Problems capturing BLE advertising packets with SA44B

I’m unable to capture BLE advertising packets using my SA44B. I know my device is advertising because I can see the packets with a passive Bluetooth sniffer. Advertising happens all the time without requiring any external stimulus. I should see spikes on BLE channels 378, 38 and 39 but I see nothing. I assume my problem is defining an appropriate trigger but I’ve tried many different trigger configurations with the same results, no signal found.

I conduct the test inside an RF shield box (with a 2.4GHz antenna right next to the device I’m testing) so there are no other emitters that might somehow interfere with the measurements.

If I place the BLE device in test mode and transmit a CW signal I have no problem seeing the transmission. Therefore, I know that my connection from the SA44B, through the coax, into the RF shield box and finally to the antenna next to the device being tested is OK.

Does anyone have any recommendations what I need to do?

Thanks

Have you tried turning off the image rejection feature in Spike? I’m assuming Bluetooth transmissions are pulsed, and that the image rejection feature is declaring the pulses as non-legit and blanking them.
That’s all I can think of!

Andy is correct, if software image rejection is enabled, the Bluetooth packet would be identified as a spur. You can disable it in the File->Settings menu.

Also, increasing your RBW and selecting the min/max detector will increase your chances of capturing a transmission.

The bandwidth of a Bluetooth transmission is greater than the instantaneous bandwidth of the SA44B, so it will be difficult to make accurate measurements on this type of signal.

Let me know if these suggestions help.
Regards,
Andrew

Hi,
I had to deal with some other problems so I did not have a chance to try this yet. I plan to test it this week and let you know if it solves the problem.

Thanks

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