JPS61274561A - Selective calling system for digital circuit - Google Patents

Abstract

PURPOSE:To improve the reliability of a selective calling system by transmitting the output of a PCM coder and the output obtained by giving the parallel/serial conversion to the value of a call setting switch after switching them with each other at the transmission side and detecting the coincidence between these outputs and the value of an own device number setting switch at the reception side. CONSTITUTION:The number of the reception side is set to a call setting switch 3 for execution of an operation at the transmission side. Thus the set value of the switch 3 is supplied to a switching circuit 4 via a parallel/serial converting circuit 2. The circuit 4 transmits the signal of the circuit 2 to a transmission line 5 in response to the synchronism of a PCM transmission line with an indication given from the switch 3 in a calling operation mode. At the reception side the signal received from the line 5 is supplied to a serial/parallel converting circuit 7 and compared with the set value of an own device number setting switch 9 through a comparator 8. If the coincidence is secured for a fixed period of time or longer, it is informed from a fixed time detecting circuit 10 via an output circuit 11 that the own device is called. When no calling operation is performed, the output of a PCM coder 1 is sent to the line 5 and decoded by a PCM coder 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a selective calling system for digital lines, and particularly to a selective calling system for digital lines that selectively calls party line telephones using the PCM system of digital radio relay lines. Regarding the method.

[Prior Art] Conventionally, in this type of selective call meeting telephone, the PC
Analog signal side and PC before encoding to M signal
An in-band multitone selective calling method was used on the analog signal side after decoding from the M signal.

[Problems to be Solved by the Invention] The conventional selective calling method described above requires a tone generation circuit and a tone detection circuit, so if the circuit becomes complicated, the reliability will decrease and the cost will increase. It has the disadvantage of becoming.

[Means for Solving the Problems] The selective calling system for digital lines of the present invention includes a switching circuit on the transmitting side that switches between the PCM coder output and the output of a parallel-to-serial conversion circuit that converts the value of the call setting switch from parallel to serial. The receiving side is equipped with a PCM decoder, a comparison circuit that compares the output of a serial-parallel conversion circuit that converts the received signal from the transmission line into serial-parallel and the value of the own device number setting switch, and a comparison circuit that compares the output of the comparison circuit for a certain period of time or more. It includes a fixed time detection circuit that detects a match, and an output circuit that outputs the detection result of the fixed time detection circuit.

[Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the selective calling system for digital lines according to the present invention.

In the figure, the transmitting side includes a PCM coder l, a call setting switch 3 for setting a predetermined calling number for the receiving side, and a parallel-to-serial conversion circuit 2 for converting the setting value of the call setting switch 3 from parallel to serial. , the switching circuit 4 that switches between the PCM coder/output and the output of the parallel-to-serial conversion circuit 2 and sends it to the transmission path 5 is biased, and the receiving side is a PC into which the received signal from the transmission path 5 is input.
M decoder 6, serial-parallel conversion circuit 7, self-device number setting switch 1, and comparison circuit 8 that compares the output of serial-parallel conversion circuit 7 with the setting value of own device number setting switch 9.When compared by comparison circuit 8, both A fixed time detection circuit 1 that detects that the values match for a certain period of time or more.
0, and an output circuit 11 that outputs the detection result of the detection circuit 10 to the outside for a certain period of time.

Next, the operation of this embodiment will be explained.

When attempting to call a specific reception vs. registration selection from the sending side, if the receiving side number is set in the call setting switch 3 and the calling operation is performed, the setting value of the call setting switch 3 is changed to the parallel serial converter circuit 2. The received signal is subjected to parallel-to-serial conversion and input to the switching circuit 4. During a calling operation, the switching circuit 4 sends the signal from the parallel-to-serial conversion circuit 2 to the transmission line 5 in synchronization with the PCM transmission line according to an instruction from the call setting switch 3.

On the receiving side, the signal received from the transmission line 5 is input to the serial-parallel conversion circuit 7, and is compared with the setting value of the own device number setting switch 9 by the comparison circuit 8, and the signal is input for a certain period of time (for example, 0.
If the match continues for more than 1 second, the detection circuit 10
An external buzzer or the like is sounded through the output circuit 11 to notify that the own device has been called.

Note that when no calling operation is performed on the transmitting side, the switching circuit 4 transmits the output of the PCM coder 1 to the transmission path 5.
On the receiving side, the signal is decoded by a PCM decoder 6 and general PCM communication is performed.

〔Effect of the invention〕

As explained above, the present invention has the advantage of being able to provide services with high reliability and at low cost, since selective calling is performed using a relatively simple circuit in a meeting telephone on a digital wireless relay line.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the selective calling system for digital lines according to the present invention. 1----P CM Korg, 2---Parallel-serial converter circuit, 3--- Call setting switch, 4--- Switching circuit, 5--- Transmission line ,6・
--P CM decoder, 7 parallel-serial conversion circuit, 8.--comparison circuit, 9...-compressor number setting switch, 10--fixed time detection circuit, 11-output circuit. Agent Patent Attorney Uchihara Otono'

Claims (1)

[Claims] The transmitting side is equipped with a switching circuit that switches between the PCM coder output and the output of a parallel-to-serial conversion circuit that converts the value of the call setting switch from parallel to serial, and the receiving side is equipped with a PCM decoder and a PCM decoder that converts the received signal from the transmission line from serial to parallel. A comparison circuit that compares the serial-parallel conversion circuit output and the value of the own device number setting switch, a fixed time detection circuit that detects that the comparison circuit outputs match for a fixed time or more, and detection of the fixed time detection circuit. A selective calling method for a digital line, characterized by comprising an output circuit for outputting a result.