A novel use of the sigma-delta modulator to insert arbitrary training signals into a 1-bit (clipped) data stream for 1-bit beamforming processing

This paper describes a novel application of a sigma-delta modulator. The system described forms the sum of a 16-bit training signal and a 1-bit tactical data stream obtained as the hard-limited output of a set of hydrophones and returns the sum as another 1-bit sequence. The modified 1-bit data streams are processed by a 1-bit beamformer and the inserted signals (which are used for operator training) must not affect the normal operation of the 1-bit beamformer and the insertion process must be transparent to the operator. A description of the system which accomplishes these tasks, an analysis of its noise performance, and a demonstration of its nonlinear merging capabilities is included