| This work introduces the new weighted stepped chirp code signal for direct sequence spread spectrum (DS/SS) communications systems. This code signal uses the truncated cosine series functions as the chip functions. This code signal is the result of discretizing a continuous wave (CW) chirp which results in enhanced performance versus a pseudonoise (PN) code and equivalent performance and easier implementation than a CW chirp. This code signal will be shown to possess improved compression ratio (CR), peak sidelobe level (PSL), integrated sidelobe level (ISL), and bit error rate (BER) when compared to a PN code of identical code length and chip length. It also will be shown to have a similar CR, PSL, ISL, and loss in processing gain (LPG) when compared to a CW chirp with identical pulse length and frequency deviation.; The code signal is implemented on surface acoustic wave (SAW) devices which can be used as the code signal generator at the transmitter and the correlator at the receiver in a DS/SS communications system. SAW design considerations for the weighted stepped chirp signal are discussed. Experimental data is presented and compared to the predicted CR, PSL, ISL, LPG, and BER. |
