Multiplex communications – Wide area network – Packet switching
Patent
1986-07-02
1988-05-24
Olms, Douglas W.
Multiplex communications
Wide area network
Packet switching
370 50, H04J 400
Patent
active
047470950
ABSTRACT:
An analog surface acoustic wave demodulator includes a calibration section (10) for compensating for distortions, a calibrated frequency sweep (20), a pair of dispersion sections formed by reflective array compressors (24, 26 and 36, 38), a synchronizer (18, 22, 28, 118), a timing signal generator (42) and a temperature compensating readout circuit (40). Frequency domain compensations introduced at the signal input by the calibration section and by the frequency sweep compensate for distortions in time domain at the output of the demodulator. The calibration function applied to the input signal and to the sweep is stored in ROM's (14, 44) in the form of complex digital words. Timing and address generators (12, 42) read the words from the Rom's to complex multipliers (16, 52) such that each symbol period is multiplied by the sequence of words. Each complex digital word corresponds to an amplitude and phase modulation on the incoming signal over a fraction of a symbol period. The synchronizer fires the frequency sweep section at the proper time to eliminate intersymbol interference. The temperature compensating readout circuit locks on to synchronizing signals generated by the synchronizer and provides a time base which is used to readout of the demodulated signals. The synchronizing signals are employed to generate a feedback error signal which is used by the timing signal generator to generate timing signals for firing the frequency sweep section and for selecting the proper calibration function to be applied to each sweep.
REFERENCES:
patent: 3328528 (1967-06-01), Darlington
patent: 3560654 (1971-02-01), Darlington
patent: 4304000 (1981-12-01), Bonnerot et al.
patent: 4590595 (1986-05-01), Morimura
Hughes Aircraft Company
Jung Min
Karambelas A. W.
Meltzer M. J.
Mitchell S. M.
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