Baylie Damtie^{1 *}, Markku Lehtinen² , Mikko Orispaa² and Juha Vierinen^2
1Department of Physics, Bahir Dar University, P.O.Box 79, Bahir Dar, Ethiopia
²Department of Physical Sciences, Oulu University, P.O.Box 90014, Oulu, Finland

Abstract. Radars have been used extensively for ionospheric studies. In an ionospheric radar measurement one usually implements different types of codes and the choice largely depends on the geophysical phenomenon under investigation. As a result many kinds of coding and decoding methods have been used including binary phase codes. In ionospheric physics the perfor- mance of binary phase codes are usually investigated in terms of spatial and temporal resolution. This is done usually by employing a matched filter, which creates unwanted side lobes at the output of the receiver. These side lobes can be eliminated by using a mismatched filter. But there is an associated loss in signal-to-noise ratio (SNR). In this paper we have presented long optimal binary phase code-mismatched filter pairs that may be used in several applica- tions including ionospheric radar measurements. This was done by investigating 1.04 X 109 number of binary phase codes.

Keywords:plasmas - data analysis - radar astronomy

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