JPS6126258B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a time division switching system. In particular, it relates to a chance call system in a time-division exchange.

Conventionally, in the three-party call system, or in general, the conference call system, a three-party call trunk circuit or a multi-party conference trunk circuit is installed at the trunk circuit position of the switched circuit network, and all related call paths are drawn in and synthesized using analog signals. Conference calls are being held digitally.

However, these methods are difficult to use when transitioning from a normal two-party call to a three-party or multi-party call, or conversely when returning from a three-party or multi-party call to a two-party call.
It is necessary to reconfigure the related communication path. For this reason, in storage program controlled exchanges,
This has led to increased complexity in switching control software and reduced call processing capacity.

On the other hand, in conventional electromagnetic-mechanical space-division switches, the call signal is an analog signal, so in the case of an operator-interrupted call from the switchboard, three connections can be made simply by multiplexing within the switching switch network. It is possible to make a personal call. However, in the case of a digital time division switch, the information in the switch circuit network is a digital code, such as a PCM code, and even though it is possible to decode this and monitor calls using multiple connections, Talk in the reverse direction is not possible, and it has the disadvantage that all related communication paths must be reconfigured to form a three-way communication trunk.

The present invention improves upon this by allowing three-party or multi-party calls to be made in a manner similar to multiple interrupt connections in a space-division switch, without the use of analog three-party or analog multi-party call trunks. The purpose is to provide a digital time division switch.

The present invention provides a function to randomly access multiple addresses of the same time switch circuit within any time slot in a time division switch, thereby making it possible to access all call information related to multiplex calls within the same time slot. The present invention is characterized in that it is configured so that it can be connected to a digital adder, and as a result, three-party or multi-party calls can be made in a manner similar to multiple interrupt connections in a space-division type switch.

The present invention provides a digital communication device equipped with a time switch that stores voices from a plurality of subscribers in digital voice codes at addresses corresponding to each subscriber.
The present invention is characterized by comprising a switch control memory capable of simultaneously specifying a plurality of reading addresses of the time switches, and means for applying the digital signals read from the time switches to a digital synthesis circuit.

An embodiment of the present invention will be described based on the drawings.
The figure is a block diagram of essential parts of an embodiment of the present invention. In the figure, A to C are subscribers who make three-way calls, and 1 to 3 indicate telephones used by subscribers A to C, respectively. These telephones 1 to 3 are connected via exchange subscriber circuits 5 to 7 and conversion circuits 8 to 10 which perform 2-wire/4-wire conversion as well as conversion and inverse conversion between analog audio and digital PCM codes.
It is connected to multiplex circuit 11.

The output of this multiplex circuit 11 is sent to the time switch 12.
guided by. Here, the time switch 12 is constituted by, for example, a random access memory of N words, where N is the time division multiplexing degree. The contents of a counter 13 and a switch control memory 14 are led to the time switch 12 via an address selection circuit 15. The contents of this time switch 12 are routed to registers 16 and 17. The contents of registers 16 and 17 are led to digital synthesis circuit 18. The contents of this digital synthesis circuit 18 are led to a demultiplexing circuit 19.

In such a circuit configuration, subscribers A, B,
The audio signal of C is converted into a digital signal by conversion circuits 8 and 9.
It is converted into a PCM code and PCM multiplexed by a multiplexing circuit 11.

Subscriber A multiplexed by this multiplex circuit 11,
The digital voice codes a, b, c for B, C are sequentially stored in the time switch 12 at addresses A', B', C' corresponding to subscribers A, B, C. This is done by applying the address information successively generated by the counter circuit 13 to the time switch 12 via the address selection circuit 15 of the time switch 12.

Next, the characteristic operation of the present invention will be explained. The present invention is characterized by the read operation of the time switch 12. Switch control memory 1 controls readout.
It is 4. In the present invention, each word of the switch control memory 14 has twice the number of bits of the conventional word, and each of the first half and the second half can independently specify the read address of the time switch 12. The place has its characteristics.

For example, read addresses B' and C' of the time switch 12 are written at address A' of the switch control memory 14 corresponding to time slot A'. Therefore, time switch 1 is set at time slot A'.
Information on addresses B' and C' of 2, that is, subscribers B and C
digital audio codes b and c are read out simultaneously. These digital voice codes b and c are set in register circuits 16 and 17. The contents of register circuits 16 and 17 are combined by digital combining circuit 18 and transmitted to subscriber A via demultiplexing circuit 19. Similarly, subscribers C and A
The digital voice codes c and a of A and B are combined and transmitted to subscriber B, and the digital voice codes a and b of A and B are combined and transmitted to subscriber C, thereby realizing a three-way call.

Here, an example of the digital synthesis circuit 18 will be shown. For example, the digital synthesis circuit 18 may be a read-only memory, and digital code words corresponding to the digital voice code strings to be read out from the registers 16 and 17 may be stored in advance in each address of the memory, and digital code words may be read out from the registers 16 and 17 by known means. The digital audio code string is input to the above address. This configuration is described in detail in the specification of the patent application ``Digital Synthesizing Circuit'' filed by the same applicant on the same day.

In addition, as another example, since the digital voice code is non-linearly encoded, it is possible to convert it to a linear code, add the two, and then convert the result to a non-linear code. Good too.

Here, if a three-party call is unnecessary and it is a normal two-party call (for example, subscribers A and B), a time switch 1 is placed in the first half of addresses A' and B' of the switch control memory 14.
If nothing is written in the second half of read addresses B' and A' of 2, the output from the time switch 12 will not be set in the register circuit 17, and the digital synthesis circuit 1 will not be set.
The addition operation at step 8 is not performed as a result, resulting in a two-party conversation.

Further, in the above example, a case of a three-party call has been described, but if the number of bits of the switch control memory is increased, a conference call with four or more parties can be made in the same way.

As explained above, the present invention has a switch control memory that controls the readout of a time switch that stores digital voice codes of subscribers at addresses corresponding to the subscriber, each word length of which is multi-bit, and a readout address of the time switch. It has been decided that multiple specifications can be made individually in the same slot. Therefore, multiple addresses corresponding to subscribers of the time switch can be read out using any slot. Therefore, three-party or multi-party calls can be made without providing analog three-party or analog multi-party call trunks.
Therefore, the circuit is not complicated, and the program processing of the time division exchange is simplified, so the program can be made smaller, and an inexpensive digital conference call device can be obtained.

[Brief explanation of the drawing]

The figure is a block diagram of essential parts of an embodiment of the present invention. 1-3...telephone, 5-7...exchange subscriber circuit, 8-10...exchange circuit, 11...multiplex circuit,
12...Time switch, 13...Counter, 14
...Switch control memory, 15...Address selection circuit, 16, 17...Register, 18...Digital synthesis circuit, 19...Demultiplexing circuit.

Claims (1)

[Scope of Claims] 1. In a digital communication device equipped with a time switch that stores voices from a plurality of subscribers in digital voice codes at addresses corresponding to each subscriber, a plurality of reading addresses of the time switches are simultaneously specified. a switch control memory capable of reading information of the plurality of subscribers within the same time slot, and means for applying the digital signal read from the time switch to a digital synthesis circuit within the same time slot. A digital communication device characterized by: