JPH0269062A - Incoming call transferring device - Google Patents

Abstract

PURPOSE:To prevent conversations from becoming unnatural even when a difference exists in line loss by providing a loss compensation amplifier which compensates a line loss and adding voice signals damped by the line loss to a superiority/inferiority discriminator after amplifying the voice signals by means of the amplifier. CONSTITUTION:The voice of a talker A is compensated in line loss on the talker A side by means of a loss compensation amplifier 61 and the voice of another talker B is compensated in line loss on the talker B side by means of another loss compensation amplifier 62. Therefore, the voice power of the talkers A and B is compared with each other under the same condition by a superiority/inferiority discriminator 3 and, even when a difference exists in line loss between both sides, the conversation between the talkers A and B does not become unnatural.

Description

[Detailed Description of the Invention] [Summary] The purpose of this invention is to prevent conversations from becoming unnatural even in the face of line loss with regard to call transfer equipment used in call transfer services. The first step detects the level of the audio signal at the receiving input point and the transmitting output point on the side and B side and calculates the wraparound cancellation amount.
．． A second wrap-around consumption calculation means determines whether the audio signal is audible or silent based on the level of the audio signal at the transmission output points of the A side and the B side, and if the audio signal is audible, the corresponding line is connected. First, find the gain of the automatic gain control amplifier necessary to compensate for the loss. a second line loss compensation amount calculation means; a superiority/inferiority determiner for determining superiority/inferiority of the audio signal at the transmission output points of the A side and B side from the level of the input audio signal; The second line loss compensation amount calculation part uses the output from the superior/inferior determiner to give the obtained gain to the automatic gain control amplifier on the superior side and 4 to the automatic gain control amplifier on the inferior side. In a call transfer device consisting of a loop gain controller that controls the gain so as not to generate noise within the line loop, a loss compensation amplifier is provided to compensate for the corresponding loss in the A-side and B-side transmission. The level of the audio signal at the output point is amplified by the corresponding loss compensation amplifier and then determined by the superiority/inferiority determiner.

[Industrial Application Field] The present invention relates to a call transfer device used when providing a call transfer service.

A call forwarding service transfers a subscriber's telephone call to another preset telephone.When using a call forwarding device, the conversation does not become unnatural even if there is a difference in line loss. It is necessary to do so.

[Conventional technology]

Figure 3 is a block diagram of the conventional example, Figure 4 is an explanatory diagram of the operation of the wraparound cancellation amount calculation part in Figure 3, and Figure 5 is the audio detector and automatic gain control for line loss compensation in Figure 3. Functional block diagrams of the circuits 1 and 6 are diagrams explaining the operation of the voice detector and automatic gain control circuit for line loss compensation in Figure 3, and Figure 7 is a diagram explaining the operation of the loop gain controller in Figure 3. shows.

In general, the lines connected to both sides of a call forwarding device are lines with different transmission losses, regardless of whether they are local lines or long distance lines, so they are subject to automatic gain control (hereinafter referred to as automatic gain control).

(abbreviated as AGC) is required. Also, 2nd line 2 and 4'
A type A converter is provided with a hybrid transformer, but mismatching of the hybrid transformer causes echoes and noise.

Therefore, an echo canceller (hereinafter referred to as "echo canceller") shown in FIG.

(abbreviated as EC) 14.14' and AGC amplifier 52.
51, etc., as a call transfer device.

It is required to always maintain loop loss while preventing the four-wire loop from making noise. Hereinafter, the operation of the call transfer apparatus shown in FIG. 3 will be described with reference to FIGS. 4 to 7, assuming that a voice signal is transmitted from the B side to the A side. Note that 13° indicates a digital/analog converter.

First, the analog audio signal sent from speaker B is converted into a digital signal by an analog/digital converter (hereinafter abbreviated as A/D converter) 12° via the line on the B side and a hybrid transformer 11'. After that, EC14'
A part of the signal is input to the level detector 23 and the audio detector 41', and the rest is amplified to a predetermined level by the AGC amplifier 51, passes through the EC14, and is converted to a digital/analog converter (hereinafter referred to as a D/A converter). (abbreviated as ) 13, the signal is returned to an analog audio signal, and the hybrid transformer 11. is added to the handset via the A-side line.

However, due to the mismatch in the hybrid transformer 11, a part of the signal is converted back into a digital signal by the A/D converter 12 and sent out to the B side through the EC 14, and is also sent to the level detector 21. It is added to the audio detector 41.

At this time, level detectors 23', 21' and 23.21
The part to calculate the amount of wraparound cancellation using the output is as follows.

(abbreviated as ERL) 22', 22 calculates the wrap-around cancellation amount, and an AGC circuit 42' for one-line loss compensation;
42 uses the outputs of the audio detectors 41', 41 to determine gains to be given to the AGC amplifiers 51, 52. Further, the superior/inferior determiner 3 uses the outputs of the audio detectors 41° and 41 to determine the superior/inferior of the two audio signals at the transmission output points of the ECs 14' and 14.

Using these results, the loop gain controller 53 gives the AGC amplifier on the dominant side a gain that compensates for the line loss of the corresponding line, and the AGC amplifier on the inferior side does not generate noise within the 4-wire loop. In other words, the gain is controlled so that the loop gain is 1 or less.

Next, these will be explained in more detail using FIGS. 4 to 7.

+l) ERL estimation (see Figure 4) Level detector 2
In 3.21, the levels of the receiving input point and the transmitting output point on the A side are detected, and the levels of the transmitting output point and the receiving input point on the B side are detected by the level detector 23゜21''. Estimate the ERL as follows.

That is, as shown in FIG. 4(b), since 16 bits of sampling data (amplitude value) is input to the level detector every 125 μs, for example, the ERL calculation part 22°221
and a certain interval like al+ az+ a3t aa (for example.

2m5) is calculated by shifting one sampling at a time, and P・
The moving average power P is determined from Ps + Pn Pn-x. Then, from the formula shown in Figure 4(a)-■, ERL
(See Figure 4(a)-■, ■, ■).

Here, +Ps is the moving average power up to now, P, 1 is the latest power +Pn-x is the oldest power.

(2) Detection of voice/silence and control of the AGC circuit for VA loss (see Figures 5 and 6) Calculate the moving average power in the voice detectors 41 and 41' as described above, and calculate this calculated value. is compared with a threshold value for identifying voice/silence, and if it is larger than the threshold, it is determined that there is a voice and a control signal is sent to the AGC circuits 52 and 51 for line loss compensation (as shown in the left side of FIG. 5). Figure 6-■.

■Reference).

Further, when the control signal from the audio detector is input to the AGC circuit 42.42° for compensating the VA loss, the interframe power of the output of the corresponding AGC amplifier is calculated.

Note that the interframe power differs from the moving average power in that it is an added power for each fixed period, and in the next fixed period, all the previous added power is discarded.

Now, if this interframe power is calculated for the first time, it is stored as frame integrated power. However, if it is not the first time, the calculated interframe power is multiplied by a coefficient α.

The stored frame integrated power is multiplied by the coefficient β and added and stored as the updated frame integrated power. This power is compared with a reference level, and if it is greater than the reference level, the corresponding AGC amplifier is gain 1d
Lower B. However, if it is small, increase it by 1 dB. Repeat this (right side of Figure 5).

(See Figure 6-■ to ■).

(3) Loop gain controller (see Figure 7) Now, ERL calculation part 22. The wraparound cancellation amount ERL obtained at 22°,
ERL, AGC circuit for line loss compensation 42. Gain AGC1, ^GCz from 42° and superior/inferior judge 3
The power of the voice detector 41° from the voice detector 41
The data that is superior to the power of the loop gain controller 53
, the dominant side AGC amplifier 51 receives accz
A control signal is applied to increase the gain by AGC + + AGC to the AGC amplifier 52 on the inferior side.
z -ERL+ -ERLz <AG to satisfy 1
The gain of the C amplifier 52 is controlled.

This prevents noise from occurring within the 4wA loop.

In addition, the switches SW+, SWt, SI4. I is linked,
When the dominant side is selected with SW, the gain obtained by the line loss compensation AGC circuit 421 on the dominant side is directly applied to the GC amplifier 51.

[Problem to be solved by the invention]

Here, the A-side line from speaker A to the A-side transmission output point and the B-side line from speaker B to the B-side transmission output point have different distances, so for example, the line loss is 5 dB and 20 D, respectively.
Suppose there is B.

Now, when the superiority/inferiority determiner 3 determines the superiority/inferiority of two audio signals, even if speaker A and speaker B speak at the same volume, the audio signal of speaker A with less line loss is dominant. The result of the 1 determination is added to the loop gain controller 53. Therefore,
The loop gain controller gives a gain that compensates for 5 dB of line loss to the GC amplifier 52 on the dominant side, and provides a gain to the AGC amplifier 51 on the inferior side that makes noise as described above (see item 11). Therefore, speaker B cannot compensate for the line loss, and the volume transmitted to speaker A becomes small.

Additionally, ambient noise enters the handset of speaker A, and due to this noise, the superiority/inferiority determiner 3 determines that side A is superior, and AG
There is a possibility that the gain of the C amplifiers 52 and 51 is switched and the speech of the B speaker is interrupted.

That is, there is a problem that if there is a difference in line loss, the conversation may become unnatural.

[Means to solve problems]

FIG. 1 shows a block diagram of the principle of the present invention.

In the figure, 2 and 2' are the first channels that detect the level of the audio signal at the reception input point and the transmission output point on the A side and B side and calculate the wraparound cancellation amount. With the second round-trip consumption calculation means,
4.4° is from the level of the audio signal at the transmission output point of the A side and B side.

1. Determine whether the audio signal is voiced or silent, and if it is voiced, determine the gain of the automatic gain control amplifier necessary to compensate for the corresponding line loss. This is a second line loss compensation amount calculation means.

Further, 3 is a superior/inferior determiner for determining the superiority/inferiority of the audio signal at the transmission output points of the A side and B side from the level of the input audio signal, and 53 is the first and second line loss compensation amounts. Using the output from the calculation section and the superior/inferior determiner, the obtained gain is given to the automatic gain control amplifier on the superior side, and the gain is applied to the automatic gain control amplifier on the inferior side to eliminate noise within the 4-wire loop. It is a loop gain controller that controls the gain so that the line loss does not occur, and 61.61'' is a loss compensation amplifier that compensates for the corresponding line loss.

[Effect]

The present invention is a loss compensation amplifier 6161° that compensates for line loss.
is provided, and the audio signal attenuated due to line loss is amplified by a loss compensation amplifier and then applied to the superior/inferior determiner 3.

Therefore, even if there is a difference in the loss of the two lines, the superiority/inferiority of the voice signals of speaker A and speaker B can be judged under the same conditions, so even if there is a difference in the loss of yi and sti, the conversation will not be interrupted. It doesn't become natural.

〔Example〕

FIG. 2 shows a block diagram of the embodiment.

Here, the level detector 21. EI? L calculation part 22.
The level detector 23 is a component of the first wraparound consumption calculation means 2, and the audio detector 41. The line loss compensation AGC circuit 42 is connected to the first line loss compensation amount calculating means 4. The system bell detector 21", the ERL calculation part 22", the level detector 23
' is a component of the second round-trip consumption calculation means 2°. In addition, 11.11" is a hybrid transformer, 12
．． 12' is an A/D converter, and 13.13' is a D/A converter. Also, the same reference numerals refer to the same objects throughout the design.

The operation of the part of the present invention in FIG. 2 will be explained below. Here, the line loss is 5 dB on the A side, as in the conventional example.
The B side is 20 dB.

Now, the voice signal of speaker A is attenuated by 5 dB due to line loss on the A side, and the hybrid transformer 11. A/D converter 12°E
The signal is applied to the audio detector 41 through C14.

Assume that the voice detector 41 obtains the moving average power at a constant sampling width in the same manner as described above and compares it with the threshold value for recognizing it as a voice signal, and as a result, it is determined that the voice signal is sound. This determination result is applied to the AGC circuit 42 for circuit loss compensation, so this circuit 42 adjusts the power level of the audio signal output from the audio detector to a predetermined level (for example, −15d
A gain for amplifying up to Bmo) is determined and applied to the loss compensation amplifier 61.

Since this gain is a value that compensates for the line loss of 5 dB on the A side, the power level of the audio signal output from the loss compensation amplifier 61 is the same as the power level sent out by the A speaker, and this is the value that is transmitted to the superior/inferior determiner 3. Added.

In addition, in the case of speaker B, the line loss is 20 dB, so the gain output from the AGC circuit for line loss compensation is 20 dB.
Since the line loss on B side is compensated for, speaker A and B
It is possible to compare the superiority/inferiority of a speaker's voice power under the same conditions.

As a result, even if there is a difference in line loss, the conversation will not become unnatural.

〔Effect of the invention〕

As explained in detail above, according to the present invention, even if there is a difference in line loss, the conversation does not become unnatural.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a block diagram of a conventional example, and Fig. 4 is a block diagram of the wraparound erasure amount calculation part in Fig. 3. Diagram for explaining operation; Figure 5 is a functional block diagram of the voice detector and automatic gain control circuit for line loss compensation shown in Figure 3; Figure 6 is a functional block diagram of the voice detector and automatic gain control circuit for line loss compensation shown in Figure 3. Diagram for explaining the operation of the circuit. FIG. 7 shows a diagram for explaining the operation of the loop gain controller in FIG. 3. 4′ indicates a second line loss compensation calculation device, 14 indicates a first echo canceller, 14° indicates a second echo canceller, 51 and 52 indicate automatic gain control amplifiers, and 53 indicates a loop gain controller. . Mao 3 figure Zemawari) Including portrait weight calculation Ondo's gravity 乍 8 Relaxation Moe figure 3 n sound? Asayama B Ayohi/Kaiteizumi Awami 1 Mountain 2. Motion control point of P circuit for use in 1 mountain. CRHB line 41's circuit diagram automatic gain control circuit block diagram

Claims (1)

[Claims] A first step that detects the level of the audio signal at the reception input point and the transmission output point on the A side and the B side and calculates the wraparound cancellation amount.
, second round-trip consumption calculation means (2, 2'), and the A
Based on the level of the audio signal at the transmission output points of the side and B side, it is determined whether the audio signal is voiced or silent, and if there is voice, an automatic gain control amplifier ( first and second line loss compensation calculation means (4, 4') for calculating the gain of 52, 51); / Advantage to judge inferiority /
Using the outputs from the inferior determiner (3), the first and second line loss compensation calculation parts, and the superior/inferior determiner, the automatic gain control amplifier (52 or 51) on the superior side is An incoming call transfer system consisting of a loop gain controller (53) that gives the obtained gain and controls the gain of the automatic gain control amplifier (51 or 52) on the inferior side so that no sound occurs within the 4-wire loop. In the equipment, a loss compensation amplifier (61, 6
1'), and after amplifying the level of the audio signal at the transmission output point of the A side and the B side with the corresponding loss compensation amplifier,
An incoming call transfer device characterized in that it is configured to make a determination using an inferiority determiner.