On processing the radar return from an ionized trail

The radar target model that is the ionized trail of an atmospheric re-entry vehicle is considered as a channel or filter between the radar transmitter and receiver. The objective of the radar and its associated data processor is to "map" or identify the radar target channel. The target is identified as the equivalent of a spatially distributed time-varying filter or equivalently as a range and velocity distributed target. The techniques for processing the radar return from both deterministic and stochastic versions of the target model include the matched filter and a generalized correlation computer. Results of the processor output are given in terms of the transmitted signal ambiguity function and a quantity called the target scatter cross section. In general, and as expected, long time duration and large signal bandwidth transmitted signals are required in relation to the reciprocal target velocity spread and the reciprocal target range spread for accurate target model mapping. An exception is noted in the existence of an upper limit to the signal bandwidth that is useful in unambiguously mapping the stochastic target model. Alternatively, this result implies that there is a limit to the range resolution with which the range velocity distributed stochastic targets can be observed.