RE: Distance from RSSI field- NRF52-DK.

Pradeep Chl — Thu, 11 Aug 2016 08:45:30 GMT

Although nrf_esb_payload_t::rssi field is of type int8_t(singed integer), I am receiving a positive value. I am printing it with, NRF_LOG_PRINTF("RSSI = %d", rx_payload.rssi);

Am I doing some thing wrong here ?

Thanks,

RE: Distance from RSSI field- NRF52-DK.

tesc — Wed, 06 Jul 2016 14:29:51 GMT

See also some comments regarding RSSI measurements in the answer and comments to this question on RSSI variance.

RE: Distance from RSSI field- NRF52-DK.

tesc — Wed, 06 Jul 2016 14:27:41 GMT

Hi,

First note that the RSSI value can only be used for rough distance estimates, as it both depends on environmental factors and has some deviation. Further, it also depends on the RF properties of the device (which again depends on antenna, matching network and form factor of the device).

Because of the above we can not possibly have any general purpose formulas or conversion tables for RSSI to distance calculations. You should do your own meassurements, with the final devices, to find a formula or to generate a conversion table. You can have a look at this question Regarding nRF51822 RSSI to Distance Calculation for some more input.

Regarding the RSSI field value, are you sure that you interpret the value correctly? The value contained in the nrf_esb_payload_t::rssi field is of type int8_t, which is a signed integer. -50 to -70 dBm sounds like a reasonable range, might it be that you are interpreting an int8_t value as if it was a uint8_t?

Regards, Terje