The effect of increasing the bandwidth of a two-channel receiver on noise-immunity

This work discusses the effect of increasing the bandwidth of a two-channel receiver on the noise-immunity of the receiving system at low signal-to-noise ratios (S/N = 0....3). The dependency of the probability of false alarms on the signal-to-noise ratio at different ratios of the receiver bandwidth to the carrier frequency of the signal was given. It is notorious that the noise level increases with the increasing bandwidth of the receiving device, thereby reducing the sensitivity and noise-immunity of the receiving system when receiving pulse signals. In most practical cases, this problem is solved by increasing the signal-to-noise ratio at the input of the receiving device by increasing the power of the transmitter and using linear filtering on the receiving side. However, if we consider that the signal-to-noise ratio is low, the search for new methods to solve this problem is more relevant than ever. Differences in the structures of input processes were used as additional information features and identified using nonlinear converters. It should be emphasized that a phase switch was used as a nonlinear converter. The principle of its operational concept was to change the spectrum of the input process by switching the phase by 180 degrees when the envelope passes through zero. Our research proves that phase jumps in a mixture of signal and noise can be used as secondary information signs. Consequently, a conventional phase detector can be used in the second channel of the receiver. The viability of this idea has been tested in practice, so the main objective of this work was to investigate the possibility of using the above approaches to receiving short radio pulses in narrowband digital communication systems and the effect of increasing the bandwidth of a two-channel receiver on the noise immunity of the receiving system at low signal-to-noise ratios.