How can I change the reference clock from 26.0 MHz to 10 Mhz, for the u-blox M7 or M8?

0 votes
by Simon-de asked Oct 11
0 votes
26MHz is an internal u-blox clock that can't be changed.
by grumpy answered Oct 11
I was under the impression this was a fusible option for a chip level solution.  Perhaps something to discuss with sales.
The G7020 datasheet says that it can be changed, but I can't find there reference how to change it. I can easily open the lid of the u-blox and remove the 26.0 MHz TCXO, and connect it to a 10 MHz signal, but don't know how to let the G7020 know that is now should deal with 10 Mhz.
I don't think the method is publicly disclosed.
Reviewing further I don't believe the list of supported frequencies goes that low.

If you want a part that tunes out the drift of the internal oscillator you should look at the LEA-M8F. This module can also quantify two user supplied input sources.

Is your application a GPSDO or RTKLIB?
Thank You for checking. It is for GPSDO application and there are many such low cost GPSDO projects around, but I am interested in using a low cost u blox module, and steer the OCXO for zero drift by external logic and taking the clock offset message.  In the meantime, I have just added an external clock generator that converts the 10 MHz of the OCXO to the 26.0 MHz for the G7020 and it works (however, adds one more part). The LEA-M8F would be great but outside my budget.
0 votes
Information on the u-blox core chip G-7020 requires an NDA (even though some companies don't honour copyrights and NDAs and publish such docs on the internet) hence this is not a topic for public discussion.
You can generate a 10 MHz reference clock output in place of timepulse output but you may need a 10 MHz PLL with lowpass loop filter below 100 Hz to smooth out the jitter.
by grampy answered Oct 12
by grampy edited Oct 13
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