JPH0153435B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a moving object search system for measuring the position of a moving object existing within a specific search area, and particularly relates to a moving object search system for measuring the position of a moving object existing within a specific search area. , a response signal receiving unit so that the number of receiving antennas that can receive the response signal as a response confirmation signal is minimized when receiving the response signal with a plurality of receiving antennas disposed at different positions within the search area. This invention relates to a moving object search system improved to control the response level of the object.

Conventionally, technologies for measuring the position of moving objects using information media that propagate in space, typically radio waves, have conventionally been based on propagation direction and propagation time, such as PPI radar, etc. 2
While methods based on the propagation time difference between two media and methods based on the phase difference between two media such as Detsuka are often used, methods based on the relationship between the propagation distance and attenuation amount of the media have limitations in performance. Because of this, it has continued to this day without becoming very popular.

However, since the structure based on the relationship between the propagation distance and the amount of attenuation is extremely simple, it is considered to be promising as far as application fields that can meet performance requirements are concerned.

Based on the relationship between the propagation distance and the amount of attenuation,
Regarding the previous application example of the technology for measuring the position of a moving object, a schoolchild is made to carry a transmitter/receiver handset, a parent device carried by a leader sends a calling signal to the child's transmitter/receiver handset, and the call signal is sent to the child's handset. By determining whether the parent unit can receive the response signal sent by the child's transmitter/receiver in response, it is possible to detect when the child has moved out of the specific area surrounding the teacher, and the child's transmitter/receiver 2. Description of the Related Art There is a known schoolchild monitoring device that sends an alarm signal from a parent device to a parent device and makes it sound, and uses the sound as a clue to easily search for schoolchildren.

However, although such a schoolchild monitoring device can detect when a schoolchild, or more generally a moving object, has moved out of a specific area, the area in which the moving object can exist outside the specific area is extremely large. ,
Since it is substantially difficult to specify the position of the moving object, the field of use thereof is severely restricted, and there is a drawback that it cannot be widely applied to searches for various moving objects.

Furthermore, since the area subject to the presence or absence of a moving object is directly controlled by fluctuations in the transmission level of the transmitter/receiver handset and the reception level of the base unit, and expands or contracts, it is determined that the object has moved out of the area. Another drawback was that the distance between the moving object and the base unit varied widely.

An object of the present invention is to solve the problem of determining the position of a moving object based on the above-mentioned prior art, and to provide a method for transmitting and receiving signals attached to a moving object within a search area using a plurality of receiving antennas disposed at different positions within the search area. By receiving a response signal from a handset and controlling the response level so that the number of receiving antennas that can receive the response signal as a response confirmation signal is minimized, the above-mentioned drawbacks are removed, the difficulties are overcome, and the search is performed. It is an object of the present invention to provide an excellent moving object search system that can specify the position of a moving object within a minimum receivable area formed within an area based on the arrangement positions of a plurality of receiving antennas within the area.

In accordance with the above object, the present invention has a configuration in which a plurality of receiving antennas are arranged at specific intervals within a search area, and a transmitting/receiving handset is attached to a moving object within the search area. The system sends a calling signal to the space within the search area, receives the response signal sent by the transceiver handset to the space within the search area in response to the calling signal, and receives the received response signal. When the response level is equal to or higher than a specific response level, the response signal receiving section outputs a response confirmation signal, and while receiving such response signals sequentially using each of the plurality of receiving antennas, the response level is adjusted. When the number of receiving antennas that can receive the response signal as a response confirmation signal becomes the minimum, by specifying the minimum number of receiving antennas, it is possible to detect the effect of changes in the transmission level of the transmitter/receiver handset. The present invention is characterized in that it is possible to display that a moving object exists within the minimum receivable area from the specified position of the receiving antenna.

The structure and operation of the first embodiment of the present invention will be explained as follows based on FIGS. 1 to 4.

FIG. 1 is a block diagram showing the configuration of the first embodiment. The calling signal transmitting unit 1 includes a calling signal oscillation circuit 1a including a sound bar oscillator, a modulation circuit 1b following the oscillation circuit 1a, and the modulation circuit 1b.
and a subsequent output amplifier circuit 1c.

A coaxial cable a ₀ extends from the amplifier circuit 1c to the transmitting antenna 1d via a suitable feeder circuit in the circuit 1c.

Each of the plurality of receiving antennas A ₁ to _{A 16} is shown in FIG.
As shown in FIG. 2, they are arranged in a grid pattern within the search area at specific intervals.

Coaxial cables extending from receiving antennas A ₁ to A ₁₆
a ₁ to _{a 16} are connected to input terminals of an antenna switching section 2 consisting of a scanner, and an output terminal of the antenna switching section 2 is connected to a response level control section 3 including a variable attenuator.

The response signal receiving section 4 includes a tuning/detection circuit 4a, a demodulation circuit 4b following the tuning/detection circuit 4a,
A response signal detection circuit 4c following the demodulation circuit 4b
, a tuning/detection circuit 4a, and a response signal detection circuit 4c.
and a squelch circuit 4d interposed between the
The input terminal of the tuning/detection circuit 4a is connected to the output terminal of the response level control section 3.

The arithmetic processing unit 5 consists of a microprocessor,
One input port is connected to the output terminal of the response signal detection circuit 4c, and the other input port is connected to the output terminal of the transceiver handset number setting section 6 including a digital code setting device, and further, the arithmetic processing section The output port 5 is a control terminal of the response level control section 3, a control terminal of the antenna switching section 2, and a call signal transmission section 1.
, and the input terminal of the position display unit 7 including a digital display tube.

The transmitting/receiving handsets 8, 8', 8'', . . . consist of portable radio devices, and are attached to moving objects existing within the search area.

FIG. 2 is a flowchart of arithmetic processing in the arithmetic processing section 5 in FIG. 1, and FIG. 3 is a time chart of main waveforms in the configuration of FIG. 1.

In the search operation, the operator operates the digital code setting device of the transmitting/receiving handset number setting section 6 to select the moving object to be searched, that is, the transmitting/receiving handsets 8, 8', 8'', . . . attached to the moving object. When a number for specifying any one of... is set, the setting section 6 outputs a number signal _S1 .

Next, when the microprocessor of the arithmetic processing section 5 is reset, the processing section 5 starts (the second
According to the flowcharts in Figure a) and Figure 2, each part in the configuration of Figure 1 is controlled in the following steps to execute the search process.

First, the arithmetic processing unit 5 resets the counter T and the first and second flag registers FL ₁ and FL ₂ built into the microprocessor to "0", and then resets the first, second, and
K ₁ , K ₂ ,
By presetting _K3 respectively, the initial value is set (Fig. 2b).Next, the number signal _S1 is read from the transmitter/receiver handset number setting section 6 (Fig. 2c),
The calling signal assigned to the transmitter/receiver handset represented by the number signal _S1 is designated (FIG. 2d). At this time, the calling signal oscillation circuit 1a is supplied with the designation signal _S2 from the arithmetic processing section 5. (Fig. 3Aa), the oscillation circuit 1a responds to the transmitter/receiver handset 8,
8′, 8″, etc. Among the plurality of sound unit oscillators that oscillate specific frequencies assigned corresponding to _each of them, the output signal of the sound unit oscillator specified by the designation signal S Output as ₃ .

At this point, the frequency of the calling signal _S3 output from the oscillation circuit 1a changes from the frequency of the calling signal used last time to the frequency of the calling signal used this time (FIG. 3Bb).

Subsequently, the arithmetic processing section 5 outputs a transmission command signal (Fig. 2e), waits for the elapse of the set time _T1 by the timer built in the processing section 5 (Fig. 2f), and issues a transmission stop command. Until the signal is output (Fig. 2g), the transmission command signal _S4 , which is latched to the output port of the processing section 5 and continues, is supplied to the control terminal of the output amplifier circuit 1c (Fig. 3 Cc), and the command is Duration T ₁ of signal S ₄
During this period, the amplifier circuit 1c operates.

During this period, the modulating circuit 1b amplifies the carrier wave modulated with the paging signal _S3 , and sends it from the transmitting antenna 1d to the space within the search area as the paging signal _S'3 (the third Figure Dd).

Among the plurality of transmitting/receiving handsets 8, 8', 8''..., the transmitting/receiving handset corresponding to the transmitted calling signal _S'3 responds to the calling signal _S'3 and detects a competition between carrier waves of the same frequency. In order to avoid this, the response signal _S'5 is sent out to the space within the search area after waiting for the elapse of a delay time Td, which is somewhat longer than the duration _T1 of the calling signal _S'3 . 3Ee).Then, such a response signal is continuously sent out for a considerably longer time than the time required to execute all of the arithmetic processing described below (FIG. 3Ey).

During this time, the arithmetic processing unit 5 converts the response level from the address A in the A area specified by the contents of the first address counter A, that is, the response level control unit 3
It reads the signal attenuation level to be achieved at (FIG. 2h) and outputs a response level control signal S ₆ representing the response level (FIG. 2i).

Therefore, the control terminal of the response level control section 3 is
A response level control signal S ₆ is supplied (Gf in Fig. 3),
After decoding the signal S ₆ , the control unit 3 activates the built-in variable attenuator to set the response level represented by the signal S ₆ , that is, in this embodiment, the minimum signal attenuation level ( Figure 3 Hg).

Subsequently, the arithmetic processing unit 5 reads the antenna number, that is, the number specifying the antenna that should receive the response signal, from the address B in the B area specified by the contents of the second address counter B (see FIG. j),
It outputs an antenna switching signal _S7 representing the number (Fig. 2k).

The antenna switching signal _S7 is supplied to the control terminal of the antenna switching section 2, and upon decoding the signal _S7 , the switching section 2 operates a built-in scanner to detect the signal _S7 . The receiving antenna represented, i.e.
In this embodiment, the response signal S' ₅ received by the receiving antenna A ₁ is selectively supplied to the response level controller 3 (FIG. 3 Ih).

Then, the response signal _S'5 is sent to the response level control section 3.
When passing through, the signal is attenuated by a predetermined amount represented by the response level control signal S ₆ and is supplied to the response signal receiving section 4 .

Here, the tuning/detection circuit 4a extracts the carrier wave of the response signal and detects it, and the subsequent demodulation circuit 4b extracts the calling signal S' ₅ from the noise carried on the carrier wave.
extracts the modulation frequency component of and converts it into a DC voltage corresponding to the component, and furthermore, the subsequent response signal detection circuit 4c determines the arrival of the calling signal based on the level and duration of the DC voltage. Then, a response confirmation signal _S8 is output. When the signal level of the response signal S' ₅ supplied to the tuning/detection circuit 4a is below a specific value specific to the response signal receiving section 4, the squelch circuit 4d is activated (closed) to detect the response. Stops the operation of circuit 4c and sends a response confirmation signal
Prevents _S8 from being output.

The arithmetic processing section 5 reads the state of the output of the response signal detection circuit 4c (FIG. 2l) and determines whether or not the response confirmation signal _S8 is present (FIG. 2m).

However, after the calling signal S' ₃ is sent out, the transceiver handsets 8, 8', 8'', etc. do not send out the response signal S' ₅ until a specific delay time Td has elapsed. (Fig. 3 Ei), squelch circuit 4
d is closed (FIG. 3 Fj), and the output of the response confirmation signal _S8 is blocked.

Therefore, in the arithmetic processing unit 5, the determination result in FIG. 2 m is NO, and the state of the first flag register FL ₁ is determined (FIG. 2 n).
Since 0 is stored as the initial value for FL ₁ , the determination result is always YES in the first pass, and then until the timer determines that the set time T ₂ has elapsed (Fig. 2 o) , returning to the process shown in FIG. 2l, the reading and determination of the response confirmation signal _S8 are continuously repeated. At this point, the minimum response level is set in the response level control section 3, and if the system is operating normally, the response confirmation signal _S8 is guaranteed to be obtained at this response level. Since the response level control is performed at the time, the response signal S' ₅ is received before the set time T ₂ elapses, the squelch circuit 4d opens (FIG. 3 Fk), and the response signal detection circuit 4c outputs the response confirmation signal. Output _S8 .

Then, in the arithmetic processing unit 5, the determination in FIG.
Since the result is YES, the first flag register FL ₁ is set to "1" (FIG. 2, p), and 1 is added to the counter T, which has been set to an initial value of 0 (FIG. 2, q).

Thereafter, the antenna switching signal _S7 supplied to the antenna switching section 2 is read (Fig. 2r), and it is converted to the address C of the C area specified by the contents of the third address counter C (i.e., At this point, the initial value K ₃ ) is stored (FIG. 2, s), and the third address counter C is incremented to designate the next address in the C area (FIG. 2, t).

Next, the antenna switching signal S ₇ related to the above processing
It is determined whether or not it represents the final receiving antenna _A16 (Figure 2 u), and the determination result is NO.
If so, the second address counter B is incremented to specify the next address in area B (Fig. 2 v), and the process is repeated to the final receiving antenna. Repeat for all receiving antennas A ₁ to A ₁₆ until A ₁₆ is reached.

This process (Fig. 2 l to v) is performed by connecting all the receiving antennas A ₁ to A to the receiving antennas whose electric field strength is high enough to receive the response signal S' ₅ as the response confirmation signal S ₈ at the specified response level. ₁₆ , and store the antenna switching signal _S7 representing them, count the number of such receiving antennas, and store the counted value.

At the initially set response level, if the system is normal, a response confirmation signal _S8 is always obtained, so first, the antenna switching unit 2 selects and connects the receiving antenna _A1 . In the state
After the response signal S' ₅ arrives (FIG. 3 Fk) and the processing time t ₃ of the response confirmation signal S ₈ has elapsed (FIG. 3 Il), the switching unit 2 selects and connects the receiving antenna A ₂ . (Im in FIG. 3), and thereafter, every time the processing time _t3 elapses, the next receiving antenna is selected and connected.

After the last receiving antenna A ₁₆ is selectively connected,
When the processing time t ₃ has elapsed (Fig. 3 In), Fig. 2 u
The determination result is YES, and the arithmetic processing unit 5 reads the contents of the counter T (aa in Figure 2) and determines whether it is zero (bb in Figure 2), but at the first response level, If the system is normal, response confirmation signal S ₈ for all receiving antennas A ₁ to _{A 16}
is obtained, the judgment result is NO, and then the contents of counter T are temporarily stored in register R (cc in Figure 2), the counter T is cleared (dd in Figure 2), and the second Set flag register FL ₂ to “1”
(see Figure 2), and then set the second and third address counters B and C to their initial values K ₂ and
Return to K ₃ (Fig. 2 ff, gg).

Furthermore, the response level control unit 3 determines whether the set response level is the final response level (hh in FIG. 2), and the determination result is
If NO, the first address counter A is incremented to designate the next address in area A (FIG. 2 ii), and then the process returns to FIG. 2 h.

Then, the next response level control signal _S6 is supplied to the response level control section 3 (Go in FIG. 3), and the response level, that is, the attenuation amount in the control section 3 is determined by this signal. step increase (Fig. 3 Hp), and at the new response level all receiving antennas A ₁ to _{A 16}
The confirmation of the presence or absence of the response confirmation signal _S8 is repeatedly executed in the same manner as described above.

When this process is repeated, the response level increases step by step, and the receiving antenna, which is in an electric field strength that is strong enough to receive the response signal S′ ₅ as the response confirmation signal S ₈ , sends out the paging signal S′ ₅ . I narrowed it down to the one that is similar to the transmitter/receiver handset I am using.

This process will be explained more quantitatively as follows based on FIG. 4.

Figure 4A shows transmitting antenna 1d and receiving antenna
_FIG . _4B is an explanatory diagram illustrating the arrangement within a search area of one of the transmitting/receiving handsets 8, 8', 8'', A ₁ to A 16 , and FIG. 4B is the arrangement of the receiving antennas A 1 to A ₁₆ FIG. ₆ is an explanatory diagram illustrating the relationship between the reception level and response level of response signal S'5 in each case.

At the first response level (Hg in FIG. 3, BL ₀ in FIG. 4) in the operation description above, the amount of attenuation of the response level control section 3 is the minimum, so all receiving antennas A ₁ to _{A 16} are The reception level of the response signal S′ ₅ received by the receiver is equal to or higher than the response level L ₀ , and the electric field is such that all receiving antennas A ₁ to _{A 16} can receive the response signal S′ ₅ as the response confirmation signal S ₈ . Placed in strength.

As the search process progresses, the response level increases step by step and, for example, when it reaches the level of _L5 (Hq in Figure 3), the response level is received to the extent that the response signal _S'5 can be received as the response confirmation signal _S8 . The positions of the receiving antennas whose level _is the same are narrowed down to the range surrounded by _the dotted line _L5 in _FIG . ₆ , _A7 (Fig. 4, Ba).

In addition, as shown in the range where the response confirmation signal _S8 can be received at response level _L5 ( _AL5 in Figure 4), due to the presence of radio wave obstructions (Ax, y in Figure 4), the response cannot be received. The range in which the confirmation signal _S8 can be received is not necessarily circular.

On the other hand, when processing the response confirmation signal _S8 at each stage, in the arithmetic processing unit 5, the first flag register is
Since FL ₁ is set to "1", the judgment result of the first flag (n in Fig. 2) is NO, and this time the setting is made somewhat longer than the processing time t ₃ of the response confirmation signal S ₈ . Until the elapse of time T ₃ is determined (Fig. 2 jj),
Returning to the process shown in FIG. 2, the process waits for the response confirmation signal _S8 to arrive.

Therefore, at response level L ₅ , receiving antenna A ₁
Since the response confirmation signal _S8 is not obtained, the antenna switching unit 2 remains selectively connected to the receiving antenna _A1 until the set time _T3 has elapsed (Fig. 3 Ir), and then the second antenna The judgment result in figure jj is
If YES, the process moves to the steps after u in FIG. 2 without adding 1 to the counter T, and the antenna switching section ₂ switches the receiving antenna to
Select and connect A ₂ (Figure 3 Is).

As for the receiving antennas A ₂ , A ₆ , and A ₇ , a response confirmation signal S ₈ is obtained (Is,
_t ), the determination result in _{FIG .}
The antenna switching signal _S7 representing the initial value of the C area is
They are sequentially stored in the addresses following _K3 (Fig. 2, gg, r to t).

Furthermore, at this time, the contents of the counter T become 3 (FIG. 2, q), and after updating the register R to 3 (FIG. 2, cc), it is cleared (FIG. 2, dd).

Subsequently, when the response level increases to L ₆ (Figure 3 Hu), the position of the receiving antenna whose reception level is high enough to receive the response signal S' ₅ as the response confirmation signal S ₈ is further narrowed down, and the 4th In Figure A, the receiving antenna is the range surrounded by the dotted line _L6 , and the reception level of the response signal _S'5 is equal to or higher than the above response level _L6 .
Only A ₆ is available (Figure 4 Bb, Figure 3 Iv).

Furthermore, as the response level increases to L ₇ (the third
Figure Hw), the response confirmation signal _S8 is no longer obtained.

At this time, in the arithmetic processing unit 5, the determination result in FIG. 2 bb becomes YES and the second flag is determined (FIG. 2 kk), but the second flag register FL ₂ is already set to "1". (see Figure 2),
The judgment result is NO.

Then, the arithmetic processing unit 5 calculates a value obtained by adding the contents of the register R to the initial value K ₃ from the address of the initial value K ₃ of the antenna switching signal S ₇ stored in the C area. Initialize the third address counter C by setting the values stored up to the address of
The value of the contents of register R is sequentially incremented and output from _K3 (Fig. 2, ll).

In such output processing, since the response confirmation signal _S8 is not obtained, when the content of the counter T is 0 (Fig. 2 bb), in the end, when processing the response level, the judgment result shown in Fig. 2 m is obtained. becomes NO, the path from p to t in Figure 2 is not passed, and the response signal S' ₅ is received as the response confirmation signal S ₈ at the response level set prior to the corresponding response level. Antenna switching signal representing the completed receiving antenna
S ₇ is stored in area C, and the number of antenna switching signals S ₇ at that time is stored in register R. Therefore, the antenna switching signals S ₇ are stored in register R in order from the initial value address. By outputting as many contents as the number of contents, the corresponding response level, that is,
It outputs _{an antenna switching signal S7 representing} a receiving antenna that obtained a response confirmation signal _S8 at a response level that was set prior to a response level that did not obtain any response confirmation signal S8.

In this way, the arithmetic processing unit 5 selects the antenna switching signal S' ₇ representing the receiving antenna A ₆ stored in the C area, that is, the response level closest to the response level at which the response confirmation signal S ₈ is not obtained at all. At this time, an antenna switching signal S' 7 that specifies the minimum number of receiving antennas that have received the response signal S' ₅ as a response confirmation signal S ₈ is outputted to the position display section ₇ (Fig. 2 ll), and the operation is stopped. (Figure 2 mm).

The position display unit 7 visually displays each of the minimum number of receiving antennas.

Then, as in the operation example above, the receiving antenna
When only _{the antenna switching signal S' 7 representing A 6 is displayed ,} as shown in FIG. The position of the moving object is specified within the system-specific minimum receivable area in ₆ .

Furthermore, when the minimum number of receiving antennas is plural, the position of the moving object is specified within the intersection area of the minimum receivable area centered on each of the plurality of receiving antennas.

In addition, after the first response level is set (Hg in Figure 3), if the set time T ₂ elapses without the response confirmation signal _S8 being obtained (Ix in Figure 3), o in Figure 2
The determination result is YES, and an alarm indicating that the response is delayed is issued (Fig. 2 nn).

In addition, if no response confirmation signal _S8 is obtained for all receiving antennas _A1 to _A16 at the initial response level, the determination result in Fig. 2bb is YES.
Then, the second flag is determined (see Figure 2).
kk), at this point, the second flag register FL ₂ has not yet been set to "1", so the judgment result is YES, and an alarm indicating no response is output (see Figure 2). oo).

Furthermore, even when the final response level is reached (Fig.
Hw), if the acknowledgment signal S ₈ is received,
Since the determination result in FIG. 2 bb is NO and the determination result in FIG. 2 HH is YES, an alarm indicating that the response level control is out of order is output (FIG. 2 oo).

Next, the configuration and operation of the second embodiment of the present invention will be explained based on FIGS. 5 and 6 as follows.

FIG. 5 is a block diagram showing the configuration of the second embodiment, and FIG. 6 is a flowchart showing a partial modification of the flowchart shown in FIG. 2.

An output terminal of the antenna switching section 2 is connected to an input/output terminal of a transmission/reception switching section 9 including a high frequency switching circuit,
The output terminal of the switching section 9 is connected to the input terminal of the response level control section 3, and the input terminal of the switching section 9 is further connected to the output terminal of the output amplifier circuit 1c. A signal line extends from the output port of the arithmetic processing section 5 to the control terminal of the switching section 9 .

The other components are the same as those designated by the same reference numerals in the configuration shown in FIG.

The search operation starts when the arithmetic processing unit 5 is reset (Fig. 6a), and the subsequent processes shown in Figs. 6b to d are the same as those shown in Figs. 2b to d. be.

Subsequently, the arithmetic processing section 5 sends a switching command signal _S10 to the transmission/reception switching section 9 (Fig. 6 a'), connects the output terminal of the antenna switching section 2 to the output terminal of the output amplification circuit 1c, and performs a call. The signal S' ₃ can be supplied to the antenna switching section 2.

After that, read the antenna number specified by the contents of the second address counter B (see Figure 6).
b'), and outputs the antenna switching signal _S7 (Fig. 6).
c′).

Then, the antenna switching unit 2 selectively connects the first antenna A ₁ to the transmission/reception switching unit 9 in response to the antenna switching signal S ₇ .

Subsequently, the arithmetic processing unit 5 executes the processes shown in FIG. 6 e to g, and in exactly the same way as the processes shown in _FIG . ₃ , the calling signal S′ ₃
is supplied to the selectively connected first antenna _A1 , and is transmitted to the space within the search area using the antenna _A1 as a transmitting antenna.

At this time, the transmission level of the sent paging signal S' ₃ is such that, as in the case of the first embodiment, any transceiver/receiver located at any position within the search area can respond. This need not be the case, and it is sufficient that each set of transmitter/receiver response ranges formed around each of the antennas A ₁ to _{A 16} covers the search area.

Next, the arithmetic processing unit 5 calculates the final antenna.
It is determined whether up to A ₁₆ has been processed (Fig. 6 d'), and if the determination result is NO, the second address counter B is incremented and the next antenna is designated ( Returning to the steps in Figure 6 e') and Figure 6 b', the same process is repeated and all antennas A ₁ to A ₁₆ are sequentially switched and used as transmitting antennas within the search area. Call signal in space
S′ ₃ is what is sent.

Then, in response to the calling signal S′ ₃ , a response signal is generated.
The operation of the transmitter/receiver handset 8, 8', 8'', etc. that transmits S' ₅ , and further identifies and displays the antenna that can receive the response signal S' ₅ as the response confirmation signal S ₈ while changing the response level. The operation is exactly the same as in the first embodiment.

When the sending of the calling signal S′ ₃ from the final antenna A ₁₆ is completed, the arithmetic processing unit 5 performs the following operations.
The determination result in FIG. 6 d' becomes YES, and then the switching command signal S ₁₀ is outputted again (FIG. 6 f'), and in response, the transmission/reception switching unit 9 outputs the output terminal of the antenna switching unit 2. By connecting the input terminal to the input terminal of the response level control section 3, a configuration similar to that of the first embodiment is formed.

Thereafter, the response level is read from the address in area A specified by the contents of the first address counter A (Fig. 6h), and the response level control signal S ₆ is read.
(Figure 6i). Such processing is shown in Fig. 2 h,
This is the same as the process for i, and furthermore, in Fig. 2, h, i
The processing after j that follows is also applied to the second embodiment.

Note that in the configurations of the first and second embodiments of the present invention, the antennas A ₁ to _{A 16} are arranged in a grid pattern within the search area, but the arrangement form of these antennas is limited to the grid pattern. Rather, an appropriate arrangement form should be selected in consideration of the shape of the search area and the position of radio wave obstacles.

Furthermore, the response level control section 3 variably sets the amount of attenuation of the high frequency response signal S' ₅ supplied to the tuning/detection circuit 4a, but this is not limited to this, and if necessary, response confirmation can be performed. Since it is sufficient to variably set the reception level at the receiving antenna, that is, the electric field strength, which is necessary to obtain the signal _S8 , the configuration in which the operating point of the squelch circuit 4d is variably set is also referred to as response level control means in this specification. It is included in

As described above, the present invention uses a plurality of receiving antennas disposed within the search area to receive a response signal sent out in response to a call signal by a transceiver handset attached to a moving object within the search area. When specifying the position of a moving object based on the response confirmation signal obtained by is configured to receive the response signal with all receiving antennas and to identify the minimum number of receiving antennas that can receive the response signal as a response confirmation signal. The reception at multiple receiving antennas is unaffected by fluctuations in the receiving level of the response signal at the receiving antenna due to the presence of objects, etc., and also by fluctuations in the receiving sensitivity at the receiving antenna and the subsequent response signal receiving section. By specifying the minimum number of receiving antennas whose reception levels of response signals are relatively high based on the relative difference in levels, the position of the moving object can be specified within the minimum receivable area surrounding the position of the receiving antennas.

Therefore, according to the present invention, in addition to detecting that a moving object has left a specific area as in the past, it is possible to detect Not only can the position of a moving object be narrowed down and measured with high precision within a narrow area, but it also has the advantage of being able to measure the position of a moving object extremely stably, without being directly influenced by the transmitting and receiving levels as in the past. It has a positive effect.

[Brief explanation of drawings]

1 to 4 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing its configuration, FIG. 2 is a flowchart of the arithmetic processing section 5,
Figure 3 is a time chart of the main waveforms, Figure 4A is an explanatory diagram illustrating the arrangement of the receiving antenna, Figure 4B
FIG. 2 is an explanatory diagram illustrating the relationship between the reception level and response level at each reception antenna. Figures 5 and 6
The figures relate to a second embodiment of the present invention; FIG. 5 is a block diagram showing its configuration, and FIG. 6 is a partial flowchart showing a modification of the flowchart in FIG. 2. DESCRIPTION OF SYMBOLS 1...Call signal transmitting section, 2...Antenna switching section, 3...Response level control section, 4...Response signal receiving section, 5...Arithmetic processing section, 6...Transmitting/receiving handset number setting section, 7... ...Position display section, 8, 8', 8''...
...Transmission/reception handset, 9...Transmission/reception switching unit, A ₁ , A ₂ ,
A ₃ …A ₁₆ …Receiving antenna.

Claims (1)

[Claims] 1 A plurality of receiving antennas A ₁ , A ₂ ... arranged at specific intervals within the search area, and attached to a moving object within the search area, transmitting information through the space within the area during the paging period. Panning specific call signal S′ ₃
a specific response signal that is received and propagated through space within the region during a response period that follows the paging period.
one or more transmitting/receiving handsets 8 for transmitting _S'5 ;
8'... During the calling period, the transmitter/receiver handset 8,
a calling signal transmitting means 1 for selectively transmitting _a calling signal S' ₃ corresponding to each of 8'... into the search area;
When the signal _S'5 is above a certain response level,
Response signal receiving means 4 for outputting response confirmation signal _S8
During the response period, response signals S' ₅ from the plurality of receiving antennas A ₁ , A ₂ . . . are sequentially and selectively supplied to the response signal receiving means ₄ based on the antenna switching signal S 7 . response level control means 3 for changing the response level of the response signal receiving means 4 based on the response level control signal S ₆ during the response period; ₇ and response level control signal S ₆ to each of antenna switching means 2 and response level control means 3, and further supplying antenna switching signal S ₇ and a plurality of receiving antennas A ₁ , A ₂ . . . Of these,
Based on the response confirmation signal _S8 corresponding to each of the receiving antennas selected in the signal _S7 , the position of each transmitting/receiving handset 8, 8'... within the search area is determined, and the determination result is It consists of an arithmetic processing means 5 which outputs the position signal _S'7 as a position signal S'7, and a position display means ₇ which displays the position of each of the transceiver handsets 8, 8'... in response to the position signal S'7. The processing means 5 sends the response level control signal S ₆ to the response level control means 3, and transmits the response level control signal S 6 to the plurality of receiving antennas A ₁ , A ₂ .
The response level of the receiving means 4 is changed so that the number of response confirmation signals _S8 output by the response signal receiving means 4 in response to the above is minimized, and each of the minimum number of response confirmation signals _S8 is A moving object search system characterized in that the positions of transmitting/receiving handsets 8, 8', . . . are determined by specifying corresponding receiving antennas.