Method and system for performing real-time spectral analysis of non-stationary signal
First Claim
1. A method of performing real-time spectral analysis of a non-stationary signal by a spectrum analyzer, the method comprising:
- sampling the non-stationary signal using an analog to digital converter, with a short observation window having a length short enough to approximate a stationary signal, to provide an initial set of sampled data;
buffering, in one or more buffers, the initial set of sampled data to obtain a plurality of buffered sets of sampled data, the plurality of buffered sets of sampled data emulating data sampled using a longer observation window based on the non-stationary signal sampled through the short observation window, improving overall spectral resolution of the non-stationary signal;
filtering the initial set of sampled data and the plurality of buffered sets of sampled data, using a corresponding plurality of filter responses, to obtain a plurality of filtered sets of sampled data;
performing a chirp-z-transform (CZT) of the plurality of filtered sets of sampled data to provide a set of discrete Fourier transforms (DFT) coefficients; and
reconstructing a total signal spectrum of the non-stationary signal using the set of DFT coefficients; and
displaying the reconstructed total signal spectrum of the non-stationary input signal on a spectrum analyzer display in real-time.
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Abstract
A method is provided for performing real-time spectral analysis of a non-stationary signal. The method includes sampling the non-stationary signal, using an observation window having a length short enough to approximate a stationary signal, to provide an initial set of sampled data, buffering the initial set of sampled data to obtain multiple buffered sets of sampled data, filtering the initial set of sampled data and the buffered sets of sampled data, using corresponding filter responses, to obtain multiple filtered sets of sampled data, and performing a chirp-z-transform (CZT) of the filtered sets of sampled data to provide a set of discrete Fourier transforms (DFT) coefficients. A total signal spectrum of the non-stationary signal is reconstructed using the set of DFT coefficients.
24 Citations
20 Claims
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1. A method of performing real-time spectral analysis of a non-stationary signal by a spectrum analyzer, the method comprising:
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sampling the non-stationary signal using an analog to digital converter, with a short observation window having a length short enough to approximate a stationary signal, to provide an initial set of sampled data; buffering, in one or more buffers, the initial set of sampled data to obtain a plurality of buffered sets of sampled data, the plurality of buffered sets of sampled data emulating data sampled using a longer observation window based on the non-stationary signal sampled through the short observation window, improving overall spectral resolution of the non-stationary signal; filtering the initial set of sampled data and the plurality of buffered sets of sampled data, using a corresponding plurality of filter responses, to obtain a plurality of filtered sets of sampled data; performing a chirp-z-transform (CZT) of the plurality of filtered sets of sampled data to provide a set of discrete Fourier transforms (DFT) coefficients; and reconstructing a total signal spectrum of the non-stationary signal using the set of DFT coefficients; and displaying the reconstructed total signal spectrum of the non-stationary input signal on a spectrum analyzer display in real-time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A spectrum analyzer comprising:
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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. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A spectral analyzer comprising:
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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. - View Dependent Claims (19, 20)
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Specification