New product: tinyGTC, GNSS disciplined oscillator and universal 2 input Timer an

[KedasProbe]

I noticed that the Time displayed on the device is not updated on time (anymore).

I added a LED to the PPS OUT (20µs via a function generator to 50ms)
In this video you can see it is missing seconds and goes out of sync.
https://www.youtube.com/shorts/8CKgj5GSjNo

[erikka]

Sometimes the seconds count on the display skips a update and increments 2 seconds after skipping. Will see if this can be improved

[cncjerry]

Hi, interesting device.  I have a 5370 and other counting equipment. I plan to purchase one when I can find it in the US.

Can you explain what you mean in the following from your site?  Does that mean that the GPSDO does not process sawtooth information?

"It consists of a simple GPS module that can receive GPS and BDS constellations only and delivers a 1 PPS as timing output without sawtooth correction info being available."

Thank you.

Jerry

[erikka]

Does that mean that the GPSDO does not process sawtooth information?

Correct. To fit the total cost target sawtooth correction was not possible.
Adding a true timing enabled GPS module would double the price.

[erikka]

randl.com

[cncjerry]

when do you think randl.com will have them?  not listed that I see.

thanks

[erikka]

https://www2.randl.com/index.php?main_page=advanced_search_result&search_in_description=1&keyword=Tinygtc

[cncjerry]

https://www2.randl.com/index.php?main_page=advanced_search_result&search_in_description=1&keyword=Tinygtc

Thanks, the title above the unit said TinySA, that's what threw me off.  I backordered one of the 12G units.

In the write-up, you mentioned about switching the TDC used.  I've used the 7200s and wondering what you ended-up selecting.  The 7200 had 35ps stdev and a resolution of 55ps listed in the datasheet. I assume the chip you used exceeded that?  I've not looked for a replacement in a while.

thanks

[erikka]

Phase data calculated from single shot timestamp every 100 ms using 10 MHz input

[erikka]

This is a bit more challenging measurement 10.000000001 MHz so a full phase rotation every 1000 s
The histogram below shows the quantization and the stdev.
The phase plot shows both the timestamp based measurement and the phase based measurement. The later uses multiple timestamps and linear regression to enhance accuracy
You can clearly the the about 20 ps phase pulling repeating every 1000 s as I did not use ground loop isolation transformers.

[cncjerry]

Can you show a picture of the setup for the measurement above?  Also wondering what you are using for a reference oscillator.

[erikka]

No picture needed.
Put a SMA Tee on REF and connect one side of the Tee to A and the other side to your source.
The quality of the source is not very important as long as the phase noise is not too bad as it is use for both the REF and A inputs, I'm using the REF output of a signal generator so you get the 10 MHz needed for the REF input

[erikka]

Sorry, the 10000000.001 Hz variant uses the output of a SG into A and REF out of the SG into REF

[cncjerry]

Hi, do you have a residual noise floor test histogram with an ADEV as well?  Just ref split to the input?  Or just upload the .tim file.

I'd like to compare it a 5370B that I have.   I ordered the 12g model, waiting for it to get here as it is backordered at randl.

Lots of testing has been done with the 5370s, I almost hate to get mine out as that usually kicks off months of testing.  I changed the processor, upgraded the voltage reference, etc., in my 5370b.

https://www.febo.com/pages/hp5370b/

Thanks

Jerry

[erikka]

Attached the .tim files of both the phase and timestamp based noise floor measurements at a 1 mHz frequency offset and a phase measurement base .tim file with REF = A input
Let me know if you some something else

[cncjerry]

Just need my unit now... please send a 12g to randl with my name on it.

Thanks for the data.

Jerry

[cncjerry]

I'm waiting for my 12G device to get here to do some testing.  I plotted the .tim file against the HP5370B data I have and that is known.  I also have the DMTD reference line on the plot, though achieving that line plotted by Bill Riley escaped me.  I had problems with my DMTD board and cross-talk from 10Mhz signals across the room caused a sine wave type error down in the -13 to -14 range, drove me crazy. I'm amazed that the Tiny can get so close to the 5370B.

[Kurt_!]

I like this item.
It's already ordered.

[cncjerry]

Erikka,
The data in the .tim files you posted, is that raw data coming off of the timer(s), right out of the GTC into timelab, or is it averaged/processed by the device?

[erikka]

The timestamp data is raw data coming from the HW
In below phase plot you can see in blue a the timestamps of 10 MHz with 10 Hz, 0.5 degrees phase modulation. +/- 130 ps
and in pink the same 10 MHz without phase modulation
Gate time was 10 ms

[cncjerry]

Impressive. Now you just need to create a phase noise test set. I am dying to test it myself against my 5370B.  Your .tim files are almost identical to the 5370 which even today, is still a great performer. 

Two more questions:

1) Is the performance of the 7G and 12G versions the same under 5Ghz?  Most of my testing would be using ultra low noise oscillators in the 26Mhz range but I'm curious if the noise baselines are the same for the two versions of the unit, and if they differ, at what frequency does it begin?

2) Given R and L still doesn't have the 12G version, if I purchase the 7g version, can it be upgraded?

Thanks again. 

Jerry

[erikka]

Impressive. Now you just need to create a phase noise test set.

I did, but without correlation yet and the very high performance OCXO required as baseline would be rather expensive when bought new so it will not become a product.
With correlation you need the memory and processing power of a PC

1) Is the performance of the 7G and 12G versions the same under 5Ghz?  Most of my testing would be using ultra low noise oscillators in the 26Mhz range but I'm curious if the noise baselines are the same for the two versions of the unit, and if they differ, at what frequency does it begin?

Below 5 GHz performance is identical

2) Given R and L still doesn't have the 12G version, if I purchase the 7g version, can it be upgraded?

No

[cncjerry]

Phase noise is expensive even with a DIY test setup like I have that was designed by Andrew Holme http://www.aholme.co.uk/PhaseNoise/Main.htm  It uses an FPGA, external ADC, correlation in the attached PC and has an amazing noise floor.  Dual, low noise reference oscillators cost a bundle even used. Then you need filters, power splitters, good cables and connectors, and special power supplies.

Thanks for the additional input.

Jerry

[bingo600]

Will get mine tomorrow 

[Kurt_!]

I'm having trouble with the firmware update!
No problem with TinySA Ultra. Just installed the latest update.
But not with the TinyGTC.
In normal operation, the device shows 3 COM ports!?
None are available in dial-up mode, except for the AT32....
Maybe someone knows more?
Strange.