JPS59178054A - Four-wire type telephone set for extension of subscriber line - Google Patents

Abstract

PURPOSE:To eliminate a ring tone loop produced by a hybrid at both ends of a 2-wire converting circuit by using a terminal telephone set extended with a subscriber line while keeping the four-wire system. CONSTITUTION:An amplifier circuit 9' for compensating line loss, a dial signal transmission circuit RG transmitting a dial signal to a 4-wire system line, a in- band signal generating circuit 7', a signal circuit 8' and a power supply AC/DC adaptor 11 receiving commercial power supply and supplying the power to the said circuits are incorporated in a case of a subscriber telephone set 15, in a device of the subscriber side. Thus, the transmission loss attended with the conversion of two/four-wire and the member for loss required for stabilizing ring tone are not required and the entire transmission loss is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an improvement in subscriber telephone equipment that is extended by a four-wire line because of its long distance from a telephone exchange.

[Description of prior art]

Regarding the extension of subscriber lines using conventional standard leased lines,
The so-called two-wire-four-wire-two-wire conversion is required, and a hybrid (
Let the echo attenuation of HYB) be El and E2, respectively, and the gains of the two amplifiers used G1 and G2, respectively.
In order not to cause noise, it is necessary that (E1 + E2) > (Gl +02), and when both are approximately equal, the so-called quasi-noise margin 2β1 and level fluctuations in the transmission path, loss fluctuations, fluctuations due to attenuation quantum, etc. are taken into consideration. However, if the amount of variation in these is 2122, then (El -1 - E2 ) - (01 + 02 ) ≧ 2 (7
! i → -12) That is, it is necessary to set the communication path loss between two lines to two lines as L-Ili +β2, and the above-mentioned standards for use of dedicated lines are stipulated as L≧12 dB. Therefore, in conventional equipment, it is necessary to add 1° of channel loss each time it is converted to a two-wire system, and when configuring a subscriber line extension system,
There were some inconveniences, such as the system configuration being impossible due to the required communication path loss.

As a means of improving this inconvenience, the design of the conventional system that required subscriber line extensions was changed to a high-grade system by introducing a four-wire switch, making it a very expensive system, or There were times when I had no choice but to give up on the commitment.

FIG. 1 is a block diagram of a conventional system. The general telephone 1 includes a handset 2, a dial pulse generating circuit 3, a ringing tone generating circuit 5, and a two-wire telephone circuit network 4. Its output is coupled to a telephone repeater 6 containing a hybrid 6a and an RG signal generator 6b. The hybrid 6a is connected to one line loss compensation amplifier circuit 9 via one of the in-band signal circuits 8 to which the in-band signal generation circuit 7 is connected, and the output of the amplifier circuit 9 is connected to the D standard dedicated line LD. connected to. The output of the dedicated line LD is connected to the other loss compensation amplifier circuit 9.
The output of
It is connected to the hybrid 10a in 0. Reference numeral 12 is an exchange, and reference numeral 10b is an RG signal device.

In this way, in the conventional system, when extending the subscriber line, it is necessary to install the telephone repeater 6, one amplifier circuit 9, and the commercial AC power supply rectifier AC/DC AC DAC 11 as separate in-home equipment. It was necessary.

[Purpose of the invention]

The present invention solves the above problems, and eliminates the ringing loop caused by the hybrid at both ends of the two-wire conversion circuit by using a terminal telephone with an extended subscriber line as a four-wire system. It is an object of the present invention to provide an economical and compact subscriber line extension telephone device that eliminates the need for communication path loss to stabilize the line by suppressing ringing.

[Key points of the invention]

The present invention enables a terminal telephone to be extended and used as a four-wire system, eliminates the generation of ringing, and also includes a dial pulse generation circuit, a tall tire band signal generation circuit, and an in-band signal generation circuit. The present invention is characterized in that a four-wire repeater circuit for telephones, an amplifier circuit for line loss compensation, and a power supply circuit for rectifying commercial power are built into the telephone housing, resulting in a compact device.

[Explanation based on examples]

FIG. 2 is a block diagram of the system according to the embodiment of the present invention. In this example, the subscriber is far from the exchange 12, and a repeater 10 for the exchange is added to perform two-wire and four-wire conversion, and connection is made by a four-wire transmission line standard dedicated line LD.

The feature of the present invention lies in this subscriber-side device.

That is, the subscriber side equipment includes a line loss compensation amplifier circuit 9', a dial signal transmission circuit RG for transmitting a tire signal to a four-wire line, an in-band signal generation circuit 7', a signal circuit 8', and a commercial A power supply circuit AC/DC adapter 11 for receiving and supplying power is housed within the casing of the subscriber telephone 15.

The line loss compensation amplifier circuit 9' can be integrated into an extremely compact circuit. Unlike the two-wire telephone network 4, the telephone circuit network 13 is constructed such that the transmitting and receiving signals are both built in and connected directly to the amplifier circuit 9' via the in-band signal circuit 8'. Configure. The dial signal transmitting circuit RG is constituted by an extremely small electronic circuit that generates a dial signal that is directly compatible with a four-wire transmission line as a repeater for a four-wire telephone. Further, the in-band signal generating circuit 7' and the in-band signal circuit 8' can be made smaller, and the power consumption as a whole can be minimized, so that the power supply circuit 11 for the power supply can be made compact.

In this way, all of the equipment necessary for the four-wire connection can be built into the housing of the subscriber telephone.

According to this configuration, the transmission loss caused by the two-wire/four-wire conversion G and the loss member required for sound stabilization are not required, and the overall transmission loss can be reduced.

〔Effect of the invention〕

As described above, according to the present invention, an extension telephone device can be obtained in which the device installed in a subscriber's premises is simplified. Further, according to the present invention, there is an advantage that transmission loss associated with two-wire/four-wire conversion is eliminated, and speech quality is improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional structure of a subscriber line extension telephone. FIG. 2 is a block diagram showing an embodiment of the present invention. 1...General telephone, 2.2'...Handset, 3...
・Atayal pulse generation circuit, 4...Telephone circuit network, 5
...Ring tone generation circuit, 6...Telephone repeater,
7.7'... In-band signal generation circuit, 8.8'... In-band signal circuit, 9... Line loss compensation amplifier circuit, 10
...Repeater for switching equipment, 11... AC/DC adapter for commercial AC power rectification, 12... Switching equipment, 13...
- Four-wire telephone circuit network, 14... Four-wire telephone repeater, 15... Four-wire telephone for subscriber line extension. Patent applicant: NEC Corporation Representative Patent attorney: Naotaka Ide

Claims (1)

[Claims] (],) In a subscriber telephone device that is extended and connected to a subscriber located far from a switching center via a four-wire outlet line, line loss connected to the four-wire line is provided. A compensation amplifier, a dial signal generation circuit that can directly transmit a dial signal for the four-wire line to the four-wire line, and an in-band signal generator for controlling the toll dial network using the D standard dedicated line. an in-band signal circuit for coupling the output signal of the in-band signal generation circuit to the four-wire line, and a power supply circuit that receives commercial power and supplies power to the amplifier and dial signal generation circuit. A subscriber telephone set built in a housing of the subscriber telephone set, wherein a transmitting circuit and a receiving circuit of the subscriber telephone set are connected as a four-wire circuit to the transmitting input and receiving output of the line loss compensation amplifier. Four-wire telephone device for line extension.