DCT domain filtering method for multi-antenna code acquisition

For global navigation satellite system (GNSS) signals in Gaussian and Rayleigh fading channel, a novel signal detection algorithm is proposed. Under the low frequency uncertainty case, after performing discrete cosine transform (DCT) to the outputs of the partial matched filter (PMF) for every antenna, the high order components in the transforming domain will be filtered, then the equal-gain (EG) combination for the inverse discrete cosine transform (IDCT) reconstructed signal would be done subsequently. Thus, due to the different frequency distribution characteristics between the noise and signals, after EG combination, the energy of signals has almost no loss and the noise energy is greatly reduced. The theoretical analysis and simulation results show that the detection algorithm can effectively improve the signal-to-noise ratio of the captured signal and increase the probability of detection under the same false alarm probability. In addition, it should be pointed out that this method can also be applied to Rayleigh fading channels with moving antenna.