# How to get the actual value of the receiving power?

• ### Question

• Hello,all,

I want to acquire the rx power in SORA. And I learn the dot11config tools. There are rxpa and rxgain.

But both two parameter are the gain value. Now I want to get the actual receiving power (with watt unit).

How can I get it ?

Thanks a lot.

Thursday, May 19, 2011 7:03 AM

### All replies

• Hi Albert,

This is actually a new requirement to Sora.

I have the method to measure receiving power in a relative way, that is, measuring the difference of two received signals in dB. The method is to calculate energy from I and Q, according to the equation: energy = I^2 + Q^2. You should also compensate the different setting of rxpa and rxgain in the following way: (1) rxpa and rxgain are cascaded, therefore mathematically they are multiplied (2) rxpa has 3 valid values/steps, say, 0x1000, 0x2000, 0x3000. The difference in step is 15dB. (3) rxgain has 32 valid values/steps, from 0x0000, 0x0020, to 0x3E00. The difference in step is 2dB. If you are interested in details or physical meaning, please refer to the data sheet of MAX2829.

Idealy, if you have a signal generator, you can turn this relative method (in dB) into absolute method (in dBm), by a one-time calibration.

P.S. The radio chip also provides a RSSI measure, but currently it's not accessible in Sora.

-Jiansong

Monday, May 23, 2011 1:37 PM