Spur detection in a sampled waveform in a mixed analog/digital system using the phase of the frequency response
Method, apparatus and computer program product for spur detection in a sampled waveform in a mixed analog/digital system using the phase of the frequency response comprising acquiring a sample waveform including a set of discrete uniformly spaced samples from a target system, wherein the sample waveform is a time domain vector; applying FFT transforming the time domain vector into the frequency domain; analyzing the frequency domain response including calculating the phase response; and determining whether the sample waveform has spurs including comparing the phase response to a clean phase profile including determining that the phase response having a phase profile value outside a phase deviation tolerance has one or more spurs and determining that the phase response having a phase profile value inside the phase deviation tolerance has no spurs, wherein a spur indicates unaligned data having a delayed bit flip.
1 . A method comprising:
converting, by a target system, an analog signal to a digital signal, wherein the target system includes a digital to analog converter (DAC) and analog to digital converter (ADC) pair;
by program instructions on a computing device,
acquiring, from the digital signal, a sample waveform including a set of discrete uniformly spaced samples from the target system, wherein the sample waveform is a time domain vector;
applying FFT transforming the time domain vector into a frequency domain;
analyzing the frequency domain response including calculating a phase response; and
determining, based on comparing the phase response to a previously known clean phase profile without spurs, whether the sample waveform has spurs, including
determining that the sample waveform has one or more spurs based on a
determination that a phase profile value of the phase response is outside a phase deviation tolerance, wherein a spur indicates unaligned data having a delayed bit flip.
2 . The method of claim 1 , wherein determining whether the sample waveform has spurs includes:
determining that the sample waveform has no spurs when the phase profile value of the phase response is inside the phase deviation tolerance.
3 . The method of claim 1 , wherein the DAC and ADC pair in the target system are in a loopback connection.
4 . The method of claim 3 , wherein the sample waveform is acquired from an output of the DAC, and wherein a signal associated with the known clean phase profile without spurs is different from the digital signal associated with the phase response.
5 . The method of claim 3 , wherein the sample waveform is acquired from an output of the ADC.
6 . The method of claim 1 , wherein the sample waveform is acquired from an output of the DAC.
7 . An apparatus comprising:
a target system configured to carry out converting an analog signal to a digital signal, wherein the target system includes a digital to analog converter (DAC) and analog to digital converter (ADC) pair;
a computer processor; and
a computer memory operatively coupled to the computer processor, the computer memory having computer program instructions that, when executed by the computer processor, perform:
acquiring a sample waveform from the target system, including sampling the digital signal in a set of discrete, periodic, uniformly spaced samples as a time domain vector;
applying FFT transforming the time domain vector into a frequency domain;
analyzing the frequency domain response including calculating a phase response; and
determining, based on comparing the phase response to a previously known clean phase profile without spurs, whether the sample waveform has spurs, including determining that the sample waveform has one or more spurs based on a determination that a phase profile value of the phase response is outside a phase deviation tolerance, wherein a spur indicates unaligned data having a delayed bit flip.
8 . The apparatus of claim 7 , wherein determining whether the sample waveform has spurs includes:
determining that the sample waveform has no spurs when the phase profile value of the phase response is inside the phase deviation tolerance.
9 . The apparatus of claim 7 , wherein the DAC and ADC pair in the target system are in a loopback connection.
10 . The apparatus of claim 9 , wherein the sample waveform is acquired from an output of the DAC.
11 . The apparatus of claim 9 , wherein the sample waveform is acquired from an output of the ADC.
12 . The apparatus of claim 7 , wherein a signal associated with the known clean phase profile without spurs is different from the digital signal associated with the phase response.
13 . A computer program product including a non-transitory computer readable medium, the computer program product comprising computer program instructions that, when executed, cause a target system to carry out converting an analog signal to a digital signal, wherein the target system includes a digital to analog converter (DAC) and analog to digital converter (ADC) pair;
wherein the computer program instructions, when executed, further cause a computer to carry out:
acquiring a sample waveform of the digital signal including a set of discrete uniformly spaced samples from the target system, wherein the sample waveform is a time domain vector;
applying FFT transforming the time domain vector into a frequency domain; analyzing the frequency domain response including calculating a phase response; and
determining, based on comparing the phase response to a previously known clean phase profile without spurs, whether the sample waveform has spurs, including determining that the sample waveform has one or more spurs based on a determination that a phase profile value of the phase response is outside a phase deviation tolerance, wherein a spur indicates unaligned data having a delayed bit flip.
14 . The computer program product of claim 13 , wherein determining whether the sample waveform has spurs includes:
determining that the sample waveform has no spurs when the phase profile value of the phase response is inside the phase deviation tolerance.
15 . The computer program product of claim 13 , wherein the DAC and ADC pair in the target system are in a loopback connection.
16 . The computer program product of claim 15 , wherein the sample waveform is acquired from an output of the ADC.
17 . The computer program product of claim 13 , wherein the sample waveform is acquired from an output of the DAC.
18 . The computer program product of claim 13 , wherein a signal associated with the known clean phase profile without spurs is different from the digital signal associated with the phase response.