Amplitude discriminator with an adaptive threshold

Claim 2

A signal amplitude discriminator comprising: input means at which input signals of varying amplitudes are successively applied; peak detector responsive to said succession of input signals for providing a peak detector output having an amplitude which is a function of the peak amplitudes of said input signals and a selected rate of discharge; signal amplitude comparing means for providing an output signal oF a first level when the amplitude of an input signal is not less than the amplitude of a selected percentage of the amplitude of the peak detector output at the time said input signal is received by said signal amplitude comparing means; and hold means responsive to said signal amplitude comparing means output signal of said first level for holding the percentage of the amplitude of the peak detector output which is supplied to said signal amplitude comparing means constant, during the comparison duration with the input signal.

Claim 3

The signal amplitude discriminator as defined in claim 1 further including rectifying means disposed between said hold means and said signal amplitude comparing means for inhibiting other than amplitudes of a selected polarity from reaching said signal amplitude comparing means from said hold means.

Claim 4

A signal amplitude discriminator comprising: input means at which input signals of varying amplitudes are successively applied; peak detector responsive to said succession of input signals for providing a peak detector output having an amplitude which is a function of the peak amplitudes of said input signals and a selected rate of discharge; signal amplitude comparing means for providing an output signal of a first level when the amplitude of an input signal is not less than the amplitude of a selected percentage of the amplitude of the peak detector output at the time said input signal is received by said signal amplitude comparing means; said peak detector charging up to a potential substantially equal to the peak amplitude of a first of said input signals with said peak detector discharging at said selected rate and charging up the peak amplitude of any subsequent signal only if the peak amplitude of the subsequent input signal exceeds the amplitude of said peak detector output; and hold means responsive to said signal amplitude comparing means output signal of said first level for holding the percentage of the amplitude of the peak detector output which is supplied to said signal amplitude comparing means constant during the comparison duration with the input signal and further including rectifying means disposed between said hold means and said signal amplitude comparing means for inhibiting other than amplitudes of a selected polarity from reaching said signal amplitude comparing means from said hold means.

Claim 5

A signal amplitude discriminator comprising: input means at which input signals of varying amplitudes are successively applied; peak detector responsive to said succession of input signals for providing a peak detector output having an amplitude which is a function of the peak amplitudes of said input signals and a selected rate of discharge; signal amplitude comparing means for providing an output signal of a first level when the amplitude of an input signal is not less than the amplitude of a selected percentage of the amplitude of the peak detector output at the time said input signal is received by said signal amplitude comparing means; said peak detector charging up to a potential substantially equal to the peak amplitude of a first of said input signals with said peak detector discharging at said selected rate and charging up the peak amplitude of any subsequent signal only if the peak amplitude of the subsequent input signal exceeds the amplitude of said peak detector output; and hold means responsive to said signal amplitude comparing means output signal of said first level for holding the percentage of the amplitude of the peak detector output which is supplied to said signal amplitude comparing means constant during the comparison duration with the input signal and further including rectifying means disposed between said hold means and said signal amplitude comparing means for inhibiting other than amplitudes of a selected polarity from reaching said signal amplitude comparing means from said hold means.

Claim 6

A first input terminal at which input signals are applied; a second input terminal at a fixedly selected threshold level; first circuit means coupled to said first and second input terminals for providing a first signal for each input signal only when the input signal amplitude at said first input terminal exceeds said threshold level, the amplitude of said first signal being a function of the amplitudes of the input signal and said selected threshold level; peak detector means responsive to each first signal for providing a peak detector output whose amplitude is a function of the peak amplitudes of said first signals and a preselected fixed discharge rate of said peak detector; and signal amplitude comparing means coupled to said first and second input terminals and to which a selected percentage of the amplitude of the peak detector output is applied, for providing an output signal of a first level only when the amplitude of an input signal at said first terminal is not less than the sum of the amplitudes of said selected percentage of the amplitude of the peak detector output and the threshold level at said second input terminal.

Claim 7

A first input terminal at which input signals are applied; a second input terminal at a fixedly selected threshold level; first circuit means coupled to said first and second input terminals for providing a first signal for each input signal only when the input signal amplitude at said first input terminal exceeds said threshold level, the amplitude of said first signal being a function of the amplitudes of the input signal and said selected threshold level; peak detector means responsive to each first signal for providing a peak detector output whose amplitude is a function of the peak amplitudes of said first signals and a preselected fixed discharge rate of said peak detector; and signal amplitude comparing means coupled to said first and second input terminals and to which a selected percentage of the amplitude of the peak detector output is applied, for providing an output signal of a first level only when the amplitude of an input signal at said first terminal is not less than the sum of the amplitudes of said selected percentage of the amplitude of the peak detector output and the threshold level at said second input terminal.

Claim 8

The signal amplitude discriminator as defined in claim 4 further including hold means responsive to said signal amplitude comparing means output signal of said first level for holding the percentage of the amplitude of the peak detector output which is supplied to said signal amplitude comparing means constant during the comparison duration with the input signal.

Claim 9

The signal amplitude discriminator as defined in claim 5 further incLuding rectifying means disposed between said hold means and said signal amplitude comparing means for inhibiting other than amplitudes of a selected polarity from reaching said signal amplitude comparing means from said hold means.

Claim 10

The signal amplitude discriminator as defined in claim 4 wherein said peak detector charges up to a potential substantially equal to the peak amplitude of a first of said input signals with said peak detector discharging at said selected rate and charging up to the peak amplitude of any subsequent input signal only if the peak amplitude of the subsequent input signal exceeds the amplitude of peak detector output.

Claim 11

The signal amplitude discriminator as defined in claim 6 further including hold means responsive to said signal amplitude comparing means output signal of said first level for holding the percentage of the amplitude of the peak detector output which is supplied to said signal amplitude comparing means constant during the comparison duration with the input signal and further including rectifying means disposed between said hold means and said signal amplitude comparing means for inhibiting other than amplitudes of a selected polarity from reaching said signal amplitude comparing means from said hold means.