JPS62269522A - Slave station equipment in avm system - Google Patents

Abstract

PURPOSE:To eliminate crosstalk at the master station side by generating a random number in a slave station so as to check the presence of a carrier sent from other slave station at a time corresponding to the random number and sending information to a master station when no carrier is detected thereby making the data transmission from plural slave stations efficient. CONSTITUTION:In receiving a polling signal from a base station via an antenna 10 and a receiver 20, a mobile station sets a time T of a timer in a transmission controller 52 consisting, e.g., of the software to a present time T0. The time T0 is set because the data signal of the mobile station and the polling signal from the base station are sent/received in time division and subject to timer management. Whether or not the mobile station exists within an area designated by the base station is checked and in case of the station in existence, a random number Tr from a random number generator 15 is read, a carrier is detected at a point of time when the number Tr is within the mobile station sending enable time Ts and the present time T is equal to the converted time Tr, and if no carrier is detected, the carrier is used from the other mobile station to the base station and it is discriminated as the absence of data transmission and the data is sent from the mobile station to the base station.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention calls a plurality of car-pattern mobile stations, which are child stations, by a polling method from a base station, which is a parent station, and the base station receives information about the mobile stations. This invention relates to a slave station device in an AVM system.

[Technical background of the invention and its problems] In order to monitor multiple vehicles, such as home delivery vehicles and taxis, from a central base station, each vehicle is equipped with a wireless device and each vehicle is used as a mobile station. Various AVM systems have been developed in which the wireless device of each vehicle is called by a polling method to send information about each mobile station to a base station, and information is exchanged between each mobile station and the base station.

An example of a data transmission method for a mobile station in such a system is disclosed in Japanese Patent Laid-Open No. 57-20054. In this method, in order to reduce interference when multiple terminal stations, that is, multiple mobile stations transmit information to the base station at the same time, data transmission from the mobile station to the base station is combined with data registration transmission. The registered data is divided into transmissions for changing the registered data, separate time slots are provided corresponding to each divided time slot, that is, a time slot for registration and a time slot for changing, and the data is transmitted through separate time slots. It is configured as follows.

However, even with this type of system, after data registration is completed in many mobile stations, there will be an increase in the number of mobile stations transmitting data to the base station in changing time slots, so interference will naturally occur at the base station. There is still a problem that the number of opportunities for communication to occur increases without much change, and the interference situation at the base station still remains unresolved.

[Purpose of the Invention] This invention has been made in view of the above, and its purpose is to smoothly and efficiently transmit data from a slave station, which is a mobile station, and to transmit data from a master station, which is a base station. An object of the present invention is to provide a slave station device in an AVM system that eliminates interference in the AVM system.

[Summary of the Invention] In order to achieve the above object, the present invention provides a slave station device in an AVM system in which information is transmitted from a slave station called by a master station by a polling method to a master station on a carrier wave, as shown in FIG. As shown in FIG. 1, a random number generating means 1 generates a random number, and a carrier wave detecting means reads the random number from the random number generating means and detects the presence or absence of a carrier wave being transmitted from another slave station at a time corresponding to the random number. 3, and a transmitting means 5 that multiplies information on the carrier wave and transmits the information to the master station when the carrier wave detecting means does not detect a carrier wave.

[Embodiments of the invention] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 2 is a block diagram of a slave station device in an AVM system according to an embodiment of the present invention. A slave station device (not shown in the figure) is mounted on each of a plurality of delivery vehicles and used as a mobile station, and each is called by a polling method using radio from a base station (not shown), which is a master station. In response to this, predetermined information, such as position information of the own vehicle, is transmitted to the base station, or information is transmitted from the slave 8 devices to the base station as necessary, so that the base station can identify each vehicle. It is used for monitoring.

Therefore, this slave station device includes an antenna 10 for transmitting and receiving radio waves to and from a base station, a reception m20 whose input side is connected to the antenna 10, and receives transmission waves from the base station or another mobile station. A transmitter 30 whose output side is connected to the antenna 1o and transmits information to the base station, and the transceiver 2
0.30, which converts the received signal from the receiver 20 into a signal in a predetermined format that can be processed internally, and transmits information to be transmitted to the base station via the transmitter 130 and antenna 10. A modulator/demodulator 4o that converts into a predetermined signal format, a random number generator 51 and a transmitter connected to the modulator/demodulator 40! and a transmission control device 50 having 11 controllers 52. Further, the slave station device is connected to an antenna 60 for receiving a Signbost position data signal or a Loran C signal in order to detect the position of its own vehicle, and is connected to the antenna 60 to receive and detect the signal through the antenna 60. position data or Loran C signal reception 1170 for supplying own vehicle position data to the transmission controller 52;
and a voice communication microphone 80 which is connected to the transmission controller 52 and the modem 40 via the audio bus switch 81 and is used by the vehicle occupant to communicate with the base station by voice; The transmission system m
device 52 and receiving t! ! 20 for receiving voice information from the base station, and the voice communication microphone 80 and speaker 100 for voice communication with the base station. The switch 90 includes various switches 90 including a breath talk switch and the like.

The transmission control device 50 is composed of, for example, a microcomputer to control the overall operation, and performs the processing shown in the flow chart shown in FIG. 3 using a program stored in its memory section.

The operation of the apparatus shown in FIG. 2 will be explained below according to the flowchart shown in FIG.

The processing flow shown in FIG. 3 is started by turning on the power to the slave station device, initialization is first performed, and initial values necessary for subsequent operations are set (step 201).

Then, the vehicle number of the own vehicle in which the slave station device is installed is read from a pre-stored memory and stored in the mobile station transmission data memory (step 202).

Next, the polling signal from the base station is transmitted to the antenna 10.
, performs an operation of receiving via the receiver 20 (step 203). If this polling signal is received, the time T of a timer made of, for example, software in the transmission controller 52 is set to the current time To (step 204).
), here, the reason why the current time To is set is to time-divisionally transmit and receive polling signals from the base station, data signals from the mobile station, voice signals, etc., and to manage the timer.

After receiving the polling signal from the base station and setting the current time, it is checked whether the mobile station exists within the area specified by the base station, and if the mobile station exists within the specified area, the random number generator 51 Read the random number Tr from
Checks whether "is within the mobile station's transmittable time TS, and if it is within the mobile station's transmittable time TS, the current time To
Wait until the time T of the timer set, that is, the current time T, becomes equal to the time 1'-r represented by the random number Tr, and when the current time T becomes equal to the time Tr, the carrier, which is the carrier wave, is activated. (Step 2)
06-210>.

The numbers represented by the random number Tr are considered to be time data Tr. The carrier is detected when the time 1''r represented by this random number Tr is within the mobile station transmission available time TS and the current time T is equal to the time Tr represented by this random number Tr. That is, random number 7r
The time Tr represented by determines the timing at which the mobile station detects the carrier, and if the carrier is not detected at this timing, data transmission from another mobile station to the base station using the carrier is performed. In this case, the mobile station is trying to transmit data to the base station. Like this, Ki1! By detecting the absence of the base station and using the random number Tr to determine the timing of transmitting data such as fys', collisions with other mobile stations during carrier detection are avoided as much as possible, and interference in data transmission to the base station is avoided. It is being prevented.

To explain in more detail, when a mobile station receives a polling signal from a base station, it transmits predetermined data to the base station, but in this case, the transmission timing is set to avoid interference with other mobile stations. The random number Tr output from the random number generator 51 is used as time data representing the transmission timing, thereby making the timing completely unrelated to the transmission timing from other mobile stations, and further expressed by the random number Tr. At time Tr, in order to avoid interference with other mobile stations, it is checked whether there is a carrier for data transmission from other mobile stations.

When transmitting data from each mobile station to the base station, it is transmitted on a carrier, so by confirming that no carrier exists, you can avoid interference with other mobile stations. be.

As described above, when it is detected that there is no carrier for data transmission from another mobile station, the mobile station data is transmitted to the base station in a predetermined transmission format (steps 211 and 212).

If a carrier from another mobile station is detected in step 211, the process returns to step 207 and the random number generator 5
The random number Tr is read again from 1 and the same process is performed until it is detected that there is no carrier.

After confirming that there is no carrier as described above and transmitting the mobile station data to the base station, the process proceeds to step 213. Further, if the polling signal is not received in the step 203, the lower time of the timer is set to the current time To, and the process proceeds to step 205>, step 213, and furthermore, in the step 206, it is determined that the polling signal does not exist within the designated area. If it is found, or if the time Tr corresponding to the random number Tr is not within the mobile station transmittable time TS in step 208, the process similarly proceeds to step 213.

Step 213 and subsequent steps are processes for performing voice transmission/reception operations, and for this purpose, in step 213, it is first checked whether the current time T is greater than the mobile station transmittable time Ts, and the current time T is determined as the mobile station transmittable time Ts. The mobile station waits until the current time T becomes larger than Ts, that is, until the current time T passes the mobile station transmittable time TS. When the current time T passes the mobile station transmittable time TS, processing within the voice communication time slot is performed in subsequent steps.

First, in step 214, the mobile station checks whether there is a transmission request, and if there is a transmission request, it is checked whether a carrier from another mobile station exists (steps 215 and 216). If there is no carrier, voice transmission is possible without interference with other mobile stations, so the mobile station sets the voice reply state and starts voice transmission operation (step 217). Next, in this voice transmission state, it is checked whether the current time T is within the voice communication time slot Ta (step 218). The voice transmission operation is performed within the voice communication time slot Ta. If the current time T is within the voice communication time slot Ta, it is determined in step 219 whether the transmission operation has ended.
Check it out.

If the audio transmission operation is not completed, step 218
Return to and wait for the audio transmission operation to end. When the voice transmission operation is completed, check whether the current time T has come out of the voice communication time slot Ta (step 220).
), if it has come out of the i-voice communication time slot Ta, the process returns to step 203 and repeats from the beginning, but if it still exists within the voice communication time slot Ta, it returns to step 214 and repeats the same process again. Repeat voice transmission/reception operations.

In step 218, if the current time T is not within the voice communication time slot Ta, that is, if it is out of the voice communication time slot Ta, the process proceeds to step 221 to abort the voice transmission operation even if the voice transmission operation is in progress;
Proceed to step 203 and repeat from the beginning.

If there is no voice transmission request in step 214, the process proceeds to step 222, where the voice reception state is set and the voice reception operation is started. Thereafter, the voice reception state is continued until the current time T exceeds the voice communication time slot Ta8, and when the time T exceeds the voice communication time slot Ta8, the voice reception operation is terminated (steps 223 and 224), and the process returns to step 203 to repeat from the beginning.

As described above, in this embodiment, transmission and reception time is time-divisionally processed using time slots, and data transmission by a mobile station is performed after confirming that no carrier exists, so that it can communicate with other mobile stations. This is to prevent any confusion. Note that the above processing of the mobile station can be similarly applied to transmission control at the base station.

In the above embodiment, a case has been described in which a large number of home delivery systems are monitored by a base station, but the present invention is not limited to this and can be applied to other similar devices.

[Effect of the Invention J As explained above, according to the present invention, since the transmission is performed after confirming that there is no carrier wave from another slave station at the time corresponding to the random number from the random number generating means,
At the same time, there is no interference with transmissions from other slave stations, and transmission can be performed smoothly and efficiently. Furthermore, in this case, a random number is used and the presence or absence of a carrier wave is detected at the time corresponding to this random number, so even if another slave station tries to perform a carrier wave detection operation in the same way, the time based on the random number is usually ignored. Since it is extremely rare for a mobile station to perform a detection operation at the same time as another slave station, not only the carrier detection operation but also the subsequent transmission operation are unlikely to collide with other slave stations, ensuring smooth operation. transmission operations are possible.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to this claim, FIG. 2 is a block diagram of a slave station device in an AVM system according to an embodiment of the present invention, and FIG. 3 is a flowchart showing the operation of the device in FIG. 2. 1...Random number generation means 3...Carrier detection means 5...Transmission means 1st section

Claims (1)

[Claims] Random number generating means for generating random numbers in a slave station device in an AVM system in which a slave station called by a master station by a polling method carries information on a carrier wave and transmits it to the master station;
A carrier wave detection means reads a random number from the random number generation means and detects the presence or absence of a carrier wave being transmitted from another slave station at a time corresponding to the random number; and when the carrier wave detection means does not detect a carrier wave, information is transmitted to the carrier wave. A slave station device in an AVM system, characterized in that it has a transmitting means for transmitting a message to a master station.