Products > Test Equipment
bg7tbl gpsdo master reference
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:
--- Quote from: Ringmodulator on August 07, 2023, 07:59:18 am ---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
--- End quote ---
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
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