Frequency discrimination based on the different number of peaks in envelope detection of two‐tone continuous‐wave radar systems

This study proposed a method for distinguishing the baseband signal for each frequency in two‐tone radar systems using the difference in the number of peaks of the envelope detected signal. The proposed method is based on the characteristic that the baseband signal for each frequency exhibits a different number of peaks, depending on the operating frequency, at a fixed sampling frequency in data acquisition. The phase difference between the transmitting and receiving signals for each frequency can be obtained using envelope detection of the baseband signals in two‐tone radar systems, and the proposed method can effectively match the phase difference and operating frequency without using additional controls and synchronization. This simplifies the procedure to estimate the absolute range up to the maximum unambiguous range, corresponding to a phase difference of 2π. Measurement results demonstrate that the absolute range, using a two‐tone radar with a frequency spacing of 150 MHz, can detect the distance with an accuracy of 97.8% up to the maximum unambiguous range using the proposed method.