Signal analysis apparatus, control circuit, storage medium, and signal analysis method
A signal analysis apparatus includes: a reception unit outputting sampling sequences obtained by adding different delay times and sampling each signal at a sampling rate lower than a Nyquist rate; a time-frequency conversion unit converting each sampling sequence to a frequency domain signal; a signal processing unit collectively performing phase compensation processing and processing for canceling phase rotation between the sampling sequences; a frequency estimation unit estimating frequency of the target signal by determining a sub-Nyquist zone in which the target signal has been folded; a frequency selection unit selecting a frequency group with a higher estimated spectrum amplitude value based on a sum of values for each sub-Nyquist zone, the values being obtained by multiplication of the sampling sequences by the corresponding coefficients; and a separation unit performing separation processing for separation of an error in the target signal by using the frequency group selected.
1 . A signal analysis apparatus comprising:
reception circuitry to output a plurality of sampling sequences obtained by adding, to respective signals obtained by branching a target signal into a plurality of branches, different delay times and by sampling each of the signals at a sampling rate lower than a Nyquist rate;
time-frequency conversion circuitry to convert each of the plurality of sampling sequences from a time domain signal to a frequency domain signal;
signal processing circuitry to collectively perform phase compensation processing and processing for multiplying the sampling sequences by coefficients that cancel phase rotation caused by delay time differences between the sampling sequences, the phase compensation processing corresponding to sub-Nyquist zones of each of the sampling sequences converted into a frequency domain signal;
frequency estimation circuitry to estimate a frequency of the target signal by determining a sub-Nyquist zone in which the target signal has been folded;
frequency selection circuitry to select a frequency group with a higher estimated spectrum amplitude value based on a sum of values for each of the sub-Nyquist zones, the values being obtained by multiplication of the sampling sequences by the corresponding coefficients; and
separation circuitry to perform separation processing for separation of at least one of a cause of an error or an error portion in the target signal by using the frequency group selected by the frequency selection circuitry.
2 . The signal analysis apparatus according to claim 1 , further comprising:
a controller to handle the error based on separation information that is a result of the separation processing.
3 . The signal analysis apparatus according to claim 2 , wherein
the controller includes a phase compensation coefficient adjustment circuitry to adjust the coefficients based on the separation information.
4 . The signal analysis apparatus according to claim 2 , wherein
the controller includes a delay time difference adjustment circuitry to adjust the delay times to be added by the reception circuitry, based on the separation information.
5 . The signal analysis apparatus according to claim 2 , wherein based on the separation information, the controller takes measures including at least one of resetting, restarting, rewriting, or disconnection of at least one of a delay time addition circuit included in the reception circuitry and a control circuit for the delay time addition circuit, an analog-to-digital conversion circuit included in the reception circuitry, a time-frequency conversion circuit included in the time-frequency conversion circuitry, or a complex multiplier included in the signal processing circuitry.
6 . The signal analysis apparatus according to claim 1 , wherein
the frequency estimation circuitry stores interim information including at least one of the values obtained by multiplication of the sampling sequences by the corresponding coefficients or a sum of the values, and
the frequency selection circuitry and the separation circuitry reuse the interim information.
7 . The signal analysis apparatus according to claim 1 , wherein as a result of performing frequency estimation for all combinations of branches drawn from the plurality of branches, a number of the drawn branches being one less than a number of the plurality of branches, the separation circuitry determines that a branch not included in a combination that maximizes the estimated spectrum amplitude value obtained as a result of the frequency estimation is a branch in which an error has occurred.
8 . The signal analysis apparatus according to claim 1 , wherein the separation circuitry determines that a branch with a largest deviation from an average complex amplitude value of the plurality of branches is a branch in which an error has occurred, the branch with the largest deviation being any of the plurality of branches.
9 . The signal analysis apparatus according to claim 3 , wherein the phase compensation coefficient adjustment circuitry performs frequency estimation for the plurality of branches, and adjusts the coefficients such that a deviation from an average complex amplitude value is reduced for each of the branches.
10 . The signal analysis apparatus according to claim 4 , wherein the delay time difference adjustment circuitry performs frequency estimation for the plurality of branches, and adjusts the delay times such that a deviation from an average complex amplitude value is reduced for each of the branches.
11 . The signal analysis apparatus according to claim 1 , further comprising reference signal addition circuitry to add a reference signal to the target signal before the target signal is branched into the plurality of branches.
12 . The signal analysis apparatus according to claim 1 , wherein the reception circuitry adds the delay times by a track-and-hold circuit.
13 . A control circuit for controlling a signal analysis apparatus that outputs a plurality of sampling sequences obtained by adding, to respective signals obtained by branching a target signal into a plurality of branches, different delay times and by sampling each of the signals at a sampling rate lower than a Nyquist rate, converts each of the plurality of sampling sequences from a time domain signal to a frequency domain signal, collectively performs phase compensation processing and processing for multiplying the sampling sequences by coefficients that cancel phase rotation caused by delay time differences between the sampling sequences, the phase compensation processing corresponding to sub-Nyquist zones of each of the sampling sequences converted into a frequency domain signal, and estimates a frequency of the target signal by determining a sub-Nyquist zone in which the target signal has been folded, the control circuit causing the signal analysis apparatus to perform:
selecting a frequency group with a higher estimated spectrum amplitude value based on a sum of values for each of the sub-Nyquist zones, the values being obtained by multiplication of the sampling sequences by the corresponding coefficients; and
performing separation processing for separation of at least one of a cause of an error or an error portion in the target signal by using the selected frequency group.
14 . A non-transitory storage medium with a program stored thereon, the program being for controlling a signal analysis apparatus that outputs a plurality of sampling sequences obtained by adding, to respective signals obtained by branching a target signal into a plurality of branches, different delay times and by sampling each of the signals at a sampling rate lower than a Nyquist rate, converts each of the plurality of sampling sequences from a time domain signal to a frequency domain signal, collectively performs phase compensation processing and processing for multiplying the sampling sequences by coefficients that cancel phase rotation caused by delay time differences between the sampling sequences, the phase compensation processing corresponding to sub-Nyquist zones of each of the sampling sequences converted into a frequency domain signal, and estimates a frequency of the target signal by determining a sub-Nyquist zone in which the target signal has been folded, the program causing the signal analysis apparatus to perform:
selecting a frequency group with a higher estimated spectrum amplitude value based on a sum of values for each of the sub-Nyquist zones, the values being obtained by multiplication of the sampling sequences by the corresponding coefficients; and
performing separation processing for separation of at least one of a cause of an error or an error portion in the target signal by using the selected frequency group.
15 . A signal analysis method comprising:
outputting a plurality of sampling sequences obtained by adding, to respective signals obtained by branching a target signal into a plurality of branches, different delay times and by sampling each of the signals at a sampling rate lower than a Nyquist rate;
converting each of the plurality of sampling sequences from a time domain signal to a frequency domain signal;
collectively performing phase compensation processing and processing for multiplying the sampling sequences by coefficients that cancel phase rotation caused by delay time differences between the sampling sequences, the phase compensation processing corresponding to sub-Nyquist zones of each of the sampling sequences converted into a frequency domain signal;
estimating a frequency of the target signal by determining a sub-Nyquist zone in which the target signal has been folded;
selecting a frequency group with a higher estimated spectrum amplitude value based on a sum of values for each of the sub-Nyquist zones, the values being obtained by multiplication of the sampling sequences by the corresponding coefficients; and
performing separation processing for separation of at least one of a cause of an error or an error portion in the target signal by using the selected frequency group.