Programmable down-sampler having plural decimators and modulator

Details Programmable down-sampler having plural decimators and modulator Programmable down-sampler having plural decimators and modulator

1997-09-23

1999-02-16

Grimm, Siegfried H.

Demodulators

Phase shift keying or quadrature amplitude demodulator

341 61, 3647241, 375324, 375329, H03M 700, H04L 2722

Patent

active

058724800

ABSTRACT:
A digital QPSK demodulator includes a plurality of two-input-two-output (TITO) two-fold decimators where each TITO two-fold decimator operates at a rate equal to its input data rate. The in-phase I signal and the quadrature Q signal are computed in an interleaved sequence of {Q"(n), I"(n), Q"(n+1), I"(n+1), . . . } to generate Q" decimation output and I" decimation output. The TITO two-fold decimators are cascaded in a reverse order to form a programmable down-sampler which decimates the input data by factors of 1, 2, 4, 8 or more. In a first embodiment, the programmable down-sampler is coupled between a complex multiplier and an interpolator. In a second embodiment, the in-phase and quadrature signals are fed through a complex multiplier, an interpolator, then the programmable down-sampler. In the third embodiment, the in-phase and quadrature signals are fed through an interpolator, a complex multiplier, then the programmable down-sampler.

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CAS 1643 Dual Digital Low Pass Filter Preliminary Information. Comatlas, Chateaubourg, Jan. 1997, pp. 1, 3-4 and 13.

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