An asynchronous spread spectrum (SS) wireless modem has been implemented using an efficient Zn0-Si02-Si surface acoustic wave (SAW) convolver. The modem is based on a direct-sequence I frequency-shift-keying (DS/FSK) method for the modulation. The demodulation is carried out asynchronously utilizing the coherent correlation characteristics of the SAW convolver. In order to improve the narrowband interference rejection capability, we propose a new technique based on the reference signal control. A notched-reference-signal circuit and a selfconvolution canceler are implemented in the SS modem for the reference signal control. It is found that the antijam capability for narrowband interference is at least -24dB of desired-toundesired power ratio (DIU); the improvement of the antijam capability is 16dB up as compared with our previous SS modem.
|Number of pages
|Published - 1992
|2nd IEEE International Symposium on Spread Spectrum Techniques and Applications, ISSTA 1992 - Yokohama, Japan
Duration: 1992 Nov 29 → 1992 Dec 2
|2nd IEEE International Symposium on Spread Spectrum Techniques and Applications, ISSTA 1992
|92/11/29 → 92/12/2