JPH061920B2 - Time division multiplex communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention is a time-division multiplex communication system, in which a subscriber side sends a chattering signal by a switch operation such as matching a phase with an allocation timing of the own station, or a voltage fluctuation causes another subscriber. In order to solve the conventional problem that a data error occurs on the line, a blank bit is provided immediately after or immediately before the frame timing or burst timing on the frame format, and the control signal obtained by the above switch operation is set to the frame timing or burst timing. By synchronizing with the blank bits, the chattering and the voltage fluctuation due to the switch operation are generated only in the blank bit even if the switch operation is performed at any timing so that the data error does not occur during the data transmission period. .

[Industrial application field]

The present invention relates to a time division multiplex communication system, and more particularly to a switching operation system of switches (operated by mechanical contact) for phase adjustment, bit adjustment, etc., performed on the side of a subscriber vehicle. In the time division multiplex communication system, as shown in FIG. 5, the base station 1 sets the timing (hereinafter referred to as allocation timing) in a time division manner at the data transmission rate of each subscriber 2a, 2b ,. 2a, 2b, ... Detect the allocation timing of the own station with reference to the frame timing (for example, a cycle of 1 ms) sent from the base station 1, and send data to the base station 1 corresponding to this allocation timing. .

For example, as shown in the frame format in FIG. 6, the start position of the frame is designated by the frame timing FT,
In the frame, the data transmission timing of each station is designated by the burst timing BT, and the allocation timing is set to each subscriber 2
.. are set on the base station 1 side in a time-divisional manner for each of a, 2b, ..., And each subscriber 2a, 2b, ... Assigns its own station based on the frame timing FT sent from the base station 1, respectively. The timing (burst timing) is detected by a counter or the like, and as a result, the own station (CH _a , CH
_b , ...) Transmits data of its own station at the burst timing BT. In this case, the allocation timing is different for each subscriber, and the allocation timing of the own station is adjusted by appropriately changing the count set value of the counter by operating the switch. Since the allocation timing is set in a time division manner, each subscriber 2
The transmission data of a, 2b, ... Are also time-divisional as shown in FIG.

In such a time division multiplex communication system, a large number of subscribers use the same frequency, and in particular, in recent years, there is a demand for setting up many new subscriber lines in parallel with services of adjacent channels. Therefore, when each subscriber performs the above-mentioned phase adjustment, bit adjustment, or switch operation involving mechanical contact such as loopback operation, an abnormal signal should not be sent to other subscriber lines. Therefore, a switch switching system that does not cause chattering or voltage fluctuation due to switch operation is required for this purpose.

[Conventional technology]

FIG. 7 shows a circuit diagram of a switch circuit used in the conventional system. In the figure, 3 is a switch which is operated by mechanical contact for setting each bit of the burst timing of the own station counting from the frame timing and performing each operation such as phase adjustment and bit adjustment. When turned on, the count set value switching control signal is output in synchronization with the clock having a cycle (for example, 60 ns) shorter than the cycle (1 ms) of the frame timing FT. By this switching control signal, the count set values of the counters provided for the respective subscribers 2a, 2b, ... Are switched and set, and as described above, the counters set the respective counts set in the own station based on the frame timing FT. Counting is performed until reaching the set value, the allocation timing of the own station is detected, and the data of the own station is transmitted from the data transmission circuit at the burst timing BT of the own station.

[Problems to be solved by the invention]

In the above-mentioned conventional method, the output timing of the switching control signal obtained by operating the switch 3 is not particularly specified, and it is not known at what timing in the frame format shown in FIG.

Therefore, if chattering, voltage fluctuation, or the like due to switch operation occurs at the data transmission timing of the subscriber line, the chatter link or voltage fluctuation causes switch 3 to become unstable in subsequent circuits, and noise, for example, on other subscriber lines. There was a problem that an error occurred when mixed with the transmitted data, or the burst timing became unstable and an error occurred on the receiving side. The timing at which chattering occurs due to this switch operation also varies depending on the operating speed at the time of switching.

The present invention has been made in view of the above points, and by causing chattering and voltage fluctuations associated with switch operation during a blank bit period, an error may occur in the data of another subscriber line, or at the receiving side. An object of the present invention is to provide a time division multiplex communication system that prevents an error from occurring.

[Means for solving problems]

FIG. 1 shows a block diagram of the principle of the method of the present invention. In the figure,
Reference numeral 15 designates a switching setting section such as a counter for switching the allocation timing of each subscriber, and 16 synchronizes a switching control signal obtained by all switch operations involving mechanical contact including the switching setting section.

According to the method of the present invention, a blank bit period (DC) is provided at a timing immediately after the frame timing FT or each burst timing BT on the frame format, or at a timing immediately before the frame timing FT or each burst timing BT. Switch control signal to frame timing F
T or each burst timing BT to generate an abnormal signal accompanying the generation of the switching control signal in the blank bit period (DC), and the blank bit period (DC) is don't care, or Blank bit period (DC) pulse masking is performed to prevent the abnormal signal from being transmitted.

[Action]

When the switch of the switch unit 16 is switched, a switching control signal is taken out in synchronization with the frame timing FT or each burst timing BT, whereby the switching setting unit 15 is switched and set, and the allocation timing for each subscriber (burst timing BT ) Is detected. In this case, chattering and voltage fluctuations due to the generation of the switching control signal occur in the blank bit period DC provided in the frame format, and thus no error occurs in the data.

〔Example〕

FIG. 2 shows a block diagram of the main part of the line terminating device on the side of each subscriber used in the system of the present invention. In the figure, 4 is a switch circuit, which adjusts the timing with the switch 3, the resistor 5, the inverter 6, and the frame timing FT from the base station 1, for setting the bit number of the burst timing of the local station counted from the frame timing. A timing adjuster 7 such as a flip-flop and an AND gate 8 for performing In the principle block diagram of FIG. 1, it is shown as a switch circuit 16. The switch circuit 4 outputs a switching control signal in synchronization with the frame timing FT as described later, but the generation timing of this switching control signal is the same for all the subscribers 2a, 2b, ... In the frame format.

Reference numeral 9 denotes a counter, the count setting value of which is switched and set by a switching control signal from the switch circuit 4, and the clock is counted up to the count setting value set in the own station with reference to the frame timing FT to determine the allocation timing of the own station. The corresponding burst timing BT signal is output. In the principle block diagram of FIG. 1, it is shown as the switching setting unit 15. 10 is a data transmission circuit, which is a burst timing B
T signal and local station (eg, telephone, computer, etc.)
And sends it to the base station 1 together.

On the other hand, FIG. 3 shows an embodiment of the frame format of the present invention. In the figure, DC is a blank bit (don't care part), and is provided, for example, at the timing next to the frame timing FT. The blank bit period is set to the time until the chattering and the voltage fluctuation caused by the operation of the switch 3 described later converge. in this case,
One frame timing FT, a blank bit DC, each burst timing BT corresponding to each subscriber's allocation timing, data assigned to each subscriber, radio maintenance bits, and the like are included in each frame.

The blank bit DC is provided at the timing immediately after the frame timing FT as described above, at the timing immediately after each burst timing BT, or at the timing immediately after any one burst timing BT. Alternatively, they may be provided immediately before the frame timing FT or the burst timing BT, respectively.

Here, the operation of the method of the present invention will be described together with the time chart shown in FIG. Generally, the switch operation is performed not only once but several times. For example, assume that the switch 3 in FIG. 2 is operated at time t ₁ in FIG. 4A as the first switch operation.
In the conventional method shown in FIG. 7, the switching control signal is output immediately in synchronization with the operation of the switch 3, but in the method of the present invention, the switching control signal is not yet output at the time of operating the switch 3.

The signal obtained by operating the switch 3 is supplied to the timing adjuster 7 to be a signal synchronized with the timing of the frame timing FT (FIG. 4 (A)), and is supplied to the counter 9 as a switching control signal via the AND gate 8. Supplied. The counter 9 has its count set value switched and set by this switch control signal, counts clocks up to the count set value set in its own station with reference to the frame timing FT, and performs alignment as described above.

Since the switching control signal is always generated in synchronization with the frame timing FT, chattering and voltage fluctuation due to the generation of the control signal will always occur as a blank bit DC as shown in FIG. Will occur in. In this case, chattering occurs in each subscriber in the blank bit DC period synchronized with the frame timing FT.

Therefore, as shown in FIG. 4B, the signal transmitted from the data transmission circuit 10 causes noise and voltage fluctuation only in the blank bit period, and does not generate noise and voltage fluctuation in the data transmission period. As a result, no error occurs in the data of other subscriber lines.

After that, the second switch operation and the third switch operation are the same as in the above case, and the chattering and the voltage fluctuation due to the switch operation still occur in the blank bit period.

It should be noted that, in addition to the chattering or the like caused by the generation of the control signal in the blank bit DC period as in the above embodiment to make this blank bit DC period a don't care, the chattering or the like generated in the blank bit DC period is shown in FIG. The pulse masking may be performed so that the data is not supplied to the data transmission circuit 10 as shown in FIG.

〔The invention's effect〕

According to the present invention, since chattering and voltage fluctuation due to switch operation occur in the blank bit period, error does not occur in data of another adjacent subscriber line,
It is possible to prevent an error from occurring on the receiving side due to an unstable burst timing, and it is possible to provide a stable service as a time division multiplex communication system that accommodates many subscribers.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention system, FIG. 2 is a block diagram of essential parts of the present invention system, FIG. 3 is a frame format of the present invention system, FIG. 4 is a time chart of the present invention system, and FIG. FIG. 6 is a conceptual diagram of a system of a time division multiplex communication system, FIG. 6 is a frame format of a conventional system, and FIG. 7 is a circuit diagram of a switch circuit used in the conventional system. In the figure, 1 is a base station, 2a and 2b are subscribers, 3 is a switch, 4 is a switch circuit, 7 is a timing adjuster, 9 is a counter, 10 is a data sending circuit, 15 is a switch setting section, and 16 is a switch section. Is.

Claims (1)

[Claims] 1. A plurality of subscribers (2a, 2) from a base station (1).
b), ..., The same frame timing (FT) is periodically output, and each of the plurality of subscribers (2a, 2b, ...) Has its own burst timing (BT) as the frame timing (FT). From the base station (1), the burst timing (BT) indicating the allocation timing of the local station on the frame format switched and set by the switching setting unit (15) of the local station for setting the bit number from Burst timing (BT) indicating the allocation timing of the local station by detecting the frame timing (FT) as a standard
In the time division multiplex communication system in which the data of its own station is transmitted in response to the above, and the plurality of subscribers (2a, 2b, ...) As a whole time division multiplex signal in the frame format, Frame timing (FT) or each burst timing (BT) above
A blank bit period (DC) is provided at a timing immediately after, or a timing immediately before the frame timing (FT) or each burst timing (BT), and mechanical contact including the switching setting unit (15) is started. A switching control signal obtained by all the accompanying switch operations is generated in the switch section (16) in synchronization with the frame timing (FT) or each burst timing (BT), and an abnormal signal accompanying the generation of the switching control signal is generated. It is characterized in that it is generated in a blank bit period (DC) and the blank bit period (DC) is don't care, or the blank bit period (DC) pulse is masked so that the abnormal signal is not transmitted. Time division multiplex communication system.