Adaptive filter wherein opposite conductivity transistors are operative in response to signals in excess of predetermined amplitude

Claim 2

An adaptive filter circuit including in combination; filter means having an input terminal and an Output terminal, said filter means having a first predetermined attenuation characteristic for attenuating and filtering signals coupled therethrough from said input terminal to said output terminal, first and second opposite conductivity transistors coupled together and to said input terminal and a first terminal of said filter means, said first transistor operative in response to portions of said signals coupled to said filter means input terminal having a first polarity and in excess of a predetermined amplitude to conduct, said second transistor operative in response to portions of said signals having a second polarity and in excess of said predetermined amplitude to conduct, said first and second transistor conduction being operative to change the first predetermined attenuation characteristic of signals coupled through said filter means from said input terminal to said output terminal to a second predetermined attenuation characteristic.

Claim 3

The adaptive filter of claim 1 wherein said first and second transistors further include base, emitter and collector electrodes, said base electrodes being coupled together and to the input terminal of said filter means, said emitter electrodes being coupled together and to the first terminal of said filter means.

Claim 4

The adaptive filter of claim 2 wherein said signals coupled thereto are alternating current signals, each of said transistors when conductive coupling the base electrode to the emitter electrode for coupling said input terminal to said first terminal to change the attenuation characteristic of said filter.

Claim 5

The adaptive filter of claim 3 wherein said filter means includes resistance means and reactance means coupled together and to said input and first terminals, said filter means having a first filter resistance and a first attenuation characteristic when said transistors are non-conductive, and a second filter resistance and second attenuation characteristic when said transistors are conductive.

Claim 6

The adaptive filter of claim 4 wherein said filter means includes, first resistance means having a first end coupled to said input terminal and a second end, second resistance means having a first end coupled to said first terminal and a second end, third resistance means coupled between said first and second resistance means second ends, and fourth resistance means and first reactance means series connected and coupled between said second resistance means second end and a ground potential, said transistor means when conductive being operative to couple said input and first terminals together to provide said second filter resistance and second attenuation characteristic.

Claim 7

The filter of claim 5 wherein said first resistance means is a resistor and said second resistance means is a resistor, said first resistance means having substantially greater resistance than said second resistance means.

Claim 8

The filter of claim 6 wherein said output terminal is coupled to said first resistance means second end.

Claim 9

An adaptive filter circuit for filtering and attenuating signals coupled thereto including in combination; first and second transistors of opposite conductivity types and each having base, emitter and collector electrodes, said base electrodes being coupled together and said emitter electrodes being coupled together, said first transistor operative in response to portions of said signals coupled to said filter having a first polarity and in excess of a predetermined amplitude to conduct, said second transistor operative in response to portions of said signals having a second polarity and in excess of said predetermined amplitude to conduct, filter means having an input terminal and an output terminal and including resistance means and reactance means coupled together and to said base electrodes and emitter electrodes, said filter means having a first filter resistance and first attenuation characteristic of signals coupled therethrough from said input terminal to said output terminal when said transistors are non-conductive, and a second filter resistance and second attenuation characteristic of signals coupled therethrough from said input terminal to said output terminal when said transistors are conductive.

Claim 10

An adaptive filter circuit for filtering and attenuating signals coupled thereto including in combination; first and second transistors of opposite conductivity types and each having base, emitter and collector electrodes, said base electrodes being coupled together and said emitter electrodes being coupled together, said first transistor operative in response to portions of said signals coupled to said filter having a first polarity and in excess of a predetermined amplitude to conduct, said second transistor operative in response to portions of said signals having a second polarity and in excess of said predetermined amplitude to conduct, filter means having an input terminal and an output terminal and including resistance means and reactance means coupled together and to said base electrodes and emitter electrodes, said filter means having a first filter resistance and first attenuation characteristic of signals coupled therethrough from said input terminal to said output terminal when said transistors are non-conductive, and a second filter resistance and second attenuation characteristic of signals coupled therethrough from said input terminal to said output terminal when said transistors are conductive.