Hi,
I wonder if you can help with this query.. I'm using the nRF52811 in a design that uses a proprietary protocol. The system is currently using 8 channels, hopping and keying up every 4.17 ms and sending a short packet in 125k coded mode. I'm currently using another board to perform RSSI measurements on all channels from 2401 to 2483 MHz with 1 MHz spacing. The boards are both synchronised to GPS 1 PPS and the RSSI Task is scheduled to occur smack in the middle of the burst sent by the first board. I just grab one sample per channel. The transmitting board is set to -16 dBm, and I am connecting it to the second board via a 20 dB attenuator, so expect to see approx -36 dBm reported, which I do. But I am seeing surprisingly high numbers 1 MHz and 2 MHz above and below the active channel, especially given I am using a 125k mode. Below are some max-hold captures generated by a PC application I wrote to plot the RSSI samples. The scale is -110 dBm to -36 dBm. The first board is using 2407, 2415, 2435, 2439, 2443, 2447, 2467 and 2475 MHz. Each bar is a sample from a channel, so they are 1 MHz apart. What's also alarming is that if I replace the first board with a clean, unmodulated IFR/Marconi bench source, the two channels above are always reported only ~35 dB down (middle plot). Something is not quite right.
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Any useful feedback welcome !
Cheers
Pete
UK
