How to continuously memorize the RSSI values?

Hello,
I am a beginner of XBee, and
I would like to know if there is any command or tool that can
continuously memorize the RSSI value displayed in X-CTU.

I am now using the XBee-Pro for 15.4d and I want to do time
averagings of RSSI values in some certain positions,
so I need a record of RSSI values for statistics.

Best Regards
Yun