Anti-sidetone circuit

[Detailed Description of the Invention]

Field of the Invention The present invention relates to the Anti-tone sound circuit which prevents the side sound in 2 line 4 line conversion of telephone. PRIOR ART In recent years, an echo canceller is put in practical use by development of digital signal-processing art, and the trial which applies an echo canceller to the Anti-tone sound circuit of telephone, and reduces side sound is conducted. The conventional Anti-tone sound circuit mentioned above is explained, referring to drawings below. Drawing 4 shows the composition of the conventional Anti-tone sound circuit. As for a 2 line 4 line converter and 3, in Drawing 4, 1 is [ the microphone in handset 3 and 5 ] the speakers in handset 3 a handset and 4 echo cancellation means and 2. About the Anti-tone sound circuit constituted as mentioned above, the operation is explained below. If a speaker with handset 3 utters, a sound will be collected with microphone 4 and the sound will be taken into echo cancellation means 1 as a receiver input. On the other hand, via 2 line 4 line converter 2, a microphone output signal turns into 2 line signals, and is outputted. However, all input signals are not only outputted to the 2 line side, but in 2 line 4 line converter 2, a part leaks to the receiver side. Echo-cancellation-means l presumes the characteristic of the echo course by the side of 2 line 4 line converter 2, and negates the signal by which it leaked and came to the 4 line receiver side by compounding and deducting an echo leaking from a receiving input signal. For this reason, no matter it may connect with what circuit, sufficient side noise insulator effect is acquired. Side sound oppression of 30 dB or more can be performed by using echo cancellation means. Object of the Invention However, in the above composition, since side sound is Depression * Pressed too much and its voice stops being able to hear, there is a fault of talk-coming to be hard. The present invention provides the Anti-tone sound circuit where a proper side sound is obtained in view of the above-mentioned subject. Means for solving problem In order to solve the above-mentioned subject, a Anti-tone sound circuit of the present invention comprises the following: An echo course profit estimation means which presumes a profit of an echo course including echo cancellation means, An adaptation loss means to compound a suitable side sound from a profit of a presumed echo course, An adding means which loads a compound side sound. OPERATION The profit of the echo course which the echo which arises in a 2 line 4 line converter by the above-mentioned composition is negated by echo cancellation means, and includes echo cancellation means by an echo course profit estimation means is presumed, It can be considered as the Anti-tone sound circuit where a proper side sound is obtained by adding the side sound which compounded a suitable side sound from the profit of the echo course presumed by the adaptation loss means, and was compounded by the adding means. EXAMPLE Hereinafter, while referring to drawings for one example of the present invention, it explains. Drawing 1 shows the composition of the Anti-tone sound circuit in one example of the present invention. In Drawing 1, l of a 2 line 4 line converter and 3 is [ the microphone in handset 3 and 5 ] the speakers in handset 3 a handset and 4 an echo canceller and 2, and these are the same as that of a conventional example. As for 6, an adaptation loss means and 8 are adding means an echo course profit estimation means and 7. Drawing 2 is a figure showing the details of the adaptation loss means in Drawing 1, and it is a loss quantity determining means as which 10 determines a comparison means, 11 determines a variable loss means, and 12 determines the amount of losses of variable loss means 11. About the Anti-tone sound circuit constituted as mentioned above, the operation is explained below. First, if a speaker with hand cent 3 utters, a sound will be collected with microphone 4 and the sound will be taken into echo canceller l as a receiver input. on the other hand, a microphone output signal turns into 2 line signals via 2 line 4 line converter 2 -- output -- last . However, all input signals are not only outputted to the 2 line side, but in 2 line 4 line converter 2, a part leaks to the receiver side. Echo canceller 1 presumes the characteristic of the echo course by the side of a 2 line 4 line converter, and negates the signal which leaks to the 4 line receiver side by compounding and deducting an echo leaking from a receiving input signal. In echo course profit estimation means 6, the profit of the echo course containing echo canceller l is presumed from the receiving input signal and transmitting output signal of echo canceller l. From the profit of the echo course presumed by echo course profit estimation means 6, a suitable side sound is compounded as follows, the At least(ed) side sound is added and outputted to the transmitting output signal of echo canceller l by adding means 8, and adaptation loss means 7 gets across to a speaker through speaker 5 in handset 4. In adaptation loss means 7, comparison means 10 compares the profit of the echo course beforehand decided to be a profit of the echo course presumed by echo course profit estimation means 6. In loss quantity determining means I2, the amount of losses of a variable loss means is determined as follows using the result of comparison means 10 and echo course profit estimation means 6. In Drawing 2, the profit of the echo course which G and cHo presumed by echo course profit estimation means 6, the profit of the echo course which G7□ determined beforehand, and L show that the amount of insertion losses of variable loss means 11 and ■ have infinite insertion loss, and the following relations between G, cHo, and GT□ are. GEc, 10 >=GrHII (L=■) GECHO< GTHII (L = 1/) The echo which arises with 2 (it is tcoo to GTHR) line 4 line converter 2 is large, And when adaptation loss means 7 does not add side sound when echo canceller l has not negated the echo, but the echo which arises with 2 line 4 line converter 2 is very small or echo canceller l comes to negate an echo enough, According to the profit of the echo course containing echo canceller 1 and 2 line 4 line converter 2, suitable side sound is At least(ed) and it is added as a side sound by adding means 8. According to this example, the profit of the echo course which the echo which arises in a 2 line 4 line converter is negated by the echo canceller, and contains an echo canceller by an echo course profit estimation means is presumed as mentioned above, It may come to be a proper side sound by adding the side sound which compounded a suitable side sound from the profit of the echo course presumed by the adaptation loss means, and was compounded by the adding means. Since the volume of a favorite side sound changes with people, it may enable it to set up freely, for example by volume etc. by external inputting means 20 from the exterior, as shown in Drawing 3 although one input of comparison means 10 of adaptation loss means 7 was made into the value (GECHO) defined beforehand. EFFECT OF THE INVENTION Since the present invention is constituted as mentioned above, an effect which is indicated below is demonstrated. The profit of the echo course which the echo which arises in a 2 line 4 line converter is negated by echo cancellation means, and includes echo cancellation means by an echo course profit estimation means is presumed, It may come to be a proper side sound by adding the side sound which compounded a suitable side sound from the profit of the echo course presumed by the adaptation loss means, and was compounded by the adding means. It also becomes possible to obtain the side sound of each one of liking from the exterior using a switch etc.

[Brief Description of the Drawings]

The block diagram in which Drawing 1 shows the composition of the Anti-tone sound circuit of the 1st example of the present invention, the block diagram in which Drawing 2 shows the details of an adaptation loss means, the block diagram showing the details of the adaptation loss means of the example of others [ Drawing / 3 ], and Drawing 4 are block diagrams showing the composition of the conventional Anti-tone sound circuit. 1 ...... Echo cancellation means, 2 ...... A 2 line 4 line converter, 3 ...... A handset, 4 ...... A microphone, 5 [ ...... An adding means 1 * / ...... A comparison means, 11 / ...... A variable loss means, 12 / ...... A loss quantity determining means, 20 / ...... Volume. ] ...... A speaker, 6 ...... An echo course gain detecting means, 7 ...... An adaptation loss means, 8