bg7tbl gpsdo master reference

[ToThePub]

Wow. On aliexpress as well. In super sexy black no less.
It's out of my "just buy it and play" budget, so someone else will have to check it out.

[usagi]

p.s love your content usagi, the Centurion (and up coming pdp) stuff has been fascinating. All the best to Sue. (p.s just joined as a new patron)

thanks, but i'm not usagi electric 

[ToThePub]

Doh! Well, I'm sure you produce something, and all the best to "insert a person or pet in your life"..  hahaha..

[erialor]

Will be interesting to see pics of the inside of that - appearently it might be the same PCB as my GPSDO w/LCD (no dates on front/end of case), so wonder if it would be a 'simple' modification.

Main PCB says: GNSS-D-OCXO(RB)  2021-06-10
Display board says: 20210527

And LCD says: BG7TBL V20220808 when powering up.

I've already opted for a different gps disciplined rubidium standard, though.

Also; for the Trimble OCXO inside my unit - date code 1337, is that YYWW, ie. Week 37 Year 2013?

[usagi]

Also; for the Trimble OCXO inside my unit - date code 1337, is that YYWW, ie. Week 37 Year 2013?

that would be my guess. lucky number 

[dekagon]

Hi @all,

I have a BG7TBL GPSDO with date from 2017-10-09.
After reading this thread here I also decided for better performance to change the CTS OCXO to a OSCILLOQUARTZ 8663-XS DOCXO and the GPS Module to a NEO-M8T from Mouser.
Regarding the infos I changed the resistor for the antenna voltage from 3.3 to 5 Volts and the multiplicator for the VC for the DOCXO to x2.
The Controlvoltage now is 4.7 Volts. I have to configure a little bit with U-Center to get all Sats (GPS, GLONASS and GALILEO) running. The stability is much better and I can use much more sats
to lock as before. Even a simple Puck antenna near my windows gets 22 Sats quickly.
On the downside of the circuit board the PPS led is blinking and Lady Heather is displaying a lot of data when I use the /rxu switch.

The one problem I see is that the BG7TBL device has its ALM and RUN leds permanently on. There will be a decreasing current after the DOCXO is stable:
(appr. 668 mA at the beginning to appr. 335 mA after nearly 2 minutes).
The pps output is running a normal pps signal and the 10 Mhz are also present.

The serial output at start is:
$GATXT,01,01,02,u-blox AG - www.u-blox.com*41
08:21:34  $GATXT,01,01,02,HW UBX-M8030 00080000*6F
08:21:34  $GATXT,01,01,02,EXT CORE 3.01 (111141)*36
08:21:34  $GATXT,01,01,02,ROM BASE 2.01 (75331)*16
08:21:34  $GATXT,01,01,02,FWVER=TIM 1.10*5F
08:21:34  $GATXT,01,01,02,PROTVER=22.00*17
08:21:34  $GATXT,01,01,02,MOD=NEO-M8T-0*72
08:21:34  $GATXT,01,01,02,FIS=0xEF4015 (100111)*57
08:21:34  $GATXT,01,01,02,GPS;GLO;GAL;BDS*78
08:21:34  $GATXT,01,01,02,SBAS;IMES;QZSS*46
08:21:34  $GATXT,01,01,02,GNSS OTP=GPS;GLO*38
08:21:34  $GATXT,01,01,02,LLC=FFFFFFFF-FFFFFFED-FFFFFFFF-FFFFFFAE-FFFFFF69*28
08:21:34  $GATXT,01,01,02,ANTSUPERV=*2D
08:21:34  $GATXT,01,01,02,ANTSTATUS=DONTKNOW*22
08:21:34  $GATXT,01,01,02,PF=3F2*30

Do I probably have to modify some further parameters in u-center to get the mcu working right?
There is as I see only UART1 active.

Thanks for helping.

Chris

[dekagon]

Update:

I have the suspicion that the 8663-XS may be no longer reach the 10 MHz because the Control Voltage was already high (4.7 Volts). This Voltage stays stable still after after 30 Minutes and longer running.

The ALM LED was on too. No switch to off after I exchanged the OCXO to the 8663.

I decided to change back the OCXO to the previous CTS OCXO and also the board mods as the supply voltage to 5 volts and the multiplicator back from x2 to x1 as well.

After Restart of the BG7TBL GPS OCXO the ALM Led and the RUN Led are on. With the old Ublox 7M the RUN Led was flashing after Start of the device.

Now after a few minutes the ALM Led switches off but no GPS Lock Led was going on as before. u-center sees more the 22 Satellites but no lock. The RUN Led is still permanently on.

Some ideas?

[Ringmodulator]

Hi Chris,

I did something simimlar and changed to a ublox 8t and a morion ocxo.
Worked for me.

Regarding the leds:

The blinking stops as soon as you start LH in ublox mode -ru .
If you start LH in NEMA mode, the ledes will start to behave as before.

This did bug me for a while too, until I found out.

Regards
Chis

[dekagon]

Hi Chris,

thank you for this tip. I will try this out and hopefully all seems to be normal again.

Cheers Chris

[dekagon]

Hi Chris,

I did something simimlar and changed to a ublox 8t and a morion ocxo.
Worked for me.

Regarding the leds:

The blinking stops as soon as you start LH in ublox mode -ru .
If you start LH in NEMA mode, the ledes will start to behave as before.

This did bug me for a while too, until I found out.

Regards
Chis

Hi Chris,
unfortunately that does not help. On the pic you can see that my gps sat view is very good (active puc antenna on my window outside).
But the LOCK LED is still off and the RUN LED is permanently lighting.

Cheers Chris

[Ringmodulator]

Hi Chris,

afaik, the 8663-XS needs 12V

https://www.miedema.dyndns.org/fmpics/Circuits_online/ocxo/8663_datasheet_ed.03-2003.pdf

Please check. You can configure the board to supply 12V to the OCXO.

Regards
Chris

[dekagon]

Just wanted to add, finally getting the ublox NEO-M8T configured, enabled Galileo and tracking 20+ sats now. After a few other configuration changes I can say it seems to lock down to 0.00ppb very quickly and is rock solid.  Still sorting through the 400 page book on this chip.

Hi kj7e,

did you have some configuration tips for my neo-m8t configuration? I can see all sats which I want (gps, galileo and glonass) but after exchange of the neo module my bg7tbl gpsdo will not run properly.
The RUN Led ist permanently on and the LOCK Led will no longer light on after the gpsdo is going in lock mode. It seems so because the frequency will be relatively stable after a few minutes but I cannot proof it.

Would be nice if you could help.

Cheers Chris

[nctnico]

There are many settings in the uBlox module to make it work as a stationary GPSDO (including setting the OCXO parameters and teach-in time for the stationary position). Having it locked doesn't say much as your clock output can still wander like crazy due to wrong settings. You need at least 2 other know-good GPSDOs to make a 3 cornered hat assesment of whether you modified GPSDO works OK. Every measurement needs to run for at least 24 hours, preferably 48 hours.

[dekagon]

Hi Chris,

afaik, the 8663-XS needs 12V

https://www.miedema.dyndns.org/fmpics/Circuits_online/ocxo/8663_datasheet_ed.03-2003.pdf

Please check. You can configure the board to supply 12V to the OCXO.

Regards
Chris

Hi Chris,

yes I changed the SMD resistor to the 12 Volts place (see pictures in message #955) after exchange to the 8663 ocxo and  back to the 5 volts place after changing back to the original ocxo.

Cheers Chris

[dekagon]

There are many settings in the uBlox module to make it work as a stationary GPSDO (including setting the OCXO parameters and teach-in time for the stationary position). Having it locked doesn't say much as your clock output can still wander like crazy due to wrong settings. You need at least 2 other know-good GPSDOs to make a 3 cornered hat assesment of whether you modified GPSDO works OK. Every measurement needs to run for at least 24 hours, preferably 48 hours.

Hi nctnico,

I have the suspicion that I forgot to configure the external ocxo source correct. So the pll is running infinitely without getting locked.

Cheers Chris

[dekagon]

Hi all,

I am looking for a NEO-M8T config file created with u-blox u-center 22.07 for comparing.
I was foolish not to save mine before I switched the NEO-7M receiver to an NEO-M8T 
After desoldering the config has been gone (stored in the battery backed ram).

So now I can fiddle out which config I have to set for disciplinig the CTS ocxo (for minimizing more failure sources I put the builtin CTS ocxo back on the circuit board).

Cheers Chris

[MIS42N]

Hi all,

I am looking for a NEO-M8T config file created with u-blox u-center 22.07 for comparing.
I was foolish not to save mine before I switched the NEO-7M receiver to an NEO-M8T 
After desoldering the config has been gone (stored in the battery backed ram).

So now I can fiddle out which config I have to set for disciplinig the CTS ocxo (for minimizing more failure sources I put the builtin CTS ocxo back on the circuit board).

Cheers Chris

I configured a LEA-M8T a while back. I can't remember all the details (I should have written it down) but IIRC u-center 22.07 did not support the M8T (to set up the timing mode required a TIMER2 message, and for unknown reasons that isn't in 22.07). I found V8.29 online, and it worked fine.

There's a lot of things can be changed but I skipped most of it. Using u-center I reset the configuration, enabled some messages, restricted the satellite constellations to GPS and one other (I think Galileo) as recommended by others, ran the survey in for 24 hours, disabled the extra messages just leaving the normal NMEA messages, then saved the whole configuration to permanent memory (otherwise it gets lost on power down). It takes some reading of the u-blox8-M8_ReceiverDescrProtSpec_UBX-13003221-1.pdf document to understand the process, but it's all there.

I know I was confused by the survey in process, so I set it to survey in for a short period to learn about it. IIRC when it completes it doesn't say it has, but automatically goes into timing mode. But the details are a bit hazy now.

Good luck.

[dekagon]

I configured a LEA-M8T a while back. I can't remember all the details (I should have written it down) but IIRC u-center 22.07 did not support the M8T (to set up the timing mode required a TIMER2 message, and for unknown reasons that isn't in 22.07). I found V8.29 online, and it worked fine.

There's a lot of things can be changed but I skipped most of it. Using u-center I reset the configuration, enabled some messages, restricted the satellite constellations to GPS and one other (I think Galileo) as recommended by others, ran the survey in for 24 hours, disabled the extra messages just leaving the normal NMEA messages, then saved the whole configuration to permanent memory (otherwise it gets lost on power down). It takes some reading of the u-blox8-M8_ReceiverDescrProtSpec_UBX-13003221-1.pdf document to understand the process, but it's all there.

I know I was confused by the survey in process, so I set it to survey in for a short period to learn about it. IIRC when it completes it doesn't say it has, but automatically goes into timing mode. But the details are a bit hazy now.

Good luck.

Thank you for your tips. I found the u-center 8.29 on the u-blox download page for u-center. I give it a try. The over 400 pages of the M8 receiver description is hard stuff 

Cheers Chris

[MIS42N]

The over 400 pages of the M8 receiver description is hard stuff 

Once you get the hang of u-center it isn't so hard. You don't need to know the format of every message, and that is over 300 pages. I played around modifying things without storing them in the permanent configuration, not knowing really what I was doing (but learning). A reboot cleared any mistakes and start again. I think 22.07 prompts to say do you want to store this, but 8.29 doesn't and you have to remember in the end that data has to be stored in the permanent config to become permanent. I've seen a few comments "I did this but when I rebooted it went back to how it was".

Hang in there.

[Ringmodulator]

The display versions of the BG7TBL GPSDO can display an indication of the accuracy of the 10MHz signal.
It is not clear to me, how the unit determins this

Maybe a calculated result of TDOP?

Is there a way to get this info from a non-display BG7TBL GPSDO, for example via LadayHeather?

Regards
Chris

[foxale08]

I have two of the 2021-06-10 GPSDO boards upgraded to UCT 108663-01's, was curious if anyone knows how to use the crystal vref to drive EFC? I can confirm swapping R4/R5 for 5V/12V and the X1/X2/X3 information from older boards is still valid but botched my attempt to validate swapping C53 to C44 for the upgrade from a CTS 196 to UCT 108663-01, as such I didn't attempt it on my second unit (currently using a bodge wire from the new to old crystal RF output post)

[Mkpirulo]

Hi, general question for the group. I have a BG7BTL with date code of 2019-10-20, PCB date code is 2021-06-10. This unit has a Trimble 72344 ocxo, would anyone have the specs on this ocxo. Mainly interested in the EFC pin control specs.. Trying to see if it might be possible to remove this reference and use the Efratom FRS-C rubidium in its place. The FRS-C has a control pin 0 - 5V. If anyone can point me in the right direction that would be much appreciated. Picture attach of the reference.

There is a PCB on eBay that seems to be already setup for rubidium but no info on EFC output. Here is a picture of that board. Picture 7001 is the back of the rubidium PCB.

[FPSychotic]

Could you please share the right configuration for M8T? Of if you have a link where is already explained I would thank you. Cheers.
Got one of these in a bid and I have m8T module.
By thr way my M8T has the time pin exposed, would be enough use that pin without need solder /desolder the chip?

[points2]

Hi,
just a question : what's the short term stability of this populated PCB ?

[mojoe]

I was able to purchase a BG7TBL on Amazon and wanted to post pics of the internals here. It seems that this original design has matured to the point where the only real difference we're going to see is different OCXOs and possibly GPS modules.

I know that you posted on this a year ago, but I wonder if you know anything about that connector on the PCB, labeled LCD? It would be nice to add an LCD display to this.