JPS61280129A - Position information collecting device for mobile body - Google Patents

Abstract

PURPOSE:To eliminate the need for a receiver in a mobile station and to attain small size and light weight by setting the reception zone of each reception station so as not to be overlapped, changing at random the sending interval of each mobile station and allowing a base station to display or record the relation between the zone sectioned by each reception station and a mobile body existing in it. CONSTITUTION:The reception ranges 8A, 8B,... of reception stations 3A, 3B,... are set narrower so as not to be overlapped together and in limiting the reception range to 3m, the transmission output can be weak and the power consumption is reduced. On the other hand, since the mobile body 1 at the outside of the reception is increased, it is discriminated that the mobile body passing a gate 7A is in the zone A and the mobile body passing a gate 7B is in the zone B. Further, when the gate 7B is passed for an odd number of times, the mobile body is discriminated to be in the zone B and when even number of times, it is discriminated that the mobile body is in the zone A. The mobile station 2 is for transmission only and sends automatically and repetitively a specific identification signal. All the mobile stations use the carrier of the same frequency and sends the own identification signal by applying direct FM modulation to the carrier or FSK modulation to the subcarrier.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position information collection device for a mobile body that uses a distributed reception method.

[Conventional technology]

Methods of detecting the current location of a moving object using radio waves include:
Taking automatic vehicle position display (AVM) systems as an example, the 0-dispersion transmission method, which includes a distributed transmission method, semi-automatic method, and distributed reception method, is also called the signpost method, and uses position information signals ( sign post signal)
When the mobile station receives the position data, the mobile station sends the position data along with the individual signal back to the individual signal receiver. If a polling method is used in conjunction with this to avoid data collisions, distributed stations will need polling signal transmitters in addition to sign posts, and mobile stations will need sign post receivers, polling signal receivers, and A separate signal transmitter is required.

By the way, taking a mine shaft as an example, some workers work in a specific area, while others patrol multiple areas for security reasons, so it is important to know the current location of each worker. This is essential in case of emergencies. However, if the mobile station carried by the worker for this purpose is large or heavy, as in the case of a distributed transmission system, this is not preferable because it increases the burden on the worker who also carries lamps, batteries, and the like.

Therefore, when considering the other two methods, the semi-automatic method, which requires the operator to set the position every time he or she moves from one area to another, is complicated to operate and is not reliable.

In this respect, the distributed reception method, in which the mobile station requires only an individual signal transmitter, is preferable because it also allows automatic transmission.

[Problem that the invention seeks to solve]

However, because the distributed reception method has a simple configuration in which multiple receiving stations are distributed within a mobile range, and the mobile station is only equipped with a transmitting function, when two or more mobile stations transmit simultaneously, some or There may be cases where not all are received. The present invention attempts to improve this point.

[Means for solving problems]

The present invention attaches transmission-only mobile stations to a plurality of mobile bodies moving on a predefined route, causes each mobile station to repeatedly transmit a unique identification signal, and transmits a unique identification signal along the movement route of the mobile bodies. In a mobile location information collection device in which multiple receiving stations are distributed and the received signals of each receiving station are collected by a common base station via a wired line, the receiving area of each receiving station does not overlap. At the same time, the transmission interval of each mobile station is changed randomly, and the base station displays or records the relationship between the area divided by each receiving station and the mobile objects existing there. This is a characteristic feature.

[Effect]

The reception rate of the distributed reception method can be increased by shortening the length of the identification signal transmitted by each mobile station and randomizing the transmission interval. Furthermore, this type of mobile station has a simple configuration and is convenient to carry, and is therefore advantageous in realizing a system for grasping the distribution of personnel in a mine shaft. This will be explained in detail below with reference to illustrated embodiments.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which (a) is a block diagram of the entire system, and (b) is a block diagram of the inside of a mine shaft. In the figure, 1 is a mobile object (in this example, a worker), 2 is a portable mobile station, and 3A to 3
T is a distributed receiving station, 4A to 4T are wired lines, 5
is the monitoring center equipment (base station). Receiving station 3A-3
T is 3A along the movement route in the mine shaft 6, for example from the entrance to the smell inside the mine.

3B, . . . , and the areas divided by each receiving station are called A, B, . . . . In this case, it is preferable to provide gates 7A, 7B, etc. that narrow the passage so that the moving objects 1 pass in a line through the installation locations of the receivers 3A, 3B, etc. .

Receiving range 8A of receiving stations 3A, 3B,...
8B.

. . . are narrow and set so that they do not overlap each other.

This is a balance with the transmission output of the mobile station 2, but if the reception range is limited to about 3 m, the transmission output can be a weak output that is not subject to the regulations of the Radio Law, and power consumption can also be reduced. On the other hand, the number of cases where the mobile object is outside the reception range increases, so
At the center 5, it is necessary to determine which region the vehicle has entered from the direction of passage through the gates 7A, 7B, . . . . For example, game)? A mobile object that has passed through A is determined to be in area A, and a mobile object that has passed through 7B is determined to be in area B. A mobile object traveling back and forth between areas A and B is judged to be in area B if it passes through gate 7B an odd number of times, and area A if it passes through gate 7B an even number of times.

The mobile station 2 is for transmission only, and automatically and repeatedly transmits individual identification signals (individual signals). All mobile stations use carrier waves of the same frequency and transmit their own identification signals (codes) by directly FM modulating the carrier waves or by FSX modulating subcarriers. Each identification signal has a length of 60 ms at a time, for example, as shown in FIG. 2, and includes frame and bit synchronization signals, check bits, and the like. In this example, the repetition interval of this identification signal is set to 100m from a minimum of 100m5 to a maximum of 2s.
There are 20 levels in 5 increments, and these are randomly switched using a random number table. Therefore, when two mobile stations 2 enter the reception range 8 of the same receiving station 3 at the same time, the probability that two identification signals will overlap is quite high the first time, but the probability that the same identification signals will overlap consecutively is very high. decreases to Therefore, if the speed of the moving body 1 is 1 m/s,
Further, if the reception range is 4 m, each mobile station 2 transmits at least twice within the same reception range, so a reception rate of 99% can be obtained. At this time, the gate 7 prevents a large number of moving objects from entering the same reception range at the same time, but this function can also be replaced by traffic rules (such as passing through a checkpoint in one line).

In actual mine shafts (coal mines, etc.), the inner walls are covered with metal to prevent cave-ins, so there is a lot of reflection, and low frequencies are severely attenuated. Therefore, radio waves in the 800 MHz band, for example, are generally used to extend the communication distance. In such a case,
If the reception range 7 is narrow as in the present invention, the transmission output of the mobile station 2 can be weak, and even if the frequency is low (for example, 40
0MI(z) can be achieved.

The monitoring center equipment 5 includes a wired line terminal that collects the received signals from the receiving stations 3A to 3T through the wired lines uA4A to 4T, a CPU that processes the signals, and a display that displays the processing results of the CPU and a printer for printing. etc., so that it is possible to understand which moving objects are in which areas. Note that the present invention can also be applied to tunnels, underground malls, inside buildings, etc.

〔Effect of the invention〕

As described above, according to the present invention, since a distributed reception method is adopted, there is no need for a receiver in the mobile station, and there are advantages that the mobile station can be made smaller and lighter, and does not require position setting by the mobile unit. In addition, the installation position of the distributed receiving station can be changed or newly installed at will in response to the expansion or change of the movement range. Furthermore, since the time required for each mobile station to transmit an identification signal is short and the transmission intervals are random, a high reception rate can be ensured even when a plurality of mobile stations pass through the same reception range. Furthermore, since the mobile object passes near the reception station as a checkpoint, the reception range is narrow and the transmission distance is also short. Therefore, the transmission output may be weak and the frequency may be low.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of its identification signal. In the figure, 1 is a mobile body, 2 is a mobile station, 3 is a receiving station, 4 is a wired line, 5 is a base station, 6 is a mine shaft, 7 is a gate, and 8 is a reception range. Applicant Fujitsu Ten Ltd. Representative Patent Attorney Minoru Aoyagi (min,) (mdX,) Hyoma IJ (No. Q Name J Otsuguchi 11 Ladder Figure 2)

Claims (1)

[Claims] A transmission-only mobile station is attached to a plurality of mobile bodies moving along a predefined route, and each mobile station repeatedly transmits a unique identification signal, and a plurality of receiving stations are attached to the mobile body along the travel route of the mobile body. In a mobile location information collection device that distributes and collects the received signals of each receiving station at a common base station via a wired line, the receiving area of each receiving station is set so as not to overlap, and A mobile device characterized in that the transmission interval of each mobile station is randomly changed, and the base station displays or records the relationship between the area divided by each receiving station and the mobile objects existing there. Body position information collection device.