Telephone-speech-activity-detector
This circuit is designed for speech activity detection in telephone lines. It is particularly useful for half-duplex conversations between two stations, where simultaneous transmission of voice and data occurs over the same pair of cables by interspersing data with voice traffic. It is also applicable in echo suppressor devices. The circuit includes a class-A amplifier to enhance weak analog signals in the range of 25-400 mV. The integrated circuit (IC1) operates as a retriggerable monostable multivibrator. The transistor TR2 discharges the timing capacitor C3 when a pulse train reaches the trigger input 2 of IC1, provided the pulse period is less than THIGH, which is approximately 1.1 times R3 times C3. The output at pin 3 of IC1 remains active when an analog or digital signal is present, and it reverts to a low level, THIGH seconds after the input signal ceases.
The circuit's primary function is to detect speech activity, which is crucial in communication systems where voice and data are transmitted simultaneously. By utilizing a class-A amplifier, the circuit is capable of amplifying weak signals, ensuring that even low-level audio signals can be processed effectively. The retriggerable monostable multivibrator configuration using IC1 allows for flexible timing control, enabling the circuit to respond to varying input signal durations.
The timing capacitor C3 plays a vital role in determining the output pulse width and is discharged by TR2 when the conditions are met at the trigger input. The resistive component R3 influences the charge and discharge time of C3, thus affecting the timing characteristics of the output signal. This design ensures that the output remains active as long as speech or data signals are detected, providing a robust solution for echo suppression and efficient communication in half-duplex systems.
The circuit's versatility makes it suitable for various applications where accurate speech detection is necessary, including telecommunication devices and audio processing equipment. By integrating these components effectively, the circuit enhances the overall performance of communication systems that rely on simultaneous voice and data transmission.This circuit can be used in telephone lines for speech activity detection purposes. This detection is very useful in the case of half-duplex conversation between two stations-in the case of siroultaneous transmission of voice and data over the same pair of cables by the method of interspersion data on voice traffic, and also in echo suppressor devices. The circuit consists of a class-A amplifier to amplify the weak analog signals (25-400 mV). The IC1 which follows, is conneGted as a retriggerable monostable multivibrator with the TR2 discharging the timing capacitor C3, if the pulse train reaches the trigger input 2 of IC1 with period less than the time: THIGH ~ 1.1 R3C3. The output 3 of!C1 is active on when an analog or digital signal is presented at the output, and it drops to a low level, THIGH, seconds after the input signal has ceased to exist.
🔗 External reference
The circuit's primary function is to detect speech activity, which is crucial in communication systems where voice and data are transmitted simultaneously. By utilizing a class-A amplifier, the circuit is capable of amplifying weak signals, ensuring that even low-level audio signals can be processed effectively. The retriggerable monostable multivibrator configuration using IC1 allows for flexible timing control, enabling the circuit to respond to varying input signal durations.
The timing capacitor C3 plays a vital role in determining the output pulse width and is discharged by TR2 when the conditions are met at the trigger input. The resistive component R3 influences the charge and discharge time of C3, thus affecting the timing characteristics of the output signal. This design ensures that the output remains active as long as speech or data signals are detected, providing a robust solution for echo suppression and efficient communication in half-duplex systems.
The circuit's versatility makes it suitable for various applications where accurate speech detection is necessary, including telecommunication devices and audio processing equipment. By integrating these components effectively, the circuit enhances the overall performance of communication systems that rely on simultaneous voice and data transmission.This circuit can be used in telephone lines for speech activity detection purposes. This detection is very useful in the case of half-duplex conversation between two stations-in the case of siroultaneous transmission of voice and data over the same pair of cables by the method of interspersion data on voice traffic, and also in echo suppressor devices. The circuit consists of a class-A amplifier to amplify the weak analog signals (25-400 mV). The IC1 which follows, is conneGted as a retriggerable monostable multivibrator with the TR2 discharging the timing capacitor C3, if the pulse train reaches the trigger input 2 of IC1 with period less than the time: THIGH ~ 1.1 R3C3. The output 3 of!C1 is active on when an analog or digital signal is presented at the output, and it drops to a low level, THIGH, seconds after the input signal has ceased to exist.
🔗 External reference