| 摘要 |
An automatic frequency-hop controller for a surface acoustic wave (SAW) synthesizer is used with a means for generating two chirp signals, one having a delay with respect to the other. It comprises a SAW device, adapted to receive the chirp signals. The SAW device comprises a substrate and a pair of sets of interdigitated electrodes, disposed on the surface of the substrate, one set at each end, the electrodes receiving the electrical chirp signals or corresponding impulse signals. Another set of interdigitated electrodes, which are output electrodes, are also disposed on the surface of the substrate, the electrodes of all sets being parallel. The output set of electrodes are so disposed as to receive the acoustic waves generated by the pair of sets of electrodes, and transduce them back to electrical signals. For the case when quadrature summation is performed by offset acoustic delays on the substrate, the pair of sets of electrodes and the output set of electrodes are so disposed with respect to each other that the signal received from the top parts of the output set of electrodes has a phase shift of 90 DEG , at a frequency fc, with respect to the phase shift of the signal received from the bottom parts of the output electrodes.
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