JPH08211141A - Positioning system - Google Patents

Abstract

PURPOSE: To provide a positioning system by which the position of a mobile station can be decided precisely without precisely synchronizing respective fixed stations in terms of time in order to solve a problem caused by the necessity of the synchronization in terms of time between the respective fixed stations in a system in which the position of the mobile station is decided by the radio- wave arrival time of the fixed stations. CONSTITUTION: A positioning system is constituted of at least three fixed stations A, B, C, of a mobile station M which is provided with only a transmitting function and of a repeater station R (a fixed position) which receives a signal from the mobile station M and which transmits the received signal as it is. A time delay to a certain extent occurs until the repeater station R receives radio waves from the mobile station M so as to transmit them. As a result, the fixed stations detect a signal S directly received from the mobile station M and a signal S through the repeater station in different times. In the positioning system, a position is decided by utilizing the time difference between the two signals detected in the different times. Consequently, the positioning system does not require the synchronization in terms of time between the respective fixed stations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning system for determining a position on the ground, and more particularly to a positioning system for detecting a relatively narrow position (local area) including indoors.

[0002]

2. Description of the Related Art The most popular method for determining the position on the ground at present is GPS. This is to receive microwaves emitted from three or more satellites on an orbit around the earth and determine a three-dimensional position by a pseudo distance between the satellites. L1 for positioning from GPS satellites
Two waves called the band (1.6 GHz) and the L2 band (1.2 GHz) are transmitted at all times, and there are two types of digital codes, the C / A code and the P code, in the L1 band.
There is only a P code in the L2 band.

The C / A code is open to the public, but the P code is secret for military use. The C / A code has a bit period of 1.023 Mbps and the P code has a bit period of 10.23 Mbps. Therefore, it is possible to perform highly accurate positioning by using the P code. Furthermore, since the P code is in both the L1 and L2 bands as described above, the radio wave propagation velocity in the ionosphere can be corrected by utilizing this, and positioning with higher accuracy can be performed.

However, as described above, the P-code is for military use and cannot be used by general users, and the GPS system is not suitable for US security.
In case of an emergency, it may be converted into a secret code called Y code. As described above, the current GPS system cannot perform high-precision single positioning in real time, and there is a possibility that the GPS system cannot be used when the United States is in an emergency. Also,
Due to its nature, GPS is intended to determine the position in a wide area, and cannot be used in a room where radio waves from satellites do not reach.

On the other hand, at present, there are the following methods for detecting the indoor position. (1) Method using ultrasonic wave This is a method of emitting an ultrasonic wave and measuring the time until the reflected wave arrives to obtain the distance. According to this method, since the speed of the sound wave is slow, the distance can be measured with relatively high accuracy. (2) Method of detecting changes in magnetic field Information for artificially forming a magnetic field in a room and attaching a search coil capable of measuring a magnetic field in a three-dimensional direction to a moving body and detecting a position from a three-dimensional change in the magnetic field. Are used in virtual reality. (3) Method of using leaky radio wave guiding path This is a method of laying a cable that leaks radio waves along the moving path of a mobile carrier and using it to control movement. (4) Method of image processing by camera This is a method of calculating the position from images at a plurality of locations obtained by installing the camera on the ceiling or the like. (5) Method Using Spread Spectrum System Next, there is a positioning system using radio waves that utilizes the characteristics of spread spectrum communication. The spread spectrum communication system is a system used for communication by spreading a spectrum wide band limited to a certain band. There are many documents on spread spectrum communication systems, and one example is "Spread spectrum communication system system" by Mitsuo Yokoyama (Science and Technology Publishing Company, published May 30, 1988). In the spread spectrum, the energy of the transmission signal is spread over a band much wider than the band required for information transmission and occupies a wide communication band. The receiving side despreads the spectrum using the code used for spread spectrum and demodulates it. The spread spectrum method is currently classified into a direct spread method and a time hopping method, but the direct spread method is mainly used for positioning.

The direct spread system is a system in which a signal for spreading a spectrum is multiplied by a signal in a band much higher than that to realize spread spectrum, and a signal for spreading for this purpose satisfies the following conditions. There is a need. A large number of signal types that can be assigned to many users. Cross-correlation is small. To have a sharp autocorrelation so that signals can be reliably captured and synchronization can be easily established. Random and long cycle, difficult for a third party to decipher.

As a spreading code satisfying the above conditions,
Pseudo Noise (PN) codes are typically used. Also, PN
As a code, an M-sequence code or a GOLD code is often used. From the above-mentioned documents, the characteristics of spread spectrum communication are: (a) Interference and interference are rarely given or received. (B) The ability to conceal a signal increases. (C) It is hard to be intercepted. (D) A communication system suitable for confidential communication can be configured. (E) Distance measurement and time synchronization are possible at the same time as communication. (F) Code division multiple access is possible, and the system brings about an elegant deterioration as the number of users performing simultaneous communication increases. (G) Fading measures can be easily taken.

Since the spread spectrum method spreads the spectrum in a wide band and is used, the wide band can improve the distance measurement performance. That is, when the bandwidth of the transmission line is narrow, the response of the pulse waveform becomes slow and the distance resolution is lowered, but when the bandwidth is wide, the rise of the pulse is steep and the time resolution, that is, the distance resolution is improved. Due to these reasons, the spread spectrum method is suitable for distance measurement.

In the following description, the positioning system using the spread spectrum system is classified into two systems, a "transmission only system" and a "repeater system" (described later). In the following, "moving body" means something whose position is desired to be measured (for example, lost child, automatic guided vehicle), and "mobile station" means a device equipped with or installed in the moving body and having a reception and / or transmission function. , "Fixed station" means a device fixedly installed in the local area for recognizing the position of the moving body from the position of the mobile station, "reference station" controls the operation of the fixed station, and Means a device for determining the position of a moving body by collecting and processing the above data.

The "transmission-only method" means a positioning system in which a mobile station has only a transmission function. In the transmission-only method, a plurality of fixed stations receive data (signals) transmitted from the mobile station, and the received data are received. Measure the distance based on. In this case, the fixed station cannot measure when the mobile station transmitted the signal, so the relative time difference between the mobile station and multiple fixed stations can be measured, but the absolute distance (time) is measured. You cannot do it. Therefore, in order to know the position of the moving body, 3
It is necessary to calculate the position using the hyperbolic navigation used in Loran C etc. by using the signals received at the fixed stations at more than one place at the same time. It should be noted that the transmission-only type mobile station need only have a transmission function, and the device can be made compact and can be manufactured at low cost.

FIG. 5 shows a conceptual diagram of the transmission only system. In FIG. 5, 51 is a mobile station (moving body), and 52-1 to 52-4 are fixed stations. The "repeater system" is a positioning system in which a mobile station has a reception and transmission function. In the repeater system, a mobile station receives a signal transmitted from a fixed station, and, for example, converts the frequency and transmits again. . The fixed station receives the transmission signal from the mobile station, calculates the time required for the radio wave to make a round trip to and from the moving body based on the transmission start time of the fixed station, and calculates the distance. In the repeater system, the distance can be measured based on the fixed time, so that the absolute distance can be measured. However, in the repeater system, the mobile station needs to have both receiving and transmitting functions, which increases the system scale.

FIG. 6 shows a conceptual diagram of the repeater system. Figure 6
Then, the mobile station 61 changes the frequency f1 from the fixed station 62 to the frequency f
It is converted to 2 and returned to the fixed station 62. Although only one station (fixed station 62) is shown as a fixed station in FIG. 6, in order to know the two-dimensional position of the mobile station, three or more fixed stations are fixed in the same manner as the above-mentioned transmission-only system. is necessary.

[0013]

However, in the method (1) using ultrasonic waves, there is a problem that the attenuation due to the atmosphere is large and it is impossible to measure a long distance, and the sound velocity has a large temperature dependency. In the method (2) of detecting a change in magnetic field, a three-direction coil must be attached to a plurality of places in order to form a magnetic field in the room, and the position can be determined from the measured magnetic field. There is a problem in that the calculation algorithm is complicated. With the method of using the leaky radio wave guide path of (3), the control can be performed accurately, but the movement range is limited to the place where the cable is laid, and the mobile carrier. There is a problem in that it is necessary to install such equipment in a place (for example, a factory) in which the equipment is used.
Note that instead of detecting leaked radio waves, there is also a method in which a white line or the like is drawn on the moving path and the white line or the like is tracked while capturing an image with a camera, but in any case, the range of movement is limited to the location where the white line is laid. It Further, in the method (4) of image processing by the camera, there is a problem that an algorithm for calculating the position becomes complicated and the position determination range is limited to the installation location of the camera.

In addition to the above-mentioned GPS system, there is a system using a radar device as a system for detecting the position of a moving body outdoors. In this case, the radar normally emits a short pulse until the reflected wave returns. Although the distance is calculated by calculating the time, it is necessary to concentrate and radiate the electric power in a short time, which causes a problem that the device becomes large in size.

As described above, in the above conventional method,
Detecting the position of a moving object in a room requires the installation of a fairly large-scale facility and has the disadvantage that the amount of calculation for calculating the position becomes large.

Next, in the positioning method using the spread spectrum method, the repeater method is suitable for knowing the absolute distance. However, the repeater method is as described above. However, in the repeater method, the mobile station performs both reception and transmission. Since it is necessary to provide the function, there is a problem that the system scale becomes large and the cost becomes high.

On the other hand, in the transmission only system, the mobile station only needs to have a transmission function, and the device can be made compact and can be manufactured at low cost. However, in a positioning system in which the position of a mobile station is calculated by using the radio wave arrival time of each fixed station, each fixed station needs to be synchronized in time. Therefore, when the synchronization between the fixed stations is incomplete, the reference time of the radio wave attachment time obtained by each fixed station is uncertain, and the accurate position of the mobile station cannot be calculated. That is, in the transmission-only method, it is essential to synchronize each fixed station with time.

For example, when using electromagnetic waves to measure a distance with an accuracy of 10 cm, the reference time is 1 n.
Although accuracy of s (nanosecond) is required, there is a problem that it is very difficult to synchronize in the time of accuracy of 1 ns in the transmission-only method regardless of whether the method is wired or wireless.

The present invention solves the problems caused by the need for time synchronization between fixed stations in a positioning system in which the position of a mobile station is calculated by using the radio wave arrival time of each fixed station. An object of the present invention is to provide a positioning system capable of accurately determining the position of a mobile station without requiring each fixed station to perform accurate time synchronization in the transmission only method.

[0020]

In order to achieve the above object, a positioning system according to a first invention is a positioning system using a spread spectrum communication system, and a mobile station transmitting a reference signal and a mobile station. At least 3 to receive signals from
It is characterized by comprising one fixed station and a repeater station for receiving a signal from a mobile station and transmitting the received signal.

A second invention is characterized in that, in the positioning system of the first invention, the repeater station has a frequency conversion section for converting the frequency of the received signal at the time of transmission.

According to a third invention, in the positioning system of the first invention, the mobile station is a plurality of mobile stations to which a unique PN code is assigned, and each fixed station can switch the code pattern of the PN code on the receiving side. And a time measuring unit configured as described above.

[0023]

With the above configuration, in the positioning system of the first invention, a certain time delay occurs before the repeater station R receives the radio wave from the mobile station M and transmits it. Therefore, the fixed station A receives the signal S directly received from the mobile station M.
Then, the signal S passing through the repeater station, that is, the same signal is detected at different times. The positioning system uses the time difference between the two signals detected at different times to determine the position. Therefore, the positioning system does not require accurate time synchronization between fixed stations.

In the positioning system according to the second aspect of the present invention, the frequency conversion unit converts the frequency of the received signal and transmits the signal. Therefore, it is possible to prevent interference caused by transmitting at the same frequency.

In the positioning system of the third aspect of the present invention, each fixed station further switches the code pattern of the PN code of the reference signal at an arbitrary time point, so that the time measuring means can receive signals from a plurality of mobile stations at different times. It is possible to detect the reception time of the signal from the repeater station.

[0026]

1 is a conceptual diagram showing a basic configuration of a positioning system of the present invention, in which A to C are fixed stations, M is a mobile station having only a transmission function (that is, a transmission only system), and R is a transmission station. A repeater station having a receiving function (that is, a repeater-type fixed station).

A major feature of the positioning system of the present invention is that it has a repeater station R having a repeater function,
The repeater station R has a function of returning (transmitting) the received signal as it is. In addition, a signal amplification function or a frequency conversion function may be added according to the necessity of the positioning system. The exact position of the repeater station R is known. The operation of this system will be described below. Here, the operation of the system will be described taking the fixed station A as an example, but the same applies to the other fixed stations B and C. 2 is a diagram in which the fixed station A, the repeater station R, and the mobile station M are extracted.

In FIG. 2, if the mobile station M transmits a radio wave at time T0 and the fixed station A receives a signal from the mobile station M at time T2, the time difference between the times T0 and T2 is that the radio wave is transmitted by the mobile station M.
And the fixed station A.
Further, the radio wave from the mobile station M is similarly received by the repeater station R, but the repeater station R transmits the received signal as it is.

When the attenuation of the signal received by the repeater station R is large, the signal is amplified at the time of transmission, and when there is a risk of interference when transmitting at the same frequency, the frequency is converted and transmitted. There is a certain time delay before the repeater station R receives the radio wave from the mobile station M and transmits it. Here, the time when the repeater station R receives the signal S from the mobile station M is T1, and the time when the same signal S is transmitted is T3.
And Further, the time when the fixed station A receives the signal S from the repeater station R is T4.

In the above process, the fixed station A detects the signal S directly received from the mobile station M and the signal S passed through the repeater station, that is, the same signal at different times. The positioning system of the present invention uses two signals detected at different times to determine the position.

FIG. 3 is an explanatory diagram showing signal transmission / reception timings in the fixed station A, the repeater station R, and the mobile station M. The relationship between these is expressed as follows. In the following mathematical formula, c is the propagation velocity of the radio wave, Δ
t is the time delay until the repeater station R receives the radio wave from the mobile unit M and transmits the same radio wave, and t is the fixed station A
Is the time required to receive the signal from the repeater station R after receiving the radio wave from the mobile station M.

[0032]

[Equation 1]

The above relationship can be rewritten as follows.

[Equation 2]

The following relational expression (5) can be derived from the above expressions (3) and (4).

(Equation 3)

Since Δt is known and the positions of the fixed station A (B, C) and the repeater station R are also known, t0 is known in the following equations (6) and (7). Becomes the value,

[Equation 4]

The relationship of can be derived.

The meanings of the above equations (6) and (7) mean that by measuring t, the radio wave propagates between the mobile station M and the repeater station R, and the radio wave propagates between the mobile station M and the fixed station A. This means that it is possible to obtain the difference (time difference) from the time when That is, by utilizing this time difference, it is found that the moving body M exists somewhere on the hyperbola between the fixed station A and the repeater station R (which can be drawn).

Since the hyperbolas can be similarly drawn in the other fixed stations B and C, if there are at least two hyperbolas, the position of the moving body M can be determined from the intersection of these hyperbolas. In this case, since two hyperbolas have two or more intersections and uncertainty in position determination,
As is well known in hyperbolic navigation, three or more fixed stations (ie, three or more hyperbolas) are used to eliminate intersection uncertainty.

As is apparent from the above description, as long as the mobile unit M does not move so much that an error of a predetermined accuracy or more occurs until each fixed station completes the calculation, the fixed stations A, B,
C, ... do not need to be synchronized in time.

FIG. 4 shows the transmitter of the mobile unit M in FIG.
FIG. 4 is a block diagram showing a configuration example of receivers of fixed stations A, B, and C, and FIG. 4A shows a configuration example of a transmitter of mobile unit M.
In FIG. 4A, 21 is a PN code generator (PNG), 22
Is a carrier signal generator, and 23 is a modulator, and a unique PN code is assigned to the mobile body. The transmitter of the mobile unit generates a PN code assigned to the mobile unit from the PN code generator (PNG) 21, modulates the PN code by the carrier from the carrier signal generator 22, and spreads and transmits it from the transmission antenna. .

Although not shown, the repeater station R receives the spread signal transmitted from the mobile station M at the receiving section and transmits it from the transmitting section as it is, but when the level of the received radio wave is lower than the reference value, the received signal is amplified. It has an amplifying section that operates. A frequency converter (not shown) for converting the frequency and transmitting the signal may be provided when there is a risk of interference when transmitting at the same frequency.

Next, the time measuring means for detecting the arrival time by receiving the transmission wave (spread spectrum signal) from the mobile unit by the receivers on the fixed stations A, B and C will be described. Here, the signal in which the carrier is modulated by the PN code as described above will be described. When the PN code is used as a signal, the input P is detected in order to detect the arrival time at the receiver side.
The N code and the PN code on the receiving side must be correlated to detect the time point at which the correlation peak is obtained. As a method of obtaining such correlation, there are a method using a DLL, a method using a matched filter, and a method using a convolver.

Of these, the method using the DLL can be used when the modulated waves by the PN code are continuously input. However, in the positioning system, the signal from the transmitter of the mobile unit may be transmitted intermittently for a certain period of time instead of the continuous wave in order to save the power consumption due to the radio wave transmission of the mobile unit. DLL when waves are transmitted
Matched filters or convolvers are better than matched filters.

Among them, the matched filter is a specific PN.
Since only the code patterns can be correlated, if a matched filter is used, each fixed station is equipped with as many matched filters as there are PN codes of different types from many mobiles. It has to be done, which is not realistic from the viewpoint of line scale and cost.

On the other hand, when the convolver is used, the above-mentioned inconvenience does not occur. Therefore, the arrival time is detected on the receiver side, the input PN code is correlated with the PN code on the receiving side, and the correlation is calculated. It is desirable to use a convolver to detect when the peak is obtained.

FIG. 4 (b) is a block diagram showing a basic configuration when a convolver is used for the receivers of the fixed stations A, B and C, 6 is a BPF (band pass filter), 7 and 1
3 is an amplifier, 9 and 11 are local oscillators, 8 and 12 are mixers, 10 is a convolver, 14 is a detector, and 15 is a time measuring unit. Further, in this embodiment, the convolver 10, the local oscillator 11, the mixer 12, the amplifier 13, the detector 14, and the time measuring unit 15 constitute a time measuring means.

As shown in FIG. 4B, the convolver 10
When using, the two input terminals 10a of the convolver,
The input terminal 10a of the 10b has a BPF 6, an amplifier 7,
The modulated wave by the PN code transmitted from the mobile body M is input by the local oscillator 9 and the mixer 8, and the convolver 10
A reference signal in which the carrier is modulated by a bar PN code generated by the PN code generator 16 (which is a time-reversed version of the PN code) is input to the other input terminal 10b.

By using such a reference code, the convolver 10 can take the correlation between the PN code transmitted from the mobile and the bar PN code of the fixed station, and the resulting correlation output signal is detected by the detector 14 Then, the time measuring unit 15 can detect the reception time T _1s of the signal from the moving body M from the detected time. Here, by switching the PN code pattern of the reference signal at any point in time, the receiving time T _p is similarly time measurement of the signal from the receive time T _IS and repeater stations R signals from a plurality of mobile stations It can be detected at 15.

That is, the PN code generator 1 of FIG.
It is desirable that 6 not only generate a constant bar PN code but can switch the code pattern of the bar PN code in time. Further, it is well known that such PN code switching can be easily performed by using ordinary digital circuit technology.

When the PN code of the reference signal of the convolver is switched as described above, the convolver produces a large correlation output only when the PN code having a time-reversal relationship with the PN code is input, and this is used to identify the moving body. can do.

In other words, when there are a plurality of mobile units as described above, a unique PN code is assigned to each mobile station,
In the receiver of the fixed station, P is the reference signal of the convolver.
By switching the code pattern of the N code in time,
Since only the PN code having a time-reversal relationship with the reference signal can be discriminated (from the magnitude of the correlation output), the mobile body corresponding to each PN code can be identified (that is, a plurality of mobile bodies). Can be identified).

<Application Example 1> Lost Child Search System / Position Emergency Notification System For example, as a method for knowing the position when a child gets lost or is separated from a friend at an amusement center, G
Application of a PS transceiver (mobile station) can be considered, but it is not suitable for portable use because of the large scale of the device. On the other hand, the mobile station of the present invention is small in size and can be configured so that it can be worn in the size of a badge. If each of them is attached, the position of the lost child can be easily known from the signal transmitted from the badge type mobile station. In addition, if there is no way to inform the emergency squad of your position if you are injured or unable to move at a ski resort, etc., the skier carries the above-mentioned portable mobile station (radio wave transmission device) in an emergency. When an emergency code (unique code for a mobile station) is transmitted, a fixed station provided at several places around the ski area receives the radio wave, and the reference station can determine its position and notify the rescue team.

<Application 2>: Control of mobile unit As a typical example, control of a mobile carrier for improvement can be mentioned. In the present invention, since the moving range of the moving body is not limited by the taxiway or the like, a flexible factory layout is possible.

<Application Example 3> Control of agricultural robots One of the ways to reduce agricultural production costs is to promote large-scale mechanization. In this field as well, the positioning system of the present invention can be applied to improve the effect. You can For example, the mechanization of rice planting in the case of rice cultivation has been improved by the rice planting machine from the past, but the operation of the rice planting machine requires manpower. On the other hand, in order to perform full automation, it is necessary to accurately detect the position of the rice transplanter and control it. G
Such position control is possible using PS,
As mentioned above, it is unsuitable for industrial use because it is assumed that it will be useless in an emergency. However, the positioning system of the present invention can be used stably without such a risk. Further, with the increase in scale, it is possible that the seeds and pesticides are sprayed over a wide area by an airplane or the like, but in this case as well, it is necessary to accurately grasp the target position and control the flight course. A positioning system can be applied.

<Application 4>; Grazing As an example of increasing the scale in the field of livestock farming, livestock management using the positioning system of the present invention, for example, a transmitter (mobile station) identifiable to grazing cattle. By wearing it, you can know which cow is where on a large farm.

<Application Example 5>: Position detecting device for virtual reality Virtual reality is a system that allows a subject to experience as if they were in another world, and is one of the application fields of computer technology. Is. In virtual reality, a subject's head is equipped with a goggle device (for example, a head-mounted display) to limit the field of view of a person to recognize a computer-generated image for a virtual experience. Therefore, it is necessary to detect the subject's movement in some form and feed it back to the subject. Above all, the above-mentioned methods based on the detection of ultrasonic waves and magnetic fields are used to detect the position of a person in space, but these methods have been pointed out to have problems in terms of equipment installation and detection range. In such a case, by applying the positioning system of the present invention, it is possible to detect the position of a person easily and without much limitation on the detection range.

<Application Example 6> Position detecting device for disabled persons For example, as a part of an auxiliary information system for disabled persons, which informs the visually impaired person of his / her position and direction, distance from a target, etc. through a voice device. The positioning system of the present invention can be used. As a specific example, a person with a disability wears a mobile station in the badge field, and the radio station receives radio waves from the mobile station, and the computer of the reference station determines where and in which direction the person with a disability is going to move. It can be configured to collate the geographical information around the person with the disability, transmit the result to the mobile station worn by the person with the disability, and transmit the information to the person with the disability via a voice device provided in the mobile station. This allows visually impaired people to know what kind of store is in a narrow area such as a shopping district, in what direction and from what position they are, or if a pedestrian crossing is You can know which direction it is.

[0058]

As described above, according to the positioning system of the first aspect of the invention, there is a certain time delay before the repeater station receives the radio wave from the mobile station and transmits the radio wave. The station detects the signal received directly from the mobile station and the signal passed through the repeater station at different times.
Since the position can be determined from the time difference between the two signals, accurate time synchronization between each fixed station is not required.

In the positioning system according to the second aspect of the present invention, the frequency of the received signal is further converted by the frequency conversion section and transmitted, so that interference due to transmission at the same frequency can be prevented.

In the positioning system of the third aspect of the invention, each fixed station further switches the code pattern of the PN code of the reference signal at an arbitrary point of time, so that the time measuring means can receive signals from a plurality of mobile stations and It is possible to detect the reception time of the signal from the repeater station.

Further, in the first, second, and third inventions, the mobile station need only have a transmitting function, so that the configuration of the mobile station can be simplified and downsized. Further, since the cost of the mobile station can be reduced because only the transmitting function is required, it is possible to reduce the system configuration cost particularly in an application system that requires identification of many mobile stations (that is, many mobile units).

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a basic configuration of a positioning system of the present invention.

FIG. 2 is a diagram in which one of fixed stations, a repeater station, and a mobile station are extracted from the system of FIG.

FIG. 3 is an explanatory diagram showing signal transmission / reception timings in a fixed station, a repeater station, and a mobile station.

FIG. 4 is a block diagram showing a configuration example of a mobile transmitter and a fixed station receiver.

FIG. 5 is a conceptual diagram of a transmission only method.

FIG. 6 is a conceptual diagram of a repeater system.

[Explanation of symbols]

 10 Convolver (Time measuring means) 11 Local oscillator (Time measuring means) 12 Mixer (Time measuring means) 14 Detector (Time measuring means) 15 Time measuring section (Time measuring means) A, B, C Fixed station R Repeater station M mobile station

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriyuki Sato 5-35-2 Shirayama, Bunkyo-ku, Tokyo Clarion Co., Ltd.

Claims (3)

[Claims] 1. A positioning system using a spread spectrum communication method, comprising: a mobile station transmitting a reference signal; at least three fixed stations receiving a signal from the mobile station; and a signal from the mobile station. A positioning system comprising: a repeater station for receiving and transmitting the received signal. 2. The positioning system according to claim 1, wherein the repeater station has a frequency conversion unit that converts the frequency of a received signal during transmission. 3. The mobile station is a plurality of mobile stations to which a unique PN code is assigned, and each fixed station is a receiving side PN.
The positioning system according to claim 1, further comprising a time measuring unit configured to be able to switch a code pattern of the code.