JPH01130651A - Telephone set - Google Patents

Abstract

PURPOSE:To easily listen to a voice of a talking party even with a large line loss by adjusting the level of a side tone in response to a level of a ring-back tone. CONSTITUTION:A tone level detector 8 detecting the level of a ring-back tone from a line network and a gain controller 11 adjusting the level of the side tone in response to the level of the ring-back tone to be detected are provided. When the level of the ring-back tone is lower than the reference level in case of calling, the side tone level is decreased. Thus, the voice of the communication party is easily listened to even with a large line loss.

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention) (Industrial Application Field) The present invention relates to a telephone that improves call quality by adjusting the level of sidetone.

(Prior Art) In recent telephone networks, the trunk network for relays transmits call voices using digital signals, but the subscriber network for terminals transmits call voices mostly using analog signals.

In such an analog network, line loss cannot be ignored, and for this reason, designing a two-wire network is extremely difficult. That is, since the communication route of the call voice changes every time a call is made, the line loss changes. If the line loss is large, it becomes difficult to hear the voice of the other party. Therefore, the network must be designed so that line loss does not become too large no matter how the voice communication route changes.

By the way, if the line loss is large, reducing the level of sidetone on the telephone will make it easier to hear the voice of the other party. However, conventional telephones fixed the sidetone level to a certain level, making it impossible to deal with cases where line loss was large.

(Problems to be Solved by the Invention) As described above, in conventional telephone systems, the sidetone level was fixed at a constant level, so it was not possible to reduce the sidetone level when the line loss was large. There was a problem in that it became difficult to hear the voice of the person on the other end of the call.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a telephone that makes it easier to hear the voice of the other party when the line loss is large.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a detection means for detecting the level of a ringback tone from a line network when making a call, and a detection means for detecting a sidetone according to the level of the ringback tone detected by the detection means. The present invention is characterized by comprising a sidetone level adjustment means for adjusting the level.

(Function) According to the present invention, the level of the sidetone is adjusted according to the level of the ring bank tone. Here, if the ringback tone is small, the line loss is large. Therefore, if the line loss is large, the sidetone level will be reduced, making it easier to hear the voice of the other party.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a digital telephone to which the present invention is applied. Digital telephone 111 shown in the figure
Is network i! It is connected to the digital line 3 through the a device 2. This digital line 3 is derived from the digital network 21 shown in FIG.

Now, when a call is made from this digital telephone 1fi1 to a telephone I23 connected to the subscriber network 22 shown in FIG. 2, the local exchange I24 in the subscriber network 22 sends a ringing signal to the telephone 23 on the called side. At the same time, a ringback tone signal is sent to the digital network 21 through the 2'FiA type analog line 25 in the subscriber network 22. The digital network 21 converts this ringback tone signal from analog to digital, and applies a digital signal indicating the ringback tone to the calling side digital telephone 111 through the four-wire digital line 3. In the digital telephone tE11, this digital line is input through the network control charge @2, and is further connected to the digital-to-analog converter (hereinafter referred to as D/A converter) 6 via the booster 5 in the sidetone circuit 4.
Add to. The D/A converter 6 forms the ringback tone signal by digital-to-analog conversion of this digital signal, and the ringback tone signal is sent to the amplifier 7.
and tone level detector 8, respectively. Amplifier 7 amplifies this ringback tone signal and applies the amplified output to handset 10 of handset 9.

As a result, a ringback tone is generated from the receiver 10. On the other hand, when the tone level detector 8 receives the ring bank tone signal, it compares the level of the ring bank tone signal with a preset reference level and determines whether the level of the ring back tone signal is equal to or higher than the reference level. Detect.

Here, if the distance between the local exchange 11124 and the digital network 21 in the subscriber network 22 is not very long, the line loss due to the analog line 25 is small, so the level of the ringback tone signal hardly decreases.
It becomes more than the above-mentioned reference level.

At this time, the tone level detector 8 detects that the level of the ringback tone signal is higher than the reference level, and applies a high level signal S11 indicating this to the gain controller 11 in the sidetone circuit 4. When the gain controller 11 receives this signal SH1, it maintains a preset first gain.

Now, the telephone 1123 on the called side responds to the call, and a conversation is thereby started between the digital telephone l11 and the telephone 1123. At this time, when the voice of the call is input to the transmitter 12 of the handset 9, the transmitter 12 sends out an analog signal indicating the voice of the call. After this analog signal is amplified by the amplifier 13, it is sent to an analog-to-digital converter (hereinafter referred to as A).
/D converter) 14. A/D converter 1
4 converts the analog signal into analog to digital, and adds a digital signal representing the voice of the call to the network control device A 2 and the gain controller 11 (respectively. The network control device 2 sends this digital signal to the digital network 21 through the digital line 3. Furthermore, upon receiving the digital signal, the gay controller 11 performs a process of attenuating the call voice indicated by the digital signal by the first gain, thereby reducing the level of the digital call voice indicating the call voice as appropriate. form a signal and apply this digital signal to an adder 5.

On the other hand, a digital signal representing the voice of the called party transmitted through the digital line 3 is inputted via the network control device 2 and further added to the adder 5. The adder 5 performs processing to add the call voice from the called side indicated by this digital signal and the call voice whose level has been appropriately lowered, indicated by the digital signal from the gain controller 11, and the sum of the two is the sum of the two. A digital signal representing a certain call voice is applied to the D/A converter 6. D/A! The converter 6 performs digital-to-analog conversion on this digital signal to form an analog signal tone representing the call voice, which is the sum of the two, and sends out this analog signal. This analog signal is amplified by amplifier 7 and then applied to receiver 10.

As a result, the receiver 10 emits the voice of the call from the called party, and also the voice of the voice from the transmitter 12 whose level has been appropriately lowered. In other words, an appropriate sidetone is generated and F,! , people can make natural calls.

Next, when making a call from the digital telephone f11 to the telephone 23 on the called side, if the distance between the local exchange 24 and the digital network 21 is long, the analog line 25 is used to make a call.
*Since the loss is large, the level of the ringback tone signal from the local traffic 11124 decreases on the digital telephone fiI side, and becomes lower than the reference level set in the tone level detector 8.

At this time, the tone level detector 8 detects that the level of the ringback tone signal is lower than the reference level,
A low level signal S indicates this.

is added to the gain controller 11. When the gain controller 11 receives this signal 'S1, it maintains a preset second gain that is lower than the first gain.

Now, when a call is started between the digital telephone 111 and the telephone IE 123, the A/D converter 14 applies a digital signal indicating the call voice from the transmitter 12 to the gain controller 11. When the gain controller 11 receives this digital signal, it performs a process of attenuating the call voice indicated by this digital signal by the second gain, thereby forming a digital signal indicating the call voice whose level is greatly reduced. Then, this digital signal is added to adder 5.

On the other hand, the adder 5 receives a digital signal transmitted through the digital line 3 indicating the voice of the called party. Then, the adder 5 performs a process of adding the voice of the call from the called party indicated by this digital signal and the voice of the call whose level has been significantly lowered indicated by the digital signal from the gain controller 11, so that both of them are combined. A digital signal representing the call voice, which is the sum, is applied to the D/A converter 6.

The D/A converter 6 performs digital-to-analog conversion on this digital signal to form an analog signal representing the call voice, which is the sum of the two, and sends out this analog signal.

This analog signal is amplified by amplifier 7, and the receiver 1
Added to 0. As a result, the handset 10 emits the painful voice from the called party, and at the same time, the voice from the transmitter 12 is generated at a very low level. That is,
Since the sidetone level is reduced, even if the line loss is large and the voice from the other party is low, the voice can be easily heard.

If the ringback tone level is lower than the reference level when making a call, line loss is large, so
Reduces the level of sidetones.

Therefore, even if the line loss is large, the voice of the other party can be easily heard.

Although this embodiment uses a digital telephone as an example,
The invention can also be applied to analog telephones.

〔Effect of the invention〕

According to the present invention, since the sidetone level is adjusted based on the level of the nine-tone back tone, it is possible to provide a telephone that allows the user to easily hear the voice of the other party even when the line loss is large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a digital telephone to which the present invention is applied, and FIG. 2 is a diagram showing an example of a line network. 1...Digital telephone, 2...Network control device, 3...
・Digital line, 4... Sidetone circuit, 5... Adder,
6...Digital analog converter, 7...Amplifier, 8
...Tone level detector, ・9...Handset,
10...Telephone receiver, 11...Gain controller, 1
2...Transmitter, 13...Amplifier, 14...Analog-digital converter.゛－；Kawaden・.

Claims (1)

[Scope of Claims] Detection means for detecting the level of a ringback tone from a line network when making a call; and sidetone level adjustment means for adjusting a sidetone level according to the level of the ringback tone detected by the detection means. A telephone characterized by comprising: