Real-time monitoring BLE advertisements using tshark

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Hi Andre,

Thanks for getting back to me so quickly. I removed shell = True, but unfortunately that doesn't work. Both python script and tshark (run from cmd line) are only returning 'bursts' of ~ 5 advertisements in an interval of about one second. I guess I want to stop the buffering occuring within tshark?

Probably related: I can pull dongle out of the USB port while running tshark and, strangely, new advertisements continue to be displayed on the console.

Damian

In my case your Python script works when capturing from Ethernet NIC, and fails when shell=True is present. What happens if you try another NIC? If that works than the problem is with the Bluefruit LE Sniffer.

I guess I want to stop the buffering occurring within tshark?

That's where the -l option is for.

Probably related: I can pull dongle out of the USB port while running tshark and, strangely, new advertisements continue to be displayed on the console.

In that case the buffering occurs in the sniffer/driver. The -l option controls the output of tshark, not the input.

I think you are right that is something to do with the sniffer because when I use the Ethernet NIC, the output seems more like real-time (using either wireshark or tshark or tshark via the python script) compared with the sniffer.

Nevertheless, there are a few things I am confused about: When I use the sniffer to capture BLE packets over a given amount of time (e.g. 30 s), there are about 1/5 of the BLE packets in the .pcapng file generated using tshark -i -a duration:30 -l than when generate a file using Wireshark. Additionally, I can use the SnifferAPI python module provided Nordic Semiconductor (who make the nRF51822 chip in the sniffer) and I don't encounter the buffering issue - perhaps that indicates that it is caused by a driver issue rather than the hardware.

Thanks for all your help!