JPS6310399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radio wave generation system in a raymark beacon device that can suppress reception due to side lobes of a radar antenna.

A conventional raymark beacon device is shown in FIG. In the figure, 1 is an antenna, 2 is a transmitting circuit, 3 is a frequency sweep voltage generating circuit, and 4 is a pulse generating circuit.The oscillation output of the transmitting circuit 2, which is composed of a klystron, etc., is amplitude-modulated by the pulse of the pulse generating circuit 4. Furthermore, a frequency-swept beacon radio wave is generated in accordance with the sweep voltage outputted from the frequency-sweep voltage generating circuit 3, and is radiated into the air from the antenna 1.

If the radar on a ship is able to receive the beacon radio waves in terms of frequency and power, it will receive the above beacon radio waves, display a bright line starting from the base point of the sweep on the PPI image display screen, and install the raymark beacon device. Indicates the direction of a point.

However, since the above-mentioned Raymark beacon device constantly emits beacon radio waves regardless of the operation of the radar side, at relatively short distances, the beacon radio waves are also received by the side lobe of the radar antenna, and the PPI image display screen displays the beacon radio waves. Bright lines were displayed over a wide angle range. In the case of the Raymark beacon device currently in use in Japan, reception is performed by the side lobe of the radar antenna from within a few nautical miles between the installation point of the Raymark beacon device and the ship equipped with the radar. Initially, it may appear over several dozen degrees within and outside one nautical point. When bright lines caused by beacon radio waves are displayed at a wide angle on the PPI image display screen in this way, it is not only difficult to determine the direction of the true installation point of the Raymark Beacon device, but also the radar image is obstructed. It was hot.

In order to eliminate the above-mentioned conventional drawbacks, the present invention focuses on the fact that the period of the radar pulse differs depending on the range in which the radar indicator is used, and also differs between individual radars even within the same range. A radar pulse radio wave emitted from a radar is received, and the cycle of the radar pulse with a high reception level among the radar pulses obtained from the radar pulse radio wave is temporarily stored, and the cycle of the radar pulse with a high reception level from the radar pulse is received, and the cycle of the radar pulse with a high reception level is stored. removes the radar pulse with the same period as the above memorized period, generates a code pulse that lasts slightly shorter than the interval with the previous pulse in synchronization with the remaining radar pulse, and transmits with this code pulse. It is designed to modulate radio waves, and its purpose is to suppress the transmission of raymark beacon radio waves by the side lobe of the radar antenna, and display a raymark beacon corresponding to the main lobe on the PPI image display screen of the radar. An object of the present invention is to provide a radio wave generation system in a raymark beacon device that can display bright lines at a narrow angle using radio waves. The drawings will be described in detail below.

Figure 2 shows a ray mark showing an embodiment of the present invention.
FIG. 2 is a block diagram of a beacon device. In the figure, 10 is an antenna, 11 is a circulator, 12 is a video detection circuit, 13 and 14 are video amplifier circuits, 15 is a time measurement circuit, 16 is a pulse interval measurement circuit, 17 is a memory circuit, 18 is a comparison circuit, and 19 is a A blocking gate circuit, 20 an OR circuit, 21 a code pulse generating circuit, 22 a sweep voltage generating circuit, 23 a transmitting circuit, and 24 a clock generating circuit.

The antenna 10 receives radar pulse radio waves and emits beacon radio waves, and the circulator 1
1 transmits the received radar pulse radio wave only to the video detection circuit 12 and the beacon signal generated from the transmitting circuit 23 only to the antenna 10.
The video detection circuit 12 video-detects the radar pulse radio wave and outputs it as a radar pulse. The video amplifier circuit 13 amplifies all the radar pulses to a level that can operate the time measurement circuit 15, the OR circuit 20, etc., but the video amplifier circuit 14 has a smaller amplification degree than the video amplifier circuit 13 (the difference in amplification degree is set at 20 dB), so that only the radar pulse with a high input level, that is, the radar pulse due to the main lobe of the radar, is amplified to a level that allows the pulse interval measuring circuit 16, OR circuit 20, etc. to operate. ing. The time measurement circuit 15 measures the time interval of the radar pulses output from the video amplifier circuit 13, and is composed of a counter, counts the clock pulses (CP) generated by the clock generation circuit 24, and calculates the time interval between the radar pulses outputted from the video amplifier circuit 13. Therefore, it is reset and the count value is sent to the comparator circuit 18. The pulse interval measuring circuit 16 measures the time interval of radar pulses output from the video amplifier circuit 14, and is composed of a counter, counts clock pulses, and receives radar pulses output from the video amplifier circuit 14. At this point, the count value is sent to the memory circuit 17, where it is temporarily stored and reset. Comparison circuit 18 compares the count value temporarily stored in memory circuit 17 and the count value of time measurement circuit 15, and outputs a pulse to blocking gate circuit 19 when both values become the same. The blocking gate circuit 19 is inserted between the video amplifier circuit 13 and the OR circuit 20,
It operates in response to pulses from the comparator circuit 18 and blocks radar pulses sent out by the video amplifier circuit 13, otherwise passing them through. The code pulse generating circuit 21 receives the radar pulse from the OR circuit 20 and successively generates code pulses in synchronization with the radar pulse, which serve as an initial point and last for a time slightly shorter than the interval with the immediately preceding radar pulse. The sweep voltage generating circuit 22 generates a sweep voltage necessary for frequency sweeping the transmitted radio wave and outputs it to the transmitting circuit 23. The transmitting circuit 23 amplitude-modulates the oscillation signal with the code pulse, and generates a transmitted radio wave (beacon radio wave) whose frequency is swept in accordance with the sweep voltage. A clock generating circuit 24 generates a clock pulse (CP) and supplies it to a time measuring circuit 15, a pulse interval measuring circuit 16, and a code pulse generating circuit 21.

Next, the operation will be explained. Now, assume that a ship equipped with radar A is sailing near the Raymark beacon device, and a ship equipped with radar B is sailing far away, and both radars A and B are operating. Main lobe and side lobes of radar A and radar B
The radar pulse radio waves emitted from the main lobe are received by the antenna 10 and sent to the circulator 11.
The signal is transmitted to the video detection circuit 12 via the video detection circuit 12, where it is video detected and sent as a radar pulse to the 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.) Among the input radar pulses, the video amplifier circuit 14 receives the radar pulses with a high reception level, that is, the main radar pulses of radar A. Only the radar pulse due to lobe radiation is amplified to reach the operating level of the subsequent circuit, and the radar pulse due to the main lobe of radar A is sent to the OR circuit 20 and the pulse interval measuring circuit 16 calculates the pulse interval. is measured, and the counted value is temporarily stored in the memory circuit 17. On the other hand, the video amplifier circuit 13 amplifies all the input radar pulses to reach the operating level of the subsequent circuits, and the time interval of the radar pulses is measured by the time measurement circuit 15.
The count value is compared with the count value stored in the memory circuit 17 by the comparator circuit 18 . Video amplifier circuit 1
Of the radar pulses output from 3, radar A
Radar and side lobes based on the main lobe and side lobes
The pulses coincide in time and block gate 19
, and only the radar pulses of radar B with non-coinciding intervals are sent to OR circuit 20. Therefore, the OR circuit 20 outputs 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 synchronization with this, a code pulse that lasts for a time slightly shorter than the interval with the immediately preceding pulse is generated by the code pulse generation circuit 21, and a beacon radio wave whose amplitude is modulated by the code pulse and whose frequency is swept by the sweep voltage is generated. It is generated in the transmitting circuit 23 and radiated from the antenna 10 via the circulator 11.

In this way, since beacon radio waves are generated only in response to radar pulses from the main lobes of radars A and B, the radar A and B sides also receive beacon radio waves only through the main lobes of their antennas, and the side lobes receive beacon radio waves. Not receiving radio waves. Also, since the beacon radio waves received by radars A and B are synchronized with the radar pulse,
On the PPI video display screen, a code pulse signal train aligned in the distance direction is displayed from the sweep base point toward the installation direction of the raymark beacon device. Therefore, on the PPI image display screen, a code pulse signal train that is clear and has strong brightness due to the additive integration effect is displayed with a spread comparable to the directivity of the main lobe of the radar antenna.

Next, the above operation will be explained in more detail using FIGS. 3, 4, and 5.

Figure 3 shows the relationship between the reception level and distance when the Raymark Beacon device of this embodiment receives radar radio waves emitted from Radar A, and LM is the radio wave emitted from the main lobe of Radar A's antenna. Similarly, LS indicates the reception level for radio waves radiated by a sidelobe level above a certain level (approximately -23 dB relative to the main lobe). Also, LT1 in Figure 3
and LT2 are video amplifier circuits 13 and 1, respectively.
4 indicates the minimum reception level for radar pulse output, R1 and R2 are the reception level LS
and the minimum reception levels LT2 and LT1 intersect, respectively, and R3 and R4 are the reception levels LM
This is the distance at which the minimum reception levels LT2 and LT1 intersect, respectively.

Figure 4 shows the marine service range of the Raymark beacon device of this embodiment, and Q is the Raymark beacon device of this embodiment.
The installation position of the beacon device, S1 is the distance R in Figure 3.
1, S2 is the range between distances R2 and R1, S3 is the range between distances R3 and R2, S4 is the range between distances R4 and R3, and QA and QB indicate the positions of ships equipped with radar A and radar B, respectively, at a certain time.

FIG. 5 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. 3, respectively. In the same figure, a indicates a radar pulse (above the minimum reception level LT1 in Fig. 3) emitted from radar A and received by the Raymark beacon device of this embodiment, and P1 and P3 are radar pulses of radar A, respectively. P2 shows the radar pulse due to the side lobe, and P2 indicates the radar pulse due to the main lobe. b in the same figure shows the radar pulse (minimum reception level) which is also emitted from radar B and received by the Raymark beacon device of this embodiment.
LT1 or higher), and P4 indicates the radar pulse due to the main lobe of radar B. In the figure, c and d are video amplifier circuits 13 and 14, respectively.
In the figure, e and f indicate the measurement times (intervals of time being measured) of the time measurement circuit 15 and the pulse interval measurement circuit 16, respectively. In the figure, g and h indicate the output pulses of the comparator circuit 18 and the blocking gate circuit 19, respectively. Further, in the same figure, i indicates the output pulse of the OR circuit 20, and P5 indicates the radar pulse P due to the main lobe of radar B.
P6 is the pulse corresponding to the first pulse in radar pulse P1 due to the sidelobe of radar A, P7 is the pulse corresponding to pulse P2 due to the main lobe of radar A, and P8 is the pulse corresponding to the pulse P2 due to the main lobe of radar A. This pulse corresponds to the first pulse in the radar pulse P3 due to the side lobe.

The performance of radar A is assumed to be the average performance of a marine radar, and the reception levels LM and LS in Fig. 3 are drawn with a frequency of 9.4 GHz, an antenna gain of 30 dB, and a peak transmission output of 20 KW (in this example, The antenna gain of the Raymark beacon device shall be 6 dB). Further, it is assumed that radar B also has the same performance as radar A.

As explained in the above operation, when radar A is located at a short distance at position QA within the range S2 in FIG. 4, and radar B is located at a far distance at position QB within the range S4 in FIG. Referring to Figure 3, the main lobe radar pulse of radar A is obtained from the video amplifier circuits 13 and 14, the side lobe radar pulse is obtained only from the video amplifier circuit 13, and the radar pulse from radar B is obtained from the main lobe. The lobe is obtained from the video amplifier circuit 13. From this, the waveforms shown in a, b, c and d of FIG. 5 are obtained. Note that since the rotation of the antenna of radar A and the rotation of the antenna of radar B rotate independently, the temporal relationship between pulses P1, P2, P3 of a and pulse P4 of b differs depending on the rotation of the antenna. It becomes ivy. Video amplifier circuit 1 shown in c of the same figure
The time interval measured by the time measuring circuit 15 using the output pulse No. 3 is as shown in e in the figure. d in the same figure
The time interval of the pulses measured by the pulse interval measuring circuit 16 using the output pulses of the video amplifier circuit 14 shown in FIG. The count value of the pulse interval outputted from the pulse interval measuring circuit 16 to the memory circuit 17 is calculated based on the pulse interval of radar A, the last pulse among the pulses caused by the main lobe of the previous antenna rotation of radar A, and the current pulse. There are two types of time interval values between the main lobe and the first pulse among the pulses when the antenna rotates. e in the same figure
The output pulse of the comparator circuit 18 corresponds to the measurement time of and f as shown in g in the figure. Assuming that the pulse interval of radar B is not the same as that of radar A (usually
(Different radars rarely have the same pulse interval), there is no output pulse from comparator circuit 18 that corresponds to the radar pulse of radar B. There is also no comparator output pulse 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 previous radar pulse is different from the radar A pulse interval.

There is also no output pulse of the comparison circuit 18 corresponding to the second pulse of radar pulse P2 of radar A. This means that the count value of the pulse interval that is output and temporarily stored in the memory circuit 17 by the first pulse of the radar pulse P2 is the one that is not the radar A pulse interval of the two types of time interval values mentioned above. This is because it is the latter time interval value (the comparator circuit 18 is configured to perform a comparison with the content stored by the previous pulse of the memory circuit 17).
As a result, output pulses are obtained from the comparison circuit 18 in response to radar pulses other than those mentioned above, that is, the second and subsequent pulses of radar pulses P1 and P3 and the third and subsequent pulses of radar pulse P3. The blocking gate circuit 19 outputs radar pulses other than the above output pulses output from the comparison circuit 18, namely radar pulse P4, the first pulse of radar pulses P1 and P3, and the first and second radar pulses P2. A pulse corresponding to the pulse is output as shown in h of the figure. OR circuit 2
0, the output pulse shown in the figure i is obtained as the logical sum of the output pulses d and h 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 P1 or P2 due to radar A's side lobe exists, in that overlapping period, Since part of the pulse P1 or P2 is not blocked by the blocking gate circuit 19,
This will result in radio wave radiation. 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. 4, the chance of the above-mentioned overlap increases accordingly.

Next, if radar A is still in range S2 in Figure 4 and radar B is at a short distance such as range S3, S2 or S1 in Figure 4, at least the pulse due to the main lobe of radar B is The signal is output to the video amplifier circuit 14. Therefore, the pulse interval count value of the pulse interval measuring circuit 16 includes not only the pulse interval of radar A but also that of radar B, and the blocking effect against the pulses due to the side lobe of radar A becomes ineffective. 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.
4 will be output. Therefore, radio waves are emitted with respect to the radar pulse due to this side lobe, and the blocking effect against the side lobe 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.

Note that when a ship equipped with radar B approaches the Raymark beacon device, the radar pulse radio waves due to the side lobe will be received by the antenna 10, but at that time the radar pulse radio waves due to the main lobe will be received by the antenna 10.
the pulses are amplified by a video amplification circuit 14;
The pulse width is measured by the pulse interval measuring circuit 16, and is removed in the same manner as the radar pulse due to the side lobe of radar A described above. The same applies even if there are three or more radars.

As can be seen from the above description of the operation of the embodiment, the present invention cannot always suppress radio wave radiation due to side lobes, regardless of the distance of the ship equipped with the radar or the presence of other ships equipped with the radar. However, by selecting an appropriate location for installing the raymark beacon device in a location where the amount of nearby ship traffic is relatively low, a significant suppression effect can be expected. In addition, Raymark beacon equipment is actually used as a first recognition beacon to provide a direction signal to the radar of a long-distance ship, and its installation location is selected to be an important location for providing geographical information for navigation. However, there is not necessarily a lot of ship traffic nearby. Therefore, when the present invention is applied, it can be expected that the reception of beacon radio waves by side lobes on the radar side will be considerably reduced compared to the conventional method.

As explained above, according to the present invention, beacon radio waves synchronized with radar pulses are emitted only to the main lobe of the radar, so reception of beacon radio waves due to side lobes can be suppressed, and the beacon radio waves are transmitted to the radar. It can be displayed on the PPI image display screen as a coded pulse train with the spread of the directivity of the main lobe, which has the advantage of improving the accuracy of direction indication and reducing interference with the image on the display screen.

[Brief explanation of the drawing]

The drawings are for explaining the present invention, and FIG. 1 is a circuit diagram of a conventional Raymark beacon device, and FIG.
The figure is a circuit diagram of a Raymark beacon device showing an embodiment of the method of the present invention, Fig. 3 is a diagram showing the relationship between the reception level of radar radio waves and distance according to the present embodiment, and Fig. 4 is a diagram showing the relationship between the reception level and distance of radar radio waves according to the present embodiment. Diagram showing the service range of
FIG. 5 is a diagram showing signal waveforms, etc. of each part of this embodiment. 10...Antenna, 11...Circulator, 1
2... Video detection circuit, 13, 14... Video amplifier circuit, 15... Time measurement circuit, 16... Pulse interval measurement circuit, 17... Memory circuit, 18... Comparison circuit, 19... Blocking gate circuit, 20...OR circuit, 21...sign pulse generation circuit, 22...
Sweep voltage generation circuit, 23... Transmission circuit, 24...
Clock generation circuit.

Claims (1)

[Claims] 1 Receive radar pulse radio waves emitted from a radar on a ship, etc., temporarily store the period of the radar pulse with the highest reception level among the radar pulses obtained from the radar pulse radio wave, and determine the reception level from the radar pulse. Remove radar pulses that are low and whose period is the same as the stored period, generate a code pulse that lasts for a period slightly shorter than the interval with the previous pulse in synchronization with the remaining radar pulse, and A radio wave generation method in a Raymark beacon device characterized by modulating the transmitted radio waves with pulses.