I am not able to get stable RSSI value with nrf51822

[Nilesh Bhavsar]

Hi,

I am using nrf51822 with SDK 12.2.0. As of now, we are using RL-51822-A1 for beacon as well as scanner.

But, we are not getting stable pattern for RSSI at 2m, 4m and 6m range. Herewith i attached images which represent the graphical pattern. Blue marked line represent the RSSI value fluction for RL-51822-A1 and red line repesent the Radioland nRF51822 Model B1(new).

Please suggest which settings required from application side for scanner as well as beacon to get better accuracy in RSSI.

[Sigurd]

Hi,

From the product specification the RSSI accuracy is listed as +/- 6dB. There is a  chip to chip production variance + variance over input power + margins. You will also always have slightly different performance across the different BLE channels. The environment in which you measure this would also affect the result as you will have reflections that can vary over frequency.

If you want to use the RSSI to something useful, I would recommend doing some filtering on the raw RSSI measurements. E.g. use a Low Pass Filter, these are often used to reduce the deviation of RSSI measurements.