Abstract: An echo suppressor uses a multi-state operating sequence to provide non-disruptive monitoring of a remotely broadcast program during a performer's live performance at a local site. The operating sequence is actuated by a voice activated switch that initiates signal processing for correlating a locally originating audio (e.g., the performer's voice) to its echo in the broadcast program. During correlation states in the operating sequence, the echo suppressor switches monitoring to a local microphone signal to allow the performer to hear his or her own voice while preventing echo from being heard before correlation is achieved and echo suppression can begin. The correlation states include an initial correlation at a reduced sampling rate to detect echo within a wide delay time window and determine the locally originating audio is on-the-air.

Abstract: An echo suppressor uses a multi-state operating sequence to provide non-disruptive monitoring of a remotely broadcast program during a performer's live performance at a local site. The operating sequence is actuated by a voice activated switch that initiates signal processing for correlating a locally originating audio (e.g., the performer's voice) to its echo in the broadcast program. During correlation states in the operating sequence, the echo suppressor switches monitoring to a local microphone signal to allow the performer to hear his or her own voice while preventing echo from being heard before correlation is achieved and echo suppression can begin. The correlation states include an initial correlation at a reduced sampling rate to detect echo within a wide delay time window and determine the locally originating audio is on-the-air.

Abstract: A noise reduction system including a signal path (34) between an input terminal (12) and an output terminal (36), a voltage control amplifier (38) and a control path (40) between the input terminal and the voltage control amplifier is disclosed. A nonlinear element such as a voltage squarer (32) is in the controlled path. In one arrangement, the control path also includes a signal level detector (22), a one-pole high pass filter (16) and a direct current level shifter (26). A precision diode (30) is interposed in the control path between the direct current level shifter and the signal squarer. One form of the noise reduction system includes a voltage-controlled low pass filter (20) interposed in the signal path between the input terminal and the voltage-controlled amplifier. A weighing control path (46) provides the control signal for the voltage-controlled low pass filter. A two-pole high pass filter (18) followed by a level sensor (48) is interposed in the weighting control path.

Abstract: A voltage controlled resistor includes an operational transconductance amplifier (OTA) including first and second linearizing diodes which not only optimize signal-to-noise distortion levels but also represent the AC impedance from the inverting input to ground. The OTA turns on and off in response to the amount of gain control current being supplied thereto. A Darlington transistor is coupled to the output of the OTA for providing a low impedance buffered output. A first resistor provides current flow through the diodes. A feedback resistor supplies and controls bias current to one of the diodes. A third resistor maintains bias to the Darlington pair when the OTA output approaches open circuit output impedance conditions.

Abstract: A circuit for peak limiting an audio signal comprises a first "M" derived filter, a first clipping circuit, a second-order low pass filter, a second clipping circuit and a second "M" derived filter. Each "M" derived filter includes a series resonant shunt leg for eliminating clipping harmonics within selected frequency ranges depending upon the resonant frequency of each shunt leg.