Methods and apparatus for reducing the effect of impulse noise on receivers
First Claim
1. A method of detecting impulse noise in a signal including a plurality of symbols, the method comprising the steps of:
- generating an error estimate by comparing a symbol in the signal to a target value;
comparing the error estimate to an impulse noise threshold; and
generating an impulse noise signal when the error estimate exceeds the impulse noise threshold.
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Accused Products
Abstract
Methods and apparatus for detecting the presence of impulse noise in a signal representing digital data and for performing a limiting or blanking operation in a receiver in response thereto are disclosed. In accordance with the present invention, to detect the presence of impulse noise, in one embodiment, the instantaneous sliced error energy for each received symbol is estimated and compared to either a predetermined threshold level indicative of impulse noise or to an adaptive impulse noise threshold level. In an adaptive impulse noise threshold embodiment, an adaptive impulse noise threshold value is generated by averaging the instantaneous sliced error energy values over a period of many symbols and by then applying a preselected gain to the averaged sliced error energy value to obtain an impulse noise threshold value. When impulse noise is detected a signal is asserted to indicate the detection and presence of the impulse noise and carrier recovery phase error correction operations and other decision dependent operations blanked or left unchanged until the impulse noise is no longer detected or for a preselected period of time after impulse noise has been detected.
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Citations
25 Claims
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1. A method of detecting impulse noise in a signal including a plurality of symbols, the method comprising the steps of:
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generating an error estimate by comparing a symbol in the signal to a target value; comparing the error estimate to an impulse noise threshold; and generating an impulse noise signal when the error estimate exceeds the impulse noise threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 24, 25)
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9. An impulse noise detection circuit, comprising:
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a slicer for receiving an amplitude modulated signal including baseband symbols and for generating target symbols; a sliced error estimation circuit coupled to the slicer for generating an instantaneous error energy signal as a function of the baseband and target symbols; a comparator coupled to the sliced error estimation circuit for comparing the instantaneous error energy signal to an impulse noise threshold, the comparator generating an impulse indicator signal indicative of the presence of impulse noise when the instantaneous error energy signal assumes a value that exceeds the impulse noise threshold. - View Dependent Claims (10, 11, 12, 13)
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14. An impulse noise detection circuit, comprising:
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a slicer for receiving baseband symbols and for generating target symbols; a sliced error estimation circuit coupled to the slicer for generating an instantaneous error energy signal as a function of the baseband and target symbols; a comparator coupled to the sliced error estimation circuit for comparing the instantaneous error energy signal to an impulse noise threshold, the comparator generating an impulse noise indicator signal indicative of the presence of impulse noise when the instantaneous error energy signal assumes a value that exceeds the impulse noise threshold; an averager coupled to the sliced error estimation circuit for generating an average error energy signal; means responsive to the impulse noise indicator signal for inputting either the instantaneous error energy signal or a signal representing a fixed number into the averager; and a multiplier coupled to the averager and the comparator for applying a gain greater than one to the average error energy signal to generate the impulse threshold. - View Dependent Claims (15)
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16. An apparatus for detecting impulse noise in a signal including a symbol, the apparatus comprising:
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error estimation means for generating an estimate of the error between a measured symbol value and a target symbol value; and comparison means for comparing the estimated error to an impulse noise threshold and for generating a signal indicative of the presence of impulse noise when the estimated error exceeds the impulse noise threshold. - View Dependent Claims (17, 18, 19)
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20. A method of detecting impulse noise in a signal which represents digital data, the method comprising the steps of:
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generating an estimate of an error between a measured signal value and one of a plurality of discrete signal target values; and comparing the estimated error to an impulse noise threshold to determine if the impulse noise threshold has been exceeded. - View Dependent Claims (21, 22, 23)
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Specification