from the controller...  the desired CLK0 freq and  the measured (by using the 1PPS) xtal freq.

The "... just to give timing signals for a micro-processor." is a non sequitur, the only microprocessor involved uses its internal RC oscillator.

And finally:

"If you want to measure the stability of anything, you need to have the test equipment better than the unit you are testing to get any meaningful results. In the case of frequency, what standard are you going to use??"

I have twice given this information, but here comes number three...
"...my frequency standard is a Trimble ICM-SMT GPSDO and my ultimate 'sanity check' is the 10 MHz xmtr at WWV in Colorado."

Sid




 

 

Alan G4ZFQ
 

Sid,

Going back to your first post

after a few minutes
the GPS receiver acquires enough sats to begin the 1PPS.  At that
point the (10 MHz) CLK0 freq error will be several KHz. The
ATtiny84 controller will begin pulling the freq towards 10 MHz. The Si5351 Reg 2 can be seen changing the 27,004,xxx MHz as
expected.  After another few minutes the Reg 2  value settles and
the CLK0 freq will be 10MHz +/-   2 or 3 Hz .  But the CLK0 freq
will not remain at any freq for very long...just a degree or two
temperature change will start it moving and the Reg 2 value will
not change as necessary to correct the error.
This is expected if register 3 is left at default. have you set it to 0 when it has got near to correct? (Manual section 4.4)
The PPS is obviously working but it will not adjust correctly if the 27MHz drifts too fast. Have you checked that?

You have detailed a lot of redundant information, perhaps that has confused people.

73 Alan G4ZFQ

Alan de G1FXB
 

Hi Sid,

No intention to make you look an idiot.

The "insertion" of ?????? is something related to use of a particular mail client, it has being present for a while since an "upgrade", and on two machines
especially prevalent when quoting in posts where the original poster does not share identical character sets?
(We may both "speak English" but different variations there of...........)
I do have a propensity to use a string of ....... to encourage stop & think, over topics. ?:-)?
To make it clear to all readers, I make a conscious effort to highlight through the use of bold type to draw attention to, or adding colour to the text where I cut and paste quotes.
Please do not feel singled out, check back on some of my past replies to others as far back as April(?), hopefully you should see similar findings.

Being open source and donation ware it perhaps owes me what I pay for it....... & off topic for this board.



To Progrock Business & recap.......

" But that is not the issue, the issue to me is that the controller is not making the necessary corrections. "
It's strange both you and Robin both have similar(?) setting problems currently.....

a/. searching the progrock threads is something encouraged for all for a global view to what the group knowledge is.
the progrock kit has being sold since, early 2016.
Hans hasn't indicated any recent changes, indeed he is otherwise occupied elsewhere.
If there were major flaws to it's operation it would be revealed by now.
It's a simple & cheap $18 kit it does what it advertises very well.
Indeed it has a unique PSU noise filter not found in any other kit?

b/. Enabling GPS correction resulting in 2 - 3KHz frequency swings in the 10MHz output over 15 minutes while a straight out of the box progrock is expected to have a 1KHz accuracy without any GPS correction
is a plain indication something is wrong.

two possibilities?

c/. A none intentional problem in the assembly or out of spec components.
There is little on the progrock PCB to go wrong without showing in areas other than the known 2-3KHz errors, you are communicating with the AVR fine through Hyperterminal.
The Si5351 pcb is harder to identify, but at the instance of manually updating the reg2 bin resulting a more stable condition, then increasing wild swings infers a clean bill of health to this as well,
as it can be be disciplined albeit manually.....
A next case check could be to make a observation of the 27MHz Osc, stability. It's what everything depends on.........

d/. I
ncorrect settings causing a race condition.
My initial post encouraged a reply to what you had modified beyond the defaults....
(especially the opportunity to reveal if you had opened "Pandora's box" and modified register 28 contents.)

e/. something I take aspects as a nothing more than perhaps a typo and inadvertently transferred the values, inconveniently it is also in a greater finding....
In your
" Some additional details...
4) I have tried different values for Reg 5 with no observable difference. It is otherwise set to 0. "
(Register 5 is reserved to set output frequency of Bank 0, Clk 1)

Without putting words in your mouth,
You meant to type something approximating
Register 3 (which has a default value of 5)
you have tried different settings beyond a value of 0, (0 being the instruction applying "continuous" GPS discipline.)
With no observable difference?

The no " observable difference " is perhaps a red flag as I'm sure you realise.
5 should equate to 5KHz threshold before correction, presumably values up to 9 are equally acceptable in the absence of a max value in the manual .
Which brings you back to your starting point, why have you residual 2-3KHz deviations.....

f/. Out of interest have you tried setting up another Bank & CLK 0/1 and does it exhibit the same fault symptoms, science suggests it will

g/. Hans has not revealed use of register 0.

h/. There is no chance you have anything generating EM / RF field around your measurement bench getting into either the progrock or test gear?

i/. A honest thought, having so many unknowns?
(Having easy serial access to editing some powerful registers and not pointing fingers.)
Nothing to loose in a factory reset, at this stage and taking stock of the symptoms again from a known, out of the box starting point..........

If Robin is reading this thread and makes similar checks he can perhaps provide the most useful second findings.


Alan


On 13/07/2019 17:21, w7qjq wrote:

for Alan de G1FXB
If you are going to quote my text, please don't edit it to make me sound like an idiot.?
What is the purpose?for all the "?????" that you added??

You said:
"I stand by a belief a OCXO reference is more preferable than applying correction to a less stable source.
?If a normal SI5351 module is used then best case construction applies, give the controller the easiest possible job.
?With thermal masses (others use the term heatsinks ;-)) & avoiding draughts....
?With GPS correction there needs to be a trade off between the choice of continuous discipline (reloading Reg2 every sec) or allowing an determinable amount of drift but maintaining a stable 50/50 duty cycle in the mean time. Ideally you don't want to have to recalculate Register 2, ever........"

I agree that stabilizing the xtal temp would allow for less frequent corrections.? But that is not the issue, the issue to me is that the controller is not making the necessary corrections.? Please look at my Photo 2.? I can? open the loop by removing the 1PPS and insert my self at the keyboard to close the loop by loading Reg 2 with whatever value is required to bring the CLK0 freq back to 10 MHz to within about 0.37 Hz.? (the Reg 2 resolution is 1 Hz at 27 MHz which is???? 10??/?27? =? 0.37 Hz? at 10 MHz).
But I don't have the patience to have to do this every few minutes, or hours, or days depending on how well I am controlling the xtal temp (or using an OCXO or whatever).? I want to let the controller use the 1PPS to do this for me...it's called disciplining an oscillator.
You continue:
"Maybe phase disturbance caused in the discipline process has more than an influence in the counter readings than it first appears / more so if clashing with the gate period?
?(It's something that often gets omitted in many discussions.... )"

Yes, thank you, I am aware that?when Reg 2 changes (either from the ATtiny84 or from the keyboard) that the current 10-sec count is to be disregarded.? Further, the visual info given by the technique of Photo 3 is as good or perhaps better than the counter value.

*******************************************************
for geoff M0ORE
you said:

"I think that it should be borne in mind that some builders are attempting to achieve stability from a unit costing a few dollars, in some cases the cost of a mug of coffee, that professionals spend thousands of dollars to achieve."

This builder was/is expecting to "...achieve stability from a unit costing a few dollars..." that was given on the web site.

and:

"The crystals supplied are standard computer grade units which are not intended to be used as a frequency standard, just to give timing signals for a micro-processor."

Nowhere?in the ProgRock description does is say, nor do I expect,??that the 27 MHz xtal is a "frequency standard".? The Si5351 does not measure the xtal freq.? It wants only two numbers (aside from some house-keeping stuff) from the controller...? the desired CLK0 freq and??the measured (by using the 1PPS) xtal freq.

The "...?just to give timing signals for a micro-processor." is a non sequitur, the only microprocessor involved uses its internal RC oscillator.

And finally:

"If you want to measure the stability of anything, you need to have the test equipment better than the unit you are testing to get any meaningful results. In the case of frequency, what standard are you going to use??"

I have twice given this information, but here comes number three...
"...my frequency standard is a Trimble ICM-SMT GPSDO and?my ultimate 'sanity check' is the 10 MHz xmtr at?WWV in Colorado."

Sid




?

?


Alan G4ZFQ
 

Register 3 (which has a default value of 5)
5 should equate to 5KHz threshold before correction, presumably values
Lets get the units correct, Sid has also used KHz. I hope this is a typo. No K, just Hz.

73 Alan G4ZFQ

Alan de G1FXB
 


Alan, Thanks for catching that.

Indeed my turn for a typo, a value of 5 equates to 5Hz threshold for the register 3 entries.
Not 5KHz my bad.....:-[

How many ???????? will get inserted on a UK character set this time(?)..........

Alan

On 13/07/2019 21:36, Alan G4ZFQ wrote:
>Register 3 (which has a default value of 5)
5 should equate to 5KHz threshold before correction, presumably values

Lets get the units correct, Sid has also used KHz. I hope this is a typo. No K, just Hz.

73 Alan G4ZFQ




Alan de G1FXB
 

Hi Sid,

Created from a blank sheet of paper so all (?) will be my own, and no errant strings of ???????
Hopefully..........

Is this the same progrock build, you had the problem with in end of April where you report a consistent 1-3 Hz inaccuracy
What is different to now, where the current results reported are in the order of 2-3 KHz?


for the purposes of diagnosis.
Trial the progrock with it's minimum requirements

a/. In your additional details in section 2, you describe that the 5v supply is clean,
presumably this is reference to your "bench" top supply.
This suggests you are not using the 4.3.1. build choice, but it's built according to option given at step 4.3.2

b/. Therefore on the progrock PCB.
IC2 not fitted but in / out pads are jumpered across, and R1 & R2 are not fitted.

c/. On the Si5351 PCB.
IC2, R5, R6, C1 are not fitted.


d/. (the LM317 is not fitted on either progrock or the Si5351 PCB's. as you have taken over the task of providing the 5v supply)
(See all sections of 4.3.x of the build manual for verification)
As a final check, perhaps redo step 8 of page 10, and verify 5 and 3.3v (likely on the high side) voltages are present off board to the Si5351 module.

The progrock just requires just power in,
There are no other dependencies in order to output an signal to a "normal" Xtal controlled accuracy, the default is 10MHz.
Get that verified first before moving to PPS discipline

e/.
having removed the PPS signal make sure that pad of the progrock is grounded to the adjacent pad, to guarantee not inadvertently placing FW in PPS correction mode.

f/.
perform a factory reset, to give known straight out of the box settings

g/. Power cycle, to make sure latest configuration changes are applied

h/. what are the measurements results when made on the CLK0?
There "should" be a calibration error, and a smaller element of drift, likely caused by temperature variation

i/. if the CLK output is still "walkabout" in the order of KHz.? Taking care not to load it's oscillator, how stable is the 27MHz reference from which CLK0 is derived?


Alan


w7qjq
 

Alan, I thank you for your response.  I must be away from the radio bench until July at which time I will act on each of your suggestions.  Meanwhile, I have ordered two additional ProgRock kits.

Sid

Graham W
 

I have built a few prog rocks. I did not use the 27 mhz crystal as supplied, but installed a TCXO as suggested in the manual. I find ,even without GPS control that it is very stable. The pads are already there for the TCXO.
Graham VE3WGW

Andy Brilleaux <punkbiscuit@...>
 

On Sat, Jul 13, 2019 at 05:21 PM, w7qjq wrote:
If you are going to quote my text, please don't edit it to make me sound like an idiot. 
You don't need a third party to make you sound like a twat.

73 de Andy

Robin Midgett
 

Hi Graham & the group,
The issue Sid & I and possibly others who aren't reading the mail on this subject isn't about stability with the TCXO or OCXO. The stability with those optional oscillators is well documented and not in question, and for a broad range of applications, mine included, well more than sufficient.
The issue here is making the ProgRock work reliably with GPS discipline, and why that isn't happening reliably.
Diatribes about the NEED for GPS discipline in anyone's application are irrelevant simply because the fact is the product doesn't perform reliably as advertised with GPS discipline, and, very importantly, within the context of kit building and the price of the kit, this is not a deal breaker or terribly surprising. This is part of the value of kit building; the builder has the opportunity to improve the kit as they see fit, or not.
What is perhaps more interesting and worth studying is why the GPS discipline isn't as reliable as it should be, and what's to be done to mitigate that deficiency. Based on the current responses to our (Sid & my) posts, Hans may be the only person qualified to really answer the questions regarding the apparent deficiency.
Further, personal attacks are not helpful, Andy Brilleaux. Let's leave those for the elementary school playground. Let's approach this issue scientifically and see if a successful solution can be had. I suspect it can and will.
Thanks,
Robin Midgett K4IDC


On Sun, Jul 14, 2019 at 3:15 PM Graham W <gram.warrington@...> wrote:
I have built a few prog rocks. I did not use the 27 mhz crystal as supplied, but installed a TCXO as suggested in the manual. I find ,even without GPS control that it is very stable. The pads are already there for the TCXO.
Graham VE3WGW

geoff M0ORE
 

I built my ProgRock a few months ago and it worked as expected. I found it has to be in an enclosure to keep daughts away from the crystal. My earlier comment about the crystal being intended for use in computer clocks was mis-read or my poor explanation. I am fully aware that in this application, the processor uses its own timing circuit.

The accuracy of the output signal depends on the value set in register 2.

As an experiment, try setting an output to a nominal value somewhere in the region of 10MHz. With no GPS discipline applied, set the value of register 2 to obtain a reference frequency as close to the required 10MHz ( or whatever frequency you want) as possible. Now increase the value of register 2 by 1Hz and see what the new output frequency is. Now try the same tests with the output set to something like 100MHz and see the effect of changing the value of register 2 by 1Hz.

I am still of the opinion that this kit performs well and does its job of replacing several crystals exactly as intended and described in paragraph 3 of the assembly instructions.

Geoff


On 15/07/2019 16:31, Robin Midgett wrote:
Hi Graham & the group,
The issue Sid & I and possibly others who aren't reading the mail on this subject isn't about stability with the TCXO or OCXO. The stability with those optional oscillators is well documented and not in question, and for a broad range of applications, mine included, well more than sufficient.
The issue here is making the ProgRock work reliably with GPS discipline, and why that isn't happening reliably.
Diatribes about the NEED for GPS discipline in anyone's application are irrelevant simply because the fact is the product doesn't perform reliably as advertised with GPS discipline, and, very importantly, within the context of kit building and the price of the kit, this is not a deal breaker or terribly surprising. This is part of the value of kit building; the builder has the opportunity to improve the kit as they see fit, or not.
What is perhaps more interesting and worth studying is why the GPS discipline isn't as reliable as it should be, and what's to be done to mitigate that deficiency. Based on the current responses to our (Sid & my) posts, Hans may be the only person qualified to really answer the questions regarding the apparent deficiency.
Further, personal attacks are not helpful, Andy Brilleaux. Let's leave those for the elementary school playground. Let's approach this issue scientifically and see if a successful solution can be had. I suspect it can and will.
Thanks,
Robin Midgett K4IDC


On Sun, Jul 14, 2019 at 3:15 PM Graham W <gram.warrington@...> wrote:
I have built a few prog rocks. I did not use the 27 mhz crystal as supplied, but installed a TCXO as suggested in the manual. I find ,even without GPS control that it is very stable. The pads are already there for the TCXO.
Graham VE3WGW

Hans Summers
 

Hi Robin, Graham, Sid, all

There have been a lot of posts on this topic and being on vacation at the moment I kind of lost track of where this got to.

ProgRock should work as advertised on the web page and documentation. If it doesn't, something is wrong. 

A GPS disciplined ProgRock should be accurate well within 0.05ppm (note that this parts-per-million specification means that the absolute precision in Hz, scales with frequency). This is what I have seen in all my tests and has been verified by other constructors too. To get the system working does require:

1. GPS correction threshold register must he understood properly. To get maximum precision requires setting the GPS correction threshold register to zero (default is 5Hz). 

2. The 1pps signal needs to be at 5V logic level. Many GPS units have 2.8V logic level outputs and need level conversion. This can be done with pull-up resistors with some care and some inevitable degradation in noise immunity. Or with proper level conversion.

3. The GPS pulse needs to be long enough for the processor to handle it properly. I'm not actually sure what the minimum is. Many common modern GPS modules have 0.1 second positive pulses, these work fine. Some modules with very short pulses e.g. 1 microsecond wouldn't work.

Note that the QRP Labs QLG1 GPS kit http://qrp-labs.com/qlg1 was used in all my testing and works very well. It has 0.1 second positive pulse and it has proper logic level conversion. The QLG1 has a very accurate 1pps specified with max 11 nanosecond r.m.s error.

If the ProgRock isn't performing as expected then something is wrong. That could be an electrical problem (soldering problem, dead component etc); or some issue with the characteristics of the 1 pulse-per-second signal input. 

If there's any question I haven't covered here, please let me know.

73 Hans G0UPL 







On Mon, Jul 15, 2019, 16:31 Robin Midgett <K4IDC@...> wrote:
Hi Graham & the group,
The issue Sid & I and possibly others who aren't reading the mail on this subject isn't about stability with the TCXO or OCXO. The stability with those optional oscillators is well documented and not in question, and for a broad range of applications, mine included, well more than sufficient.
The issue here is making the ProgRock work reliably with GPS discipline, and why that isn't happening reliably.
Diatribes about the NEED for GPS discipline in anyone's application are irrelevant simply because the fact is the product doesn't perform reliably as advertised with GPS discipline, and, very importantly, within the context of kit building and the price of the kit, this is not a deal breaker or terribly surprising. This is part of the value of kit building; the builder has the opportunity to improve the kit as they see fit, or not.
What is perhaps more interesting and worth studying is why the GPS discipline isn't as reliable as it should be, and what's to be done to mitigate that deficiency. Based on the current responses to our (Sid & my) posts, Hans may be the only person qualified to really answer the questions regarding the apparent deficiency.
Further, personal attacks are not helpful, Andy Brilleaux. Let's leave those for the elementary school playground. Let's approach this issue scientifically and see if a successful solution can be had. I suspect it can and will.
Thanks,
Robin Midgett K4IDC


On Sun, Jul 14, 2019 at 3:15 PM Graham W <gram.warrington@...> wrote:
I have built a few prog rocks. I did not use the 27 mhz crystal as supplied, but installed a TCXO as suggested in the manual. I find ,even without GPS control that it is very stable. The pads are already there for the TCXO.
Graham VE3WGW