JPH05316021A - Position recognition device - Google Patents

Abstract

PURPOSE:To attain position recognition by means of a radio wave even for a short distance. CONSTITUTION:A transmitter 1 sends a spread spectrum signal and it is received by plural receivers 2. Then a controller 3 selects a reception output with a highest correlation, then it is discriminated that the transmitter is in existence in the vicinity of the receiver. By which of plural receivers a signal is received is identified by an ID number sent from the receiver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position recognizing device which uses a spread spectrum communication system and detects a position of a transmitter in which a fixed receiver is moving.

[0002]

2. Description of the Related Art Conventionally, a method called GPS using three or four artificial satellites has been used as a device for accurately recognizing a position. This is to find the time difference for the radio waves from the artificial satellites to reach the receiving point, then find the distance between the receiving station and the satellite, and determine the position of the receiving station in the manner of triangulation.
The receiving station determines it by itself.

[0003]

However, such a conventional method is not practical unless the distance between the radio waves passing through different paths causes a time difference, and the radio waves from the artificial satellite can be directly received. Since it can only be used in places, it is impossible to recognize the position indoors or in the shade.

The present invention has been made in view of such circumstances, and provides a device capable of recognizing a position by radio waves even at a short distance.

[0005]

In order to solve the above problems, the present invention provides a transmitter for transmitting a spread spectrum signal, a plurality of receivers for receiving the spread spectrum signal from the transmitter, and each receiver. And a controller for detecting the position of the transmitter based on the correlation value of the signal received by the machine.

[0006]

The transmitter 1 transmits a spectrum spread signal, which is received by a plurality of receivers 2. Then, the controller 3 selects the reception output having the highest correlation, and it is determined that the transmitter is near the receiver. From which of the multiple receivers was received,
It is identified by the ID number sent from the receiver.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention. As an example, it is used for personal position recognition, and a receiver is arranged for each room in each room so that an individual who wants to recognize it can use it. I
An example in which a transmitter having D information is used to know who is in which room, and when the transmitter 1 moves, the moving position is detected on the receiving side will be described. Reference numerals 2 _{1 to} 21 _n are receivers that are distributed and arranged at necessary locations, and the output of the receiver 1 is the controller 3
The position of the transmitter 1 is detected there.

FIG. 2 is a block diagram showing the internal configuration of the spread spectrum communication transmitter 1. When the carrier of the frequency f1 generated by the reference carrier generating circuit 12 is modulated by the data of the memory 11 in the baseband modulator 13, A narrow band signal as indicated by the symbol A is obtained. Then, the pseudo-random code generation circuit 1 is generated by the narrow band signal.
When the pseudo-random code generated in 5 is modulated by the spread spectrum modulator 14, a signal whose frequency is spread as shown by symbol B is obtained, and the signal is transmitted from the antenna 16.

FIG. 3 is a block diagram showing the internal configuration of the spread spectrum communication receiver 2. The signal received by the antenna 21 is demodulated by the spread spectrum demodulation section 23 by the signal generated by the pseudo random code generation circuit 22. It

A pseudo-random code used on the transmitting side,
The pseudo-random code used on the receiving side is the same, and when it is synchronized, a sharp correlation peak is generated.
A narrow-band signal as shown in the part (2) is supplied to the baseband demodulation unit 25, where it is baseband demodulated, and the same signal read from the memory 11 of FIG. 2 is supplied to the controller 3.

When the received signal and the pseudo random code generated by the pseudo random code generation circuit 22 are correlated, the spread spectrum demodulation section 23 detects the correlation value by the correlation value detection circuit 24 and supplies it to the controller 2. It

The correlation value detected by the correlation value detection circuit 24 shows a low value when the disturbance between the transmitter and the receiver is large,
It shows a high value when there is little disturbance. Since the spread spectrum communication has a bandwidth more than several thousand times wider than that of the conventional communication method, it is not easily affected by disturbance. But,
It is not totally unaffected, and when the distance between the transmitter and the receiver is short, the influence of the disturbance is small, and the influence of the disturbance tends to increase as the distance increases.

When the influence of the disturbance is small, the correlation value is large as shown in FIG. 4A, but when the influence of the disturbance is large, the correlation value is large.
The correlation value becomes smaller as shown in (b). Therefore, when the position detection range is fixed, the distance between the transmitter and the receiver corresponds to the correlation value.

In the present invention, a plurality of receivers are arranged for this detection, and position detection is performed based on the output from the receiver having the largest correlation value. Then, an identification code (hereinafter referred to as an ID) is attached to the output from each receiver,
It is made possible to know from which receiver the position information detected by the controller 3 is supplied.

FIG. 5 shows an example of the spread spectrum demodulation section 23. The digital data d (t) and the spread code p (t) are input in the modulated d (t) .p (t) state.
The input n-bit signal is received by the shift register 23a of N = 2 ⁿ −1 stages, and each has a plus 1 or minus 1 indicated by a _{1 to} a _N which is the same as the one cycle pattern of p (t). By being multiplied by the coefficient output from the coefficient circuit 23b and added by the adder 23c,
Positive and negative correlation peaks are generated for "1" and "0".

FIG. 6 shows an example of the configuration of the controller 3 when there are a plurality of transmitters 1. The correlation value discriminated by the correlation value discriminating circuit 31 is received in order to discriminate from which receiver the signal is received. The transmitter ID discriminating circuit discriminates and the transmitter ID discriminating circuit 33 discriminates from which transmitter the signal is transmitted.

The circuit of FIG. 6 is based on the premise that the signals from the transmitters do not collide. If a collision occurs, the previously accessed data is processed, and if the next received signal does not collide, It may be used for updating the data.

FIG. 7 shows an example in which signals from such a plurality of transmitters are received by a plurality of receivers, and the signal from transmitter #A is most often received by receiver # 2. The correlation value is large, the signal from transmitter #B has the largest correlation value when received by receiver # 4, and the signal from transmitter #C has the highest correlation between those received by receivers # 1 and # 2. The signal received from the receiver # 1 has the largest correlation value among the signals from the transmitter #D.

In such a case, each transmitter is in the vicinity of the receiver having the highest correlation value. The accuracy of detection varies depending on the position and number of receivers, but when used for personal position recognition, it is the size of one room, which is 5m x
It is sufficient to be able to identify a space of about 5 m. To further improve accuracy, the main receiver is placed in the center of the room and the sub-receiver is placed around it. Then, the position recognition uses the information of the main receiver. When the data of the transmitter is received by the main receiver, it is expected that it is also received by the sub-receiver arranged around it. In the environment where the signal is received in the adjacent room, when the level of the correlation value of the main receiver in the adjacent room cannot be determined, the correlation value levels of the sub-receivers are compared with the receiver in the room next to it. In this way, by increasing the number of receivers and increasing the judgment material, the position can be specified with high accuracy.

[0020]

As described above, according to the present invention, when the spread spectrum communication is used, the position detection is performed by using the correlation value, so that the position detection can be easily performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a transmitter for spread spectrum communication.

FIG. 3 is a block diagram showing a configuration of a spread spectrum communication receiver.

FIG. 4 is a diagram showing a correlation state of received signals.

FIG. 5 is a diagram showing a configuration of a spread spectrum demodulation unit.

FIG. 6 is a diagram showing a configuration of a controller when there are a plurality of transmitters.

FIG. 7 is a diagram showing a state of correlation values received by a plurality of receivers when there are a plurality of transmitters.

[Explanation of symbols]

 1 Transmitter 2 Receiver 3 Controller 11 Memory 12 Reference Carrier Generation Circuit 13 Baseband Modulation Section 14 Spread Spectrum Modulation Section 15, 22 Pseudo Random Code Detection Circuit 23 Spread Spectrum Demodulation Section 24 Correlation Value Detection Circuit 25 Baseband Demodulation Section 31 Correlation Value discriminating circuit 32 Receiver ID discriminating circuit 33 Transmitter ID discriminating circuit

Claims (1)

[Claims] 1. A transmitter for transmitting a spread spectrum signal, a plurality of receivers for receiving the spread spectrum signal from the transmitter, and a position of the transmitter based on a correlation value of signals received by each of the receivers. A position recognition device including a controller that detects a position.