Frequency spectrum analyzing apparatus and transmitter characteristics measuring apparatus using the same

摘要

In a frequency spectrum analyzing apparatus which utilizes a DFT (discrete Fourier transform) filter bank, and can detect the peak value of the amplitude of an input signal, a time sequence signal generation circuit samples an input signal to convert it into a time sequence signal. A memory stores the time sequence signal. The DFT filter bank receives a time sequence signal read out from the memory by a control device, and performs DFT filter bank processing corresponding to a plurality of desired frequencies while shifting a window function by a predetermined number of sample point units. An absolute value calculation unit calculates absolute values in units of outputs from the DFT filter bank. A peak value detection unit detects peak values in units of outputs from the absolute value calculation unit. A display device displays the frequency spectrum on the basis of these peak values.