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GPS Interference with cc1200+cc1190

Theodore MORICHAU-BEAUCHANT
Prodigy 200 points
Other Parts Discussed in Thread: CC1190, CC1200

Hi all,

Our CC1200+CC1190 board seems to be interfering with a GPS system on our application. We get intermittent loss of GPS signal and overall poor reception on the GPS module while the CC radio is active.

We are set on 869.55MHz with a power output of 24.5dBms. 2-GFSK at 250kbps.

I've ran the board through the spectrum analyzer and see huge amounts of spurious emissions all over:

Around 869.55MHz:

And around GPS L1 frequency:

Any suggestions?

Thanks!

Theo

  • 0
    TI__Guru**** 317180 points

    - The reference level on the spectrum looks low. Have you checked that what you are seeing actually is the board and not spectrum that generates this.

    - Since you have in issue with GPS it looks like some of the spurious are real. For a proper CC1200+CC1190 design you should only see harmonics (n*869.55 MHz).  If you actually have the spurious on air it could look like your board is unstable. Are the measurements conducted or radiated?

  • 0 in reply to TER
    Prodigy 200 points

    Ya, the ADC range on this analyzer is pretty limited. I have to lower the ref to lower the floor.

    These are conducted measurements.

    It looks like a power supply issue. When using a lab power supply instead of the on-board regulator the spurs disappear entirely.