JPH10145464A - Telephone set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the telephone set that has a transfer function having a circuit where proper correction is applied to an input signal so as to establish a speech at transfer in a pleasant way. SOLUTION: When a signal detection circuit 1 detects a signal whose level is in excess of a noise level, an arithmetic circuit 3 starts sampling of an input signal and stores the input signal to a buffer 5 as data. The data stored in the buffer 5 are fed again to the arithmetic circuit 3, where a difference from a level of a reference signal is calculated again. Since it is considered that a telephone line connecting to a telephone set having a transfer function has a similar loss, a control circuit 4 changes an amplification factor of an amplifier so as to be the amplification factor twice the attenuation obtained by the calculation thereby correcting not only the signal level but also the attenuated high frequency signal component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone having a transfer function corresponding to a plurality of telephone lines.

[0002]

2. Description of the Related Art In general, in a telephone having a transfer function corresponding to a plurality of telephone lines, an amplification factor and a maximum level are determined, and amplification is performed when a signal is input. At this time, when the signal level after amplification becomes higher than the set maximum level, the feedback circuit operates, and the level of the input signal is changed so as not to exceed the maximum level.

Therefore, regardless of whether the attenuation due to the line loss is large or small, the level of the output signal may be constant, and the correction is not performed in consideration of the line loss at the output destination.

[0004]

Since the telephone line is a distributed constant circuit, the longer the line length, the lower the signal level itself due to transmission loss, and the higher the frequency component of the signal is attenuated. Will come. For this reason, it is necessary to amplify the signal. However, since the state of the line in which the telephone is installed is not uniform, it is impossible to know the state of the line in advance and set the amplification factor. Also, unless the amplification factor is changed according to the sound quality and volume of the speaker and the level of the audio signal after passing through the transfer phone is not set to be too large or too small, the call during transfer is very difficult to hear. Could be

The present invention has been made in consideration of the above-mentioned conventional problems, and provides a telephone having a transfer function having a circuit for appropriately correcting an input signal and making a call at the time of transfer comfortable. Aim.

[0006]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention relates to a telephone having a plurality of telephone lines connected and having a transfer call function, wherein a signal level input to a circuit during a transfer call is used as a reference signal. A means for comparing the level with the level and a means for amplifying the amount of attenuation obtained by the comparison by a factor of two are provided, and an automatic loss correction device in a transfer telephone that performs appropriate correction for line loss is provided.

According to the present invention, the signal attenuated in the telephone line from the relay station to the telephone having the transfer function is corrected by twice the amount of attenuation, and the line loss from the telephone having the transfer function to the relay station is reduced. Amplification can be performed in consideration of the above, and the attenuated high-frequency signal component can be similarly corrected.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention relates to a telephone having a transfer function by connecting a plurality of telephone lines, and means for automatically correcting a loss added during a transfer call. It is an automatic loss correction device in a transfer telephone having a, automatically detects the line loss added at the time of transfer,
It has the function of performing appropriate correction.

According to a second aspect of the present invention, there is provided an automatic loss correcting apparatus for a transfer telephone according to the first aspect, wherein the means for automatically correcting the added loss includes an input signal to the circuit. It comprises a means for continuously comparing the level and the reference level, and a means for sequentially changing the amplification factor, and has the function of sequentially correcting the change in the input signal and keeping the output level constant.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram showing an automatic amplification factor correction circuit of a telephone having a transfer function according to Embodiment 1 of the present invention.

As shown in the figure, the automatic amplification factor correction circuit of the telephone having the transfer function includes LINE1 and LINE2 on the input side.
Signal detection circuits 1 and 2 for detecting the presence / absence of a signal from a computer, an arithmetic circuit 3 for comparing an input signal level with a reference set level, and calculating a signal amplification factor based on the output, and an arithmetic circuit 3 A control circuit 4 for controlling the amplification factor of the amplifier based on the result of the above, a buffer 5 for storing the sampled signal,
It comprises amplifiers 6 and 7 for amplifying signals from LINE1 and LINE2 on the input side and outputting the amplified signals to LINE1 and LINE2 on the output side.

In the above configuration, the signal detection circuits 1 and 2 always detect the input signals from the LINEs 1 and 2 on the input side. If there is no input higher than a certain level (noise level), it is regarded as a signal input. Set to none.
When signals are input from the LINEs 1 and 2 on the input side, the signal detection circuits 1 and 2 send the signals to the arithmetic circuit 3. Upon receiving this signal, the arithmetic circuit 3 samples the input signal. The sampled signal is sent to the buffer 5.
The reference level and the level of the input signal are compared for each sampling signal to calculate the amount of attenuation. Since the telephone line connected to the telephone having the transfer function is expected to have a uniform line loss, the attenuation is set so that the signal is output to the relay station at the reference level even if the line is attenuated by the output line. The gains of the amplifiers 6 and 7 are set so as to have a double amplification rate. The control circuit 4 changes the gains of the amplifiers 6 and 7 so as to have this value. The input signal passes through the amplifiers 6 and 7, and is amplified and output to the LINEs 1 and 2 on the output side.

FIG. 2 is an input / output characteristic diagram of the automatic loss compensating device in the telephone set.
Is compared with the reference level A, and the output signal level C is corrected to a level that is twice the attenuation amount calculated and compared.

Although the input signal has components of various frequencies, it is possible to simultaneously correct the attenuated high frequency component by performing an operation for each sampling.

It is assumed that the input signal level is higher than the reference level due to the combination of the line state of the caller and the volume of the caller. In this case, the arithmetic circuit 3 determines that the line loss is very small, and suppresses the output level to the reference level.

[0016]

As is apparent from the above description, the transfer telephone according to the present invention can appropriately correct the level of the signal attenuated by the line and the high-frequency signal component during the transfer function operation. Therefore, the effect of the added line loss can be removed, and the advantageous effect of making the transfer call equal to the level of a normal two-party call can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an automatic amplification factor correction circuit of a telephone having a transfer function according to a first embodiment of the present invention;

FIG. 2 is an input / output characteristic diagram of an automatic loss correction device in the telephone.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal detection circuit 2 Signal detection circuit 3 Arithmetic circuit 4 Control circuit 5 Buffer 6 Amplifier 7 Amplifier

Claims (2)

[Claims] 1. A telephone having a transfer function by connecting a plurality of telephone lines, the telephone having means for automatically correcting a loss added during a transfer call. 2. The means for automatically correcting the added loss comprises means for continuously comparing the level of an input signal to a circuit and a reference level, and means for sequentially changing the amplification factor. The telephone according to claim 1, wherein: