Research of High Precision Frequency Measure Algorithm Based on LabVIEW

In order to get the frequency (f) of an intermediate frequency (IF) signal, during the measure of frequency modulated continuous wave (FMCW) radar, we often use the fast Fourier transform (FFT) for transforming time signal to discrete frequency signal, then we can get the frequency by the position of the frequency spectrum´s peak. While the data was collecting, the collecting circuit does always not synchronize with the signal, what we collect is the truncated discrete signal, When we apply the discrete Fourier transform on this kind of signal, we can only get some discrete value of the continuous spectrum, the peak of the spectrum always has a departure with the envelope of the spectrum by using the not integral period sampling, and this causes the leak error. For improving the precision of the frequency measure, this paper presents a frequency measure algorithm by integrating automatic adjusting the sampling parameter and spectrum correction. By using this algorithm, we first adjust the sampling number based on current frequency for meeting the request of the integral period sampling, afterwards, the spectrum is further corrected by using the balancing of the energy rules, so we can get a more precise measure.