Using Beagle board to get RSSI of a device

I am working on a project using BeagleBoard-xM. The goal of the project is to get received signal strength indicator (RSSI) of a mobile device in the vicinity of the board. . We use TL-WN722n wireless usb adapter to get RSSI of a mobile device.

All the code implementations have been successfully made. We can get RSSI of a particular device using its MAC Address. However we are encountering a problem in that the RSSI doesn’t change much when we move our device to different points in the test area.

If we connect the wireless adapter directly to a PC and run our code on the standalone PC we get accurate results. However running the same code on the board doesn’t produce the same results. We used tcpdump and wireshark to get RSSI on the board and we get the same bad results. So this eliminates the possibility that there is something wrong with the code.

Can someone provide an insight as to what might be different on the board compared to a PC that cause this difference in RSSI?