Miscellaneous active electrical nonlinear devices – circuits – and – Specific signal discriminating without subsequent control – By amplitude
Reexamination Certificate
1999-01-13
2001-02-13
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific signal discriminating without subsequent control
By amplitude
C327S058000
Reexamination Certificate
active
06188250
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an apparatus for detecting peaks of positive and negative polarity in an information signal, the apparatus comprising first peak detector means for detecting the positive peaks in the information signal and second peak detector means for detecting the negative peaks in the information signal.
An apparatus as defined above is known from U.S. Pat. No. 4,736,163 (PHN 11.112). The known apparatus is meant for detecting scratches in an audio signal so as to mute such scratches.
SUMMARY OF THE INVENTION
The invention aims at providing an apparatus for detecting peaks that is suitable for use in a reproduction apparatus for reproducing information from a hard disk. Therefore, in accordance with the invention, the apparatus for detecting peaks of a first polarity, such as a positive polarity, in an information signal, the comprises first peak detector means for detecting the peaks of said first polarity in the information signal,
the first peak detector means comprising a first capacitor, the first peak detector means having an attack time for charging the first capacitor and a decay time for discharging the first capacitor, the attack time being shorter than the decay time. The first peak detector means has an output for generating an output signal having a first output signal value when the first peak detector means is in a charging state for charging the first capacitor and has a second output value when the first peak detector means is in a non-charging state. The first peak detector means is adapted to discharge the first capacitor to a first level and to further maintain the first capacitor charged at said first level during time intervals that the information signal level is below said first level, said first level being larger than the zero signal level and the first peak detector means further being in a charging state when the information signal level exceeds the charging level of the first capacitor. For further detecting peaks of a second polarity, such as a negative polarity, in said information signal, the apparatus further comprises second peak detector means for detecting the peaks of said second polarity in the information signal
the second peak detector means comprising a second capacitor. The second peak detector means has an attack time for charging the second capacitor and a decay time for discharging the second capacitor. The attack time being smaller than the decay time, the second peak detector means has an output for generating an output signal having a third output signal value when the second peak detector means is in a charging state for charging the second capacitor and having a fourth output value when the second peak detector means is in a non-charging state, the second peak detector means being adapted to discharge the second capacitor to a second level and to further maintain the second capacitor charged at said second level during time intervals that the absolute value of said information signal level is below said second level, said second level being larger than the zero signal level and the second peak detector means further being in the charging state when the absolute value of said information signal level exceeds the charging level of the second capacitor.
The invention is based on the recognition to provide a peak detection apparatus that is robust, so that it does not react to small spurious peaks and further locates the exact position in time where the maximum peak value of the peaks occur. The robustness has been realized by maintaining the capacitor in the peak detector means charged at a certain threshold level which is greater than zero. Further, the change of the output signal of the peak detectors from the first to the second output value (in the case of the first detector means) is an indication of the location in time of the maximum of the peak.
REFERENCES:
patent: 4736163 (1988-04-01), Berkhout et al.
patent: 5357150 (1994-10-01), Jaquette
patent: 5428307 (1995-06-01), Dendinger
patent: 5469090 (1995-11-01), Narahara
patent: 97-2016596 (1998-03-01), None
Lugthart Mareel L.
Ramalho Joao N. V. L.
Voorman Johannes O.
Franzblau Bernard
Tran Toan
U.S. Philips Corporation
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