Effective subtraction technique at the Irkutsk Incoherent Scatter Radar: Theory and experiment

We describe a sounding technique that allows us to improve spatial resolution at the Irkutsk Incoherent Scatter Radar (IISR) without losing spectral resolution. The technique also allows us to decrease temperature estimation errors caused by the Faraday effect. The technique is based on transmitting various duration pulses without any modulation and on subtracting correlation matrices of the received signal grouped by sounding pulse duration. We show theoretically and experimentally that the technique allows us to solve the problem of improving spatial resolution. Accumulation time for the technique is approximately four times longer than that for the alternating codes technique with the same spatial resolution.The number of lags in the correlation function with high spatial resolution does not depend on necessary spatial resolution. In the proposed technique, all the lags are obtained with the same spatial resolution and with the same signal-to-noise ratio. The technique is valid within the quasi-static ionospheric parameter approximation.