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US 4,383,324 AGranted
Digital data transmission systems
AssigneeGeneral Electric Company
InventorsMichael T. Dudek, John M. Robinson
Life of this patent
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Abstract
In a receiver arrangement for a quadrature phase-shift digital data transmission system including an adaptive equalizing regenerator, a phase control signal for the local oscillator is derived from an output of the regenerator and decision feedback signals within the regenerator are applied by way of balanced current switching circuits.
Claims11
A receiver arrangement for a quadrature phase-shift digital data transmission system comprising:
- (A) two quadrature phase detectors,
- (B) a local oscillation generator,
- (C) means to apply signals from said generator to each of said phase detectors to derive from a phase-shift modulated received signal respective phase detector output signals varying substantially between at least two discrete values in dependence upon data digit values being transmitted over the system,
- (D) at least two main threshold detectors arranged respectively to compare said respective phase detector output signals with a main threshold value intermediate two said discrete values during each of a succession of received data digit periods to provide first binary output signals having values dependent upon the results of said main threshold comparisons,
- (E) at least one auxiliary threshold detector arranged to compare one of said phase detector output signals with an auxiliary threshold value of substantially one of said two discrete values during said received data digit periods to provide second binary output signals having values dependent upon said auxiliary threshold comparison, and
- (F) logic circuit means to derive from said first and second binary output signals at least one analogue control signal for said receiver arrangement.
3 more elements
A receiver arrangement for a quadrature phase-shift digital data transmission system comprising:
- (A) two quadrature phase detectors,
- (B) a local oscillation generator,
- (C) means to apply signals from said generator to each of said phase detectors to derive from a phase-shift modulated received signal respective phase detector output signals varying substantially between at least two discrete values in dependence upon data digit values being transmitted over the system,
- (D) at least two main threshold detectors arranged respectively to compare said respective phase detector output signals with a main threshold value intermediate two said discrete values during each of a succession of received data digit periods to provide respective first binary output signals having values dependent upon the results of said main threshold comparisons,
- (E) at least two auxiliary threshold detectors arranged respectively to compare said respective phase detector output signals with an auxiliary threshold value of substantially one of said two discrete values during said received data digit periods to provide respective second binary output signals having values dependent upon said auxiliary threshold comparisons,
- (F) decision feedback means selectively to combine with the output signals from one at least of said phase detectors a weighting signal, during a received data digit period, in dependence upon the value of at least one of the first binary output signals during a preceding data digit period,
- (G) logic circuit means to derive from said first and second binary signals at least one analogue voltage signal dependent upon any intersymbol interference in said binary signals, and
- (H) means to apply said analogue voltage as a control voltage in such a sense as to minimize said intersymbol interference.
5 more elements
Dependencies are inferred from the claim text.