Sampling apparatus, sampling method and recording medium

1. A sampling apparatus that samples a signal under measurement, comprising:

a sampling section that samples the signal under measurement at a plurality of sampling phases at non-uniform intervals for each sampling repetition cycle; and

an inverting section that cancels out a replica that is not an observation target, from among replicas in a sampling band of the signal under measurement and the replicas in the sampling band of a negative frequency component of the signal under measurement, by inverting a sign of a value of the signal under measurement sampled at at least one of the plurality of sampling phases.

2. The sampling apparatus according to claim 1 , further comprising a clock control section that generates a plurality of sampling clocks at a plurality of sampling phases at non-uniform intervals for each sampling repetition cycle, wherein

the sampling section samples the signal under measurement with each of the plurality of sampling clocks.

3. The sampling apparatus according to claim 1 , further comprising a plurality of delay circuits that delay the signal under measurement by delay amounts corresponding to the plurality of sampling phases, wherein

the sampling section samples the signal under measurement delayed by each of the plurality of delay circuits, according to a reference clock.

4. The sampling apparatus according to claim 1 , further comprising a setting section that sets the phases at which the signs of the values of the signal under measurement are inverted by the inverting section.

5. The sampling apparatus according to claim 4 , further comprising an input section that receives an observation band of the signal under measurement as input, wherein

the setting section sets whether the inverting section inverts the signs of the values of the signal under measurement sampled at each of the plurality of sampling phases, based on the observation band.

6. The sampling apparatus according to claim 4 , wherein

in order to cancel out the replica that is generated by shifting the signal under measurement or the negative frequency component by an integer multiple of a sampling repetition frequency, the setting section sets the inverting section to invert the sign of the value of the signal under measurement sampled at a second sampling phase and to not invert the sign of the value of the signal under measurement sampled at a first sampling phase, where the first sampling phase is set such that a time corresponding to said integer multiple of a phase difference becomes equal to an integer multiple of the sampling repetition cycle and the second sampling phase is different from the first sampling phase.

7. The sampling apparatus according to claim 1 , further comprising:

a Fourier transform section that Fourier transforms an output signal from the inverting section into the frequency domain;

an extracting section that extracts the replica that is an observation target in the frequency domain;

a frequency converting section that converts the signal under measurement into the frequency domain, based on the replica that is the observation target in the frequency domain; and

an inverse Fourier transform section that generates waveform data of the signal under measurement in the time domain by inverse Fourier transforming the signal under measurement converted into the frequency domain.

8. The sampling apparatus according to claim 2 , wherein

the sampling section includes a plurality of samplers that are disposed to correspond one-to-one with a plurality of sampling clocks, and that each sample the signal under measurement with the corresponding sampling clock.

9. The sampling apparatus according to claim 1 , wherein

the sampling section samples the signal under measurement at the plurality of sampling phases selected from among phases obtained by uniformly dividing the sampling repetition cycle into a number of cycles greater than a number of the sampling phases.

10. A method for sampling a signal under measurement with a sampling apparatus, the method comprising the steps of:

sampling, by a sampling section of the sampling apparatus, the signal under measurement at a plurality of sampling phases at non-uniform intervals for each sampling repetition cycle; and

canceling out, by an inverting section of the sampling apparatus, a replica that is not an observation target, from among the replicas in a sampling band of the signal under measurement and the replicas in the sampling band of a negative frequency component of the signal under measurement, by inverting a sign of a value of the signal under measurement sampled at at least one of the plurality of sampling phases.

11. A non-transitory recording medium storing thereon a program that, when performed by a computer, causes the computer to perform operations comprising:

sample a signal under measurement at a plurality of sampling phases at non-uniform intervals for each sampling repetition cycle; and

cancel out a replica that is not an observation target, from among the replicas in a sampling band of the signal under measurement and the replicas in the sampling band of a negative frequency component of the signal under measurement, by inverting a sign of a value of the signal under measurement sampled at at least one of the plurality of sampling phases.