10MHz GPSDO by "BH3SAP"

[Name00]

Yes and no. You can connect two oscillators and and  compare them against each other, but you cannot determine which one is "better".
This is generally a chicken/egg issue, unless you have a known better reference.

If you have three oscillators, you can measure, which combination has the best stability and identfy  the worst oscillator  of the three.

Hello, been watching this thread on and off, I have a TinyPFA which I've used in my Symmetricom X99 thread (https://www.eevblog.com/forum/metrology/symmetricom-x99-rubidium-oscillator/msg5927170/#msg5927170) and I also have BH3SAP which I also compared against.  I used Fredzo's v0.1.13 version previously in those test and it performed fairly well, not to the same degree as the Rubidium Oscillator, but good for an OCXO.   My units are stock except for the GPS module change and firmware upgrade.

I recently decided to upgrade and test against v0.1.16, the newer changes have made the performance worst using an Allystar TAU1202, I'm currently testing it against a Trimble 66266-45 (just swapped will need to run it for a day to stablize) on the PPS signal only.  If it works well, I'm debating on modifying the source to handle the output of a Trimble Resolute instead of NEMA.   If anyone is interested on the comparison of v0.1.13 vs v0.1.16 using a Allystar TAU1202 vs Trimble 66266-45; let me know and I'll post the results.

[KungFuJosh]

Hello, been watching this thread on and off, I have a TinyPFA which I've used in my Symmetricom X99 thread (https://www.eevblog.com/forum/metrology/symmetricom-x99-rubidium-oscillator/msg5927170/#msg5927170) and I also have BH3SAP which I also compared against.  I used Fredzo's v0.1.13 version previously in those test and it performed fairly well, not to the same degree as the Rubidium Oscillator, but good for an OCXO.   My units are stock except for the GPS module change and firmware upgrade.

I recently decided to upgrade and test against v0.1.16, the newer changes have made the performance worst using an Allystar TAU1202, I'm currently testing it against a Trimble 66266-45 (just swapped will need to run it for a day to stablize) on the PPS signal only.  If it works well, I'm debating on modifying the source to handle the output of a Trimble Resolute instead of NEMA.   If anyone is interested on the comparison of v0.1.13 vs v0.1.16 using a Allystar TAU1202 vs Trimble 66266-45; let me know and I'll post the results.

Did you adjust the settings in the new version? If not, you won't get good performance.

What GPS module did you put in the BH3SAP?

[Kurt_!]

Yes and no. You can connect two oscillators and and  compare them against each other, but you cannot determine which one is "better".
This is generally a chicken/egg issue, unless you have a known better reference.

If you have three oscillators, you can measure, which combination has the best stability and identfy  the worst oscillator  of the three.

Hello, been watching this thread on and off, I have a TinyPFA which I've used in my Symmetricom X99 thread (https://www.eevblog.com/forum/metrology/symmetricom-x99-rubidium-oscillator/msg5927170/#msg5927170) and I also have BH3SAP which I also compared against.  I used Fredzo's v0.1.13 version previously in those test and it performed fairly well, not to the same degree as the Rubidium Oscillator, but good for an OCXO.   My units are stock except for the GPS module change and firmware upgrade.

I recently decided to upgrade and test against v0.1.16, the newer changes have made the performance worst using an Allystar TAU1202, I'm currently testing it against a Trimble 66266-45 (just swapped will need to run it for a day to stablize) on the PPS signal only.  If it works well, I'm debating on modifying the source to handle the output of a Trimble Resolute instead of NEMA.   If anyone is interested on the comparison of v0.1.13 vs v0.1.16 using a Allystar TAU1202 vs Trimble 66266-45; let me know and I'll post the results.

Yes, sure...

I already have a Neo m8n module in front of me.
I'll test it out sometime. Although the ATGM e isn't bad.
But I don't have a TAU yet...

Ps.:
The protocol shouldn't be a problem.

[Name00]

Did you adjust the settings in the new version? If not, you won't get good performance.

What GPS module did you put in the BH3SAP?

No not tuned, is there any recommendations and suggestions on tuning it?  I'm not sure I read any thin on the tuning process itself other than the new menu being added.
Currently have a Trimble 66266-45 in there, previously had a TAU1202. 

The Trimble is my goto for timing and I use this for the GPSDRO setup, I haven't had any GPS lost signals yet even on the stormiest of days while with the same feed I've already lost it on ATGM336H, LEA-8T (even surveyed), and TAU1202  (only lost after it being week after 2 hours).

[KungFuJosh]

Did you adjust the settings in the new version? If not, you won't get good performance.

What GPS module did you put in the BH3SAP?

No not tuned, is there any recommendations and suggestions on tuning it?  I'm not sure I read any thin on the tuning process itself other than the new menu being added.
Currently have a Trimble 66266-45 in there, previously had a TAU1202. 

The Trimble is my goto for timing and I use this for the GPSDRO setup, I haven't had any GPS lost signals yet even on the stormiest of days while with the same feed I've already lost it on ATGM336H, LEA-8T (even surveyed), and TAU1202  (only lost after it being week after 2 hours).

Interesting. Do you have any photos, or could you take some, with the Trimble installed in your BH3SAP?

The new settings include things like selecting the correct GPS module. We might need to request some new options it sounds like.

Thanks,
Josh

[ME]

I have just got a ttl to usb c modual , it has a jumper to set for 3.3 or 5v what should i set it to and what pins go where to connect it to the gpsdo to use it with gns toolkit ?, thanks.
https://www.aliexpress.com/item/1005006445462581.html?spm=a2g0o.order_list.order_list_main.11.26f71802NmLLRb

[Kurt_!]

You don't need 5 volts or 3.3 volts.
Just RX + TX + GND.
This applies to this case

[Name00]

Took a 90 degree connector and bent it straight and just a pin to pin match to what the GPS module puts out.  The antenna is up to you i but I used a short cable with the correct ends.

The only catch is to make sure to put Kapton on the bottom of the board so you don't sort anything out.

The tweaking should be clarified in the main page.  But for now: it is in the PPS, set the OCXO type AND the algo you want to use, exit, and goto PWM to save and power it off and start it back up.

What I noticed is the tuning is sensitive to the saw pattern of the GPS, for the Trimble it's not going to work well, and anything that generates an artificial 1 pps would work better.  I'll try to drive this PPS from a picdiv to verify it works better when I have some free time to rig up one.

[Kurt_!]

I haven't seen that item on AliExpress yet.
I don't think it's that cheap!

[KungFuJosh]

I haven't seen that item on AliExpress yet.
I don't think it's that cheap!

I just bought a pair of them on eBay for $23 including shipping.

[ME]

You don't need 5 volts or 3.3 volts.
Just RX + TX + GND.
This applies to this case

So where does the jumper go thats on the ali ttl modual?.

[Kurt_!]

I don't have this module. But it connects to the pin header and is for the modules...
I already wrote that you don't need it with the GPS devices.
Everything is labeled as usual, so you can measure it...

[ME]

I don't have this module. But it connects to the pin header and is for the modules...
I already wrote that you don't need it with the GPS devices.
Everything is labeled as usual, so you can measure it...

So where do i put the jumper on this? as far as i know its to select 5v or 3.3v levels?.the seller cant give me a datasheet and i dont want to kill the bp!.

[flash2b]

The Blue Pill runs internal on 3.3V so the logic levels (from the ARM processor) are 3.3V.

[ME]

thank you , Thats what i needed to know.

[Kurt_!]

thank you , Thats what i needed to know.

I think you would have gotten this answer faster if you had removed the cover from the GPS and measured the chip with an oscilloscope!?

[Kurt_!]

I haven't seen that item on AliExpress yet.
I don't think it's that cheap!

I just bought a pair of them on eBay for $23 including shipping.

I ordered two myself...just because.
What kind of software, etc. (data) is available?
There's a lot of information, but something faster...

Thanks

[fredo_]

I ordered two myself...just because.
What kind of software, etc. (data) is available?

Found that : https://www.compel.ru/item-pdf/d31a59230ece6dc101411a384f72964c/pn/trimble~resolution-smt-66266-00.pdf
The default communication mode for Port 1 (the one available on the Carrier board found on ebay) is TSIP (Trimble Standard Interface Protocol) not NMEA.
To have it work with GPSDO you need to use TGS (Trimble GPS Studio) software to configure it to NMEA.
See page 26 in this guide : https://cdn.sparkfun.com/datasheets/GPS/GPSStudioUG_1B_August2011.pdf
And Timple Studio dowload link : https://cdn.sparkfun.com/datasheets/GPS/TrimbleStudio_V1-64-00.zip

[Kurt_!]

I have another page for you.
If anyone's interested or hasn't read it yet.
I still need to finish reading it myself.

https://hackaday.io/project/190634-repurposed-wifi-controller-as-gps-based-ntp-server/log/218745-experimenting-with-a-weird-gps-receiver

P.S.: I still have to wait for the order.

[ME]

my gpspo with the new fredo fw shows the time as 6.50 when its actualy 5.50 since clocks changed for winter in the uk , How do i correct this?, thanks.

[Kurt_!]

my gpspo with the new fredo fw shows the time as 6.50 when its actualy 5.50 since clocks changed for winter in the uk , How do i correct this?, thanks.

Under GPS settings. Press TZ ofs...

[ME]

Thanks but What should the offset be?

[Kurt_!]

Thanks but What should the offset be?

That means a difference from the original value.
For example: + 1 hour - 1 hour

[Kurt_!]

What's been on my mind lately is how far some of the American jamming satellites actually affect things.
Some are even said to distort the signal...

I just read about it again!

[ME]

Would these still work around kallingrad or ukraine with the gps spoofing happening?.