Robert Boyd Curtis

US Patent:

48478768, Jul 11, 1989

Filed:

Dec 31, 1986

Appl. No.:

6/948276

Inventors:

Randall L. Baumbach - Arnold MD
Richard G. Berard - Chelmsford MA
Robert G. Curtis - Sudbury MA

Assignee:

Raytheon Company - Lexington MA

International Classification:

H04L 706
H03D 324

US Classification:

375113

Abstract:

A timing recovery apparatus for a burst mode communication receiver. The apparatus provides for optimum sampling and digitizing of received data at a plurality of data rates. In particular, a VCO is phase-locked to a local frequency reference prior to data being received. A reference timing preamble transmitted prior to the data is filtered and fed to the VCO causing it to injection lock such that the VCO becomes phase aligned with the preamble. The VCO is then permitted to "free run" during data transmission and continues to operate at substantially the same frequency. A synchronous divider and multiplexer, responsive to the VCO, allows selection of sampling clocks for the plurality of data rates. The divider is forced to a known state during VCO injection locking, to assure that the sampling clocks have maintained the proper phase for optimal sampling at the corresponding data rate. Further, means is provided to monitor the frequency of the VCO.

US Patent:

47730838, Sep 20, 1988

Filed:

Nov 8, 1985

Appl. No.:

6/796342

Inventors:

Randall L. Baumbach - Arnold MD
Robert G. Curtis - Sudbury MA
Richard G. Berard - Chelmsford MA

Assignee:

Raytheon Company - Lexington MA

International Classification:

H04B 710

US Classification:

375100

Abstract:

A receiver including two optimizers for demodulation, sampling and quantization of received QPSK digital data. One optimizer adjusts the phase of a reference signal used for demodulating the QPSK data into baseband in-phase and quadrature channels and another optimizer adjusts a sampling clock used to sample and quantize the baseband channels. The reference signal and the sampling clock are dithered in quadrature. Variations in the amplitude of the quantized data extracted by an eye quality monitor. Each optimizer multiplies the eye quality monitor output by a corresponding dither clock and integrates to form an error signal. Phase shifters, responsive to corresponding error signals and dithered clocks, adjust the phase of the demodulation reference signal and sampling clock. The data quality signal monitor translates the magnitude of the quantized data signals to a common set of signals for each state of the data signal. These common signals are translated into a voltage representing the degree to which the data signal amplitude corresponds to a predetermined value.

US Patent:

49184067, Apr 17, 1990

Filed:

Apr 26, 1989

Appl. No.:

7/343225

Inventors:

Randall L. Baumbach - Arnold MD
Richard G. Berard - Chelmsford MA
Robert G. Curtis - Sudbury MA

Assignee:

Raytheon Company - Lexington MA

International Classification:

H03B 512
H03L 706

US Classification:

331117R

Abstract:

A timing recovery apparatus for a burst mode communication receiver. The apparatus provides for optimum sampling and digitizing of received data at a plurality of data rates. In particular, a VCO is phase-locked to a local frequency reference prior to data being received. A reference timing preamble transmitted prior to the data is filtered and fed to the VCO causing it to injection lock such that the VCO becomes phase aligned with the preamble. The VCO is then permitted to "free run" during data transmission and continues to operate at substantially the same frequency. A synchronous divider and multiplexer, responsive to the VCO, allows selection of sampling clocks for the plurality of data rates. The divider is forced to a known state during VCO injection locking, to assure that the sampling clocks have maintained the proper phase for optimal sampling at the corresponding data rate. Further, means is provided to monitor the frequency of the VCO.