Frequency measuring method using AD converters with different sampling frequencies

For an AD converter, it is necessary to convert the analog signal into a digital one with a sampling frequency of 2 times the maximum Doppler frequency. In lightwave Doppler radar, the Doppler frequency of a target is several hundred MHz, so a high speed AD converter is needed. But its cost is very high, making the system cost higher so that high speed devices which meet the sampling frequency requirement become necessary for peripheral circuits. This paper proposes a method of measuring the Doppler frequency that is higher than the sampling frequency using low speed AD converters