Pulse or digital communications – Receivers – Angle modulation
Patent
1997-04-10
1999-03-02
Chin, Stephen
Pulse or digital communications
Receivers
Angle modulation
375324, 375326, 375355, 375371, 375373, 375260, 375261, 329304, 329306, H04L 2714, H04L 2716, H04L 2722, H04L 700
Patent
active
058780882
ABSTRACT:
A receiver is arranged for receiving a transmitted quadrature amplitude modulated (QAM) signal representing successive symbols, and including an in-phase (I) component and a quadrature (Q) component. In such a receiver, a timing recovery system includes a source of samples representing the QAM signal produced at a fixed frequency. A first chain of processing circuitry for the I component includes a first demodulator, coupled to the sample source, for demodulating the I component of the QAM signal to baseband; and a first interpolator, coupled to the first demodulator and responsive to a control signal, for producing I component samples taken at times synchronized to the transmitted symbols. A second chain of processing circuitry for the Q component includes a second demodulator, also coupled to the sample source, for demodulating the Q component of the QAM signal to baseband; and a second interpolator, coupled to the second demodulator and responsive to a control signal, for producing Q component samples taken at times synchronized to the transmitted symbols. A phase error detector is coupled to the first and the second interpolators, and detects the phase error between the sample times of the I and Q component samples from the first and second interpolators and times of the successive transmitter symbols. A summer is coupled to the phase error detector and a source of a nominal delay signal. A numerically controlled delay circuit, is coupled to the summer, for producing the respective control signals for the first and second interpolators.
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Knutson Paul Gothard
McNeely David Lowell
Ramaswamy Kumar
Chin Stephen
Herrmann Eric P.
Kurdyla Ronald H.
Maddox Michael W.
Thomson Consumer Electronics Inc.
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