JPS61278235A - Data collection system of optical transmission system - Google Patents

Abstract

PURPOSE:To improve the data collecting efficiency by providing a line using state discriminating function by other station and transmitting a data with a standby time set differently from each station. CONSTITUTION:In case of line idle state, after the closing of squelch is con firmed, a CPU 2 sends a press signal to a radio equipment 1 to switch the equipment 1 into the outgoing state for data transmission. When the squelch is opened while the transmission trigger is applied, the CPU 2 does not send the press signal to the radio equipment 1 and awaits the squelch closing. In mobile stations A, B applied with a transmission trigger, the station A sends a data after a standby time t1 elapses. Further, since the station A transmits during the initial count of t2 (>t1) and the squelch is opened again, the mobile station B is in standby until the sending of the station A is finished. Thus, the collision of outgoing data by the station A, B is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an arbitrary transmission type data collection system, and particularly to an improvement in the data collection efficiency thereof.

[Conventional technology]

AVM systems that collect vehicle position information, etc. have a boring method and an arbitrary transmission method.In the boring method, each mobile station transmits data under the control of a base station, so multiple stations transmit data at the same time. will not collide.

However, even if new data to be transmitted occurs on the mobile station side, it cannot be transmitted until it is polled by the base station, resulting in a lack of responsiveness. In this respect, the arbitrary transmission method has the advantage that data to be transmitted can be transmitted immediately when the mobile station generates the data.

[Problem that the invention seeks to solve]

However, in the arbitrary transmission system where the wireless line is operated using a simplex system, when multiple stations simultaneously transmit, there are cases where some or all of the transmissions are not received by the base station. The present invention attempts to improve this point.

Means for Solving Problem C] The present invention provides a data collection system using an arbitrary transmission method in which a plurality of mobile stations share a radio line with the same frequency and arbitrarily transmit data to a base station. Added a function to determine the state of line usage by a station, and a function to wait for transmission until a certain period of time has elapsed after the line becomes idle when a transmission trigger is applied on the own station while another station is using the line. , and the fixed time is different for each station.

[Effect]

By providing a function for determining the state of line use by other stations, it is possible to avoid overlapping transmission by the own station while another station is transmitting. However, if two or more stations are waiting for a free line at the same time, they will transmit at the same time when the line becomes free. Therefore, if each station is set to transmit after a standby time unique to each station after the line becomes free, the probability of data collision will be reduced and data collection efficiency by the base station will be improved. This will be explained in detail below with reference to illustrated embodiments.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, showing the configuration of one mobile station. The same goes for other mobile stations.
Furthermore, the base station is omitted in the drawing.

In the figure, 1 is a radio device with transmitting and receiving functions, 2 is a control C
PU, 3 is a modem interposed in the data transfer path between the two. The data transferred from the CPU 2 to the radio device 1 is the transmission data to the base station, and includes data such as the taxi number and whether the taxi is empty or real. On the other hand, the data transferred from the radio device 1 to the CPU 2 is a return signal etc. from the base station. The CPU 2 checks the squelch signal of the radio device 1 when data to be transmitted is generated and an external activation (transmission trigger) is applied. At this time, the radio 1 is in a receiving state, and if it is receiving radio waves from another station (the line is in use), the squelch is open, and if it is not receiving radio waves (the line is idle), the squelch is closed.

FIG. 2(a) is a time chart of the line being idle,
In this case, after confirming that the squelch is closed, CPU2 will
Sends a press signal to switch to the transmission state and transmit data. One data transmission takes, for example, 0.2 seconds, and when this is received by the base station, a return signal is sent. However, if the line condition is poor and the transmitted data is not received by the base station, the return signal from the base station cannot be received. In this case the CPU
2 retransmits the same data after a timeout of a certain period (for example, 0.5 s).

On the other hand, if the squelch is open when the transmission trigger is applied as shown in Figure 2(b), the line is in use by another station, so the CPU 2 cannot send a press signal to the radio 1 at that point. Wait for the squelch to close. However, even if the squelch is closed, the transmission operation does not proceed immediately; instead, the waiting times tl, t2゜, etc. assigned to each mobile station A, B, etc. are different. During this period, monitor to see if the squelch opens again.

Taking mobile stations A and B, which have been triggered for transmission, as an example, mobile station A can transmit data after waiting time t1 has elapsed. However, mobile station B transmits during the first count of t2 (>t+) and the squelch opens again, so mobile station A
is made to wait until the transmission is completed. And mobile station A
After completion of transmission, if the squelch does not open during the waiting time t2, mobile station B can also transmit. In this way, collisions between the transmitted data of mobile stations A and B are avoided, but this waiting time is assigned different values to all stations, including the base station.

〔Effect of the invention〕

As described above, according to the present invention, in a data collection system using an arbitrary transmission method, the number of cases in which transmission is repeated while another station is transmitting is significantly reduced, so there is an advantage that data collection efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a mobile station showing an embodiment of the present invention;
FIG. 2 is a time chart showing the operation. In the figure, 1 is a radio, 2 is a CPU, and 3 is a modem.

Claims (1)

[Claims] In a data collection system using an arbitrary transmission method in which multiple mobile stations share a radio line with the same frequency and arbitrarily transmit data to a base station, each station has a function to determine the line usage status by other stations, and a function to determine the line usage status of other stations. We have added a function that makes transmission standby until a certain period of time has passed after the line becomes idle when a transmission trigger is applied on the own station while the line is in use, and that the certain period of time is different for each station. A data collection system that uses an arbitrary transmission method.