System for the quantitative measurement of impairments in the communication channel of a quadrature amplitude modulation data communication system
AssigneeParadyne Corporation
InventorThomas R. Armstrong
Life of this patent
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Abstract
A system is provided for measuring communication channel impairments in a data transmitting system which employs quadrature amplitude modulation. The system rotates each point of sampled eye diagram information by a phase angle determined by the ideal value of the received point information so that the rotated point has its nominally maximum component on the real axis.
Claims16
In a data communications system employing quadrature amplitude modulation comprising;
- a transmitter receiver, and a communication channel linking said transmitter and receiver, said receiver producing sampled eye diagram point information wherein each received point is defined in a coordinate system in which a first axis is the in-phase channel axis and a second axis is the quadrature channel axis, the improvement comprising:
- means for rotating said received points by an operand determined by the ideal value of the receiving point information so that each rotated point has a first nominally maximum component on a new first axis and a nominal second component on a new second axis and means for determining the characteristics of said communication channel from variances and means of the components.
A method for obtaining quantitative data regarding the status of the communications channel in a data communications system employing quadrature amplitude modulation and comprising a transmitter, a receiver and a communications channel linking the transmitter and receiver, said method comprising the steps of:
- (a) producing sampled eye diagram point information by the receiver wherein each received point is defined in a coordinate system in which a first axis is the in-phase channel axis and a second axis is the quadrature channel axis;
- (b) rotating said received points by an operand determined by the ideal value of the received point information so that each rotated point has its nominally maximum component on a new first axis and a second nominal component on a new second axis;
- and,
- (c) determining the characteristics of the communications channel from variances and means of the components.
Dependencies are inferred from the claim text.