Abstract
Abstract. The standard analysis of Barker-coded incoherent scatter experiments is based on a matched filter with an impulse response which is a mirror image of the code itself. The method produces small sidelobes which cause contamination from regions outside the nominal range gate. A corresponding effect is also encountered in the lag direction, where individual lag estimates are biased by the variation of the plasma autocorrelation function around the nominal lag value. The present paper introduces a new method of analysing Barker-coded experiments by means of stochastic inversion. Since it does not apply a decoding filter, it does not suffer from drawbacks caused by the sidelobes of the range ambiguity function. The method combines the profile of each full lag and a number of surrounding fractional lags into a single inversion problem. Error analysis also indicates that the statistical accuracy given by inversion is better than that obtained by means of standard decoding. Furthermore, the inversion method gives a possibility to reduce the bias due to the variation of the autocorrelation around the nominal lag. In this paper the method is described and applied to data obtained by means of the EISCAT Svalbard radar. In addition, it is shown that mathematical inversion can be used instead of the the conventional height integration. Key words. Radio science (ionospheric physics; signal processing; instruments and techniques)
Highlights
The task of the incoherent scatter radar is to measure the range profile of the plasma autocorrelation function (ACF ) in the ionosphere
Barker codes have provided a means for improving the range resolution of incoherent scatter measurements
The disadvantages of Barker codes can be reduced by means of various methods designed for suppressing the sidelobes (e.g. Blinchikoff and Zverev, 1987, and references therein)
Summary
The task of the incoherent scatter radar is to measure the range profile of the plasma autocorrelation function (ACF ) in the ionosphere. A standard way of obtaining range resolutions of a few hundreds of metres is Barker coding (Barker, 1953) This has been applied to single pulses to obtain power profiles of high range resolution (Ioannidis and Farley, 1972), to multipulses to obtain all lags of the ACF with the same high resolution (Turunen et al, 1985; Huuskonen et al, 1986; Turunen et al, 1988) and later to alternating codes (Wannberg, 1993). Decoding Barker coded incoherent scatter measurements without sidelobes can be made using an infinitely long filter. This was suggested by Sulzer (1989), who pointed out that this process decreases the signal-to-noise ratio (SNR). The solution is obtained by applying Bayesian stochastic inversion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
