CPC H04L 27/14 (2013.01) | 7 Claims |
1. A signal processing device for processing a frequency signal having a first frequency or a second frequency higher than the first frequency, comprising:
an acquisition circuit configured to acquire signal waveform data corresponding to the frequency signal;
a generation circuit configured to generate a sine wave and a cosine wave of demodulation waveform data having a demodulation frequency between the first frequency and the second frequency;
a first phase calculation circuit configured to calculate a first phase based on a multiplication result of the sine wave and the signal waveform data at a first time and a multiplication result of the cosine wave and the signal waveform data at the first time;
a second phase calculation circuit configured to calculate a second phase based on a multiplication result of the sine wave and the signal waveform data at a second time advanced from the first time by a specified time interval less than one cycle of the demodulation frequency and a multiplication result of the cosine wave and the signal waveform data at the second time; and
a conversion circuit configured to output a signal value of the acquired frequency signal, based on comparison between the first phase and the second phase.
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