Noise cancellation system for active headsets

A noise cancellation system, comprising:

• an active headset, having at least a first earphone, a first microphone, and a first gain control element for controlling the gain of the first microphone;
• a noise cancellation circuit which is contained within the active headset;
• and
• a connection means having four contacts for connecting the noise cancellation circuit to the active headset, wherein the four contacts are used to power the noise cancellation circuit contained within the active headset.

A noise cancellation system having compatibility with existing socket configurations, comprising:

• an active headset, having at least a first earphone, a first microphone, and a first gain control element for controlling a gain of the first microphone;
• a noise cancellation circuit, at least a portion of which is contained within the active headset;
• a plurality of electrical connections for connecting the active headset to the noise cancellation circuit wherein the electrical connections are compatible with standard audio equipment;
• and
• a powering means, remote from the active headset, that provides power to the portion of the noise cancellation circuit that is contained within the active headset.

A noise cancellation system having compatibility with existing socket configurations, comprising:

• an active headset, having at least a first earphone, a first microphone, and a gain control element for controlling a gain of the first microphone;
• a noise cancellation circuit, a portion of which is contained within an external device;
• a plurality of electrical connections for connecting the active headset to the noise cancellation circuit;
• and
• a powering means that provides power to the portion of the noise cancellation circuit that is contained within the external device.

A noise cancellation system having compatibility with existing socket configurations, comprising:

• an active headset, having an earphone and a microphone coupled to a common ground;
• a noise cancellation circuit, a portion of which is contained within an external device;
• a plurality of electrical connections for connecting the active headset to the noise cancellation circuit;
• and
• a powering means that provides power to the portion of the noise cancellation circuit that is contained within the external device,
• wherein crosstalk between a earphone signal produced by the earphone and a microphone signal produced by the microphone is eliminated by placing a resistive element between the common ground and circuit ground, sensing a voltage drop across the resistive element, and subtracting a proportion of the voltage drop from the microphone signal necessary to eliminate the crosstalk.

A transient elimination circuit contained within a headset, comprising:

• a first resistive element having a first terminal and a second terminal, with the first terminal coupled to a headphone common;
• a potentiometer having a first terminal and a second terminal;
• a decoupling capacitor having a first terminal and a second terminal, with the first terminal of the decoupling capacitor coupled to a second terminal of the first resistive element and a first terminal of the potentiometer;
• a coupling capacitor having a first terminal and a second terminal;
• a microphone having a first terminal and a second terminal, with the first terminal of the microphone coupled to the second terminal of the potentiometer and the first terminal of the coupling capacitor;
• and
• a second resistive element having a first terminal and a second terminal, with the first terminal of the second resistive element coupled to the second terminal of coupling capacitor to form a microphone output signal and with the second terminal of the second resistive element coupled to the second terminal of the decoupling capacitor and the second terminal of the microphone to form a microphone common,
• wherein the headphone common is at a DC voltage potential with respect to the microphone common and is filtered to provide power to the microphone, and
• wherein when the headset is plugged or alternately unplugged, the decoupling capacitor is slowly charged or alternately discharged through the first resistive element so as to not cause a transient condition.