Passband DQPSK detector for a digital communications receiver

Details Passband DQPSK detector for a digital communications receiver Passband DQPSK detector for a digital communications receiver

1997-11-20

2000-04-25

Ghebretinsae, Temesghen

Pulse or digital communications

Receivers

Angle modulation

375324, 329304, H04L 2722

Patent

active

060552816

ABSTRACT:
A digital communications DQPSK passband detector having a matched filter, a differential decoder, and a slicer that use elementary circuit components. In the matched filter, recovered carrier reference signals are fed along with the received signal to a pair of XNOR gates. This arrangement effectively results in a multiplication operation without any complex circuit elements. The outputs of the XNOR gates control the direction of counting of a pair of binary counters that generate correlated values of the I and Q components in the received signal. Thus, the integrate/dump circuits of a conventional matched filter are replaced with simpler digital counters. A digital differential decoder to extract the phase difference information between two consecutive received symbols is built from a network of delay elements, multipliers, and adders to recover the phase data. The digital differential decoder produces a digital complex-signal output that can be quantized in a digital slicer to decode the plurality of binary bits transmitted through the data symbols. All these operations are performed on digital signals with basic digital circuit elements, thus resulting in a repeatable robust receiver design without complex hardware components.

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