Method for implementing digital enhanced radar beacon positioning function with solid state radar

Abstract

The application provides a method for realizing a digital enhanced radar beacon positioning function by a solid-state radar, a special frequency band for triggering a digital coded response of the digital enhanced radar beacon is arranged for the solid-state radar; the special frequency band is separated from a working frequency band of the solid-state radar and is realized by extending the available frequency band of the solid-state radar; only when the digital enhanced radar beacon receives a request signal of the special frequency band, the digital coded positioning information including the longitude and latitude information is returned. The mechanism of the solid-state radar and the digital enhanced radar beacon is not adapted, and the practical value, the application range, the working efficiency and the signal recognition accuracy of the digital enhanced radar beacon are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of radio navigation, and particularly relates to a method for realizing digital enhanced radar beacon positioning function by a solid-state radar. BACKGROUND

[0002] The marine radar beacon is also called a radar transponder or a radar beacon, and is generally fixedly installed at a key position on the sea or a coast and used in cooperation with a marine navigation radar. When the radar beacon receives a radar signal, the radar beacon sends a signal with a short MOS code as a response, so that a staff on a ship obtains position information by checking a table. A new generation of enhanced radar beacon adds more coded information on the basis of a simple MOS code, so as to realize the addition of more information including latitude and longitude information. On one hand, this is helpful for realizing automatic positioning of a ship, and on the other hand, the enhanced radar beacon can be used as a reliable redundant backup means when a navigation means such as GPS or Beidou fails.

[0003] The applicant has designed and disclosed patent documents such as CN202210215094-Digital full-band direct forwarding type radar transponder system and working method thereof and CN202210659798-Digital full-band direct forwarding type search and rescue radar transponder system before the present application date, and proposed a new hardware structure and coding design of a digital enhanced radar transponder.

[0004] However, it is found in actual testing that the adaptability of the digital enhanced radar beacon to a solid-state radar which is relatively advanced at present is not ideal.

[0005] Unlike a traditional magnetron radar which has only one narrow frequency signal, each solid-state radar transmits about 4-6 different frequency bands and different waveforms of signals, and most of the signals are frequency-modulated signals. The time width of the solid-state radar signal is much larger than that of the magnetron radar signal (usually nanoseconds to about 1us), and the time width of the pulse compression solid-state radar signal is up to about 100us. The time width of the continuous wave solid-state radar signal is more than 1ms.

[0006] The multiple signals of the solid-state radar have increasing pulse time widths in order, and are respectively responsible for the detection of targets in different distance ranges. For example, the first signal is responsible for the detection of targets in a range of 0.1-2 nautical miles, the second signal is responsible for the detection of targets in a range of 2-6 nautical miles, the third signal is responsible for the detection of targets in a range of 6-12 nautical miles, and so on (the range is adjustable).

[0007] Solid state radar continuously emits various signals in order to detect targets in the full range of distances. But in each time period, only the echo of one signal is the valid echo signal, and the echoes of other signals are all ignored. For example, solid state radar emits the third signal to detect targets in the range of 6-12 nautical miles, during which the echo of the second signal may also be received, which will be ignored and is an invalid echo signal.

[0008] Similarly, the reply of the third signal at 5 nautical miles is also ignored because the third signal is responsible for detecting targets in the range of 6-12 nautical miles. Furthermore, the reply of the third signal at 13 nautical miles is also ignored.

[0009] For the above reasons, the digital enhanced radar beacon cannot use the traditional "receive-comparison-judge-reply" reply mode to reply to the solid state radar signal. Because it will miss the truly valid radar signal. For example, the radar beacon first receives the second signal of the radar at 7 nautical miles. If the radar beacon judges through comparison, it is the main lobe signal of the radar, and then the radar beacon replies with the second signal to make a Morse code, which will be ignored by the radar, and after the radar beacon completes the Morse code signal reply, the radar beacon may have missed the third truly valid signal.

[0010] The reason is that the radar beacon cannot know which signal is the current valid signal, and cannot judge the distance from the radar beacon to the radar, so if the radar beacon only replies to part of the signal, it is likely to be ignored because it is an invalid signal. Therefore, only if the radar beacon can reply to every kind of signal received with the least delay, the Morse code of the radar beacon can be displayed on the radar screen.

[0011] In addition, in order to realize the positioning function of the digital enhanced radar beacon, the radar beacon needs to add coded information containing the absolute latitude and longitude of the radar beacon when replying to the Morse code. Because in a busy port, the number of radar signals is huge, including the main lobe, side lobe and reflection signals of ships and buildings. Therefore, if coding is added before each signal without distinction, the radar beacon will not be able to complete it in the face of a huge number of signals. Considering the more complex types of solid state radar signals and the long pulse time, it is impossible to achieve.

[0012] If the main lobe of the radar is distinguished and replied to, because "receive-comparison-judge-reply" needs time, endless "receive-comparison-judge" will occupy almost all the time. Experiments have proved that the radar beacon cannot achieve the reply. If the complexity of the solid state radar signal and the signal superposition are considered, the signal will be more difficult to judge, and even if it is judged as a main lobe signal, it may not be a valid signal. Therefore, without taking other measures, the reply rate of the digital enhanced radar beacon in a busy port will be very low. SUMMARY

[0013] In view of the defects and deficiencies of the prior art, the purpose of the present application is to provide a method for realizing digital enhanced radar beacon positioning function by solid-state radar.

[0014] The present application specifically adopts the following technical solutions:

[0015] A method for realizing digital enhanced radar beacon positioning function by solid-state radar, characterized in that: a special frequency band for triggering digital coding response of the digital enhanced radar beacon by the solid-state radar is set; the special frequency band is separated from the working frequency band of the solid-state radar and is realized by expanding the available frequency band of the solid-state radar; only when the digital enhanced radar beacon receives the request signal of the special frequency band, the digital coding positioning information including the latitude and longitude information is returned.

[0016] Further, on the solid-state radar, a switch for starting to send the request signal of the special frequency band is set, and when the switch is not triggered, the special frequency band is in a dormant state.

[0017] Further, the digital enhanced radar beacon is provided with a sidelobe suppression function SLS for the special frequency band signal, and for the solid-state radar, the frequency of the request signal in the special frequency band is randomly or adjustably selected in the special frequency band to ensure that the digital enhanced radar beacon can distinguish different radars.

[0018] Further, when the digital enhanced radar beacon receives the request signal outside the special frequency band, the basic MOS code information is returned.

[0019] The present application and its preferred schemes provide a solution for adapting the solid-state radar and the digital enhanced radar beacon, which fully utilizes the wide frequency and variable frequency characteristics of the solid-state radar, and improves the effectiveness and response rate of the mechanism without major changes of the solid-state radar and the digital enhanced radar beacon. DETAILED DESCRIPTION

[0020] In order to make the features and advantages of the present patent more obvious and easy to understand, the following embodiments are specifically described as follows:

[0021] The technical solutions of the present application are further described below in combination with embodiments.

[0022] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be implemented in other ways different from the scope described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0023] Firstly, the theoretical basis of the scheme constructed by the present application is introduced.

[0024] According to the first paragraph of A1 of the industry document G1147 guide of the radar beacon (found on the website of the International Navigation Aid Organization IALA: (www.iala-aism.org) ) : "The eRacon does this by embedding a data packet in the leading dash of a standard racon Morse code response".

[0025] This means that the eRacon synthesizes the position coded data packet into the "dash" at the beginning of the standard Morse code.

[0026] The result of such processing makes the Morse code fuzzy. (See the third paragraph of ANNEX B of G1147: The trial also found that modulation of the eRacon signal can be visible on radar displays (e.g. "fuzzy" traces).

[0027] The reason is that the frequency of "1" in the data packet is increased by 15M on the basis of the carrier, that is, the radar frequency (see the fourth line of A3 of G1147). The radar may filter out the signal with the increased frequency of 15M as clutter, so that the "dash" of the Morse code cannot be displayed on the radar screen, and the "dash" of the Morse code becomes fuzzy.

[0028] Furthermore, one bit of the data packet needs to occupy a signal time width of 200ns (see the third line of A3 of G1147). A complete data packet is 14 bytes (see A2 of G1147), or 112 bits (14x8), that is, 22.4us (112x0.2us). This is equivalent to a display length of 3360 meters (22.4x150m) on the radar screen. 3360 meters is far more than the first "dash" of the Morse code in general cases. This will make the display of the first 3360 meters of the Morse code become fuzzy, even inaccurate.

[0029] For solid-state radar, if the frequency of the signal is artificially increased by 15M, the modulated signal will be ignored by the solid-state radar if it exceeds the bandwidth of the solid-state radar signal. If the modulated result is still within the bandwidth of the radar, some disordered bright spots may be displayed on the radar screen.

[0030] Therefore, it is inappropriate to synthesize the data packet into the "dash" at the beginning of the standard Morse code.

[0031] Therefore, the starting point of the present application is to separate the Morse code response function of the radar beacon and the positioning function of the digital code.

[0032] In the design of the embodiment of the present application, in order to improve the efficiency of the enhanced radar positioning system (ERPS) composed of the solid-state radar and the digital enhanced radar beacon, first, the detection signal frequency band of the solid-state radar and the communication signal frequency band of the ERPS are separated. The radar is mainly for detection, and once the radar is started, it will continuously transmit detection signals without interruption. The ERPS can only be realized on the premise that there is a radar beacon nearby. The radar beacon is usually installed only in ports and coastal areas. In other words, in most sea areas and during the sailing time, the radar beacon does not exist, and the ERPS cannot be realized.

[0033] Therefore, the embodiment sets a special frequency band for the solid-state radar to trigger the digital code response of the digital enhanced radar beacon. The special frequency band is separated from the working frequency band of the solid-state radar and is realized by expanding the available frequency band of the solid-state radar. Only when the digital enhanced radar beacon receives the request signal of the special frequency band, it returns the digital code positioning information including the longitude and latitude information.

[0034] In a specific implementation, a soft function button can be set on the radar, such as "radar beacon positioning". The button is in an off state in normal times, and only when the seafarer or the automatic control system of the ship feels the need to use it, the function is turned on. When the radar enables this function, the radar transmits the ERPS signal to trigger the radar beacon.

[0035] Through this way of "hibernation" of the ERPS function in normal days, the load of the radar beacon can be effectively reduced, thereby improving the effectiveness of the ERPS function.

[0036] In addition, in order to effectively avoid the false triggering of the signal of the ERPS, it is necessary to enable the sidelobe suppression function (SLS) of the radar ERPS signal of the radar beacon. The sidelobe suppression function can classify the radar signals with very similar frequencies as the signals of the same radar, so that only the signal of one radar with the strongest signal can be returned. Therefore, as a preferred, the frequency of the ERPS signal of the solid-state radar can be adjusted. This function is not a problem for the solid-state radar. Therefore, it is necessary to emphasize that the ITU, IMO, CIRM and other organizations should allocate a relatively wide frequency band for the radar user to randomly select when allocating the ERPS communication frequency channel. In this way, the enhanced radar can easily distinguish different radars, thereby improving the return rate of the ERPS signal. In summary, the implementation of the embodiment scheme includes the following design points:

[0037] 1) The ERPS needs to use a special signal channel, which is separated from the detection frequency channel of the radar. For example, the X-band radar detection uses the 9.3-9.5G frequency band, and whether the ERPS can use the 9.20-9.28G frequency band.

[0038] 2) The solid-state radar adds an ERPS function button, which can be directly realized on the software without additional hardware for the solid-state radar. When needed, the special frequency signal of the ERPS is transmitted to trigger the return of the enhanced radar.

[0039] 3) The frequency band of the ERPS should be as wide as possible to allow the radar to freely select the transmission frequency, thereby reducing the probability of using the same frequency by different radars. The function of self-adjusting the signal transmission frequency of the solid-state radar within the frequency band range can realize the above design at a low cost.

[0040] 4) The Morse code response function of the radar and the ERPS function are separated. The ERPS function of the radar can be set as a user selection mode of the radar, that is, the user self-selection mode defined in IMO A.615(15) 2.1.2 (the regulation A.615 can be searched on the website of the International Maritime Organization IMO (www.imo.org)). Because the radar does not return the Morse code in the ERPS state, the ERPS function is the last one described in 2.1.2 (i.e.,.2.3 not be shown on the radar display.), that is, no display on the radar screen.

[0041] 5) The signal of the enhanced radar positioning system designed in the embodiment can use a simple pulse signal.

[0042] The above merely describes preferred embodiments of the present application, but is not intended to limit the present application in other forms. Any person skilled in the art can make changes or modifications to the above disclosed technical contents into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution of the present application and according to the technical essence of the present application shall still fall within the protection scope of the present application.

[0043] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation of the present application. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. Here, it is not necessary and also impossible to exhaust all the implementation forms. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for solid state radar to implement a digitally enhanced radar beacon positioning function, characterized by: The special frequency band of the digital coding response of the solid-state radar trigger digital enhanced radar beacon is set; the special frequency band is 9.20-9.28 GHz, which is separated from the working frequency band 9.3-9.5 GHz of the solid-state radar, and is realized by expanding the available frequency band of the solid-state radar; On the solid-state radar, a switch for starting the request signal of the special frequency band is arranged, and when the switch is not triggered, the special frequency band is in a dormant state; Only when the digital enhanced radar beacon receives the request signal of the special frequency band, the digital coding positioning information including the latitude and longitude information is returned, and at this time, the Morse code is not displayed on the radar screen; The digital enhanced radar beacon is provided with a sidelobe suppression function SLS for the special frequency band signal, and for the solid-state radar, the frequency of the request signal located in the special frequency band is randomly or adjustably selected in the special frequency band, so as to ensure that the digital enhanced radar beacon can distinguish different radars.

2. The method of claim 1, wherein the solid-state radar implements a digital enhanced radar beacon positioning function, and wherein the method further comprises: determining a position of the solid-state radar based on the received signal. When the digital enhanced radar beacon receives the request signal outside the special frequency band, the basic MOS code information is returned.