PCAP monitor mode troubles

Good afternoon forum users,

Some background:

I am working on a WiFi localization project for a class that I am taking. The concept is that we are going to listen to WiFi signals in a room using monitor mode WiFi radios on 3 different access points (running OpenWRT.) We then parse the data and use the signal strength of the data packets we see to locate the device using triangulation of distance. We are using libpcap (C library) to capture all of this data on the APs and send it to a central server for data processing and display.

The problem:

While working on this project I have been tasked with getting the data from the access point to the server. This data includes a big group of pairs mac addresses followed by the signal strength that the AP radio received when listening in monitor mode. The problem is that I have searched far and wide for how to sniff packets using pcap with monitor mode and I haven't been able to figure out a solution (one that works anyway) on any page I search. Where I have searched includes pcap documentation, stack overflow, random web pages/forum posts I find and the TCPDump mailing list.

What I need you to help me with:

Can anyone please set me on a path to figuring out how to get the signal strength and MAC address of the packet I receive (both of which I think are in the RADIOTAP header of the packet.) Any help at all would be much appreciated.

I have been stuck for week(s) and probably missed something obvious

Thanks so much,