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Method and apparatus for noise burst detection in signal processors
| Details |
Inventors: Hsieh, Chau-Kai; Chen, Hsin-Mei;
Assignee: Windbond Electronics Corp. (Hsinchu, TW)
Primary Examiner: Le; Amanda T.
Assistant Examiner:
Attorney, Agent or Firm: Finnegan, Henderson, Farabow, Garrett & Dunner, L.L.P.
A method and apparatus for noise burst detection in a signal processor is provided. The method and apparatus is based on the zero-crossing rate (ZCR) of the received signal, which is defined as the number of times the magnitude of the received signal becomes zero during a specific counting period, to determine whether the received signal is a noise or a normal signal. The received signal is sampled at a specified sampling rate. Whether the signal waveform undergoes a zero-crossing is determined by comparing the polarity of the current sampled magnitude with that of the previous one. If the polarities are different, it indicates that the signal waveform has undergone a zero-crossing during the current sampling period; otherwise, it indicates that the signal waveform has not undergone a zero-crossing. The count of zero-crossing during each counting period is compared with a preset threshold value. If the count is larger than the threshold value, it indicates the received signal is noise; otherwise, the received signal is a normal signal. |
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DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The method and apparatus of the invention for noise burst detection is based on the zero-crossing rate (ZCR) of the received signal.
The zero-crossing rate is defined as the number of times the magnitude of the received signal becomes zero during a specific period of time (hereinafter referred to as a counting period).
In accordance with the invention, the received signal is sampled at a specific sampling rate.
Whether the signal waveform undergoes a zero-crossing can be determined by comparing the polarity of the current sampled magnitude with that of the previous one.
If the polarities are different (one is positive and the other is minus), it indicates that the signal waveform has undergone a zero-crossing during the sampling period; otherwise, if the polarities are the same (both are positive or both are negative), it indicates that the signal waveform has not undergone a zero-crossing during the sampling period.
The concept of using the zero-crossing rate for noise burst detection is further depicted in greater detail in the following with reference to FIG.
1.
Referring to FIG.
1, a graph is used to depict the zero-crossing rate of a received signal.
The zero-crossing rate is defined as the number of times the signal waveform during has crossed the zero axis during a given counting period T.
Assume that T=10 ms (millisecond).
It can be seen from the graph that, during the counting period T, the number of times the signal waveform shown here becomes zero in magnitude is eight, as indicated by the "x" marks in FIG.
1.
Therefore, the zero-crossing rate ZCR of the received signal is as follows: ZCR=8 (times) / 10 ms=800 Hz (hertz).
In accordance with the invention, whether the signal waveform undergoes a zero-crossing is determined by comparing the polarity of the current sampled magnitude with that of the previous one.
If the polarities are different (one is positive and the other is minus), it indicates that the signal waveform has undergone a zero-crossing during the current sampling period
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