Gazell's RSSI Parameter Question

[Sam Wei Quan]

What is the maximum value of RSSI parameter for nrf_gzll_device_tx_info_t structure?

I have done a test on RSSI parameter value return in nrf_gzll_device_tx_success callback function. The test was running 250Kbps transmission speed and +4dBm tx power. When tx_success callback function is called, it will convert it to decimal value (2's compliment method) and send current RSSI parameter value to PC through UART. RSSI parameter reading is around -50dBm when both host and device are next to each other. RSSI parameter reading decreasing as the distance increasing and it reach -76dBm at a certain distance but the RSSI parameter reading is always -76dBm beyond the distance even transmission success rate is 90% above. -76dBm is the maximum value of RSSI parameter? Or 2's compliment conversion is a wrong way to convert RSSI parameter?

Based on datasheet, Gazell Rx sensitivity is around -90dBm when using 250Kbps transmission speed.

• It had converted decimal value to ASCII value before send to PC.

[Ole Morten]

I'm sorry for the delayed response, but I had to check this a little.

Your measurements sounds more or less reasonable, and is within what you should expect when using the RSSI. Even though the sensitivity is actually what is specified in the product specification, you will not be able to measure this simply due to the way the RSSI functionality is built.

[Sam Wei Quan]

Thank for the helpful reply.:D

It is my misunderstanding about RSSI value. There are many parameters determine the RSSI value like SNR ,EIRP, Free Space Path Loss, and Client side.

Link below is very helpful for those who misunderstanding RSSI value like me. Hope it able to help you guys. :) https://supportforums.cisco.com/thread/2034091