JPH0427802A - Object-position detecting system - Google Patents

Abstract

PURPOSE:To recognize the positions of persons and materials in real time based on transmitted signals which have undergone spectrum diffusing modulation from a data carrier by providing the data carrier wherein a pseudo-random series inherent to many persons and materials, e.g. a gold series, is assigned. CONSTITUTION:Carrier signals are transmitted from a data carrier 10-1 and undergo spectrum diffusing modulation in a gold series G1. The signals are received with a leakage cable 12-2. The frequency of the signal from one end E1 of the cable is converted into a frequency f2 in a frequency converter 16-2. The signal is superimposed on the signal from the other end E2. The signal is sent into a receiving unit 18. In the unit 18, correlation computation of the received signal series and the gold series G1 - Gm is performed by using two frequencies f1 and f2 with respect to the received signals from a transmitting cable 14. A delay time DELTAT between peak values is detected. A distance L1 from the terminating end E1 of one cable is obtained as L1 = (L - DELTAL)/2 based on DELTAT. The data carrier 10-1 can be identified based on the reference gold series used in the correlation computation when the correlation peak values are obtained in the receiving unit 18.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an object that detects the location of an object by receiving a transmission signal from a data carrier held by a person or object in a building, factory, etc. Regarding a position detection system.

[Conventional technology] In recent years, with the progress of office automation and factory automation, it has become desirable to centrally manage the movement of people and objects within buildings and distribute information and objects appropriately and quickly. There is.

For example, in building systems that have been proposed in recent years, people entering the building are required to carry an ID card, and the building management system recognizes the ID card and always knows who is where. Consideration has been given to automatically forwarding information to a nearby telephone, or to transmit a user format specific to that person when using equipment such as a workstation to enable personal use.

In order to realize such a building system, the ID card must have a communication function as a data carrier, transmit a unique ID code wirelessly, and the system side can receive the transmitted signal and determine the ID code and location. Recognition is required.

[Problem to be solved by the invention] However, for example, if more than 10,000 people in one building are given ID cards (data carriers) and ID code signals are transmitted wirelessly, it is possible to A system that can constantly recognize a location has not yet been proposed or put into practical use.

The reason for this is that in the radio wave propagation space indoors of buildings, factories, etc., there is severe interference due to multiple reflections from installed objects, and normal communication cannot be expected with normal communication methods. Further, the transmission power from the ID card used as a data carrier is extremely weak due to power supply constraints, and highly reliable communication quality cannot be obtained due to S/N problems.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an object position detection system that can constantly recognize the positions of many people and objects in real time indoors of buildings, factories, etc. With the goal.

[Means for Solving the Problems] In order to achieve this object, the object position aspect ratio system of the present invention is configured as follows. In addition, the reference numerals in the drawings of the embodiments are also shown.

First, the present invention receives assignment of a unique pseudo-random sequence Gi (i=l~m) corresponding to an ID code, spread-spectrum modulates a carrier signal of a predetermined frequency (fl) using the pseudo-random sequence, and transmits it. Portable data carrier 10-1. 10-2. Prepare a plurality of ... and have people who enter the building hold them, for example.

On the other hand, on the building side, there are a plurality of leaky cables 12-1 to 12-n having a predetermined line length (L) distributed two-dimensionally inside the structure, and a leaky cable 12-1. ~12
Frequency converters 16-1 to 16-1 connected to one end E1 of -n and converting the spread spectrum signal from the data carrier transmitted from the leaky cable to a second frequency (r2).
16-n, a transmission cable 14 that combines the output signals of the frequency converters 16-1 to 16-n and the transmission signals from the other end E2 of the leaky cables 12-1 to 12-n and sends the synthesized signal to the receiving unit]8. and.

The receiving unit 18 calculates a correlation value between each received signal sequence and a plurality of pseudo-random sequences assigned to each data carrier using a first frequency (11) and a second frequency (12) from the received signal of the transmission cable 14. When a correlation peak value is obtained from one received signal sequence by calculating the correlation with a specific pseudorandom sequence, the correlation peak value is calculated until the correlation peak value is obtained from the other received signal sequence following the correlation peak value. The delay time ΔT is measured, and the position on the leaky cable where the data carrier exists is calculated based on this delay time ΔT, and the data carrier is identified from the pseudo rung l and series from which the correlation peak value is obtained. Configure.

Here, a gold sequence is used as the pseudorandom sequences 61 to Gm used for the data carriers 10-1 to 10-m and the receiving unit 18.

Further, the leaky cables 12-1 to 12-n are distributed in a branched manner. Further, the leakage cables 12-1 to 12-n are distributed in branch-like manner, and the leakage cables 12-1 to 12-n are arranged in a branch-like manner.
n may be arranged in a spiral.

[Function] According to the object position detection system of the present invention having such a configuration, the following function can be obtained.

For example, a carrier signal spread spectrum modulated with the gold sequence G1 transmitted from the data carrier 10-1 is received by the nearby leaky cable 12-2, transmitted to both ends of the leaky cable, and then transmitted from one end of the cable E1. The signal is frequency-converted to frequency (f2) by the frequency converter 162, superimposed on the signal at the other end of the cable E2, and sent to the receiving unit 18.

The receiving unit 18 uses two frequencies (II) and (12) for the received signal of the transmission cable 14 to calculate the correlation between the received signal sequence and the gold sequences 61 to Gm assigned to the data carriers. Through this correlation calculation, the delay time ΔT from when the correlation peak value is obtained for one received signal sequence to when the correlation peak value is obtained for the other received signal sequence is ΔT = t2 - tl. However, tl; Signal peak value detection time, t2: Detected as the peak value detection time of the signal from the cable termination E2. This delay time ΔT is the data carrier 1
0-1 or ff1A on the scattered leakage cable 12-2
Distance L1. to cable ends El, E2. It depends on L2, and the propagation velocity of the leaky cable is C[m/n s
], and the cable length is L [m], then the distance difference ΔL is found as ΔL=L2-L1=C·ΔT. Therefore, the distance L1 from one cable end E1 is determined as Ll-(L-ΔL)/2. Further, the data carrier 10-1 can be identified from the reference Gold sequence used in the correlation calculation when the correlation peak value was determined by the receiving unit 18.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, 12-1.12-2. ...12
-n is a leaky cable, which is distributed in the form of branches directly under the floor or along the ceiling inside a building, factory, or the like. One cable end E1 of the leaky cables 12-1 to 12-n is input connected to a frequency converter 16-1 to 16-n. Further, a transmission cable 14 is pulled out from the other cable termination E2 of the leaky cables 12-1 to 12-n, and the frequency converters 16-1 to 16-n are connected to this transmission cable 14.
6-n output is connected. Leakage cable 12-1~
The transmission cable 14 pulled out from 12-n is connected to the receiving unit 18. The above is the system configuration on the building side.

On the other hand, each person entering the building has a data carrier 10-1, 10-2, for example, as shown in the figure.

Gold sequences G1 and G2 of a predetermined word length, which are a type of pseudo-random sequence (PN sequence), are assigned in advance to the data carriers 10-1 and 10-2. Data carrier 10-1゜10-2 is assigned gold series G
1 and G2, the first common data carrier
A carrier signal of frequency f1 is spread spectrum modulated and transmitted.

FIG. 2 is a configuration diagram of an embodiment of a data carrier, taking the data carrier 10-1 of FIG. 1 as an example.

In FIG. 2, the data carrier 10-1 is the oscillation circuit 2.
0, multiplier 22, frequency division starting circuit 24, Gold sequence generator 25, band pass filter 26 and transmitting antenna 28
has.

That is, the oscillation circuit 20 oscillates a carrier signal of a first frequency f1 common to all data carriers and supplies it to the multiplier 22.

Further, the oscillation output of the oscillation circuit 20 is given to a frequency division starting circuit 24, and a frequency division output according to a predetermined frequency division ratio is given to a Gold series generator 25.

The gold sequence generator 25 generates a gold sequence G1 of a predetermined word length in synchronization with the frequency division pulse from the frequency division starting circuit 24.

Here, the gold sequence is known as a code in which a preferred pair is generated using an M sequence, and a preferred pair means a combination of M sequences that take a small cross-correlation value like -. Therefore, when calculating the correlation value (cross-correlation value) of different gold series, it is always -
A small cross-correlation value such as this can be guaranteed, and therefore an S/N ratio with respect to a peak value when an autocorrelation value is obtained can be guaranteed.

Additionally, the type of gold series that can be assigned to a data carrier is determined by the word length of the gold series, but if the currently discovered maximum word length of the gold series is used, approximately 100,000 different gold series can be assigned. is possible. Approximately 100,000 identifiable data carriers can therefore be provided for one building or facility.

The gold sequence generator 25 generates a gold sequence G1 having a predetermined word length at regular intervals. That is, as shown in FIG. 3, the gold series G1 is
is generated. The gold sequence is generated every chip period ΔTc as a sequence signal having values of +1 and -1 corresponding to bits 1 or 0. The gold series G1 from the gold generator 25 is multiplied by the carrier signal from the oscillation circuit 20 in the multiplier 22. Here, the chip period ΔTc of the gold series is 1 with respect to the period of the carrier signal of frequency f]
It is an integer multiple of the period or more. FIG. 3 shows a case where the chip period ΔTc is twice the period of the carrier signal. When the bold sequence changes from +1 to -1 or from -1 to +1 by multiplying this gold sequence and the carrier signal by the multiplier 22, the phase of the carrier signal is inverted. signal)
create.

The spread spectrum signal from the multiplier 22 is band-limited by a pass filter 26 and then sent to a transmitting antenna 28.
Sent from The power transmitted from the data carrier 10-1 at this time is very weak because it is powered by, for example, a solar cell, and also from the installation spacing and installation position of the leakage cables 12-1 to 12n shown in FIG. 2m
The transmission power may be weak enough to ensure the effective propagation distance before and after.

Referring again to FIG. 1, in this embodiment, there is a person near the leaky cable 12-2 with the data carrier 10-1 assigned the gold series G1, and there is also a person near the leaky cable 12-2. 1 and 12-3, there is a person who has a data carrier 10-2 that has been assigned the gold series G2. Therefore, for example, the spread spectrum signal modulated by the gold sequence G1 transmitted from the data carrier 10-1 is transmitted to the leaky cable 12.
It is received at point A (receiving point) of -2, and is split into two and propagated toward the cable terminations El and E2 on both sides. This 2
Among the propagation signals divided into two, the spread spectrum signal heading toward the cable end E1 is input to the frequency converter 16-2, and the spread spectrum signal from the data carrier 10-1 is converted into another spectrum whose second frequency is the spread spectrum center frequency f1. The frequency is converted to the spreading center frequency f2.

FIG. 4 is a block diagram of an embodiment of the frequency converters 16-1 to 16-n shown in FIG. 1, taking frequency converter 16-2 as an example.

In FIG. 4, the frequency converter 16-2 includes a high frequency amplifier 54, a mixer 56, a shifted frequency oscillator 58, and a bandpass filter 60.

That is, the transmission signal having the spreading center frequency f1 from the cable end E1 is amplified by the high frequency amplifier 54 and then applied to the mixer 56. The other side of the mixer 56 is given a shift frequency signal of frequency (f2-fl) from a shift frequency oscillator 58, and by mixing with this shift frequency signal, the input spread spectrum signal is frequency-converted to the spread frequency f2. .

Specifically, as shown in the frequency characteristic diagram of Fig. 5, the spread spectrum signal with the center frequency f1 has a frequency (f2-fl
) is frequency-converted (frequency-shifted) into a spread spectrum signal with a center frequency f2. The output of the mixer 56 is band-limited by a bandpass filter 60 and then sent to the receiving unit 18 via the transmission cable 14. FIG. 6 is a block diagram of an embodiment of the receiving unit 18 shown in FIG.

In FIG. 6, the receiving unit 18 has a leakage cable 1.
Receiving sections 18-1 to 18-n are provided for each of 2-1 to 1.2-n, and in this embodiment, the configuration of the receiving section 18-1 corresponding to the leaky cable 12-1 is It is shown in detail as a representative.

The receiving section 18-1 is provided with a first receiving system 30-1 and a second receiving system 30-2, and each system has a leakage cable 12-1.
Transmission cables from [4] are input connected in parallel.

The first receiving system 30-1 has a high frequency amplifier 32 with a center frequency f
a bandpass filter 341 with 1, a demodulator 36-1,
It includes a local oscillator 46-1 with an oscillation frequency f1, a low-pass filter 38-1, an A/D converter 40-1, a buffer memory 42-1, and a correlator 44-1 using a DSP.

On the other hand, the second receiving system 30-2 includes a high-frequency amplifier 322, a bandpass filter 342 with a center frequency f2, and a demodulator 36-.
2, a local oscillator 46-2 with an oscillation frequency f2, a low-pass filter 38-2, an A/D converter 40-2, a buffer memory 422, and a correlator 44-2 using a DSP. Furthermore, the first and second receiving systems 30-1.30-2
As a common circuit section for the A/D converter 40-1, an oscillator 48 that oscillates a sampling frequency fs at 1.40-2, and a gold sequence 61 to Gm for all data carriers for the correlator 44-1.44-2. A gold sequence generator 50 is provided that sequentially switches and generates a gold sequence.

The operation of this receiving section 18-1 is as follows.

First, if a spread spectrum signal with a center frequency f1 is received from the leaky cable 12-1 side via the transmission cable 14, it is amplified by the high frequency amplifier 32-1, passed through the bandpass filter 34-1, and then sent to the demodulator. At 36-1, a baseband signal representing the Gold sequence is demodulated using the oscillation signal of frequency f1 from the local oscillator 461. Specifically, the demodulator 36-1 can be realized by a demodulation circuit for two-phase modulated signals. The baseband received signal sequence demodulated by the demodulator 36-1 passes through the low-pass filter 38-1, and then is sampled by the A/D converter 40-1 at the sampling frequency fs from the oscillator 48. The sampling period at this time is one half of the chip period ΔTc in the gold series shown in FIG.
It is determined as follows. A/D converter 40-
The received signal sequence converted into digital data in step 1 is stored in buffer memory 42-1. Buffer memory 42-
Each data storage address of at least one received signal sequence stored in 1 indicates the reception time. When one received signal sequence has been stored in the buffer memory 42-1, it is read out to the correlator 44-1, and the correlator 44-1 receives the gold assigned to all data carriers sequentially given by the gold sequence generator 50. Using series 01 to Gm as reference series, a correlation calculation is performed for each reference series.

If the received signal sequence and the reference sequence from the Gold sequence generator 50 match as a result of this correlation calculation, a peak value appears in the correlation output C1 of the correlator 44-1.

The processor 52 recognizes the time when the peak value of the correlation output C1 is obtained based on the storage address of the received signal sequence in the buffer memory 42-1, and also recognizes the time when the peak value of the correlation output C1 is obtained from the gold sequence generator 50 when the peak value is obtained. The data carrier sending the spread spectrum signal can be recognized by the generated reference gold sequence. 2nd receiving system 3
Regarding 0-2, the first receiving system 30-2 has the center frequency f2 of the bandpass filter 34-2, and the oscillation frequency from the local oscillator 46-2 to the demodulator 36-2 is the same <f2. Same as side 1. That is, the second receiving system 30-2 side is connected to the leaky cable 12-1 in FIG.
The signal from the cable end E1 of the frequency converter 16-1
The signal that is frequency-converted to the spread frequency f2 and sent out is received and demodulated, and finally the correlator 44-2 performs correlation calculation with the reference gold series 61 to Gm to calculate the peak value of the correlation output C2. The processor 52 recognizes the data carrier from the reference gold sequence used in the process.

The processor 52 calculates the distance L1 from the cable termination E1 of the leaky cable 12-2 shown in FIG. 1 to the reception point based on the peak value detection times tl and t2 of the two correlation outputs CI and C2.

The principle of calculating the distance L1 from the cable end E] is based on the leakage cable 12 where the data carrier 10-1 is located nearby.
The explanation will be as follows with reference to FIG.

In FIG. 7, the cable length of the leaky cable 12-2 is shown, and the cable length is determined in advance. Now, if the reception point of the spread spectrum signal transmitted from the data carrier 10-1 is A, the distance from the cable termination E1 to the reception point is L1, and the distance from the cable termination E2 to the reception point A is L2.

The reception timing of each spread spectrum signal of frequency f1 and frequency f2 on the receiving unit 18 side when received at the reception point A of the leaky cable 12-2 shown in FIG. 7 is shown in FIGS. 8(a) and (b). It becomes as shown in . That is, receiving point A
The spread spectrum signal received at the terminal propagates simultaneously to both sides, but since the distance L1 is shorter than the distance L2, it reaches the cable end E1 first, and is converted into the f2 signal by the frequency converter 16-2, as shown in Fig. 8(a). The signal is first received by the receiving unit 18 as shown in FIG. Subsequently, the f1 signal propagated over a distance L2 reaches the cable end E2 and is received after a delay time corresponding to the distance difference ΔL (=L2-Ll), as shown in FIG. 8(b). A correlation calculation is performed on the receiving unit 18 side for such f2 signal and f1 signal, and by the correlation calculation using the gold series G1 of the data carrier 10-1 as a reference sequence, the f2 signal is calculated as shown in FIG. A correlation peak value is obtained as shown in c), and for the f1 signal, a correlation peak value is obtained at subsequent time t2 as shown in FIG.

When the peak values of the correlation outputs C1 and C2 are obtained in this manner, the processor 52 calculates the delay time ΔT as ΔT=t2−tl based on the times tl and t2 at which the peak values were obtained. Note that time t1 is the late arrival when the peak value of correlation output C1 was obtained, and time t2 is the time when the peak value of correlation output C2 was obtained. There is also.

The processor 52 then determines the delay propagation velocity C of the leaky cable.
Based on [m/ns] and the delay time ΔT, the distance difference ΔL is determined as ΔL=L2−L1=C·ΔT (1). Here, the cable length is L=L1+L2, and when calculating the distance L1 from the cable end E1 to the receiving point A from these simultaneous equations, Ll-(L-ΔL
)/2 (2).

In the case of Fig. 7, the distance L1 from the cable end E1 to the reception point A is calculated, but on the other hand, the distance L2 from the cable end E2 on the opposite side to the reception point A is calculated. The same is true.

Next, the overall operation of the above embodiment will be explained.

Now, as shown in FIG. 1, if there is a person holding the data carrier 10-1 near the leaky cable 12-2,
A periodic spread spectrum signal is transmitted from the data carrier 10-1 and received at the receiving point A of the leaky cable 12-2. The signal received at the reception point A advances to the cable terminations El and E2, and the transmission signal that has reached the cable termination E1 is frequency converted by the frequency converter 16-2 from the previous spreading center frequency f1 to another spreading center frequency f2. The transmission cable 14 together with the signal of the spreading center frequency f1 which is converted and transmitted to the cable termination E2 by the transmission cable 14.
is applied to the receiving unit 18 by.

In the receiving unit 18, the received signal sequence of frequency f1 is demodulated by the first receiving system 30-1 of the receiving section 182 shown in FIG. 6, which is provided corresponding to the leaky cable 12-2.
At the same time, the second receiving system 302 demodulates the received signal sequence of frequency f2. After the demodulated signal of each series is converted into digital data, it is applied to each of the correlators 44-1 and 44-2, and the gold series 61 from the gold series generator 50
Correlation calculations are performed sequentially between Gm and Gm. Here, since the gold series of the data carrier 10-1 is G1, the correlation calculation with the reference series G1 results in the results shown in FIGS. 8(C) and (d).
As shown in (1), the peak values are obtained in the order of correlation outputs C1 and C2, and the processor 52 calculates ΔT=t2−tl, obtains the distance difference ΔL from the above (1), and calculates the distance difference ΔL from the above (1).
) distance L from cable end E1 to receiving point A
Calculate 1. At the same time, the correlation output C from which the peak value was obtained
The data carrier 101 is recognized from the reference gold series G1 used in the correlation calculation of 1 and C2. Since the position of the leaky cable 1-2-2 within the building is known in advance, the position of the data carrier 10-1 within the building is recognized based on the calculated distance L1, and the host device is notified of the position and appropriate processing is performed. Let them do it.

Furthermore, if the position of the data carrier 10-2 in FIG.
It is only necessary to recognize that the data carrier 102 is located in the middle of the line connecting the receiving points A determined by the distance L1 from the receiving point A.

FIG. 9 is an explanatory diagram showing another two-dimensional arrangement of leaky cables used in the present invention. In the embodiment shown in FIG. 1, leaky cables on a straight line are distributed in a branched manner. , No. 9
The illustrated embodiment is characterized in that the leaky cable 12 is arranged in a rectangular spiral shape. Such a spiral arrangement of the leaky cables 12 can increase the cable laying density and improve the accuracy of position detection.

Of course, the leakage cable 12 is not limited to a rectangular spiral shape, but may have an appropriate spiral shape such as a circular shape or an elliptical shape.

In the embodiment shown in FIG. 1, the leakage cable 12-1
Although the signal from the cable terminal E1 side of 12-n is frequency-converted and sent, the signal from the cable terminal E2 on the opposite side may be frequency-converted.

U Effects of the Invention As explained above, according to the present invention, in a building such as a building or a factory, a large number of people and things can have data carriers assigned with a unique pseudo-random sequence, for example, a gold sequence. It is possible to recognize the location of people and objects in real time based on spread spectrum modulation signals transmitted from data carriers, and is useful for office automation and other systems that perform necessary processing based on the presence of people and objects in systems such as buildings and factories. It can greatly contribute to the realization of factory automation.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention. Fig. 2 is a block diagram of an embodiment of the data carrier used in the present invention; Fig. 3 is an explanatory diagram of the spread spectrum modulation shown in Fig. 2; Fig. 4 is a block diagram of an embodiment of the frequency converter of the present invention; Fig. 4 is an explanatory diagram of frequency conversion; Fig. 6 is a configuration diagram of an embodiment of the receiving unit of the present invention; Fig. 7 is an explanatory diagram of the receiving point position of the reactor bull in Fig. 1; 9 is an explanatory diagram showing another embodiment of the two-dimensional arrangement of leaky cables in the present invention. In the figure, 10-1.10-2 12-1 to 12-n 14: Transmission cable 16-1 to 16-n 18/Receiving unit 20 Oscillator circuit 22/Multiplier 246 Frequency division start circuit 25.50: Gold series Generator 26.34-1.34-2.60: Bandpass buoy 28: Transmission antenna 30-1 + first receiving system 30-2: Second receiving system 32-1.32-2.54: High frequency amplifier: Data carrier leakage cable frequency converter router 36-1.36-2: demodulator 38-1.38-2: low-pass filter 40-1.40
-2: A/D converter 42-1.42-2: Buffer memory 44-1.44-2: Correlator (DSP) 46-1.46
-2: Local oscillator 48: Sampling oscillator 52: Processor 56: Mixer 58: Shift frequency oscillator

Claims (4)

[Claims] (1) A freely transportable data carrier that receives a unique pseudo-random sequence assigned in accordance with an ID code, spread spectrum modulates a carrier signal of a predetermined first frequency (f1) using the pseudo-random sequence, and transmits the resultant signal. ; a plurality of leaky cables having a predetermined line length distributed two-dimensionally within the structure; and a plurality of leaky cables connected to one end of the plurality of leaky cables and transmitted from the data carrier from the leaky cables; a frequency converter that frequency converts a spread spectrum signal to a second frequency (f2); a transmission cable that combines the output signal of the frequency converter and a transmission signal from the other end of the leaky cable and sends it; the transmission cable from the received signal of the first frequency (11)
and the second frequency, a correlation value is calculated between each received signal sequence and a plurality of pseudo-random sequences assigned to each of the data carriers, and a correlation value is calculated from one received signal sequence by calculating the correlation with a specific pseudo-random sequence. When the correlation peak value is obtained, the delay time until the correlation peak value is obtained from the other received signal sequence following the correlation peak value is measured, and based on the delay time, the leakage where the data carrier exists is measured. An object position detection system comprising: a receiving unit that calculates a position on a cable and identifies the data carrier from a pseudo-random sequence from which the correlation peak value is obtained. (2) The object position detection system according to claim 1, wherein a gold sequence is used as the pseudorandom sequence used in the data carrier and the receiving unit. (3) The object position detection system according to claim 1, wherein the leaky cables are distributed in a branch-like manner. (4) The object position detection system according to claim 1, wherein the leaky cables are distributed in a branch-like manner and each leaky cable is arranged in a spiral shape.