JP2797145B2 - Information transmission method by radar - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of detecting a target by radar and transmitting information.

[Prior Art] Conventionally, as a known document of a method of detecting a target and transmitting information by using a radar, for example, "IALA Policy Document on Future Use of Radar Beacon (Racon)" (Japan Navigation Marking Association, 1986) The method is used in a radar signal time offset frequency agile racon (ITOFAR) system described in August, 1999).
In this method, the time (hereinafter referred to as a transmission pulse time interval) T between a previous transmission pulse and a current transmission pulse of a pulse radio wave transmitted by the radar is changed as follows, whereby information is received from the radar side. Transmission was in progress.

That is, eight fixed times (A, A
+ A, ..., A + 7a). Then, the fixed time set corresponding to the information to be transmitted is selected, and n of the n × b term is selected in a random manner from 0 to 7 for each transmission pulse to determine the time interval T of the transmission pulse. Was sending.

Here, n of the n × b term is randomly selected from 0 to 7 in order to avoid interference between a plurality of transmission pulses.
It has no meaning as information. Therefore, the type of time fixed as the time interval of the transmission pulse is Q (in this example, A, A +
a, ..., A + 7a), the type of information that can be transmitted is Q (eight in this example).

[Problems to be Solved by the Invention] However, in the method shown in the above-mentioned ITOFAR system, in order to increase the types of time intervals of transmission pulses, for example, when the time intervals of transmission pulses are increased, the antenna rotation speed becomes the same. At this time, the number of pulse hits to the target decreases, and the target detection capability of the radar decreases. When the time interval between transmission pulses is reduced, the receivable distance of the radar is reduced.

Therefore, there is a restriction in changing the time interval of the transmission pulse while maintaining the operation function as a radar, and the number (type) of the time interval of the transmission pulse that can be made practical is small. As a result, there is a problem that the amount of information that can be transmitted from the radar is small.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide an information transmission method by radar that can dramatically increase the amount of information that can be transmitted by radar.

[Means for Solving the Problems] A method of transmitting information by a radar according to the present invention is a radar for transmitting a pulse radio wave as a rotating beam to detect a target, wherein the rotating beam of the radar irradiates a point target. During the time that is less than half of the time, the time between the previously generated trigger pulse and the time between the previously generated trigger pulse and the previously generated Trigger pulse generating means for generating a plurality of trigger pulses each having a value assigned to information to be transmitted from among a plurality of predetermined values, and a frame configuration generated by the trigger pulse generating means Transmitting means for transmitting pulse radio waves by the plurality of trigger pulses.

[Operation] In the present invention, in a radar that transmits a pulsed radio wave as a rotating beam to detect a target, the trigger pulse generating means may include a half or less of the time during which the rotating beam of the radar irradiates the point target. In the period of time, as a plurality of trigger pulses of one frame configuration, a time between a trigger pulse generated last time is constant and a time between the trigger pulse generated last time is a plurality of predetermined values. Among them, a plurality of trigger pulses each having a value assigned in accordance with information to be transmitted are generated, and the transmitting means transmits a pulse radio wave by the plurality of trigger pulses having the generated frame configuration. As a result, information transmission can be performed simultaneously with target detection.

FIG. 1 is a block diagram of a radar according to the present invention, and FIG.
FIG. 3 is a block diagram of a trigger generator shown in FIG. 3, FIG. 3 is a diagram showing a code format of input information according to the present invention, and FIG. 4 is a waveform diagram showing a trigger pulse according to the present invention.

In FIG. 1, 10 is an antenna, 11 is a rotating unit, 12 is a switching unit, 13 is a transmitter, 14 is a receiver, and 15 is a trigger generating unit. The radar shown in FIG. 1 will be described as, for example, a port monitoring radar installed on land.

The operation of FIG. 1 will be described. The trigger generating unit 15 receives information per frame (30-bit information in this embodiment) to be transmitted from an adjacent device (indicator, video signal processing device, etc., and the same hereinafter) or another external device. Then, a plurality of trigger pulses of one frame configuration specified by the input information are generated. In the present embodiment, a plurality of trigger pulses having a one-frame configuration include a trigger pulse having a fixed time from the last generated trigger pulse (this is a synchronous pulse).
Five trigger pulses (hereinafter referred to as P ₀ ) and the time between the trigger pulse generated last time and the trigger pulse (hereinafter referred to as five trigger pulses) each having a value assigned to the input information from among a plurality of predetermined values. This is called information pulses P ₁ , P ₂ , P ₃ , P ₄ , and P ₅ ). Further, in the present embodiment, for the convenience of demodulating the information transmitted from the radar on the receiving side, it is assumed that the input information to the trigger generating unit 15 is such that the same information is repeatedly input at least twice. I do.
For example, the # 1 information and the # 2 information have the same content, and the # 3 information and the # 4 information have the same content. However, it is specified that the repeated input of the same information to the trigger generator 15 depends on the operation method of the radar to which the present invention is applied, and is not an essential matter of the present invention.

The trigger pulse generated by the trigger generation unit 15 is supplied as a trigger signal for operating the transmitter 13 and an adjacent device in synchronization. The transmitter 13 receives a trigger signal from the trigger generator 15 and generates a pulse radio wave for transmission (more precisely, a pulse-modulated microwave, the same applies hereinafter).
This pulse radio wave is sent to the rotating unit 11 by the switch 12, and is radiated from the antenna 10 to the outside via the rotating unit 11. Rotating part
From 11 the rotation angle signal is output to the adjacent device. The reflected radio wave from the target is guided to the switch 12 via the antenna 10 and the rotating unit 11, and is input to the receiver 14 by the switch 12. Receiving machine
14 generates a video signal from the input reflected radio wave and outputs it to an adjacent device as a radar video signal.

Next, the operation of the trigger generator 15 in FIG. 1 will be described in detail with reference to FIG.

In the block diagram of FIG. 2, 20 is a register, 21 is a switching circuit, 22 is a pulse interval setting circuit, 23 is a pulse generation circuit, and 24 is a timing control circuit.

The operation of FIG. 2 will be described with reference to FIG. 3 and FIG.
In the embodiment shown in FIG. 2, the register 20 is a 30-bit parallel input / parallel output register.
Input information in the code format shown in the figure is added. FIG. 3 shows a code format consisting of 30-bit data as a whole. Each frame in the figure contains a binary signal of "0" or "1" according to the content of input information. I have. This 30-bit code is divided into 5 small codes every 6 bits, and each small code is associated with a binary number.
It is represented by b ₁ , b ₂ , ..., b ₅ . The register 20 is a circuit that switches input information according to the timing signal of the timing control circuit 24.
Output to 21. Switching circuit 21 from the sequence b ₁ by a timing signal from the timing control circuit 24 to the input information to b ₅ 6
The information of the small code for each bit is sequentially switched and output to the pulse interval setting circuit 22.

The pulse interval setting circuit 22 uses the timing signal from the timing control circuit 24 to generate a first pulse as a synchronization pulse P ₀ with a time T ₀ between the last generated trigger pulse and the previous pulse.
Creating binary data B + b ₀ for generating and outputting a pulse generation circuit 23. Here, B is a constant binary number, and b ₀ is a constant negative binary number. Here, the reason why b _{0 is set} to a negative value is to make the value different from the above-mentioned small code binary numbers b _{1 to} b ₅ to facilitate detection of the pulse time interval T ₀ of the synchronization pulse P ₀ during demodulation. is there.

The pulse interval setting circuit 22 receives the timing signal from the timing control circuit 24,
The information in Decimal b _1, as the second pulse, to create a binary data B + b ₁ for generating information pulses P ₁ to the time between the last synchronization pulse P ₀ and T _1, the pulse generator
Output to 23.

Pulse interval setting circuit 22 in the same manner as a pulse from the third to sixth information pulse P ₂ to the time between the last generated pulses and T _2, T _3, T ₄ and T _5, respectively, P ₃ , P ₄
And binary data B + b ₂ for generating _{P 5, B + b 3,} B
+ B ₄ and B + b ₅ are sequentially created and output to the pulse generation circuit 23. Pulse generating circuit 23 receives the sequential binary data _{B + b i (i = 0~5} ) from the pulse interval setting circuit 22, the respective 2
Susumu data sequentially generate pulses P ₀ to P ₅ of the pulse time interval corresponding to, and output as the trigger signal of the radar.
Pulse signal of one frame composed of the six pulses P ₀ to P ₅ is that it contains one type of information to be transmitted. In the present embodiment, the same information is registered at least twice so that the information to be transmitted from the radar is reproduced on the receiving side within the irradiation time of the radar beam.
Repeatedly input to 20. Therefore, at least two pulses of one frame based on the same information are output from the pulse generation circuit 23.
The times will be generated repeatedly.

Here, a method of obtaining the pulse time interval T _i (i = 0 to 5) from the binary number B + b _i (i = 0 to 5) is formulated as follows.

First, assuming that the decimal equivalents of the binary numbers B, b _i (i = 0 to 5) are D, d _i (i = 0 to 5), respectively, the synchronization pulse P ₀ and each of the information pulses P _{1 to} P ₅ Time interval T with previous pulse
_i (i = 0 to 5) is represented by the following equation (1).

T _i = T _D + d _i · Δt (i = 0 to 5) (1) where T _D = D · Δt, where Δt is a minute unit time.

The timing control circuit 24 inputs an output pulse P ₀ to P ₅ of the pulse generating circuit 23, with reference to these pulse time register 20, switching circuit 21, the circuit of the pulse interval setting circuit 22, and pulse generator 23 Various timing signals necessary for the operation of are prepared and sent to the respective circuits.

That is, the timing control circuit 24 is supplied from an adjacent device.
The 30-bit data inputted newly to register 20 controls the timing of all the circuits from the first sync pulse P ₀ to be generated in the last information pulse P ₅ to 6 pulses sequential pulse generation circuit 23. The information when generating the pulse P _5, immediately following 30-bit data inputted from the position adjacent to the register 20, various timing as the switching circuit 21 following each circuit again carries out repeatedly from the beginning an operation of the description Create a signal.

Here, what kind of information (30-bit data) the adjacent device supplies to the register 20 in the trigger generator 15 is
It depends on the operation method of the radar to which the present invention is applied.

That is, when it is desired to transmit the same information in all directions regardless of the rotation direction of the antenna, the same information may be supplied to the register 20 during a certain period.

In addition, when it is desired to transmit different information for each beam irradiation time of the rotating antenna, the minimum number of information bits required on the receiving side is the number of 30 bits, and the same information is received. The number of frames that can be received and how many times the information to be supplied is determined by the operation method such as the number of frames.

In this implementation, 30
The description will be made on the assumption that the radar side repeatedly transmits the same information twice, on the assumption that the bit information only needs to be received once by the receiving side.

Thus, as shown in Fig. 4 from the pulse generating circuit 23, the pulse signal of the second frame with the same information comprised by the synchronization pulse P ₀ and information pulses P ₁ ~P ₅ (# ₁ frame and # 2 frame) The generated radio signal is transmitted from the transmitter 13 using the pulse signal as a trigger signal.

Further, t _{b in} FIG. 4 is the time from the time when the leading edge of the radar beam starts irradiating the target to the time when the trailing edge of the radar beam irradiates the target. That.

The beam irradiation time t _b of this radar is given by the following equation (2), where θ _b [degree] is the beam width of the radar, and N is the rotation speed of the antenna. Given by

The most important point in the present invention is the time required for the one-frame pulse signal. There is set to satisfy small time than half of the beam irradiation time t _b of the radar.

 That is, the following expression (3) must be satisfied.

1/2 t _b > T _F … (3) It is.

By setting so as to satisfy the above equation (3),
Be started from the start what radar pulses of the radar beam irradiation, the radar pulses of at least one frame in the beam irradiation time t _b is contained in a complete form from the synchronizing pulse P ₀ to the last information pulses P ₅ sequentially . This beam irradiation time t _b
The complete reception of one frame of radar pulse in the above makes it possible for the receiving side (for example, a marine vessel) receiving this information to completely reproduce the information of the one frame. FIG. 4 shows this time relationship.

Here, a specific numerical example satisfying the expression (3) will be shown. Now, assuming that the antenna rotation speed N = 10 [rpm] and the beam width θ _{b of the} radar is 0.25 [degree], t _b and 1 / (1) in the equation (2) are obtained.
2 t _b Becomes

Also, binary b _i In this embodiment (i = 1 to 5) is the decimal equivalent number for binary number 6 bits d _{i (i} = _1~5) 0
Since it can take a value in the range of ~ 63, now T _D = 292 μs,
If Δt = 1 μs and d ₀ = −1, the required time T _F of the radar pulse of one frame is T _F (= 2.066) is smaller than 1/2 t _b (= 2.0835). Therefore, equation (3) is satisfied.

In the above specific numerical example, the minimum value of the radar pulse interval is T _D -1 × Δt = 291 μs, and the maximum value is T _D + 63 ×
Δt = 355 μs. Since the radar and adjacent devices are usually designed to operate on the basis of the trigger signal every time, such a change in the radar pulse interval is not an essential problem. If the radar and the adjacent device are designed in consideration of the above-mentioned range change of the radar pulse interval, it is easy to prevent the operation and observation from being hindered.

Next, an information receiver for receiving information transmitted from the radar of FIG. 1 will be described. This information receiver is installed and used, for example, on a ship that needs information transmitted from a port monitoring radar.

FIG. 5 is a block diagram of the information receiver according to the present invention, and FIG. 6 is a block diagram of the demodulation unit shown in FIG.

In FIG. 5, 30 is an antenna, 31 is a receiver, and
32 is a demodulation unit.

The operation of FIG. 5 will be described. The radar pulse radio wave transmitted from the radar of FIG. 1 is received by the antenna 30,
A radar pulse as a video signal is generated by the receiver 31, and the radar pulse is applied to the demodulation unit 32. Demodulation unit 32 receives radar pulses from the receiver 31, detects the synchronization pulse P ₀ from the time interval T ₀ of the pulse, each information pulse P ₁ of the synchronization pulse P ₀ from the first as a time reference to the fifth each time interval between the previous pulse ~P ₅ T ₁ ~T ₅
, Demodulate the information sent from the radar and output this information. The operation of the demodulation unit 32 will be described in detail with reference to FIG.

In FIG. 6, reference numeral 40 denotes a pulse interval measurement circuit, 41 denotes a synchronization information detection circuit, 42 denotes a deviation amount calculation circuit, 43 denotes a timing control circuit, 44 denotes a switching circuit, and 45 denotes a register.

The operation of FIG. 6 will be described. The pulse interval measuring circuit 40 receives a radar pulse from the receiver 31, measures the time interval from the previous radar pulse using the minute unit time Δt as a reference unit, and uses the measured binary interval data as a synchronization information detecting circuit. It outputs to 41 and the displacement amount calculation circuit. The synchronization information detection circuit 41 receives the interval data from the pulse interval measurement circuit 40, checks whether or not the interval data is the synchronization pulse interval data, and if so, immediately creates a synchronization signal and sends it to the timing control circuit. Output to 43. The deviation amount calculation circuit 42 receives the interval data from the pulse interval measurement circuit 40, and calculates the deviation amount of the pulse interval obtained by subtracting the constant binary number B from this data in binary number (this deviation amount is If detected correctly, it is equal to the aforementioned binary number b _i (i = 0 to 5).) Except for the calculated displacement amount that is equal to the binary number b ₀ ,
The data is output to the switching circuit 44 as 6-bit binary data by the timing signal of the timing control circuit 43. Switching circuit
Reference numeral 44 denotes a configuration in which the input circuit has 6 bits and the output circuit has 30 bits. The shift amount data from the shift amount calculation circuit 42 is output in the same arrangement as the input side by the timing signal of the timing control circuit 43. 6 bits at a time, and outputs the result to the register 45. Register 45 is a 30-bit parallel input,
The parallel output register receives the 6-bit displacement data from the switching circuit 44 in order, receives the fifth displacement data, and adds all the 30 bits of data on the input side. The data on the input side is transferred to the output side by a timing signal and output to the outside. The 30-bit output data is obtained by demodulating and reproducing information transmitted from the radar. The timing control circuit 43 receives the radar pulse from the receiver 31 and the synchronization signal from the synchronization information detection circuit 41, and creates various timing signals necessary for the operation of the deviation amount calculation circuit 42, the switching circuit 44, and the register 45, It is sent to each of the above circuits.

In the present embodiment, as already described in the trigger generation unit 15 in FIG. 1 and the timing control circuit 24 in FIG. 2, the pulse signal having the frame structure based on the same information is repeatedly transmitted at least twice. since it is, the pulse signal P ₀ to P ₅ of at least one frame structure in the beam irradiation time to be included in a complete form that irradiates the information receiver. Therefore, the transmitted information can be reproduced on the receiving side.

In the above embodiment, the number of possible time intervals between each information pulse in the radar pulse and the previous pulse is Q,
If the number of information pulses in one frame is M, then Q =
Since ²⁶ and M = 5, the type of information that can be sent to one receiving side during one rotation of the radar antenna is Q ^M = ^{26 × 5} . It can be seen that this value is dramatically increased as compared with the above-described conventional value Q (eight kinds).

In the above embodiment, the amount of information that can be transmitted is 30
Bits and information types are 2 to the 30th power, that is, 1,073,741,
It was described as 824. Then, in order to ensure that the information amount of 30 bits is received and reproduced once by the receiving side within the beam irradiation time of the antenna, an example in which six transmission pulses are repeated twice and transmitted in one frame configuration is shown. . However, the present invention is not limited to this.

For example, when the amount of information to be transmitted is 6 bits (64 types) or 12 bits (4096 types), one or two information pulses are sufficient. Therefore, one frame is 2
(P ₀ , P ₁ ) or three (P ₀ , P ₁ , P ₂ ) radar pulses. In this case, the radar pulse of one frame is generated twice or more within the antenna beam irradiation time ( For example, three to four times), there is obtained a time allowance for repeated transmission.

If the information to be transmitted is information irrelevant to the rotation direction of the antenna (for example, weather information, etc.), the information input to the trigger generation unit is the same information within a certain time,
A radar pulse having a frame configuration including the same information in all directions is repeatedly transmitted many times.

The 30-bit information consisting of the radar pulse of the frame configuration transmitted first time and the 30-bit information transmitted second time have exactly the same 28-29 bits, for example.
Another use is to change only ~ 2 bits. In this case, although the data is different as the 30-bit data, the data of 28 to 29 bits that the receiving side actually wants to use is substantially the same.

Therefore, how many times a radar pulse having a frame configuration including the same information is repeatedly transmitted is a matter dependent on the operation method and is not an essential matter of the present invention. The essence of the present invention is that the synchronization pulse and the information pulse including the synchronization pulse and the information pulse are not more than half of the time when the rotating beam of the radar is illuminating the point target.
This is to transmit a plurality of radar pulse signals having a frame configuration.

Further, in the above embodiment, the deviation of the time interval between each information pulse in the radar pulse and the previous pulse corresponds to the binary number of each small code in the binary code of the information to be transmitted. In addition, the deviation of the time interval of each information pulse from the previous pulse is made to correspond to the difference between the binary numbers of two adjacent small codes in the binary code of the information to be transmitted, or 2 of each small code. It is also conceivable to make various kinds of correspondences, for example, to correspond to a number obtained by multiplying a base number by an appropriate constant and adding. Even in such a manner, the binary number of each small code is obtained by performing a calculation according to the manner of the correspondence on the transmitting side from the deviation amount of each information pulse at the time of demodulation, thereby reproducing the information. It is of course possible to do so.

In the present embodiment, an example is described in which the present invention is applied to a port monitoring radar and information is transmitted to a ship at the same time as detection of a ship. However, the following application examples can be considered.

In a system in which a transponder is mounted on a moving object such as a ship or aircraft, the moving object is identified on the radar side, and information is transmitted from the radar side to the moving object, conventionally, for information transmission, separate from radar radio waves We used radio waves. When the present invention is applied to this system, information can be transmitted by radar radio waves, so that radio waves for information transmission are unnecessary, and frequency allocation and equipment for generating and transmitting radio waves can be saved. Further, according to the present invention, it is possible to transmit different information for each radar beam width. Therefore, an address is assigned to each moving object, an address is designated by the radar, and different information is given to each moving object every time the antenna rotates. It is also possible to provide detailed services such as providing services to

In addition, there are various types of radio beacon facilities using microwaves that provide azimuth information to small vessels that currently do not have radars, such as course beacons, rotary beacons, and talking beacons. If the radar is used to provide azimuth information, the accuracy of azimuth can be improved, the time required for updating the information can be shortened, and the position information measured by the radar can be provided. Station savings. It can also provide collision danger information and other information obtained by radar. Thus, the applicable range to which the present invention can be applied is extremely wide.

[Effects of the Invention] As described above, according to the present invention, in a radar that transmits a pulsed radio wave as a rotating beam and detects a target, half of the time during which the rotating beam of the radar irradiates a point target is used. In the following time, as a plurality of trigger pulses of one frame configuration, a time interval between a trigger pulse having a fixed time and a previously generated trigger pulse and a time interval between a previously generated trigger pulse and a plurality of predetermined times are determined. From among the values, a plurality of trigger pulses each having a value assigned corresponding to information to be transmitted are generated, and a pulse radio wave is transmitted by the plurality of trigger pulses of the generated frame configuration. In addition, at the same time as the target detection as a function of the conventional radar, an effect that a remarkably large amount of information can be transmitted can be obtained.

In addition, by using the radar-based communication of the present invention instead of the conventional communication between the radar side using a transponder and an aircraft or a ship, conventional radio wave frequency allocation for information transmission and transmission equipment can be saved. The effect that can be obtained is obtained.

Also, instead of the course beacon, rotary beacon, and talking beacon as conventional radio beacon facilities that provide azimuth information, the radar of the present invention provides azimuth information, thereby reducing the number of stations in the conventional facility, Effects such as improvement of information accuracy and reduction of information update time can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a radar according to the present invention, FIG. 2 is a block diagram of a trigger generator shown in FIG. 1, FIG. 3 is a diagram showing a code format of input information according to the present invention, and FIG. FIG. 5 is a waveform diagram showing a trigger pulse according to the present invention, FIG. 5 is a configuration diagram of an information receiver according to the present invention, and FIG. 6 is a block diagram of the demodulation unit shown in FIG. In the figure, 10 and 30 are antennas, 11 is a rotating unit, 12 is a switch, 13 is a transmitter, 14 and 31 are receivers, 15 is a trigger generator, 2
0 and 45 are registers, 21 and 44 are switching circuits, 22 is a pulse interval setting circuit, 23 is a pulse generation circuit, 24 and 43 are timing control circuits, 32 is a demodulation unit, 40 is a pulse interval side constant circuit, and 41 is a synchronous circuit. An information detection circuit 42 is a deviation amount calculation circuit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (1)

(57) [Claims] 1. A radar for detecting a target by transmitting a pulsed radio wave as a rotating beam, wherein a plurality of frames of one frame are formed during a period of time equal to or less than half of a time when the rotating beam of the radar irradiates a point target. As the trigger pulse, the time between the previously generated trigger pulse and the time between the previously generated trigger pulse and the previously generated trigger pulse can be determined based on the information to be transmitted from among a plurality of predetermined values. Generating a plurality of trigger pulses each having a value assigned correspondingly, transmitting a pulse radio wave by the plurality of trigger pulses of the generated frame configuration, and performing information transmission simultaneously with target detection. Information transmission method using radar.