SU915280A1 - Loudspeaking telephone set - Google Patents

Description

The invention relates to telecommunications and can be used in telephone devices as a subscriber loud-speaking telephone with voice switching.

A loud-speaking telephone is a ^5th handset containing a series. connected microphone, microphone amplifier, transfer key, transmission amplifier, differential system and reception amplifier, serially connected reception key, power amplifier and loudspeaker, as well as a transmission level detector and a reception level detector, the outputs of which are connected to the corresponding ₅ the output of which is connected to the first input of the Schmitt trigger, the output of which is connected to the control inputs of the transmission key and the reception key, and the inputs of the transmission and reception level detectors are connected respectively from the output microphone amplifier and reception amplifier [1].

However, in the known device, the volume controls do not take into account the effects of acoustic feedback, as well as excitation when switching.

The purpose of the invention is to improve the quality of communication by reducing the effect of acoustic feedback.

This goal is achieved by the fact that a loudspeaker telephone containing a serially connected microphone, a microphone amplifier, a transmission key, a transmission amplifier, a differential system and a reception amplifier, a serially connected reception key, a power amplifier and a loudspeaker, and a transmission level detector and a reception level detector, whose outputs are connected to the corresponding inputs of the comparator, the output of which is connected to the first input of the Schmitt trigger, the output of which is connected to the control inputs of the key before Chi and receiving the key, wherein WMOs £ s transmission and level detectors pri915280

The memory is connected respectively to the outputs of the microphone amplifier and the reception amplifier; a memory block, an adjustable attenuator and a feedback block are entered, the output of the transmission level detector is connected to the first input of the memory block, the second input of which is connected to the Schmitt trigger output, the output of the memory block is connected to the control input adjustable attenuator, the information input of which is connected to the output of the receiving amplifier, and the output of the adjustable attenuator is connected to the input of the receive key, while the output of the Schmitt trigger is connected to course feedback unit, whose output is connected to the second input of the Schmitt trigger,

The drawing shows a structural electrical circuit. The proposed device.

The loud-speaking telephone contains microphone 1, microphone amplifier 2, transmission level detector 3, 4 transfer key, transmission 5 amplifier, / system 6, reception amplifier 7, reception level detector 8, comparison unit 9, Schmitt trigger 10, reception key 11, power amplifier 12, loudspeaker 13, memory unit 14, feedback unit 15 and adjustable attenuator 16.

The device works as follows.

The device switches from both the signal from the microphone 1 and the connecting line 17. Depending on the previous type of work, the loudspeaker telephone is in the receive or transmit state.

If the loudspeaker telephone circuit is in the receiving state, then the potential from the Schmitt trigger 10 is supported by the open> receive key 11 and, accordingly, the open receive channel, and the transmit key 4 is closed, and accordingly, the transmit channel is closed.

If the loudspeaker telephone circuit is in the transmission state, then the potential from the Schmitt trigger 10 supports the public key 4 transmissions and, accordingly, the transmission channel is open, and the reception key 11 is closed, and, accordingly, the reception channel is closed.

In the absence of signals from microphone 1 and connecting line 17, on · ’

the voltage at the outputs of the detector 3 transmission level and the detector 8 reception level is missing. At the output of block 9 of the comparison is also no voltage, and Schmitt trigger 10 is in the "memory" mode. Block 15 feedback in static mode on the Schmitt trigger 10 is not valid. In the absence of a signal from microphone 1 to the memory block 14 voltage is not supplied. In the transfer mode, the trigger 10 Schmitt potential sets the memory block 14 so that the adjustable attenuator 16 is set to the maximum transmission coefficient

In the transmission mode, the signal from microphone 1 is amplified by a microphone amplifier 2 and fed to the input of a transmission level detector 3, which in block 9 of the comparison is continuously compared with the reception signal. The latter enters the comparison unit 9 from the reception level detector 8. The output signal of the unit 9 comparison compares trigger 10 Schmitt trigger in the transfer position.

At the time of switching from the reception mode to the transfer of Schmitt trigger 10, the feedback unit 15 does not work. The potential from the output of trigger 10 Schmitt opens the key 4 transfer and connects the microphone amplifier 2 with the amplifier 5 transfer. The transmission channel is open and the signal from microphone 1 enters the connecting line 17.

If the signal comes from the connecting line 17 to the differential system 6, then the device circuit is in receive mode. From the differential system 6, the signal goes to the receive amplifier 7. The amplified signal is then fed to the inputs of the detector 8 receiving level and continuously adjustable attenuator 16. If the voltage at the output of the detector 8 receiving level is greater than the voltage at the output of the detector 3 transmission level, the potential at the output of the comparator 9 exceeds the trigger voltage of Schmitt trigger 10. The Schmitt trigger 10 enters the receive state. The feedback block 15 receives the voltage drop from the Schmitt trigger 10. The feedback unit 15 generates a delay pulse, which is fed to the second input of Schmitt trigger 10. The latter remains in the receive position until the end of the delay pulse. During this period

5,915

time setting the volume in the receive channel smoothly adjustable attenuator 16. The potential from Schmitt trigger 10 opens the reception key 11 and the signal from the connecting line 17 through the reception amplifier 7, the continuously adjustable attenuator 16, the reception key 11, the power amplifier 12 goes to the loudspeaker 13 "which converts electrical 1 signals into acoustic oscillations, some of which are fed back to microphone 1, which converts these oscillations into electrical signals. These signals are amplified by microphone 1 amplifier 2, straightened by a transmission level detector 3 and fed to memory block 14 and from its output go to a continuously adjustable attenuator 16, which decreases the transmission coefficient with increasing thunder-2 bones.

The memory unit 14 and the continuously adjustable attenuator 16 operate in such a way that the rate of reduction of the transmission coefficient is many times greater than the speed of 2 [increase of the transmission coefficient. That [kim way, quickly sets the desired volume level, which is supported by the memory unit 14.

Introduction to the circuit of a loudspeaker 31 telephone set of a memory unit, a feedback unit and a smoothly adjustable attenuator distinguishes the proposed apparatus from the well-known one, since it ensures reliable operation, ₃₅ protects the transmit-and-receive excitation when switching, works reliably at various microphone and loudspeaker locations.

Claims (1)

Claim ₄ A loud-speaking telephone set containing in series 6 microphone, microphone amplifier, transfer key, transmission amplifier, differential system and reception amplifier, serially connected reception key, 5 power amplifier and loudspeaker, as well as a transmission level detector and a reception level detector, the outputs of which are connected to the corresponding inputs of the comparator, the output of which is connected to the first input of the Schmitt trigger, the output of which is connected to the control inputs of the transmission key and the reception key, and the inputs of the level detectors transmitting and receiving are connected respectively to the outputs of the microphone amplifier and the receiving amplifier, about ⁴ and ⁴ , in order to improve the quality of communication by reducing the effect of acoustic feedback connection, a memory block, an adjustable attenuator and a feedback block are entered into it, the output of the level detector on the transfer is connected to the first input of the memory block, the second input of which is connected to the output of the Schmitt trigger, the output of the memory block is connected to the control input of the adjustable attenuator, information input which is connected to the output of the receiving amplifier, and the output of the adjustable attenuator is • connected to the input of the receiving key, at. This Schmitt trigger output is connected to the input of the feedback unit, the output of which is connected to the second Schmitt trigger input.