Method and system for testing phase imbalance in QPSK receivers
AssigneeQUALCOMM Incorporation
InventorScott P. Benner
Life of this patent
Estimating the term…
Abstract
A method or system (10) includes test apparatus (14) for measuring the phase imbalance in a QPSK receiver (12). A signal generator (16) provides a test signal (18) to the receiver (12), which responsively generates I channel data (20) and Q channel data (22). The system includes an oversampler (26) for producing respective sets of oversampled I and Q channel data (24) and (25). A data processing system (28) cross-correlates the sets of I and Q channel data at each of a plurality of relative phase increments, and generates a plurality of cross-correlation energy values in response to said cross-correlation. The method or system determines the phase imbalance in response to at least a largest cross-correlation energy value of said plurality of cross-correlation energy values.
Claims14
A method for measuring phase imbalance in a QPSK receiver which generates I and Q channel signals, said method comprising the steps of:
- sampling said I and Q channel signals at a first sample rate to produce a set of I channel samples and a set of Q channel samples;
- cross-correlating said set of I channel samples with said set of Q channel samples at each of a plurality of relative phase increments;
- generating a plurality of cross-correlation energy values in response to said cross-correlating step;
- determining a largest cross-correlation energy value of said plurality of cross-correlation energy values;
- determining first and second next largest cross-correlation values of said plurality of cross-correlation values;
- and
- interpolating said phase imbalance from said largest and said first and second next largest cross-correlation values.
A system for measuring phase imbalance in a QPSK receiver which generates I and Q channel signals, said system comprising:
- a digital sampler for sampling said I and Q channel signals at a first sample rate to produce a set of I channel samples and a set of Q channel samples;
- and
- a data processor for cross-correlating said set of I channel samples with said set of Q channel samples at each of a plurality of relative phase increments, for generating a plurality of cross-correlation energy values in response to said cross-correlation, for determining a largest cross-correlation energy value of said plurality of cross-correlation energy values, for determining first and second next largest cross-correlation values of said plurality of cross-correlation values, and for interpolating said phase imbalance from said largest and said first and second next largest cross-correlation values.
Dependencies are inferred from the claim text.