A novel intercept detection method for low-SNR targets using frequency domain processing

Intercept sonar is designed primarily to detect, estimate and track active underwater transmissions from long range targets. The existing detection method shows variation in performance with frequency due to non-flat frequency response of the beamformer. It gives poor performance with the reduction in the signal-to-noise ratio and shows a high false alarm rate with the variation in sea states. The proposed method of signal detection gives an improvement in SNR performance due to the availability of FFT gain. The signal detection is based on a dynamic threshold which provides a Constant False Alarm Rate. A new beam forming concept is also implemented which gives a constant detection performance irrespective of the intercepted frequency.