JPH03205579A - System for measuring transmitter position and transmitter - Google Patents

Abstract

PURPOSE:To cancel the offset of a timer and to know the position of and the distance to an object to be measured in real time by receiving a radio wave from an transmitter provided to the object to be measured by plural reference stations, measuring and processing the arrival times of respective radio waves. CONSTITUTION:When the transmitter 4 of the body to be measured operates the time t0 of the timer 6, a PN signal with a waveform (a) is generated by a carrier generator 34 and a PN signal generator 36. A carrier is pulse- modulated by a modulator 40 and fed to an antenna 18. The radio wave send by the antenna 18 at time t1 arrives at the antennas 20 of the respective reference stations 10a - 10d at time t2 of a timer 8 with DELTAt delay. In each station 10, the radio wave is converted into a pulse signal through a front end circuit 48 and a detector 52. The converted PN signal (b) is synchronized by a PN signal synchronizing circuit 42 and its PN series is discriminated. Then a range counter 44 measures the delay time and transfers the measurement result to a computer 28. The computer 28 finds the offset of the timer 6, and calculates the coordinates of the transmitter and the distances from the reference stations and outputs the results in real time.

Description

[Detailed Description of the Invention] The present invention relates to position measurement, distance measurement, and communication technology thereof, and more specifically, to receiving radio waves emitted from an object to be measured and measuring them as coordinates of the position of the object to be measured. The present invention also relates to a simple communication technique for a device under test that utilizes the signals used for measurement as they are.

For example, it is applied to local area wireless communications, factory automation, home automation, etc.

GPS (GPS) is one of the methods of measuring the position of an object.
global positioning system
There is m). This is a satellite radio navigation system. Standardly, by receiving different radio waves transmitted from four artificial satellites with a receiver on the ground, it is possible to detect four unknowns, namely the receiver's three-dimensional position (X, Y, Z) and a receiver for determining the offset of the receiver's clock (Development and Experiments of rGPS/Time Transfer Receiver," Institute of Electronics and Communication Engineers Technical Research Report, Vol. 84, No. 13.
No. 0, pp. 25-3l (SANE84-20) 19
1984, see). This system was developed primarily for military use, with some parts being released for civilian use.

This GPS system uses radio waves from artificial satellites to locate and track objects and people outdoors (on a global scale). However, indoor positioning requires much smaller units of position detection that cannot be obtained on a global measurement scale. Additionally, radio waves from such satellites rarely reach people or objects indoors. Therefore, GP
The S system cannot measure or track the location of people or objects indoors. For example, it is not suitable for managing the location of people in large-scale offices, managing the safety of robots and humans in factories, or managing the safety of young children and elderly people with dementia in ordinary homes.

In addition, a specific pseudo-noise signal is transmitted to the device under test, which is received by multiple fixed stations installed indoors or within a specified area, and the phase delay between each fixed station and the device under test is determined. A transmitter position measurement system that measures the distance of objects and tracks the position of the object in real time from those measurements is useful for managing the safety of objects to be measured and the position of mobile robots in large factories. It is valid. However, this system has the disadvantage that there is no communication means for transmitting data and audio signals from the measuring person to the measured object. Although it is possible to provide a transmitter/receiver exclusively for communication separately from the NWJ determination system, the device to be measured becomes complicated and simplicity is lost. Also,
Two different systems, a communication system and a position measurement system, must be constructed, and the complexity of the system is unavoidable.

The present invention was made in view of the above-mentioned circumstances.
The purpose of the present invention is to provide a transmitter position measurement system that can obtain accurate position information of a measured object in a limited area such as an indoor environment. After receiving the PN signal from the measured object at the reference station, the phase is adjusted using
It is used to spread the spectrum of information signals (data and audio signals), and by transmitting it, the device under test can demodulate the spread spectrum signal from the reference station using a simple demodulation circuit that does not require a synchronization circuit for the PN signal. The purpose of this invention is to provide a transmitter position measurement system that enables communication from a measurer to a measured object by simply improving the measurement system.

In order to achieve the above object, the present invention provides (1) a position measurement system that measures the position of a measured object in a specific area, the position measurement system being held by the measured object; a transmitter that transmits a PN signal using a uniquely assigned pseudo-noise sequence; and a plurality of reference stations that are fixedly placed in the area and that receive the PN signal from the transmitter and measure the arrival time of the PN signal. , clock means for giving the plurality of reference stations a time serving as a reference for measuring the arrival time, and calculation means for calculating the position of the transmitting means from the arrival time and the positions of the plurality of reference stations, wherein the reference station is a receiving means for receiving the transmitted PN signal; a synchronizing circuit means for synchronizing the received PN signal with a pseudo noise sequence specific to the transmitter; arrival time detection means for determining the arrival time of the synchronized PN signal, or (2) used in a position measurement system for measuring the position of a measured object in a specific area and held in the measured object. The transmitter includes a pseudo noise generating means for generating a PN signal with a pseudo noise sequence uniquely assigned to the transmitter, and a transmitting means for transmitting the PN signal, The received PN signal is received by a plurality of reference stations fixedly placed in the area, and each of the plurality of reference stations synchronizes the received PN signal with a pseudo-noise sequence unique to the transmitter. The arrival time of the PN signal is measured, and the position of the transmitter is calculated from the arrival time and the positions of the plurality of reference stations, or (3) a position at which the position of the object to be measured in a specific area is measured. In the measurement system, a PN signal transmitted with a pseudo-noise sequence uniquely assigned to a transmitter fixedly placed in the area and held in the object to be measured is received, and the arrival time of the PN signal is calculated. a plurality of reference stations, a clock means for giving the plurality of reference stations a time serving as a reference for measuring the arrival time, and a calculation means for calculating the position of the transmitter from the arrival time and the positions of the plurality of reference stations. Each of the plurality of reference stations includes a receiving means for receiving the transmitted PN signal, a synchronization circuit means for synchronizing the received PN signal with a pseudo noise sequence specific to the transmitter, and the clock means. (4) arrival time detection means for determining the arrival time of the synchronized PN signal based on a time given by the object to be measured; or (4) to track the position of the object to be measured in a specific area. By carrying a transmitter that transmits a unique PN signal, the PN signal is received by multiple reference stations fixedly placed in the area, and the distance between the object to be measured and the reference station is measured from the arrival time. In a position measurement system that measures the coordinates of a measured object within a region in real time, a transmitter that performs spread spectrum communication using the PN signal transmitted by the measured object is installed at the reference station, and the measured object receives the By installing a simple receiver that consists only of a multiplier and a demodulation circuit for multiplying the signal by the PN signal of the device under test, and does not require a synchronization circuit for the PN signal, it is possible to or (5) carrying a transmitter that transmits a pseudo-noise signal specific to the object in order to track the location of the object in a particular area. The coordinates of the object to be measured within the area can be measured in real time by receiving the pseudo-noise signal at multiple reference stations fixedly placed in the area, and measuring the distance between the object to be measured and the reference station based on the arrival time. In a position measurement system that performs spectral spread communication, the phase is controlled to match the timing when the measured object is transmitting a pseudo-noise signal with the same code as the pseudo-noise signal transmitted by the measured object to the reference station. A transmitter is installed, and the device under test consists of only a multiplier and a demodulation circuit for multiplying the received signal by a pseudo-noise signal possessed by the device under test, and a synchronization circuit for the pseudo-noise signal is not required. A feature of this system is that it enables communication from the measuring person to the object to be measured by installing a simple receiver that does not require a measuring device. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a block diagram for explaining one embodiment of a transmitter position measuring system according to the present invention, in which 2 is a position measuring system, 4 is a transmitter, 6 and 8 are clocks, and 10a to 10 are shown. 1
0d is a reference station, 18.20 is an antenna, 28 is a computer, and 30 is an input/output device.

The positioning system 2 basically includes four reference stations 108.
10d, a computer 28, an input/output device 30, and a clock 8. A transmitter 4, a clock 6, and an antenna 18, which are integrally configured as a single device, are attached to an object to be measured such as a person or an object whose position is to be measured.
is carried or carried.

The receiving means including the reference stations 10a to 10d is usually fixedly placed indoors, such as a large office, factory, or home, where the object to be measured moves. However, it may also be installed outdoors in a relatively narrow area, such as in an amusement park or park. In the embodiment of the present invention, the reference stations 10a, 10b, 10c and 10d are located in a coordinate system based on a certain position, respectively, and have positions (Xi, Yl, Zl), (X2,
Y2, Z2), (X3, Y3', Z3), (X4, Y4
, Z4).

Figure 2 is a configuration diagram of the transmitter and reference station, in which 34 is the carrier wave generator, 35 is the output of the carrier wave generator, and 36 is the PN
(pseudo noise) signal generator, 37 is the output of the PN signal generator, 38 is the switch, 40 is the modulator, 42 is the PN signal synchronization circuit, 44 is the range counter, 46 is the output of the PN signal synchronization circuit, 48 is the front In the end circuit, 50 is an intermediate frequency amplifier, 52 is a detector, and parts having the same functions as in FIG. 1 are given the same reference numerals.

The transmitter 4 includes an antennae 8 that transmits radio waves, and a clock 6 that measures the reference time of the transmitter 4. The antenna 18 is a transmitting antenna for transmitting radio waves to each reference station. Note that the embodiment of the present invention uses radio waves as a transmission means between the transmitter 4 and the reference station IO. However, the present invention is not necessarily limited to this, and for example, sound such as ultrasonic waves may be used.

The transmitter 4 further includes a PN (pseudo noise) signal generator 3
6, a carrier generator 34 and a modulator 4o. A clock 6 serving as a time reference on the transmitter side is connected to a PN signal generator 36 via a switch 38. The PN signal generator 36 is a device that generates a unique digital signal (a kind of call sign) for distinguishing the radio waves emitted from the transmitter 4 from the radio waves emitted from other transmitters. That is, the PN signal generator 36 generates a PN signal using a PN sequence with a random pattern uniquely assigned to each transmitter 4. Each reference station 10 synchronizes the PN signal received from the transmitter 4 with a PN sequence unique to that transmitter 4 and determines the type of the received PN signal.
can be identified.

The output 37 of the PN signal generator 36 is connected to the modulator 40 along with the output 35 of the carrier wave generator 34. The carrier wave generator 34 is a device that generates a carrier wave that serves to carry a signal at a radio frequency of, for example, 150M1{z. Of course,
The frequency is not limited to this, and may be a very short wave or an extremely short wave. The modulator 40 is the PN signal generator 3 in an embodiment of the invention.
Although this is a phase modulator that changes the phase of the carrier wave according to the signal from 6, the pulse width and pulse position may also be changed. If the carrier wave is a sine wave, frequency modulation may be used.

The reference stations 10a-10d of the reference station network may have the same configuration, and their common configuration is shown as reference station 10.

The reference station 10 includes a PN signal synchronization circuit 42, a range counter 44, a front end circuit 48, and an intermediate frequency amplifier 50.
and a detector 52. The reference station 10 is
It includes an antenna 20 that receives radio waves from the transmitter 4, and is connected to a front-end circuit 48. The output of the frontend circuit 48 is amplified by an intermediate frequency amplifier 50, detected by a detector 52, and input to the PN signal synchronization circuit 42.

The PN signal synchronization circuit 42 stores in advance a PN signal sequence uniquely assigned to each transmitter 4 belonging to the service area of the position measuring system of the present invention. P
The N signal synchronization circuit 42 compares and synchronizes the received PN signal with this stored PN signal sequence, and detects the phase to determine the PN unique to each transmitter 4.
This is a circuit that identifies series. Its output 46 is connected to a range counter 44.

A transmitter 4 is connected to one reference station network including reference stations 10a to 10d.
When a plurality of transmitters 4 exist and their positions are detected individually, the PN signal generator 36 of each transmitter 4 is configured so that each transmitter 4 generates a signal of a different PN sequence. Each of the reference stations 10a to 10d is provided with a PN signal synchronization circuit 42 that stores a PN sequence pattern corresponding to the PN sequence of the transmitter 4 covering the service.

This allows the coordinates of each transmitter 4 to be tracked in real time.

The range counter 44 is a counting circuit that measures the arrival time of the PN signal from the transmitter 4 whose synchronization has been recovered by the PN signal synchronization circuit 42 . The output of the range counter 44 of each reference station 10a to 10d is connected to the computer 28. Furthermore, range counters 44 and P of each reference station 10a to LOd
A common clock 8 is connected to the N signal synchronization circuit 42. In the embodiment of the present invention, the reference station network consisting of each of the reference stations 10a to 10d has a common clock 8, and the clock 8, like the same 6, functions as a time reference on the reference station 10 side.

The computer 28 is connected to each reference station 10, receives information representing the arrival time of the PN signal measured by the range counter 44, and uses this time information and each reference station 10.
This is a calculation system that calculates the position of the transmitter 4 from the position of the reference station 10. For example, the position coordinates in a coordinate system including the reference station 10 and the distance therefrom are calculated.The calculator 28 has an input/output device 30. The input/output device 30 is a device for inputting operator instructions into the position measurement system of the present invention and outputting the calculated results.The input/output device 30 is, for example, a CRT, a liquid crystal display,
It has an LED and displays the current position of the transmitter 4 in real time with numerical values, symbols, or graphs.

Next, the operation will be explained. For example, when the switch 38 of the transmitter 4 of the object to be measured is turned on at a certain time 10 based on the clock 6, the transmitter 4 is activated. The transmitter 4 then has a position (x, y, z) in the coordinate system of the position measuring system of the invention.
Suppose it is in When the transmitter 4 is activated, the carrier wave generator 3
4 generates a carrier wave, and a PN signal generator 36 generates a PN signal having a waveform as shown in FIG. 3(a), for example. The carrier wave is pulse-modulated with a PN signal by a modulator 40 and fed to the antenna 18 .

Radio waves transmitted from the antenna 18 at time t1 according to the clock 6 of the transmitter 4 are transmitted to each reference station 1 as shown in FIG. 3(b).
The clock 8 of the reference station network reaches time t2 with a delay of Δt seconds from the antennas 20 of 0a to 10d. This time delay △t is
It depends on the distance from the reference station 10 to the transmitter 4 (FIG. 2). In the embodiment of the present invention, if the speed of light is V, then this distance α is equal to V·Δt. Note that when the position measuring system of the present invention uses an ultrasonic method, ■ is the speed of sound. P.N.
The signal sequence has a random pattern as illustrated in FIG.
The time delay Δt with reference to the clock 8 of the reference station 10 can be measured in real time.

At each reference station 10, the radio waves that reach the antenna 2o are converted into pulse signals via the front end circuit 48 and detector 52 of each reference station. The converted pulse signal, that is, the PN signal, is synchronized by a PN signal synchronization circuit 42, and its PN sequence is identified. After that, the range counter 44 measures the delay time, and the measurement results are displayed at each reference station 1.
It is transferred to the computer 28 from 0a to 10d. Each reference station 1
The time delays calculated from 0a to lod are Δt1,
Δt2, Δt3, Δt4, and if the offset between the clock 6 of the transmitter 4 and the clock 8 of the reference station network is Δtoff,
The relational expression between the coordinates of each reference station and the transmitter is given by the following equation.

(X-Xi)2+(Y-Y 1)2+(Z-Z 1)2
=(v(Δt1−Δtoff))2(X−X2) 2
+(Y-Y 2) 2+(Z-2 2) 2 =(v(
Δt2−Δtoff)) 2(X−X3)2+(Y−Y
3) 2+(Z-Z3)2=(v(Δt3-Δtoff)
)2(X-X4) 2+(Y-Y4)2+(Z-24)
2=(v(Δt4−Δtoff)) 2 However, in the embodiment of the present invention, ■ is the speed of light, but when the position measuring system of the present invention uses an ultrasonic method, it is the speed of sound.

Therefore, the calculator 28 solves this equation to find the coordinates (x, y, z) of the transmitter 4 and the offset Δtoff of the clock 6. A calculator 28 calculates the coordinates of the transmitter 4 and the distance from the reference station 10. This calculation is performed in real time, and the calculation result is output to the input/output device 30 in real time.

In the embodiment of the present invention, the three-dimensional coordinate position of the transmitter 4 and the offset of the clocks 6 and 8 are determined, so four reference stations 1'O are provided.

However, the present invention is not limited thereto; for example, in a system that detects the position of a transmitter in a two-dimensional plane space, three reference stations may be used, and in a system that determines the l-dimensional position on a line such as a passage. , two reference stations are sufficient.

FIG. 4 is a diagram showing another embodiment of the transmitter position measuring system according to the present invention, in which 55a to 55d are reference stations;
6.57 is the antenna, 58 is the transmitter/receiver of the object to be measured, 59
, 61 is a clock, and 60 is a calculator.

This position measurement system includes four reference stations 55a to 55d installed in a specific area, a PN signal receiver installed at each of them, a computer 60 that calculates the position, a clock 61 common to the reference stations, and a clock 61 that is uniquely assigned to the object to be measured. The measuring device includes a transmitter 58 that transmits a PN signal, a clock 59 that determines the transmission time of the object to be measured, and a receiver 58 that receives the transmitted signal from the measuring person. Furthermore, one of the reference stations has a transmitter for communicating with the object to be measured.

The clock of the measured object should be synchronized with the clock of the reference station as much as possible. Antenna 57 used in transmitter and receiver 58
has wideband characteristics sufficient for transmitting and receiving PN signals. At the reference station, the PN signal specific to the object to be measured and its transmission time are known, and the distance to the object to be measured is calculated by comparing the reception time of a certain pattern of PN signals and the transmission time. The coordinates (X, Y, Z) of the object to be measured are calculated from the distance between each reference station and the object to be measured and the known coordinates of the reference station.

Since there are four reference stations, the deviation between the clock 59 of the object to be measured and the clock 6 of the reference station can also be corrected.

FIG. 5 is a configuration diagram of a transmitter/receiver included in a reference station that communicates with the object under test, and in the figure, 62 is a front-end circuit;
63 is an intermediate frequency amplifier, 64 is a PN signal synchronization circuit, 6
5 is a range counter, 66 is a PN signal generator, 67 is a phase control circuit, 68 is a modulation circuit, and 69 is an amplifier.

A PN signal unique to the measured object is emitted from the measured object, and the timing of its generation is also known at each reference station. The reference station determines the transmitted PN from the received signal.
The signal is detected, synchronized, and the range counter 65 compares it with the PN signal emitted from the PN signal generator of the reference station with the same code as that of the device under test. Arrival time of radio waves from △t
and transfer the results to a computer. On the other hand, based on Δt and the time error between the clock of the measured object and the clock of the reference station calculated by the computer, the PN of the reference station is
Adjusts the phase of the signal and uses it to spread the spectrum for transmission. The phase adjustment is performed so that when the PN signal transmitted from the reference station is received by the device under test, it matches the phase of the PN signal of the device under test. Such phase adjustment is possible since Δt and the clock error are known. For example, if the time error of the clock is 0 (the clock of the measured object and the clock of the reference station match) and the arrival time is Δt, then at the reference station P
A PN signal with the phase of the N signal advanced by 2Δt will be transmitted. Data or audio signals from the person being measured are first-order modulated to FM, FSX, etc., and then spectrum-spread using this PN signal before being transmitted.

FIG. 6 is a diagram showing an example of a simple configuration of a receiving circuit, in which 70.75 is an amplifier, 71 is a PN signal generator, and 72
is a clock, 73 is a local oscillator, and 74 is a demodulation circuit.

In the measured object, the received signal is multiplied by a PN signal possessed by the measured object to perform spectrum despreading, and an information signal is obtained by a demodulation circuit 74 corresponding to the modulation method of the reference station. Since the reference station already uses a PN signal that matches the phase of the PN signal of the device under test when transmitting, the receiver of the device under test does not require a synchronization circuit for the PN signal, making the receiving circuit extremely simple. .

As is clear from the above explanation, the present invention has the following effects.

(1) Radio waves from a transmitter installed on the measurement target in a limited area such as indoors are received by multiple reference stations, and the time of arrival of the radio waves is measured and processed. It is possible to cancel the offset of the machine's clock and know the position and distance of the measurement target in real time.

Furthermore, when there are multiple transmitters, by using different pseudo-noise signal sequences, it is possible to identify the transmitters from other transmitters and learn their positions and distances.

(2) While measuring the position coordinates of the measured object in real time by transmitting and receiving a PN signal unique to the measured object, a simple receiver without a synchronization circuit is installed on the measured object using the same PN signal. This enables communication from the measuring person to the object being measured.Therefore, it is possible not only to monitor the position of the object to be measured, but also to transmit data and audio signals to the object to be measured, making it possible to perform work in the factory. It is useful for human safety management and mobile robot control.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining one embodiment of the transmitter position measuring system according to the present invention, FIG. 2 is a block diagram of the transmitter and reference station, and FIGS. 3(a) and (b) are A diagram showing the output waveform of the transmitter and an input waveform at the reference station, FIG. 4 is a diagram showing another embodiment of the transmitter position measurement system according to the present invention, and FIG. FIG. 6 is a block diagram of a transmitter/receiver included in the present invention, and is a diagram showing an example of a simple configuration of a receiving circuit. 4...Transmitter, 6,8...Clock, 1o...Reference station,
18, 20... Antenna, 28... Computer, 30.
...I/O device.

Claims (1)

[Claims] 1. In a position measurement system that measures the position of a measured object in a specific area, the position measurement system generates pseudo noise using a uniquely assigned pseudo noise sequence held in the measured object. a transmitting means for transmitting a signal; a plurality of reference stations that are fixedly arranged in the area and receive a pseudo noise signal from the transmitting means and measure the arrival time of the pseudo noise signal; clock means for giving a time as a reference for time measurement, and calculation means for calculating the position of the transmitting means from the arrival time and the positions of the plurality of reference stations, each of the reference stations receiving the transmitted pseudo noise. receiving means for receiving a signal; synchronization circuit means for synchronizing the received pseudo-noise signal with a pseudo-noise sequence specific to the transmitter; and the synchronized pseudo-noise based on the time given by the clock means. A transmitter position measuring system comprising arrival time detection means for determining the arrival time of a signal. 2. In a transmitter that is used in a position measurement system that measures the position of a measured object in a specific area and is held in the measured object, the transmitter uses a pseudo noise sequence uniquely assigned to the transmitter. a pseudo-noise generating means for generating a pseudo-noise signal in the area, and a transmitting means for transmitting the pseudo-noise signal, and the transmitted pseudo-noise signal is received by a plurality of reference stations fixedly arranged in the area. Each of the plurality of reference stations synchronizes the received pseudo-noise signal with a pseudo-noise sequence specific to the transmitter, measures the arrival time of the pseudo-noise signal, and calculates the arrival time and the plurality of reference stations. A transmitter characterized in that the position of the transmitter is calculated from the position of the transmitter. 3. In a position measurement system that measures the position of an object to be measured in a specific area, fixedly arranged in the area,
a plurality of reference stations that receive a pseudo-noise signal transmitted in a pseudo-noise sequence uniquely assigned to a transmitter held in the object under test and calculate the arrival time of the pseudo-noise signal; The plurality of reference stations each include a clock means for giving a time as a reference for measuring the arrival time, and a calculation means for calculating the position of the transmitter from the arrival time and the positions of the plurality of reference stations, and each of the plurality of reference stations receiving means for receiving the received pseudo-noise signal; synchronization circuit means for synchronizing the received pseudo-noise signal with a pseudo-noise sequence specific to the transmitter; and arrival time detection means for determining the arrival time of the pseudo noise signal. 4. In order to track the position of a measured object in a specific area, the measured object carries a transmitter that transmits a unique pseudo-noise signal, and multiple reference stations fixedly placed in the area transmit the pseudo-noise signal. In a position measurement system that measures the coordinates of a measured object within an area in real time by receiving a signal and measuring the distance between the measured object and a reference station based on the arrival time, the measured object sends a signal to the reference station. A transmitter that performs spread spectrum communication using a pseudo-noise signal is installed, and the device under test consists of only a multiplier and a demodulation circuit to multiply the received signal by the pseudo-noise signal of the device under test. A transmitter position measurement system that enables communication from a measuring person to a measured object by installing a simple receiver that does not require a synchronization circuit for pseudo noise signals. 5. In order to track the position of a measured object in a specific area, the measured object carries a transmitter that transmits a unique pseudo-noise signal, and multiple reference stations fixedly placed in the area transmit the pseudo-noise signal. In a position measurement system that measures the coordinates of a measured object within an area in real time by receiving a signal and measuring the distance between the measured object and a reference station based on the arrival time, the measured object sends a signal to the reference station. A transmitter is installed that performs spread spectrum communication while controlling the phase to match the timing when the device under test is transmitting a pseudo-noise signal with the same code as the pseudo-noise signal being transmitted. By installing a simple receiver that consists of only a multiplier and a demodulation circuit for multiplying the pseudo noise signal of the measured object by the measured object, and does not require a synchronization circuit for the pseudo noise signal, A transmitter position measurement system that enables communication with a transmitter.