Intermodulation in channelized digital ESM receivers

摘要

This thesis investigates intermodulation distortion generated by analog-to-digital converters (ADCs) in a channelized digital ESM receiver when processing multiple signals simultaneously. The spurious free dynamic range (SFDR) associated with this distortion is discussed. Two methods for increasing the spurious free dynamic range are evaluated. First, by adding a small amount of Gaussian noise to the input of the receiver, the intermodulation distortion is found to be reduced significantly. Second, by using a narrow bandwidth sub-Nyquist sampling rate with high dynamic range ADCs it is possible to increase the spurious free dynamic range of the digital receiver. The first method is a simple approach but the ability to increase the SFDR is limited. The second method is more effective but requires greater computation and complex receiver design.