A statistical evaluation of the SMPRF range velocity ambiguity mitigation technique

The mitigation of range and velocity ambiguities for pulsed weather radars is an on going area of research. There are several techniques that have been used to mitigate this problem: staggered PRT (pulse repetition time), SZ phase coding, multiple pulse-repetition (multi-PRI), and Simultaneous Pulse Repetition Frequency code (SMPRF). The first three techniques are well established and documented in the literature. The fourth technique, SMPRF, is relatively new and was developed in Finland. A recent journal article reports on the techniques but no supporting data simulations have ever been shown.

SMPRF is a multiple staggered PRT technique, i.e., several staggered pulses (three or more) are transmitted in a block and then this block of staggered pulses is repeated many times depending on the staggers chosen. The result is that the range overlaid echoes come from ranges depending on the measurement time in relation to the block of staggered PRTs. A set of simultaneous equation for the resolution volume powers can be written and the solution can be found using standard matrix inversion methods.

Since there are multiple pulse staggers, there are many different, non-uniform estimates of the auto correlation function for a particular resolution volume. A best fit to these non-uniform points can be constructed and then the mean velocity can be calculated. Theoretically, the technique appears to yield almost unlimited expansion of the unambiguous range and velocity. Again, however, the technique has never been statistically evaluated using simulated data.

This paper shows how the SMPRF techniques can be modeled and then evaluates the statistical recovery performance for a particular SMPRF code and compares the performance of SMPRF to some of the more established range-velocity mitigation techniques.