Abstract: A new class of multiplexing filter structure has both the properties of channelized filtering and channelized linear frequency discrimination. The channelized filter-discriminator is intended for use as part of a microwave receiving system possessing a high probability of intercept for incoming signals. The selective properties of the band pass filters provide an interference-reduction capability while the discriminator property provides for instantaneous frequency measurement. The design procedure for achieving a very high degree of discriminator linearity in association with a reasonable selectivity comparable to a maximally flat filter uses theoretical design data provided in a normalized table generated by computer optimization. A hardware realization of a 64 channel multiplexer-discriminator is described and measured data is presented that agrees very closely with the theoretical predictions.