JPH0427803A - Object-position detecting system - Google Patents

Abstract

PURPOSE:To recognize the positions of persons and materials based on transmitted signals which have undergone spectrum diffusing modulation from a data carrier by providing a data carrier wherein a pseudo-random series inherent to many persons and materials, e.g. a gold series, is assigned. CONSTITUTION:A carrier signal having a frequency f0 is transmitted from a data carrier 10-1 and undergoes spectrum diffusing modulation in a gold series G1. The carrier signal is received with a leakage cable 12-2 in the vicinity. The signal from one end E2 of a cable is converted into a frequency f2 which is inherent to the cable with a frequency converter 16-2. The signal is superimposed on the signal from the other end E1 of the cable. The signal is sent into a receiving unit 18. The unit 18 sequentially performs the correlation computation between each received signal series and the gold series G1 - Gm. A delay time DELTAT between the correlation peaks is detected. A distance L1 from a terminating end E1 of one cable is obtained as L1 = (L - DELTAL)/2. The data carrier 10-1 can be identified based on the reference gold series used in the correlation computation of the correlation peak values in the receiving unit 18.

Description

[Detailed Description of the Invention] [Industrial Application Fields] 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 identify 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/H 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] To achieve this object, the object position detection system of the present invention is configured as follows. In addition, the reference numerals in the drawings of the embodiments are also shown.

First, in the present invention, a unique pseudo-random sequence Gi (i=l to m) is assigned in correspondence with an ID code, and a carrier signal of a predetermined frequency (f) is spread-spectrum modulated using the pseudo-random sequence. Portable data carrier for transmission 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 leakage cables 12-1 to 12-n.
frequency converters 16 to 1 to 16-n, which are connected to one end E2 of -n and convert the spread spectrum signal from the data carrier propagated through the leaky cable to frequencies (f1 to f,) specific to the cable; Vessels 16-1 to 16
-n output signal and the transmission signal from the other end E of the leaky cables 12-1 to 12-n are collectively connected to the receiving unit 1.
A single transmission cable 14 is provided to send data to 8.

The receiving unit 18 extracts a first frequency (fo) and a cable-specific frequency (f1) from the received signal of the transmission cable 14.
~fn) and the plurality of pseudorandom sequences 61~Gm assigned to each data carrier, and by calculating the correlation on the specific pseudorandom sequence, any one of the received signals When a correlation peak value is obtained from a sequence, the delay time Δ until a correlation peak value is obtained from any other received signal sequence following the correlation peak value
T is measured, 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-random sequence used to calculate the correlation peak value.

Here, a gold sequence is used as the pseudorandom sequences 01 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 with the transmission cable 14 as a trunk.

Further, the leaky cables 12-1 to 12-n may be distributed in a branched manner with the transmission cable 14 as a trunk, and the leaky cables 12-1 to 12-n may be arranged in a spiral manner.

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

For example, the frequency (f0) that is spread spectrum modulated with the gold sequence G1 transmitted from the data carrier 10-1.
The carrier signal is received by the nearby leaky cable 12-2 and transmitted to both ends of the leaky cable, and then the signal from one end of the cable E2 is converted into a cable-specific frequency (T2) by the frequency converter 16-2. The signal is converted, superimposed on the signal at the other end of the cable E, and sent to the receiving unit 18.

The receiving unit 18 individually demodulates the received signal sequences using frequencies (fo, f+, ... f,) for the received signals of the transmission cable 14, and demodulates each received signal sequence and the gold allocated to the data carrier. Correlations with series 61 to Gm are sequentially calculated. The delay time is defined as the time difference between the time TI at which the correlation peak value of the received signal sequence of the first frequency (fo) is obtained through this correlation calculation and the time T2 at which the correlation peak value of any one of the other signal sequences is obtained. ΔT△
T=T2~T1 However, T1: Detection time of the peak value of the carrier natural frequency f1) signal; T2: Detection time of the peak value of any one of the cable natural frequencies f1~fn. This delay time ΔT is the data carrier 1
It depends on the distances Ll and L2 from the position A on the leaky cable 12-2 where 0-1 is scattered to the cable terminations El and E2, and the propagation speed of the leaky cable is C [m/ns, and the cable length is When L [m], the distance difference ΔL can be found as ΔL=L2−L1=C·Δd. Therefore, the distance L1 from one cable end E1 is determined as L1=(L-ΔL)/2. Further, the data carrier 10-1 can be identified from the reference gold sequence used in the correlation calculation of the correlation peak value in 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.・φ・12
-n is a leaky cable, which is branch-connected to the transmission cable 14 drawn out from the receiving unit 18 via a circulator 15, respectively. That is, the transmission cable 14 is used as a trunk and the leaky cables 12-1 to 12-
n are two-dimensionally arranged, and leakage cables 12-1 to 12-n
The cable end E1 of is connected directly to the transmission cable 14 via a circulator 15.

On the other hand, the cable termination E2 on the opposite side of the leaky cables 12-1 to 12-n is connected to a frequency converter 1 provided for each cable.
6-1 to 16-n, and the outputs of the frequency converters 16-1 to 16-n are directly connected to the transmission cable 14 via the circulator 15 together with the cable termination E1.

Here, the transmission cable 14, the circulator 15, the leakage cables 12-1 to 12-n, and the frequency converter 16-1
- 16-n are installed, for example, directly under the floor or along the ceiling inside a building, factory, or the like. The system configuration on the building side is performed with the above configuration.

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

Data carriers 10-1 and 10-2 are pre-allocated with gold sequences Gl and G2 of a predetermined word length, which are a type of pseudo-random sequence (PN sequence).
A frequency f commonly assigned to all of the data carriers by each of G2 and G2. The carrier signal 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
Equipped with

That is, the oscillation circuit 20 has a frequency f common to all data carriers. (first frequency) and multiplier 2
Give to 2. The oscillation output of the oscillation circuit 20 is transmitted to the frequency division starting circuit 2.
4 as well, and supplies a frequency-divided pulse frequency-divided by a predetermined frequency division ratio to the Gold sequence generator 25.

The gold sequence generator 25 generates a gold sequence G1 of a predetermined word length allocated in advance. Here, the gold sequence is known as a code generated using a preferred pair of M sequences, and a preferred pair means a combination of M sequences that take a small cross-correlation value, such as -. Therefore, when calculating the correlation value (cross-correlation value) of different gold series, a small cross-correlation value like - is guaranteed in every case, and the S/N ratio is guaranteed when autocorrelation is obtained. I can do it.

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 maximum word length of the gold series currently discovered is used, approximately 100,000 different gold series can be assigned. can.

It is therefore possible to provide 100,000 identifiable data carriers per building or facility.

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 at regular intervals. For example, as shown in FIG. 3, this gold series G1 has a time series of chip components consisting of bits 1 or 0 of the word part over the system sub-time length T,
In terms of signals, bit 1 corresponds to +1 and bit 0 corresponds to -1.

Here, the period of one chip component is indicated by a chip period ΔTc.

The gold sequence G1 from the gold sequence generator 25 is applied to the multiplier 22 at the frequency f from the oscillation circuit 20.

is multiplied by the carrier signal. Frequency f of carrier signal. has a carrier period that is an integer fraction of the chip period ΔTc of the gold series shown in FIG. 3, and in the case of FIG. 3, the period is half the chip period ΔTc. The multiplier 22 multiplies the gold sequence and the carrier signal, and adds the third
As shown in the figure, when the Gold sequence changes from +1 to -1 or from -1 to +1, a spread spectrum signal (phase modulation signal) in which the phase of the carrier signal is inverted is created. The spread spectrum signal from the multiplier 22 is band-limited by a bandpass filter 26 and then transmitted from a transmitting antenna 28.

Here, the transmission power from the data carrier 10-1 is extremely weak because it uses a power source such as a solar cell, and the leakage cables 12-1 to 12-1 shown in FIG.
The transmitting power may be weak enough to ensure an effective propagation distance of about 2 m in terms of the installation interval and installation position of n.

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 to the gold series G1, and there is also a person near the leaky cable 12-2. A case is shown in which there is a person between 123 and 123 who has a data carrier 10-2 that has been assigned the gold series G2.

The frequency converters 16-1 to 16-n provided in the leaky cables 12-1 to 12-n, etc., have a high frequency amplifier 54, as shown in FIG.
It includes a mixer 56, a shifted frequency oscillator 58, and a bandpass filter 60.

That is, the frequency f from the data carrier 10-2 near the leaky cable 12-1 in FIG. 1 is applied to the frequency converter 16-1. A propagation signal resulting from the reception of the spread spectrum signal is inputted, is amplified by a high frequency amplifier 54, and then provided to a mixer 56.

The other input of the mixer 56 is given an oscillation output of a frequency (f+t0) from a shift frequency oscillator 58, and has a frequency f. As shown in FIG. 5, the spread center frequency f is mixed with the spread spectrum signal. The signal is frequency-converted to a signal having a diffusion center frequency f, which is unique to the leakage cable 12-1. The signal is finally band-limited by a bandpass filter 60 having a center frequency f, and then sent to the receiving unit 18 side.

The configuration of the frequency converter 16-1 shown in FIG.
Since ~f is set, the oscillator 58 generates (f2-f
0) to (f, -f0) to perform frequency conversion.

FIG. 6 is a block diagram of an embodiment of the receiving unit 18 shown in FIG.

In FIG. 6, the receiving unit 18 is provided with a data carrier compatible receiving section 18-0 corresponding to the data carrier and cable compatible receiving sections 18-1 to 18-n corresponding to the leaky cables 12-1 to 12-n. It is being

A high frequency amplifier 3 is included in the data carrier compatible receiving section 18-0.
2. Center frequency f. bandpass filter 34-0, oscillation frequency f. A demodulator 36 with a local oscillator 46-〇, a low-pass filter 38, a sampling frequency fs
an A/D converter 40 equipped with an oscillator 48 that oscillates;
A pap memory 42 and a correlator 44 using a DSP are provided.

On the other hand, the cable compatible receiving units 18-1 to 18-n have the same circuit configuration as the data carrier compatible receiving unit 18-0, but the center frequency of the bandpass filters 34-1 to 34-n is a frequency specific to each cable. f1 to f, , and the local oscillators 46-1 to f for the demodulator 36
The oscillation frequency of 46-n is the cable-specific frequency f1 to f.
The difference is that it is .

Furthermore, a correlator 4 provided in each receiving section 18-0 to 18-n
4, a plurality of gold sequences 61 to Gm commonly assigned to all data carriers by the gold sequence generator 50
are commonly given as the sequential standard gold series.

Therefore, the correlator 44 calculates the correlation between the received sequence from the buffer memory 42 and the reference Gold sequence from the Gold sequence generator 50, that is, the product for each data of one sequence length determined by the sampling period of the A/D converter 40. Performs a sum operation.

The correlation outputs CO to Cn of the correlators 44 provided in each of the receiving sections 18-0 to 18-n are provided to the processor 52. The processor 52 latches the time when the peak value of the correlation output Co-Cn is obtained.

The data is stored in each of the latches T2. That is, the correlation output C from the data carrier compatible receiving section 18-0.

The peak value detection time of is stored in the latch T1, whereas the peak value detection time from any one of the correlation outputs 01 to Cn of the cable compatible receiving units 18-1 to 18-n is stored to the latch T2. . Based on the peak detection times of the latches TI and T2, the processor 52 determines whether the circulator 1
The distance L1 from the cable termination E1 on the 5 side to the reception point A of the transmission signal from the data carrier 10-1 is calculated.

At the same time, the processor 52 recognizes the data carrier based on the Gold sequence from the Gold sequence generator 50, which is used to calculate the correlation peak value for time detection of the latches Tl and T2.

Next, the operation shown in FIG. 6 will be explained in detail together with its effects.

Now, if there is a person holding the data carrier 10-1 near the leaky cable 12-2 in FIG. 1, the frequency f from the data carrier 10-1. received at point A of leaky cable 12-2 by transmitting a spread spectrum signal with
The received signal propagates from point A toward cable terminations El and E2 on both sides.

The propagation signal that has reached the cable end El is transferred to circulator 1
5 and the transmission cable 14 to the receiving unit 18. On the other hand, the propagation signal that has reached the cable end E2 is frequency-converted by the frequency converter 16-2 to a frequency f2 specific to the leaky cable 12-2, and is sent to the receiving unit 18. Therefore, the receiving unit 18 receives the frequency f in accordance with the difference in distance from both ends of the cable to the receiving point A.
.

spread spectrum signal and frequency converted frequency f2
One sequence of spread spectrum signals is received.

Frequency f. After the spread spectrum signal is amplified by the high frequency amplifier 32 of the data carrier compatible receiving section 18-0,
Center frequency f. A/
The data is converted into digital data by a D converter 40 and stored in a buffer memory 42. The sampling frequency fs in the A/D converter 40 is determined so that sampling can be performed two or more times during the gold series chip period ΔTc shown in FIG.

On the other hand, the frequency-shifted spread spectrum signal of frequency f2 is extracted by the bandpass filter 34-2 of the cable-compatible receiving section 18-2 corresponding to the leaky cable 12-2, and is also extracted from the frequency band signal from the local oscillator 46-2. f
2, the received signal sequence is demodulated into a baseband reception signal sequence, and then stored as digital data in the buffer memory 42 in the same manner as in the case of the data carrier compatible receiving section 18-0. The correlator 44 of the data carrier compatible receiving unit 18-0 and the cable compatible receiving unit 18-2 includes a buffer memory 4
The received signal sequence stored in 2 is read out, and at that time,
A correlation calculation (sum-of-products calculation) is performed between reference gold sequences 61 to Gm sequentially given by the gold sequence generator 50. When the reference Gold sequence from the Gold sequence generator 50 is 61, it is the same sequence as the received signal sequence, so correlation peak values are obtained in the correlation outputs Co and C2 of the correlator 44.

That is, since the reception point A of the transmission signal from the data carrier 10-1 to the leaky cable 12-2 in FIG. 1 is close to the cable end E1 and far from the cable end E2, first, as shown in FIG. 8(a), to the frequency f. The signal sequence is received, and after a time delay corresponding to the distance difference from both ends to the reception point A, reception of the signal sequence frequency-converted to frequency f2 is started. In the data carrier compatible receiving unit 18-0, if correlation calculation is performed in real time, f. A peak value is generated in the correlation output Co at time t1 when the reception of the signal sequence of signals is completed, and time t1 is stored in the latch T1. Then, by performing correlation calculation on the signal sequence of the f2 signal, a peak value is obtained in the correlation output C2 at time t2,
The second peak value detection time t2 is stored in the latch T2.

In addition, the peak occurrence time 1. ．． 12 is not performed in real time, and when writing series data to the buffer memory 42, for example, the value of the write address of the series final data is at time 1. ．． It is found as 12.

In this way, the processor 52 generates a correlation output Co.

When the peak value generation time tl, t2 of C2 is detected, the processor 52 first calculates the delay time ΔT as ΔT = T 2
Calculate as T 1 = t 2 t +.

Here, as shown in FIG. 7, which shows the leaky cable 12-2 taken out from FIG. The distance from to receiving point A is L2
, furthermore, the propagation speed of the signal within the leaky cable 12-2 is C[
m/ns].

As is clear from the distance relationship with respect to the reception point A in FIG. ΔL=L2-L1=C・Δ
Calculate as T (1). As is clear from Fig. 7, there is a relationship L=L1+L2, however, Ll<L2, and by solving the simultaneous equations with equation (1) above, we can calculate the distance L from the cable end E1 to the receiving point A.
1 is calculated as L1=(L-ΔL)/2 (2).

Furthermore, the processor 52 recognizes the data carrier based on the reference Gold sequence from the Gold sequence generator 50 used to calculate the peak value of the correlation output CO and the peak value of any one of the correlation outputs 01-Cm. In this case, since the peak value of the correlation output is obtained with the reference gold sequence G1, it is possible to recognize the data carrier 10-1 to which the gold sequence G1 has been assigned.

From cable termination E1 of leaky cable 12-2 to receiving point A
When the distance L1 and the data carrier 10-1 are recognized, the processor 52 knows in advance the position of the leaky cable 12-2 within the building, so the data carrier is located within the building at the calculated distance L1. The host device is notified of the presence at the point and has the necessary processing performed.

FIG. 9 is an explanatory diagram showing another two-dimensional arrangement of the leaky cable used in the present invention. As shown as a representative example, the leakage cable 12-1 is arranged in a spiral shape. By arranging the leaky cables 12-1 in a spiral shape, it is possible to increase the cable installation density and improve the accuracy of position detection. Of course, the spiral shape of the leakage cable 12-1 is not limited to a rectangular shape, and includes any appropriate spiral shape such as a circle or an ellipse.

In the embodiment shown in FIG. 1, the leaky cable side is connected to the transmission cable 14 via the circulator 15, but the circulator 15 is removed and the leaky cable sides 12-1 to 12-n are connected to the transmission cable. You can also connect directly.

Furthermore, when the position of the data carrier 10-2 is detected by both of the leakage cables 12-1 and 12-3 in FIG.
I recognize that 2 exists.

Furthermore, in the above embodiment, the distance L1 from the cable end E1
However, on the contrary, the distance L from the cable end E2 is detected.
2 may be detected.

Furthermore, the frequency converters 16-1 to 16-n may be provided on the cable termination E1 side.

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

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention; Fig. 2 is a block diagram of an embodiment of a data carrier used in the present invention; Fig. 3 is an explanatory diagram of spread spectrum modulation of Fig. 2; Fig. 4 is a diagram of the frequency of the present invention. Embodiment configuration diagram of the converter; Figure 5 is the fourth
Figure 6 is an illustration of the configuration of an embodiment of the receiving unit of the present invention; Figure 7 is an explanatory diagram of the receiving point position of the leaky cable in Figure 1; Figure 8 is the receiving unit of the present invention. A time chart showing the correlation output when determining the delay time; FIG. 9 is an explanatory diagram showing another embodiment of the two-dimensional arrangement of leaky cables in the present invention. In the figure, IC)-1, 10-2: Data carriers 12-1 to 12
-n leakage cable 14 transmission cable 15/circulator 16-1 to 16-n: frequency converter 18, receiving unit 18-0: data carrier compatible receiving section 18-1 to 18-n cable compatible receiving section 20: oscillation circuit 22 : Multiplier 24: Frequency division start circuit 25. 50: Gold series generator 26, 34-0 to 34-n, 60: Bandpass filter 28: Transmission antenna 32. 54: High frequency amplifier 36: Demodulator 38 Narrow bass filter 40: A/D converter 42: Buffer memory 44: Correlator (DSP) 46-0 to 46-n: O-cal oscillator 48: Sampling oscillator 52: Processor 56: Mixer 58: Shift frequency oscillator

Claims (4)

[Claims] (1) A freely transportable data carrier that is assigned a unique pseudo-random sequence corresponding to an ID code, and transmits the spread spectrum modulated carrier signal of a predetermined first frequency (f_0) using the pseudo-random sequence. ; a plurality of leaky cables having a predetermined line length distributed two-dimensionally within the structure; connected to each end of the plurality of leaky cables, and from the data carrier transmitted from the leaky cables; a plurality of frequency converters that frequency-convert the spread spectrum signal of 1 to each of the frequencies (f_1 to f_n) unique to each cable; and a transmission unit that collectively connects the output of the frequency converter and the other end of the leaky cable for each cable. a cable; a plurality of pseudorandom sequences individually assigned to each of the received signal sequence and the data carrier using the first frequency (f_0) and frequencies (f_1 to f_n) unique to the cable from the received signal of the transmission cable; When a correlation peak value is obtained from any one received signal sequence by correlation calculation with a specific pseudo-random sequence, the correlation value is calculated from any other one following the correlation peak value. The delay time until a correlation peak value is obtained from two received signal sequences is measured, and the position on the leaky cable where the data carrier is located is calculated based on the delay time, and the position is used to calculate the correlation peak value. An object position detection system comprising: a receiving unit that identifies the data carrier from a pseudo-random sequence. (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 connected in a branch-like manner with the transmission cable as a trunk and are two-dimensionally distributed. (4) The object position detection system according to claim 1, wherein the leaky cables are connected in a branched manner with the transmission cable as a trunk, and each leaky cable is arranged in a spiral shape.