JPS61198998A - Electronic telephone exchange - Google Patents

Abstract

PURPOSE:To reduce harmful reflection with simple constitution by providing respective PLL in an internal interface circuit and a trunk line interface circuit, and by generating a clock signal to drive the circuits with the PLL. CONSTITUTION:The titled digital telephone exchange consists of a clock generating means 1 that generates the clock signal and a frame signal, an exchange network 2 that acts in synchronization with the said signals, and the interface circuits for extension/trunk line 3 and 4 which also acts in synchronization with the signals. And the circuits 3 and 4 are provided with the PLL circuits 8 and 9 which drive the circuits 3 and 4 themselves. Therefore, the line to supply the clock signal is drastically made short and simple, and in result, the harmful reflection of the clock signal is reduced.

Description

[Detailed description of the invention] Industrial applications The present invention relates to digital electronic exchanges.

2. Description of the Related Art Digital electronic exchanges are generally known, and all of these types are constructed as shown in FIG. In FIG. 2, I denotes signal generating means for generating clock signals, frame signals, etc.

2 is an exchange network that operates in synchronization with the clock signal and frame signal from the signal generating means 1;

3.4 are respective interface circuits for the two extension lines which operate in synchronization with the clock signal and frame signal from the signal generating means 1; 5 and 6 are the extension interface circuits 3;
7 is a central office line.

Note that the interface circuits 3 and 4 are connected to the telephone 5. The data terminal device 61 converts the signal from the office line 7 into a digital signal and sends it to each telephone 5. The data terminal device 69 has the function of allocating the above-mentioned digital signal to the time slot 7 allocated to each office line 7 and transmitting it to the switching network 2. It has the function of extracting only the signal and converting it into an analog signal etc. Although not shown in each interface circuit 3, 4,
A plurality of telephones, data terminal equipment, nine office lines, etc. are connected, and a plurality of these interface circuits 3 and 4 are also provided as necessary.

Therefore, when signals are input from each telephone, each data terminal, and each office line, they are converted into digital signals by the respective interface circuits 3 and 4, and are assigned to their respective assigned time slots.
It is transmitted to the switching network 2. Then, the exchange network 2 assigns the signals to the time slots of each partner, and transmits them to the above-mentioned interface circuits 3 and 4, where only the signals of the predetermined time slots for each partner are taken out. If both parties can talk or communicate, it will be K.

Problems to be Solved by the Invention However, in this type of electronic exchange, as shown in FIG. 2, the extension line interface circuit 32, the office line interface circuit 4. The configuration is such that all clock signals and frame signals for operating the exchange networks 2 in a synchronized state are obtained by the signal generation circuit 1 provided near the exchange network 2. Therefore, the extension interface circuit 3 and When a relatively large electronic exchange requires a large number of central office line interface circuits 4, the lines for transmitting the clock signals and frame signals become relatively long and complicated, causing unnecessary radiation within the electronic exchange. This is not desirable since the interface circuits 3 and 4 and the network 2 may malfunction. In particular, the clock signal has a problem in that its frequency is very high and unnecessary radiation is likely to occur.

The present invention eliminates the above-mentioned conventional drawbacks, and aims to provide an excellent electronic exchange with a simple configuration and less unnecessary radiation.

Means for Solving the Problems In order to achieve the above object, the present invention provides a phase-locked loop (hereinafter referred to as a PLL circuit) inside or near each of the extension line interface circuits and the waste line interface circuits. is operated in synchronization with a frame signal from a signal generating means provided near the exchange network, and a clock signal for driving each of the extension line interface circuits 2 and 7 by the PLL circuit. It is configured to generate .

Therefore, according to the present invention, the extension interface circuit 2
Even in large electronic exchanges that require a large number of field line interface circuits, malfunctions, failures, etc. caused by these unnecessary radiations can be greatly reduced.

Embodiment FIG. 1 is a schematic diagram of an embodiment of an electronic exchange according to the present invention. In the figure, the same reference numerals as in FIG. 2 indicate the same components as in FIG. 2.

8 and 9 are extension interface circuits 32, respectively.
This is a PLL circuit provided near the office line interface circuit 4, which operates in synchronization with the frame signal from the signal generating means 1 provided near the exchange network 2, and which connects the extension line interface circuit 32 to the office line interface circuit 4. It is configured to output a clock signal for driving.

In the above embodiment, telephone 5. A call 1 communication between the data terminal equipment 62 and the office line 7 is carried out in the same manner as in the conventional electronic exchange shown in FIG. However, according to the above embodiment,
Extension line interface circuit 3゜ Office line interface circuit 4
The PLL circuits 8 and 9 for driving the clock signal are provided near the extension line interface circuit 3 and the central line interface circuit 4, respectively, so that the line for supplying the clock signal is significantly shorter than in the past. , which has the advantage of being simple and significantly reducing unnecessary radiation of the clock signal.

In the above embodiment, the PLL circuit 8.9 is also used as the signal generating means 1.
In order to operate in synchronization with the clock signal, it is necessary to take in the frame signal from the signal generating means 1, which may make the line for the frame signal long or complicated, but the frame signal is Since the frequency is extremely low, it is possible to substantially eliminate the need for unnecessary radiation to be a problem.

Effects of the Invention As is clear from the above embodiments, the present invention provides PLL circuits inside or near the extension interface circuit 1 candlestick interface circuit, etc., and drives the extension interface circuit 1 candlestick interface circuit with these PLL circuits. The line for supplying the clock signal can be significantly shortened, and unnecessary radiation can be significantly reduced. Therefore, according to the present invention, even in a large electronic exchange that requires a large number of extension line interface circuits and central office line interface circuits, malfunctions and failures caused by unnecessary radiation can be minimized, which is extremely advantageous in practice. be.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of an electronic exchange according to the present invention, and FIG. 2 is a schematic diagram of a conventional electronic exchange. 1... Signal generation means, 2... Exchange network,
3... Extension line interface circuit, 4... Office line interface circuit, 5... Telephone, 6... Data terminal device, 7... Office line, 8, 9... PLL circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (1)

[Claims] A function that converts signals from telephones, data terminal equipment, office lines, etc. into digital signals, assigns them to their assigned time slots, and transmits them to a switching network;
An extension line interface circuit, a central office line interface circuit, etc., which has the function of extracting only the signals of pre-assigned time slots from the signals exchanged by the switching network and supplying the signals to telephones, data terminal equipment, central office lines, etc. A phase-locked loop is provided inside or near the switching network, and the phase-locked loop is operated in synchronization with the signal generating means by a frame signal from a signal generating means provided inside or near the switching network, An electronic exchange configured to obtain a clock signal for driving the extension line interface circuit, the office line interface circuit, etc. using the phase-locked loop.