JPH0342434B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a radio wave generation method in a radar beacon device that can suppress the return of radio waves to side lobes of a radar antenna.

(Background Art) In radar beacon devices such as Raymark, which generates radio waves in response to radar pulses by adding a receiving device to generate beacon radio waves synchronized with transponders and radar pulses, the side of the radar antenna is In order to prevent the generation of radio waves to the lobe, the interval (period) of radar pulses with a high reception level emitted from the main lobe of the radar is temporarily stored, and when the reception level is low and the pulse interval is stored as described above. Conventionally, a sensor has been used in which radar pulses having the same pulse interval are removed so as to respond only to other radar pulses. In such devices, when a radar exists near the radar beacon device and its radar pulse interval is temporarily stored, if another radar with the same pulse interval as that radar is located far away. , the pulses received by this radar were also removed, and as a result, this radar was sometimes unable to receive beacon radio waves.

(Object of the Invention) In order to improve the above-mentioned disadvantages, the present invention temporarily stores the pulse interval and pulse width of the received radar pulse with a high reception level, and stores the pulse interval and pulse width of the received radar pulse with a low reception level and The radar pulse whose pulse interval and pulse width are both equal to the memorized pulse interval and pulse width is removed, and radio waves are generated in response to the remaining radar pulses, and the radar pulse is located near the radar beacon device. When there is a radar in the area and the emission of beacon radio waves to its sidelobe is blocked, even if a radar with the same pulse period as that radar is located far away, its pulse width will be different from that of the nearby radar. If the pulse width is different from the pulse width, the beacon radio wave is emitted, and the purpose is to reduce the cases where a distant radar cannot receive the beacon radio wave and improve the service function of the radar beacon device.

(Structure and operation of the invention) The figure is a block diagram of a radar beacon device showing one embodiment of the invention. In the figure, 10 is an antenna, 11
is a circulator, 12 is a video detection circuit, 1
3 and 14 are video amplifier circuits, 15 and 16 are pulse width measurement circuits, 17 and 18 are delay pulse generation circuits,
19 and 20 are pulse width memory circuits, 21 is a pulse width comparison circuit, 22 is a time measurement circuit, 23 is a pulse interval measurement circuit, 24 is a pulse interval memory circuit, 2
5 is a pulse interval comparison circuit, 26 is an AND circuit, 2
7 is a blocking gate circuit, 28 is an OR circuit, 29 is a code pulse generating circuit, 30 is a transmitting circuit, and 31 is a clock generating circuit.

The antenna 10 receives radar pulse radio waves and emits beacon radio waves, and the circulator 11
The received radar pulse radio wave is sent to the video detection circuit 1.
2, the radio waves generated from the transmitting circuit 30 are sent to the antenna 1.
It is designed to transmit only to 0. The video detection circuit 12 video-detects the radar pulse radio wave and outputs it as a radar pulse. Video amplifier circuit 13
The video amplifier circuit 1 amplifies all the radar pulses to a level at which the following circuits can operate.
4 is set to have a smaller amplification degree than the video amplifier circuit 13 (the difference in amplification width is more than 20 dB), and the subsequent circuits can operate only with radar pulses with a high input level, that is, radar pulses from the main lobe of the radar. It seems to be amplified to the level. The pulse width measurement circuits 15 and 16 measure the pulse width of the radar pulses output from the video amplifier circuits 13 and 14, respectively, and are composed of counting counters, and are configured to measure the pulse width of the radar pulses output from the video amplifier circuits 13 and ₁₄ , respectively. is counted over the period of the pulse width,
The counted values are stored in pulse width memory circuits 19 and 20, respectively.
Send to. The delayed pulse generation circuits 17 and 18 receive the radar pulses output from the video amplifier circuits 13 and 14, respectively, and delay the radar pulses by a certain amount of time (a value slightly larger than the maximum value of the radar pulses scheduled to be received). generates pulses and inputs them to pulse width memory circuits 19 and 2, respectively.
Send to 0. Pulse width memory circuits 19 and 20
means that the pulse width count value is received from the pulse width measurement circuits 15 and 16, respectively, and when the pulse width is received from the delay pulse generation circuits 17 and 18, respectively, the count value is read, and the pulse width is temporarily read until the next pulse is received. It's starting to feel like I remember it clearly. The pulse width comparison circuit 21 receives the pulse width count values stored in the pulse width memory circuits 19 and 20, compares them, produces an output when the error is within a predetermined error, and outputs this output to the AND circuit 26. Send to. Time measurement circuit 22
The circuit measures the time interval of radar pulses output from the video amplifier circuit 13, and is composed of a counting counter, which counts the clock pulses (CP ₂ ) generated by the clock generation circuit 31 and resets them by the radar pulses. Then, the count value is sent to the pulse interval comparison circuit 25. Pulse interval measurement circuit 23
, which measures the time interval of radar pulses output from the video amplifier circuit 14, is composed of a counting counter, and counts clock pulses (CP ₂ ).
The pulse interval memory circuit 2 stores the count value at the time of receiving the radar pulse output from the video amplifier circuit 14.
4, which is then temporarily stored and reset. The above count value stored in the pulse interval memory circuit 24 is stored until the next radar pulse comes from the video amplifier circuit 14 and the count value is output from the pulse interval measurement circuit 23. The pulse interval comparison circuit 25 compares the count value stored in the pulse interval memory circuit 24 with the time measurement circuit 22.
is compared with the count value of , and when both values are the same, a pulse is output to the AND circuit 26. The AND circuit 26 receives the output of the pulse width comparison circuit 21 and the pulse output of the pulse interval comparison circuit 25, outputs a pulse only when both outputs are present, and this pulse output is sent to the blocking gate circuit 27. Ru. The blocking gate circuit 27 is inserted between the video amplifier circuit 13 and the OR circuit 28, and the AND circuit 2
It operates in response to pulses from the video amplifier circuit 13, and blocks radar pulses sent out from the video amplifier circuit 13, otherwise passing them through. The code pulse generation circuit 29 receives the radar pulse from the OR circuit 28 and generates a code pulse in synchronization with the radar pulse. Transmission circuit 30
generates a beacon radio wave for transmission by amplitude modulating the oscillation signal with the code pulse. The clock generation circuit 31 generates clock pulses (CP ₁ , CP ₂ ,
CP ₃ ) and pulse width measuring circuits 15, 16,
The signal is supplied to a time measurement circuit 22, a pulse interval measurement circuit 23, and a code pulse generation circuit 29.

Next, the operation will be explained. Now, suppose that radar A exists near the radar beacon device, and radar B exists far away, and both radars A and B are operating. Radar pulse radio waves emitted from the main lobe and side lobe of radar A and the main lobe of radar B are received by the antenna 10 and transmitted to the video detection circuit 12 via the circulator 11, where they are combined with the video detected radar pulse. The signal is then sent to video amplifier circuits 13 and 14. Note that the radar pulse radio waves due to the side lobes of radar B are not received because radar B is far away. Of the input radar pulses, the video amplification circuit 14 amplifies only the radar pulses with a high reception level, that is, the radar pulses due to the radiation of the main lobe of radar A, so that they reach the operating level of the subsequent circuit. The radar pulse is sent to the OR circuit 28 and its pulse width is measured by the pulse width measuring circuit 16, and the counted value is temporarily stored in the pulse width memory circuit 20. Further, the pulse interval is measured by the pulse interval measuring circuit 23, and the pulse interval is measured by the pulse width memory circuit 23.
4, the count value is temporarily stored. On the other hand, the video amplifier circuit 13 amplifies all the input radar pulses to reach the operating level of the subsequent circuits, the pulse width of the radar pulses is measured by the pulse width measuring circuit 15, and the counted value is stored in the pulse width memory. The stored count value is temporarily stored in the circuit 19 and is compared with the pulse width count value stored in the pulse width memory circuit 20 in the pulse width comparison circuit 21 . Further, the time interval of the radar pulse is measured by a time measuring circuit 22, and the counted value is compared with the counted value stored in the pulse interval memory circuit 24 by a pulse interval comparing circuit 25. Of the radar pulses output from the video amplifier circuit 13,
The radar pulses from the main lobe and side lobe of radar A have the same pulse width and are output to the pulse width comparison circuit 21, and when the pulses are output to the pulse interval comparison circuit 25, the AND circuit 26 is output.
The radar pulse is outputted, and the blocking gate circuit 27 operates to block the radar pulse. On the other hand, the radar pulse of radar B does not output to the pulse width comparison circuit 21 when its pulse width is different from that of radar A, so the pulse is not output to the AND circuit 26, and therefore passes through the blocking gate circuit 27. and is sent to the OR circuit 28. When the pulse width of radar B is the same as that of radar A, an output is generated to the pulse width comparison circuit 21, and when a pulse is output from the pulse interval comparison circuit 25, a pulse is output to the AND circuit 26. , when the pulse interval of radar B is different from that of radar A, the radar pulse of radar B is not blocked and is sent to the OR circuit 28. That is, if at least one of the pulse width and pulse interval of radar B is different from that of radar A, the radar pulse of radar B is sent to the OR circuit 28 without being blocked. Therefore, only the radar pulse due to the main lobe of radar A and the radar pulse due to the main lobe of radar B in the above case are output from the OR circuit 28, and a code pulse synchronized with this is output from the code pulse generation circuit 29. A beacon radio wave for transmission, which is generated by the code pulse and whose amplitude is modulated by the code pulse, is sent to the transmitting circuit 30.
is generated in the antenna 1 via the circulator 11.
Emitted from 0.

In this way, in the above embodiment, beacon radio waves are not emitted to the side lobe of radar A near the radar beacon device, but beacon radio waves are emitted to the main lobe of radar A, and For radar B, if at least one of its pulse width and pulse interval is different from radar A, a beacon radio wave is emitted to the main lobe.

Next, the above operation will be explained in more detail using FIGS. 2, 3, and 4. Figure 2 shows the relationship between the reception level and distance when the radar beacon device of this embodiment receives radar radio waves emitted from radar A, and LM indicates the reception of radio waves emitted from the main lobe of radar A's antenna. Level, LS
is also at a constant level (approximately - relative to the main lobe)
This shows the reception level for radio waves radiated with a sidelobe level of 23 dB or higher. Further, LT1 and LT2 in FIG. 2 indicate the minimum reception level for radar pulses to be output from the video amplifier circuits 13 and 14, respectively, and R1 and R2 indicate the reception level LS and the minimum reception level LT2 and
R3 and R4 are the distances at which the reception level LM and the minimum reception levels LT2 and LT1 intersect, respectively.

FIG. 3 shows the maritime service range of the radar beacon device of this embodiment, where Q is the installation position of the radar beacon device, S1 is the range within the distance R1 in FIG. 2, and S2 is also between the distances R2 and R1. range of,
S3 is also the range between distances R3 and R2, S4
also respectively indicate the range between distances R4 and R3, and QA and QB respectively indicate the positions of the ships equipped with radar A and radar B at a certain time. FIG. 4 shows signal waveforms of various parts of this embodiment when ships equipped with radars A and B are at positions QA and QB shown in FIG. 2, respectively. In the figure, a shows a radar pulse (above the minimum reception level LT1 in Fig. 2) emitted from radar A and received by the radar beacon device of this embodiment, and P1 and P3 are caused by side lobes of radar A, respectively. Radar pulse P2 indicates a radar pulse due to the main lobe. In the same figure, b indicates a radar pulse (minimum reception level LT1 or higher) emitted from radar B and received by the radar beacon device of this embodiment, and P4 indicates a radar pulse due to the main lobe of radar B. In the figure, c and d indicate the output pulses of the video amplifier circuits 13 and 14, respectively, and e and f in the figure indicate the values of the stored pulse widths of the pulse width memory circuits 19 and 20, respectively. In the figure, g indicates the output of the pulse width comparison circuit 21. Further, h and i in the same figure indicate the measurement time (interval of time being measured) of the time measurement circuit 22 and the pulse interval measurement circuit 23, respectively. In the figure, j, k, and l indicate the output pulses of the pulse interval comparison circuit 25, the AND circuit 26, and the blocking gate circuit 27, respectively. In the figure, m indicates the output pulse of the OR circuit 28, and P
5 is a pulse corresponding to radar pulse P4, P6 is a pulse corresponding to the first pulse in radar pulse P1, P7 is a pulse corresponding to radar pulse P2, and P8 is a pulse corresponding to the first pulse in radar pulse P3. This is the pulse.

The performance of radar A is assumed to be the average performance of a marine radar, and the reception levels LM and LS in Figure 2 are drawn with a frequency of 9.4 GHz, an antenna gain of 30 dB, and a peak transmission output of 20 KW (this book). It is assumed that the antenna gain of the radar beacon device in this embodiment is 6 dB.It is also assumed that radar B has the same performance as radar A.

As explained in the above operation, radar A is at position QA within range S2 in Fig. 3 at a short distance, and radar B
When A is far away and located at position QB within the range S4 in Fig. 3, referring to Fig. 2, the radar pulse of radar A is obtained by the main lobe from the video amplifier circuits 13 and 14, and by the side lobe. is obtained only from the video amplifier circuit 13, and the radar B
The radar pulse from the main lobe is obtained from the video amplifier circuit 13. From this, the waveforms shown in a, b, c and d of FIG. 4 are obtained. Note that since the rotation of the antenna of radar A and the rotation of the antenna of radar B are independent of each other, the pulses P1, P2, P3 of a and the pulse P of b
The temporal relationship with 4 differs depending on the rotation of the antenna. Corresponding to the output pulse of the video amplifier circuit 13 shown in c of the figure, the counted value of the pulse width stored in the pulse width memory circuit 19 becomes as shown in e of the figure. In the figure, τA and τB are the pulse width counts of radar A and radar B, respectively, and show the case where the pulse widths of both radars are different. The counted value of the pulse width stored in the pulse width memory circuit 20 corresponding to the output pulse of the video amplifier circuit 14 is as shown in FIG. Based on the results of e and f, the output of the pulse width comparison circuit 21 is as shown in g in the figure. That is, the output is at a high level in a time range where the count value of the memory pulse width is the same, and is at a zero level in a different time range. Further, the time interval measured by the time measuring circuit 22 based on the output pulse of the video amplifier circuit 13 shown in FIG. 3C becomes as shown in FIG. Video amplifier circuit 1 shown in figure d
The time interval of the pulse measured by the pulse interval measuring circuit 23 using the output pulse No. 4 is as shown in the figure i. The counted value of the pulse interval outputted from the pulse interval measuring circuit 23 to the pulse interval memory circuit 24 is the pulse interval of radar A and the last pulse among the pulses caused by the main lobe of the previous antenna rotation of radar A. There are two types of time interval values: and the first pulse among the pulses due to the main lobe during the current rotation of the antenna. Corresponding to the measurement times k and i in the figure, the output pulses of the pulse interval comparison circuit 25 are as shown in j in the figure. The figure shown in this j is
This is when the pulse interval of radar B is the same as that of radar A, and the pulse interval comparison circuit 25 outputs the pulse interval of radar B.
A pulse corresponding to the radar pulse is also output. There is also no output pulse from the pulse interval comparison circuit 25 corresponding to the first pulse of each of radar pulses P1, P2, and P3 of radar A. This is because the time interval between these first pulses and the immediately preceding radar pulse is different from the radar A pulse interval.

Further, there is also no output pulse of the pulse interval comparison circuit 25 corresponding to the second pulse of the radar pulse P2 of the radar A. This means that the count value of the pulse interval which is outputted to the pulse interval memory circuit 24 and temporarily stored by the first pulse of the radar pulse P2 is the pulse interval which is not the pulse interval of radar A out of the above two types of time interval values. This is because it is the latter time interval value (there is no pulse and the comparator circuit 25 compares it with the content stored by the previous pulse in the pulse interval memory circuit 24). in the end,
Output pulses are obtained from the pulse interval comparison circuit 25 in response to radar pulses other than those mentioned above, that is, the second and subsequent pulses of radar pulses 1, P3, and P4, and the third and subsequent pulses of radar pulse P2. The output pulse shown in the figure k is obtained from the AND circuit 26 as the AND of the output of the pulse width comparison circuit 21 shown in g and j in the figure and the output pulse of the pulse interval comparison circuit 25. The blocking gate circuit 27 outputs radar pulses other than the above output pulses output from the AND circuit 26, that is, radar pulses P.
4, the first pulse of radar pulses P1 and P3;
Pulses corresponding to the first and second pulses of radar pulse P2 are output as shown in FIG.
From the OR circuit 28, an output pulse shown in the figure m is obtained as the logical sum of the output pulses d and l in the figure.

In this way, predetermined radio waves are emitted in response to pulses from the main lobes of radar A and radar B. Note that because of the above-mentioned pulses P6 and P8, the radio wave corresponding to the first pulse due to the side lobe of radar A is emitted without being suppressed, but in reality, a group of pulses due to many side lobes exists. Since the radio waves correspond only to the first pulse in each, this does not pose much of a problem.

Next, as the rotation of radar B's antenna progresses, if there is an opportunity for pulse P4 due to its main lobe to overlap with the period in which pulse 1 or pulse P2 due to the side lobe of radar A exists, in that overlapping period, Since part of the pulse P1 or P2 is not blocked by the blocking gate circuit 27, radio waves will be emitted. However, since the antennas of radar A and radar B rotate independently, the chance of such overlap occurring is small, and it does not pose much of a problem in practice. However, if there are multiple radars in addition to radar B in range S4 in FIG. 3, the chance of the above-mentioned overlap increases accordingly.

Next, radar A is still in range S2 in Figure 3, and radar B is in the third range S3, S2 or S.
In the case of a short distance such as 2, at least pulses from the main lobe of radar B are output to the video amplifier circuit 14. Therefore, the pulse interval count value of the pulse interval measuring circuit 23 includes radar A.
In addition to , Radar B is now included,
It may happen that the blocking effect against the pulse due to the side lobe of radar A is not effective. In such a case, the effects of the present invention will not be fully exhibited, so care must be taken when applying the present invention.

Next, when radar A is within the range S1 in FIG.
will be output to . Therefore, radio waves are emitted with respect to the radar pulse due to this side lobe, and the side lobe blocking effect does not work. However, since the range S1 is extremely small, it poses almost no problem in practice.

Next, radar A is in range S3 or S4 in FIG.
In this case, the radar pulse due to the side lobe of the radar is not output to the video amplifier circuits 13 and 14, so radio waves are emitted only to the radar pulse due to the main lobe of the radar A.

Next, if the pulse widths of radar A and radar B are equal and the pulse intervals are different, and both radars are in the position shown in FIG. 3, the output of the pulse width comparison circuit 21 will be at a high level at any time. However,
Since the pulse interval comparison circuit 25 does not output a pulse corresponding to the pulse P4 of radar B in FIG. 4, the output pulse of the AND circuit 26 becomes like k in FIG. 4, and has the same side lobe as in the previous case. An inhibitory action is taken against. Radar A and Radar B
The same operation as described above is performed when the and is at other positions.

Next, both the pulse width and pulse interval of radar A and radar B are different, and radar A and radar B
When A is at the same position as in FIG. 3, the output pulse of the AND circuit 26 is as shown in FIG. The same operation as described above is performed when radar B and radar B are at other positions.

(Description of Effects of the Invention and Field of Application) As explained above, according to the present invention, a radar is located near a radar beacon device, and the emission of beacon radio waves to its side lobes is blocked. When a radar with the same pulse period as that radar is located far away, but its pulse width is different from that of a nearby radar, it becomes possible to emit a beacon radio wave to that radar, making it possible to emit beacon radio waves to that radar. It is possible to reduce cases where beacon radio waves cannot be received and improve the service function of the radar beacon device. Therefore, transponders (racons) or radar beacons such as radar pulse response type raymarks are required to provide accurate position information or azimuth information to multiple ship-mounted radars without interfering with radar images. It is extremely effective when applied to equipment.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a radar beacon device according to an embodiment of the present invention, and Fig. 2 shows the reception level and distance when the radar beacon device according to the embodiment of the present invention receives radar radio waves emitted from radar A. FIG. 3 is a diagram showing the maritime service range of the radar beacon device according to the embodiment of the present invention, and FIG.
The figure shows a ship equipped with radars A and B in an embodiment of the present invention located at the positions QA and B shown in FIG. 2, respectively.
FIG. 7 is a diagram showing signal waveforms of various parts when in QB. 10...Antenna, 11...Circulator, 1
2... Video detection circuit, 13, 14... Video amplifier circuit, 15, 16... Pulse width measurement circuit, 1
7, 18...Delay pulse generation circuit, 19, 20...
... Pulse width memory circuit, 21 ... Pulse width comparison circuit, 22 ... Time measurement circuit, 23 ... Pulse interval measurement circuit, 24 ... Pulse interval memory circuit, 25
... Pulse interval comparison circuit, 26 ... AND circuit,
27... Blocking gate circuit, 28... OR circuit,
29... code pulse generation circuit, 30... transmission circuit, 31... clock generation circuit.

Claims (1)

[Claims] 1. In a radar beacon device that generates radio waves in response to radar pulses emitted by a radar,
The pulse interval and pulse width of a high-level received radar pulse are temporarily stored, and both the pulse interval and pulse width of a low-level radar pulse match the pulse interval and pulse width of the stored radar pulse. A radio wave generation method in a radar beacon device characterized in that when the radar pulse is received, the radar pulse is regarded as being caused by a side lobe and is not responded to, and the radio wave generation method is characterized in that the radar pulse is responded only to other received radar pulses.