Demodulators – Amplitude modulation demodulator – Having specific distortion – noise or other interference...
Patent
1977-04-07
1978-07-11
Safourek, Benedict V.
Demodulators
Amplitude modulation demodulator
Having specific distortion, noise or other interference...
329104, H04L 2508
Patent
active
041004957
ABSTRACT:
An incoming data stream in the output of a demodulator and its derivative in the output of a differentiator are passed by respective sampling gates to a pair of equalizers operating by recursive filtration. The optimized data pulses issuing from the first equalizer are quantized and, after storage in a shift register, are algebraically combined in a first adder with a reference signal x from that equalizer representing the vector sum of weighted data pulses from a succession of N preceding clock cycles; a resulting error signal e.sub.n is delivered to three cumulative multipliers forming part of three feedback loops which supply an optimized phase signal .zeta. to the demodulator, an optimized timing signal .tau. to the sampling gates and an optimized gain coefficient K to the equalizers. These three multipliers respectively receive the reference signal x from the first equalizer, an optimized differential signal dx/d.tau. from the second equalizer and an updating signal z from the first equalizer. A further cumulative multiplier forms part of a fourth feedback loop delivering an optimized channel coefficient G to the equalizers, this latter loop including a second adder which synthesizes another error signal e' from the incoming data pulses z and from the complex product G.multidot.x produced by the last-mentioned multiplier. Each feedback loop includes a selective delay circuit effective only during an operating phase, in contrast to an acquisition phase during which the first adder receives a locally generated test signal in lieu of the quantized data pulses.
REFERENCES:
patent: 3971996 (1976-07-01), Motley et al.
patent: 4004226 (1977-01-01), Qureshi et al.
patent: 4019149 (1977-04-01), Kustka et al.
patent: 4035625 (1977-07-01), Chiu et al.
Luvison Angelo
Pirani Giancarlo
CSELT - Centro Studi E Laboratori Telecomunicazioni
Ross Karl F.
Safourek Benedict V.
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