Abstract
An asynchronous spread spectrum (SS) wireless modem has been implemented using an efficient (ZnO-SiO2-Si surface acoustic wave (SAW) convolver. The modem is based on a direct-sequence/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 self-convolution canceler are implemented in the SS modem for the reference signal control. It was found that the antijam capability for narrowband interference is at least -24 dB of desired-to-undesired power ratio (D/U); the improvement of the antijam capability is 16 dB up as compared with our previous SS modem.
| Original language | English |
|---|---|
| Pages (from-to) | 947-953 |
| Number of pages | 7 |
| Journal | IEICE Transactions on Communications |
| Volume | E76-B |
| Issue number | 8 |
| Publication status | Published - 1993 Aug |