Geolocation of digital wireless signals via remodulated side-channel

A system for direction finding (DF) comprising:

• a DF antenna array to convert a modulated RF signal received by the DF antenna array to multiple modulated RF channels;
• a side-channel antenna to convert the modulated RF signal to a modulated RF side-channel;
• and
• a signal processor configured to perform:
• converting the multiple modulated RF channels to multiple channels of in-phase (I) and quadrature (Q) (I/Q) data;
• converting the modulated RF side-channel to a side-channel of I/Q data;
• demodulating and decoding the side-channel of the I/Q data to produce demodulated data;
• remodulating the demodulated data to produce remodulated reference I/Q data;
• correlating the remodulated reference I/Q data against each of the multiple channels of the I/Q data to produce correlation results for the multiple channels of the I/Q data;
• and
• determining an angle-of-arrival of the modulated RF signal to the DF antenna array based on the correlation results.

A non-transitory computer readable medium encoded with instructions that, when executed by a processor of a direction finding (DF) system that includes a DF antenna array to receive a modulated RF signal and convert the modulated RF signal to multiple modulated RF channels, and a side-channel antenna to convert the modulated RF signal to a modulated RF side-channel, cause the processor to perform:

• converting the multiple modulated RF channels to multiple channels of in-phase (I) and quadrature (Q) (I/Q) data;
• converting the modulated RF side-channel to a side-channel of I/Q data;
• demodulating and decoding the side-channel of the I/Q data to yield demodulated data;
• remodulating the demodulated data to produce remodulated reference I/Q data;
• correlating the remodulated reference I/Q data against the multiple channels of the I/Q data to produce correlation results for the multiple channels of the I/Q data;
• and
• determining an angle-of-arrival of the modulated RF signal to the DF antenna array based on the correlation results.