The use of multipulse zero lag data to improve incoherent scatter radar power profile accuracy

Abstract

In incoherent scatter radar experiments, multipulse methods are used for measuring the plasma autocorrelation function when the spatial resolution provided by long pulse methods is too coarse. The zero lag increment from a multipulse is often stated to be useless as data and useful only in channel balancing, because the signal cross-products for zero lag contain information from several different ranges. Thus it is necessary to send one or more single pulses at different frequencies to get the zero lag increment, which is also called the power profile. In this paper we show that multipulse zero lag information can be combined with the information from separate power profile channels leading to a significant improvement in the power profile estimate accuracy. The method can be applied to all multipulse measurements and also to Barker coded ones. We show practical results of an application of the method to a modulation that consists of four four-pulse channels and two single pulse channels. In this case the theoretically estimated improvement is a factor of 5.2 in variance, and the improvement can clearly be seen in real data.