Measuring impairments of digitized signals in data and timing recovery circuits
A method of measuring signal impairments is disclosed for use in an asynchronous Digital Signal Processing (DSP) based data and timing recovery circuit including an interpolator circuit. The method includes: calculating amplitude values for data and timing recovery; calculating an interpolation index for the interpolator circuit; and overriding the interpolation index. In another implementation, a method of measuring signal impairments in an asynchronous DSP-based data and timing recovery circuit including an interpolator circuit includes: calculating amplitude values for data and timing recovery; calculating a timing control signal; and overriding the timing control signal.
1. A method of measuring signal impairments in a received signal in an asynchronous Digital Signal Processing (DSP) based data and timing recovery circuit, comprising:
calculating, at an interpolator circuit, amplitude values of the received signal at a plurality of interpolation index time points, the amplitude values for data recovery and timing recovery;
calculating, at a timing recovery circuit, an interpolation index for the interpolator circuit, the interpolation index based on the calculated amplitude values; and
overriding the interpolation index in order to provide a modified interpolation index to the interpolator circuit for calculating a modified amplitude value of the received signal at a modified interpolation index time point, the measured signal impairments based on the modified amplitude value.
2. The method of claim 1 wherein the interpolation index for the data recovery is overridden.
3. The method of claim 1 wherein the interpolation index for the timing recovery is overridden.
4. The method of claim 1 wherein the calculated modified amplitude value is obtained at an output of the interpolator circuit.
5. The method of claim 1 wherein the calculated modified amplitude value is obtained at an output of an equalizer in communication with the interpolator circuit.
6. The method of claim 1 wherein the calculated modified amplitude value is obtained at an internal node of an equalizer in communication with the interpolator circuit.
7. A method of measuring signal impairments in a received signal in a synchronous Digital Signal Processing based data and timing recovery circuit, comprising:
sampling, at an analog to digital converter (ADC), amplitude values of the received signal at a plurality of timing control signal time points, the amplitude values for data recovery and timing recovery;
calculating, at a timing recovery circuit, a timing control signal for the interpolator circuit, the timing control signal based on the sampled amplitude values; and
overriding the timing control signal in order to provide a modified timing control signal to the ADC for sampling a modified amplitude value of the received signal at a modified timing control signal time point, the measured signal impairments based on the modified amplitude value.
8. The method of claim 7 further comprising:
collecting the modified amplitude value when the timing control signal is overridden.
9. The method of claim 8 wherein the modified amplitude value is obtained at an output of the ADC.
10. The method of claim 8 wherein the modified amplitude value is obtained at an output of an equalizer in communication with the ADC.
11. The method of claim 8 wherein the signal amplitude is obtained at an internal node of an equalizer in communication with the ADC.
12. A non-transitory computer-readable medium storing statements and instructions for execution by a processor to perform a method of measuring signal impairments in a received signal in an asynchronous Digital Signal Processing (DSP) based data and timing recovery circuit, comprising:
calculating, at an interpolator circuit, amplitude values of the received signal at a plurality of interpolation index time points, the amplitude values for data recovery and timing recovery;
calculating, at a timing recovery circuit, an interpolation index for the interpolator circuit, the interpolation index based on the calculated amplitude values; and
overriding the interpolation index in order to provide a modified interpolation index to the interpolator circuit for calculating a modified amplitude value of the received signal at a modified interpolation index time point, the measured signal impairments based on the modified amplitude value.
13. The non-transitory computer-readable medium of claim 12 wherein the interpolation index for the data recovery is overridden.
14. The non-transitory computer-readable medium of claim 12 wherein the interpolation index for the timing recovery is overridden.
15. The non-transitory computer-readable medium of claim 12 wherein the calculated modified amplitude value is obtained at an output of the interpolator circuit.
16. The non-transitory computer-readable medium of claim 12 wherein the calculated modified amplitude value is obtained at an output of an equalizer in communication with the interpolator circuit.
17. The non-transitory computer-readable medium of claim 12 wherein the calculated modified amplitude value is obtained at an internal node of an equalizer in communication with the interpolator circuit.