Re: ProgRock not working #progrock

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




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