The effects of amplitude and phase imbalances between the in-phase and quadrature channels of a digital radio frequency (RF) receiver on a phase analysis processing technique are studied. Particular attention is given to the effect that these errors have on the detection and accurate frequency resolution of simultaneous signals. It is shown that these error effects can appear to be identical to a simultaneous signal condition. Thus using this technique in a practical electronic warfare (EW) receiver could cause incorrect conclusions unless the amplitude separation of the signals is small. Simulation results and data collected from a 250 MHz, 8 b digital receiver are presented to show how these errors, along with other anomalies, affect the performance of phase analysis processing, and specifically how they affect detection and determination of simultaneous signals.< >

The results of a study of the sensitivity of digital electronic warfare (EW) receivers are reported. It is demonstrated with actual digitized data that the sensitivity of a digital receiver can be improved if enough signal processing is applied. The approach presented can be considered as a brute force one. This approach does not provide the best sensitivity that can be accomplished, but it will provide an improvement over conventional EW receivers. In this approach, the digital Fourier transform (DFT) is used to find the frequencies of the input signals. Several DFTs with fixed lengths are used. This approach will approximate the performance of a superheterodyne receiver with a fixed bandwidth, and is equivalent to several channelized receivers, each having a different resolution bandwidth. The technique improves the sensitivity of the receiver with reasonable complexity

A novel approach to an instantaneous frequency measurement receiver simplifies the design by using less hardware. This design is an essential approach to building an IFM receiver with simultaneous signal capability. Delay lines and correlators are used to measure the frequency of the input signals. To achieve a wide input bandwidth with fine frequency resolution, the novel receiver uses only two delay lines. To simplify the design, the algorithm used is related to the Chinese remainder theorem, modified to guard against noise. The receiver will have a resolution of 1 MHz and a bandwidth of 500 MHz, although only two phase correlators need to be digitized