JPH09298493A - Transmitter, receiver and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system in which random access is possible and setting of a total communication time within a prescribed communication time limit is easily set. SOLUTION: A transmitter 1S being a slave set is provided with a pseudo noise generating section 4 generating a pseudo noise code, a timing decision section 5 to decide a transmission timing of transmission data synchronously with a pseudo noise code generated by the pseudo noise generating section 4 and a data transmission section 6 conducting data transmission for a prescribed number of times within a prescribed time based on the timing decided by the timing decision section 5. Furthermore, a receiver 1R acting like a master station is provided with a pseudo noise generating section 8 generating a pseudo noise code corresponding to a plurality of the transmitters 1S and a data reception section 9 receiving the transmission data synchronously with the pseudo noise ode code generated by the pseudo noise generating section 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of communication systems of random access type, and more particularly to communication systems for unidirectional communication.

[0002]

2. Description of the Related Art Conventionally, various devices called telemeters or telecontrols (hereinafter referred to as telemeters) have been developed as devices for collecting various information about nature such as temperature, water temperature and water level. There is. FIG. 5: is a figure which shows the specific example of the conventional telemeter system, and has shown the telemeter system which measures the road surface temperature of a road.

A telemeter system 11 shown in FIG. 5 is a system for detecting the presence or absence of road surface freezing on an asphalt road, and is roughly classified into a road surface temperature telemeter transmitter (hereinafter referred to as a telemeter transmitter) 12 serving as a plurality of slave stations.
And a road surface temperature telemeter receiver (hereinafter, telemeter receiver) 13 serving as a master station. Note that FIG.
In the example shown in (1), a total of 10 telemeter transmitters 2 are buried in the road surface of the asphalt road, and the telemeter receiver 13 is installed near the road in the tunnel.

Data communication in the telemeter system 11 includes various communication methods such as bidirectional communication by polling and unidirectional communication by terminal activation (hereinafter, terminal activation communication). In the system system shown in FIG. 5, the terminal activation communication is conventionally adopted in which data is transmitted to the telemeter receiver 13 by randomly activating a plurality of telemeter transmitters 12 at the same carrier frequency.

However, in the terminal-started communication, if the carrier frequencies are the same, collisions may occur when the transmission timings from the telemeter transmitters 12 coincide with each other, resulting in interference, resulting in improper reception. Therefore, in the above telemeter system 11, as shown in FIG.
Transmission interval T of transmission data from each telemeter transmitter 12
1, T2, T3, ... Have randomness, so that collisions of mutual transmissions are reduced and data transmission is reliably performed to the telemeter receiver 13.

FIG. 7 is a block diagram showing the main configuration of the road surface temperature telemeter transmitter. As shown in FIG. 7, the telemeter transmitter 12 includes a temperature sensor 14 and a controller 1.
5, a random number generator 16, a transmitter 17, and an antenna 18. The temperature sensor 14 measures the road surface temperature of the asphalt road and outputs the measured data to the controller 15. The controller 15 takes in the measurement data from the temperature sensor 14 and outputs the measurement data to the transmission unit 17 based on the generation timing of the random number code from the random number generator 16 at regular intervals.

The random number generator 16 generates a random number code based on a predetermined arithmetic expression, and the random number code generated here is output to the controller 15. The transmission unit 17 modulates the measurement data input from the controller 15 into a high frequency, and transmits the measurement data to the telemeter receiver 13 via the antenna 18. In this example, the antenna power in the transmission unit 17 is several hundred mW or less, and the telemeter transmitter 12 can be used as a specific low-power radio equipment like a citizen band transceiver or PHS (Personal Handy phone System). being classified.

In the above configuration, the telemeter transmitter 1
2 is the temperature data of the road surface measured by the temperature sensor 14,
It is transmitted to the telemeter receiver 13 at regular time intervals. In this case, the transmission timing of the temperature data to be transmitted is determined based on the random number code generated by the random number generator 16 in each telemeter transmitter 12. If the random number code has a high randomness and a small periodicity, the rate of collision of the transmissions from the respective transmission units 17 becomes extremely small, and the respective transmission data can be surely transmitted by the telemeter receiver 1.
It will be received at 3.

[0009]

However, in the conventional telemeter system 11 as described above, each transmission data output from the plurality of telemeter transmitters 12 is
In order to have a low correlation with each other and a high degree of randomness, the circuit scale of the random number generator 16 becomes large, which causes a cost increase.

Further, in the above specified low power radio equipment, 1
It is stipulated that the communication time for each time is within a predetermined time, and it is required that the total communication time within a certain communication time period can be freely set. However, in the system that performs data transmission based on the random number generator 16 described above, since the generation timing and the number of times of generation of random numbers are random, the transmission time cannot be accurately determined or calculated in advance. was there.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, to provide a communication system which enables random access and which can easily set a total communication time within a fixed communication time limit.

[0012]

A transmitter of the present invention is a transmitter for converting desired transmission data to be transmitted into a high frequency signal and transmitting the high frequency signal, and a pseudo noise generating section for generating a pseudo noise code code. A timing determination unit that determines the transmission timing of the transmission data in synchronization with the pseudo noise code code generated by the pseudo noise generation unit, and within a fixed time based on the timing determined by the timing determination unit. A data transmission unit that transmits data a predetermined number of times is configured to further include a sensor unit that acquires desired external information in the above configuration, and the external information acquired by the sensor unit is used as transmission data. And a data conversion unit for converting to.

A receiving device of the present invention is a receiving device for receiving transmission data transmitted from a plurality of transmitting devices,
A pseudo noise generating unit that generates a pseudo noise code code corresponding to each of the plurality of transmitting devices, and a data receiving unit that receives the transmission data in synchronization with the pseudo noise code code generated by the pseudo noise generating unit. And are provided.

In addition, the transmission data includes at least time information indicating the next transmission time, and based on the pseudo noise code code generated by the pseudo noise generating unit and the time information included in the transmission data. By providing a time predicting unit that predicts the transmission time of the transmission data, the data receiving unit synchronizes with the pseudo noise code code generated by the pseudo noise generating unit at the time predicted by the time predicting unit. It is preferable to configure so as to receive the transmission data.

Further, in the communication system of the present invention, a plurality of transmitters are provided to form a plurality of slave stations, and the receiver is configured as a master station for the slave stations.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the embodiment shown in the drawings. FIG. 1 is a block diagram showing a main configuration of a transmission device and a reception device in a communication system of this embodiment. FIG. 1A shows a transmission device, and FIG. 1B shows a reception device. Show. In the following description, it is assumed that the communication system shown in FIG. 1 is a telemeter system that measures the road surface temperature as in the conventional example shown in FIG.

The communication system 1 in this embodiment comprises a plurality of transmitters 1S as slave stations and a receiver 1 as a master station.
R and the same carrier frequency f1 and the master station:
Slave station = 1: N (N is a positive integer and N> 1), and the system is such that the slave station transmits control data or sensor data to the master station. As shown in FIG. 1A, the transmission device 1S includes a sensor unit 2, a data conversion unit 3,
The pseudo noise generating unit 4, the timing determining unit 5, and the data transmitting unit 6 are included.

The sensor unit 2 is a temperature sensor for measuring the road surface temperature of the asphalt road as desired external information. Specifically, the temperature is measured by comparing the output of the crystal sensor with a reference value. . The temperature measurement by the sensor unit 2 is performed every 10 minutes by the built-in timer of each transmitter 1S. The data conversion unit 3 includes the sensor unit 2
The measured data of the road surface temperature acquired by is shaped into a predetermined format and converted into transmission data.

The pseudo noise generation unit 4 generates M-sequence pseudo noise having a chip width of 150 msec, and the timing determination unit 5 generates the M-sequence pseudo noise generated by the pseudo noise generation unit 4. The transmission timing of the transmission data is determined in synchronization with the noise pulse rising edge (or pulse falling edge). The data transmission unit 6 performs burst transmission a plurality of times (8 times in this embodiment) based on the timing determined by the timing determination unit 5, and 130 chips (19.5).
sec), the burst transmission ends.

As shown in FIG. 1B, the receiver 1R has a time predicting section 7, a pseudo noise generating section 8 and a data receiving section 9.
It is composed of The data received by the reception device 1R, that is, the transmission data from the transmission device 1S, includes the scheduled time at which the transmission device 1S will perform the next data transmission as time information, and the time prediction unit 7 will be described.
Predicts the time for the next data reception based on this time information and the pseudo noise code code generated by the pseudo noise generation unit 8 described later.

The pseudo noise generating section 8 includes a plurality of transmitters 1S.
, And the data receiving unit 9 receives the transmission data in synchronization with the pseudo noise code code generated by the pseudo noise generating unit 8. Further, the receiving device 1R including the data receiving unit 9 is configured to, once receiving the data, completely stop the function related to the reception until the time predicted by the time predicting unit 7 and restart at the scheduled time. There is.

Next, the transmitter 1 in the above-mentioned embodiment
An operation example of S and the receiving device 1R will be described based on FIGS.

First, different pseudo-noise code codes are assigned to the respective transmitters 1S serving as slave stations, and the pseudo-noise generator 4 uses the assigned pseudo-noise code codes for each transmitter 1S. Generate a unique pseudo-noise code. Specifically, when the number of slave stations is four, as shown in FIG.
As shown in FIG. 5, different pseudo noise code codes can be generated by setting the code length to 31 bits by using the shift register of 5 stages.

FIG. 2 is a diagram showing an example of assigning a pseudo noise code to four slave stations. In FIG. 2, T indicates a communication time limit, and D indicates a timing for performing data communication. Also, when the number of slave stations is greater than four, different pseudo noise code codes can be assigned by increasing the number of stages of the shift register according to the number.

The data transmission section 6 transmits the temperature data acquired by the sensor section 2 as transmission data based on the pulse rising timing of the pseudo noise code code. At this time, since the transmission data is synchronized with the pseudo noise code, the data transmitted for each transmitting device 1S has low correlation and high noise like the random number code in the conventional example.

FIG. 3 is a timing chart showing the relationship between the pseudo noise code and the transmission timing.
The part indicated by Z indicates a collision. In addition, FIG. 4 is a diagram showing the number of collisions when transmission is performed by 10 transmitting devices, and is a result of repeating monitoring for 10 minutes 50 times. In the figure, the thick solid line indicates the number of transmissions from the slave station, the thin solid line indicates the number of collisions in the simulation result, and the broken line indicates the number of collisions in the actual measurement result.

The ratio of the number of collisions to the number of transmissions is shown in FIG.
As shown in (1), it is understood that the data transmitted by each transmitter 1S is sufficiently low and the correlation between the codes is low, and sufficient randomness is obtained. Also, the pseudo-noise code is not only highly correlated and has low noise, but also has reproducibility, so that synchronization can be achieved.
The transmission time can be limited.

As described above, in this embodiment, the time T for surely collecting data by the sensor unit 2 is set.
Is finely set, the pseudo noise code code is dispersed within the time T, and the data is transmitted in synchronization with the rising (or the falling) of the pseudo noise code code, whereby the data can be collected within the time T. As a result, reliable data transmission becomes possible.

Further, as described above, by transmitting the data for transmission including the information of the scheduled time to be transmitted next time, the receiving apparatus 1R side completely turns off the receiving function until the scheduled time, and the scheduled time is reached. Then, the receiver 1R can be started up to receive data. As a result, it is possible to significantly save power on the receiving device 1R side.

In the above-described embodiment, the telemeter system having the temperature sensor has been described as an example, but the present invention is not limited to this and can be applied to all one-way communication for performing random access. Also, when applied to a telemeter system, it is not limited to measurement of road surface temperature.

[0031]

As is apparent from the above description, according to the present invention, by using the pseudo noise code code for the processing timing of the transmission / reception data, random access is possible and total communication within a fixed communication time limit. A communication system whose time can be easily set can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main configuration of a transmission device and a reception device in a communication system of this embodiment.

FIG. 2 is a diagram showing an example of assigning a pseudo noise code to four slave stations.

FIG. 3 is a timing chart showing a relationship between a pseudo noise code code and transmission timing.

FIG. 4 is a diagram showing the number of collisions when transmission is performed by ten transmitters.

FIG. 5 is a diagram showing a specific example of a conventional telemeter system.

FIG. 6 is a diagram showing a transmission interval of transmission data transmitted from a road surface temperature telemeter transmitter.

FIG. 7 is a block diagram showing a main configuration of a road surface temperature telemeter transmitter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 communication system 1S transmitter (slave station) 1R receiver (master station) 2 sensor section 3 data conversion section 4 pseudo noise generation section 5 timing determination section 6 data transmission section 7 time prediction section 8 pseudo noise generation section 9 data reception section 11 Telemeter System 12 Road Surface Temperature Telemeter Transmitter 13 Road Surface Temperature Telemeter Receiver 14 Temperature Sensor 15 Controller 16 Random Number Generator 17 Transmitter 18 Antenna

Claims (5)

[Claims] 1. A transmission device for converting desired transmission data to be transmitted into a high frequency signal and transmitting the high frequency signal, wherein the pseudo noise generation unit generates a pseudo noise code code, and the pseudo noise generation unit generates the pseudo noise generation code. A timing determining unit that determines a transmission timing of the transmission data in synchronization with a pseudo-noise code, and a data transmitting unit that transmits data a predetermined number of times within a fixed time based on the timing determined by the timing determining unit. A transmitting device comprising: 2. The transmission according to claim 1, further comprising: a sensor unit that acquires desired external information; and a data conversion unit that converts the external information acquired by the sensor unit into transmission data. apparatus. 3. A receiver for receiving transmission data transmitted from a plurality of transmitters, wherein the pseudo noise generator generates a pseudo noise code code corresponding to each of the plurality of transmitters, and the pseudo noise generator. And a data receiving unit that receives the transmission data in synchronization with the pseudo noise code generated by the noise generating unit. 4. A receiving device for receiving transmission data, which is transmitted from a plurality of transmitting devices and includes at least time information indicating a next transmission time, and pseudo noise corresponding to each of the plurality of transmitting devices. Pseudo noise generating section for generating a code code, and a time predicting section for predicting a transmission time of the transmission data based on time information included in the pseudo noise code code and the transmission data generated by the pseudo noise generating section. And a data receiving unit that receives the transmission data in synchronization with the pseudo noise code code generated by the pseudo noise generating unit at the time predicted by the time predicting unit, . 5. A plurality of slave stations are configured by providing a plurality of transmitters according to claim 1 or 2, and the receiver according to claim 3 or 4 is configured as a master station for the slave stations. Communication system.