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US 2007/0195913 A1Published application
Phase lock loop and method for coded waveforms
AssigneeHarris Corporation
InventorsClifford Hessel, Paul Voglewede
Life of this patent
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AssigneeHarris Corporation
InventorsClifford Hessel, Paul Voglewede
Estimating the term…
A novel system and method is disclosed for maintaining synchronization in a communication system in which a communication signal comprising a carrier and a data signal is sent from a transmitter to a receiver which includes a phase lock loop. The receiver compares the output of a Viterbi decoder with the output of a quick decision circuit. The Viterbi decoder, which incorporates traceback, determines the minimum aggregate Euclidean distance for multiple symbols. The quick decision circuit determines the minimum Euclidean distance for a single symbol without decoding the symbol. A delay circuit is placed in series with the quick decision circuit to compensate for the traceback delay in the Viterbi decoder. If the difference in the output signals of the Viterbi decoder and the quick decision circuit is greater than a predetermined threshold, the phase error signal in the phase lock loop is prevented from updating the phase lock loop filter. A synchronization loss detector may also be used to prevent the phase error signal from updating the phase lock loop filter if synchronization loss is detected. Additionally, the output signal from the Viterbi decoder is used to extract the carrier from the received communication signal by use of a lookup table to generate phase angle information as a function of the Viterbi decoder output signal. The phase angle information is combined with the Viterbi decoder output signal to reconstitute the data signal in the communication signal. The reconstituted data signal is combined with the communication signal, which has been delayed to compensate for the traceback delay in the Viterbi decoder, in order to extract the carrier.
In a phase lock loop in a communication system receiver for maintaining synchronization of the local oscillator of the receiver with the oscillator of a transmitter in response to the receipt of a communication signal by the receiver from the transmitter, where said phase lock loop produces a phase error signal responsive to the difference between the phase of the received communication signal with the phase of a reference signal produced by said local oscillator and automatically adjusts the phase of the reference signal responsive to the phase error signal, the improvement of only adjusting the phase of the reference signal responsive to a determination that the phase error is less than a predetermined threshold value.
In a communication system comprising a transmitter and a receiver for the transmission of a communication signal comprising a carrier signal and a coded data signal, wherein said receiver includes a mixer for producing the carrier signal by mixing the communication signal with a signal representative of the coded data signal, the improvement of
In a communication system comprising a transmitter and a receiver for the transmission of a communication signal comprising a carrier signal and a coded data signal, wherein said receiver includes a phase lock loop comprising a phase detector for producing a phase error signal responsive to the difference in phase between the carrier signal and a reference signal, a voltage controlled oscillator for producing the reference signal, and a low pass filter for producing a control signal responsive to said phase error signal, wherein said voltage controlled oscillator adjusts the frequency of the reference signal in response to the control signal, the improvement wherein an outlier rejection filter is used to prevent the phase error signal from being input to the low pass filter in the event the outlier rejection filter determines the communication signal is an outlier.
The method of reducing noise in a fast acquisition, phase lock loop having a reference oscillator, mixer and filter comprising the steps of:
A method of maintaining phase lock between a transmitter and a receiver including a phase lock loop having a dynamic bandwidth filter, whereby plural symbols which are representative of an encoded data signal are sent by the transmitter and received by the receiver, comprising the steps of:
A method of maintaining phase lock between a transmitter and a receiver including a phase lock loop having a dynamic bandwidth filter, whereby plural symbols each of which are representative of a two bit encoded data signal are sent by the transmitter and received by the receiver, comprising the steps of:
A method of maintaining synchronization between a transmitter and a receiver including a phase lock loop having a filter, whereby plural symbols which are representative of an encoded data signal are sent by the transmitter and received by the receiver, comprising the steps of:
29-42. (canceled)
Dependencies are inferred from the claim text.