Exploiting RMS time-frequency structure for data compression in emitter location systems

An effective way to locate RF transmitters is to measure the time-difference-of-arrival (TDOA) and the frequency-difference-of-arrival (FDOA) between pairs of signals received at geographically separated sites, but this requires that samples of one of the signals be sent over a data link. Often the available data link rate is insufficient to accomplish the transfer in a timely manner unless some form of lossy data compression is employed. A common approach in data compression is to pursue a rate-distortion criterion, where distortion is the mean-square error (MSE) due to compression. This paper shows that this MSE-only approach is inappropriate for TDOA/FDOA estimation and defines a more appropriate, non-MSE distortion measure. This measure is based on the fact that in addition to the inverse dependence on SNR, the TDOA accuracy also depends inversely on the signal´s RMS (or Gabor) bandwidth and the FDOA accuracy also depends inversely on the signal´s RMS (or Gabor) duration. The paper discusses how the wavelet transform can be used to exploit this measure