Method and system for performing real-time spectral analysis of non-stationary signal

A spectrum analyzer comprising:

• an analog to digital converter (ADC) for receiving and sampling a non-stationary signal from a device under test (DUT), using a short observation window to approximate a stationary signal, to provide sampled signals;
• a processing device programmed to:
• filter the sampled signals using a first polyphase filter to provide first filtered sampled signals;
• delay the sampled signals to provide delayed sampled signals;
• filter the delayed sampled signals using a second polyphase filter to provide second filtered sampled signals;
• perform chirp-z-transforms (CZTs) of the first and second filtered sampled signals to provide discrete Fourier transforms (DFT) coefficients;
• and
• reconstruct a total signal spectrum of the non-stationary signal using the DFT coefficients;
• and
• a display configured to display the reconstructed total signal spectrum of the input signal in real-time.

A spectral analyzer comprising:

• an analog to digital converter (ADC) configured to receive and sample a non-stationary input signal from a device under test (DUT), and to provide first sampled data, wherein the sampling is performed using a short observation window having a length short enough to approximate a stationary signal;
• a filter bank comprising a first polyphase filter configured to filter the first sampled data to provide first filtered sampled data, a second polyphase filter configured to filter second sampled data to provide second filtered sampled data, and a third polyphase filter configured to filter third sampled data to provide third filtered sampled data;
• a first buffer configured to delay the first sampled data by a first delay to provide the second sampled data;
• a second buffer configured to delay the second filtered sampled data by a second delay to provide the third sampled data;
• an adder configured to add the first, second and third filtered sampled data to provide summed filtered data;
• a chirp-z-transform (CZT) circuit configured to perform a CZT on the summed filtered data to provide frequency domain samples corresponding to the input signal, the frequency domain samples enabling reconstruction of a total signal spectrum of the input signal;
• and
• a display configured to display the reconstructed total signal spectrum of the input signal in real-time.