Satellite-borne ocean wavelength dispersive spectrometer and ocean wave spectrum measurement system

Abstract

The invention belongs to the related technical field of sea wave spectrum detection, and discloses a satellite-borne ocean wavelength dispersive spectrometer and a sea wave spectrum measuring system.The wavelength dispersive spectrometer sequentially transmits wave beams in a macro period, the transmitting azimuth angle is kept unchanged, when detection of the last wave beam in the macro period is finished, the wavelength dispersive spectrometer adjusts the antenna pointing direction and enters the next macro period, and the wavelength dispersive spectrometer transmits the wave beams in the macro period; the azimuth angles of the beams with the same emission sequence number between two adjacent macro periods have intervals, and a set formed by the azimuth angles of the beams with the same sequence number in different macro periods has periodicity; wherein the first wave beam in the macro period is a 0-degree wave beam, and the other wave beams are selected from 2-degree wave beams, 4-degree wave beams, 6-degree wave beams, 8-degree wave beams and 10-degree wave beams; the interval delta psi between adjacent azimuth angles in all emission azimuth angles of the same kind of multiplexed beams is k, and k is the multiplexing times of the kind of beams. According to the method, a relatively high rotating speed can still be kept when the integration time of the along-rail region is increased, so that the calculation precision of the sea wave spectrum is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field related to ocean wave spectrum detection, and more specifically, relates to a satellite-borne ocean spectrometer and an ocean wave spectrum measurement system. Background Art

[0002] Ocean waves are a random process that varies in time and space. Studying ocean waves is crucial for engineering design, disaster warning, national security, and ecological conservation. The wave directional spectrum, or simply the wave spectrum, is the power spectrum of the wave surface function. It represents the distribution of wave energy at different frequencies and directions, making its observation extremely important.

[0003] The Surface Waves Investigation and Monitoring (SWIM) ocean spectrometer carried by the China France Oceanography SATellite (CFOSAT) is a Ku-band radar with a small incidence angle. It can continuously detect ocean wave spectra over a long period of time on a global scale.

[0004] SWIM's classic operating mode uses a standard macrocycle. Within each macrocycle, the spectrometer probes the sea surface at angles of incidence of 0°, 2°, 4°, 6°, 8°, and 10°, referred to as the 0° beam, 2° beam, 4° beam, 6° beam, 8° beam, and 10° beam, respectively. After completing each macrocycle, it moves on to the next. Each beam corresponds to a transmitting antenna. Because the spectrometer antenna rotates and scans at a constant speed over an azimuth range of 0° to 360°, at approximately 5.6 revolutions per minute, the azimuth interval between consecutive macrocycles for the same beam is approximately 7.5°. At each angle of incidence, the spectrometer transmits a series of pulses to the sea surface and receives the echo signals reflected from the sea. The signals are then processed onboard and transmitted back to a ground receiver, which removes speckle noise from the signals and inverts the ocean wave spectrum.

[0005] However, because the observation azimuth of the along-track region is relatively close to the satellite's flight direction, the Doppler bandwidth in the along-track region is significantly smaller than that in the off-track region. If the integration time in the along-track region remains unchanged, the number of independent pulses in the along-track region is smaller, resulting in a significantly larger speckle noise spectrum than in the off-track region, even drowning out normal ocean wave signals. In other words, the signal-to-speckle ratio (SSR) in the along-track region (the ratio of the ocean wave modulation spectrum to the speckle noise spectrum) is very low, resulting in a blind spot in sea surface detection. To improve the along-track SSR, the integration time in the along-track region needs to be increased. However, if the classic SWIM beam timing design scheme is still used, the total integration time corresponding to the macrocycle will increase, the total scanning time will increase, and the antenna rotation speed will decrease, which will in turn reduce the detection accuracy of the ocean wave spectrum.

[0006] Therefore, the beam timing of the spaceborne ocean spectrometer needs to be redesigned to maintain a high antenna rotation speed while increasing the integration time in the along-track area. Summary of the Invention

[0007] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a spaceborne ocean spectrometer and an ocean wave spectrum measurement system, the purpose of which is to redesign the beam timing of the spaceborne ocean spectrometer so as to maintain a high antenna rotation speed while increasing the integration time in the along-track area.

[0008] To achieve the above objectives, according to one aspect of the present invention, a spaceborne ocean spectrometer is provided. The spectrometer transmits beams sequentially within a macrocycle and maintains a fixed transmission azimuth angle each time a beam is transmitted. The residence time in the along-track area is greater than the residence time in the off-track area. When the last beam detection of the current macrocycle is completed, the spectrometer adjusts the antenna pointing and enters the next macrocycle. The transmission azimuth angles of beams with the same transmission sequence number between two adjacent macrocycles have a fixed azimuth angle interval. is the default value, The value of satisfies the periodicity of the set of transmission azimuth angles of beams with the same serial number in different macrocycles; wherein, the type of the first beam in the macrocycle is a 0° beam, and the types of the remaining beams are selected from 2° beams, 4° beams, 6° beams, 8° beams, and 10° beams; the intervals between adjacent azimuth angles in all transmission azimuth angles of the same type of multiplexed beams are fixed azimuth equivalent intervals ΔΨ, k≥2 is the number of times this type of beam is reused.

[0009] Optionally, the beams transmitted within the macro cycle are 0° beam, 8° beam, 10° beam, 8° beam, and 10° beam in sequence.

[0010] Optionally, in the first macrocycle, the starting azimuth angle of the first 8° beam is 3°, the azimuth angle of the first 10° beam is 135°, the starting azimuth angle of the second 8° beam is 45°, the azimuth angle of the second 10° beam is 273°, and the azimuth interval is The azimuth equivalent spacing of the 8° beam is ΔΨ=6°, and the azimuth equivalent spacing of the 10° beam is ΔΨ=6°.

[0011] Optionally, the beams transmitted within the macro cycle are 0° beam, 2° beam, 10° beam, 10° beam, 10° beam, and 10° beam in sequence.

[0012] Optionally, in the first macrocycle, the starting azimuth angle of the 2° beam is 279°, the starting azimuth angle of the first 10° beam is -1°, the starting azimuth angle of the second 10° beam is 64°, the starting azimuth angle of the third 10° beam is 149°, and the starting azimuth angle of the fourth 10° beam is 214°. The azimuth interval is The azimuth equivalent spacing of the 10° beam is ΔΨ=5°.

[0013] Optionally, the spectrometer uses a phased array to control the antenna direction, so as to keep the transmission azimuth angle fixed each time the beam is transmitted.

[0014] Optionally, the integration time of the along-track area is increased to ensure that the signal-to-spot ratio of the along-track area is greater than 1.

[0015] According to another aspect of the present invention, there is provided an ocean wave spectrum measurement system comprising a spaceborne ocean spectrometer and a ground receiver;

[0016] The satellite-borne ocean spectrometer is a satellite-borne ocean spectrometer as described in any one of the above items, which is used to transmit pulses to the sea surface, receive echo signals reflected by the sea surface, and process them on board to obtain satellite-borne signals and transmit them back to the ground receiver;

[0017] The ground receiver is used to receive the satellite-borne signal and remove speckle noise to invert the ocean wave spectrum. When detecting along-track areas, the ground receiver uses a cross-spectrum method or a post-integration method to remove speckle noise.

[0018] Optionally, when detecting a non-along-track area, the ground receiver uses an empirical formula method to remove speckle noise.

[0019] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0020] T i is the duration of the i-th macrocycle, M is the number of macrocycles experienced by the antenna during one scan, M = 360° / the azimuth interval between the two adjacent macrocycles transmitting the same beam number (which can be called the azimuth interval between macrocycles). In the traditional SWIM scheme, the azimuth interval of the beam is equal to the azimuth interval between macrocycles. In the present invention, by multiplexing the beams, when the azimuth interval between macrocycles is After integrating all azimuths of the same type of multiplexed beam, the adjacent azimuth interval is the equivalent azimuth interval That is, the technical solution of the present invention can make the equivalent azimuth interval of the multiplexed beam 1 / k of the azimuth interval between macrocycles. Since the azimuth interval of the beam cannot be too large in order to ensure the accuracy of detection when performing ocean wave spectrum detection, the technical solution of the present invention can be used to obtain the equivalent azimuth interval between macrocycles. A smaller equivalent azimuth interval ΔΨ is achieved, while the azimuth interval between macrocycles is As the antenna scans once, the number of macrocycles M that the antenna experiences decreases. To meet the signal-to-spot ratio requirements of the along-track area, the dwell time in the along-track area is greater than the dwell time in the non-along-track area. That is, the durations Ti of different macrocycles are not exactly the same. When a multiplexed beam is used to detect the along-track area in a macrocycle, the duration of the macrocycle increases. However, since the number of macrocycles M decreases, the antenna scan time can still be kept short, that is, the antenna can maintain a high rotation speed. Overall, the technical solution of the present invention can maintain a high rotation speed while increasing the integration time in the along-track area. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the relative position of the starting beam positions of each beam in embodiment 1 of the present invention;

[0022] Figure 2 is the integration time for each azimuth angle of the 8° beam in Example 1 of the present invention;

[0023] Figure 3 is the integration time for each azimuth angle of the 10° beam in Example 1 of the present invention;

[0024] Figure 4 This is the beam center trajectory diagram drawn in Example 1 of the present invention;

[0025] Figure 5 is the relative position of the starting beam positions of each beam in embodiment 2 of the present invention;

[0026] Figure 6 is the integration time for each azimuth angle of the 10° beam in Example 2 of the present invention;

[0027] Figure 7 This is the beam center trajectory diagram in Example 2 of the present invention. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0029] To facilitate understanding, several related concepts are first explained.

[0030] Angle of incidence: the angle between the beam emission direction and the direction in which the spectrometer is pointing perpendicular to the horizontal plane;

[0031] Azimuth: The angle between the beam emission direction projected onto the ground and the satellite flight direction;

[0032] The along-track area is an area with a small angle to the satellite's flight direction. Generally, the area with an angle between -20° and 20° to the satellite's flight direction or the opposite direction is considered to be the along-track area. The azimuth angle range of the beam used for detection in the along-track area is 160° to 200°, 0° to 20°, and 340° to 360°.

[0033] Observation azimuth: the direction of the spectrometer's emitted beam projected onto the ground.

[0034] The present invention provides a spaceborne ocean spectrometer that maintains a fixed azimuth angle each time a beam is emitted, and the dwell time in the along-track area is greater than the dwell time in the off-track area. When the last beam detection in the current macrocycle is completed, the spectrometer adjusts the antenna pointing (i.e., adjusts the azimuth angle) and enters the next macrocycle, and the emission azimuth angles of each nth beam in the two adjacent macrocycles have a fixed azimuth rotation interval. n is the number of the transmitted beam in the macrocycle, is the preset value, that is, when the last beam in the current macrocycle is transmitted, the direction of the antenna azimuth changes The current macro cycle ends and enters the next macro cycle and continues to transmit beams in sequence. At this time, the transmission azimuth of each beam with the same sequence number changes compared with the previous macro cycle.

[0035] In the present invention, The design is performed so that its values ​​satisfy the periodicity of the set formed by the transmission azimuth angles of each n-th beam in different macrocycles. That is, for any n-th beam, its transmission azimuth angles in different macrocycles will show periodic characteristics when arranged according to the transmission timing. After several macrocycles, the transmission azimuth angle of the n-th beam returns to the initial transmission azimuth angle of the beam.

[0036] Furthermore, the present invention selects the beam type. The first beam in a macrocycle is a 0° beam, and the remaining beams are selected from 2° beams, 4° beams, 6° beams, 8° beams, and 10° beams. Except for the 0° beam, a beam can be transmitted multiple times within a macrocycle. Thus, multiple beam types are reused within a macrocycle. Furthermore, the intervals between adjacent azimuths in all transmission azimuths of the same type of reused beam are all equivalent intervals, ΔΨ. k is the number of times the beam is reused. Due to beam reuse, when all the transmission azimuths of the same beam are combined, the interval between adjacent azimuths is called the equivalent interval of the reused beam. This equivalent interval is the average of the azimuth intervals during the macrocycle.

[0037] In one embodiment, the integration time of the along-track region needs to satisfy the signal-to-speckle ratio of the along-track region being greater than 1, so that the speckle noise of the along-track region can be calculated more accurately.

[0038] The technical solution of the present invention can achieve the goal of larger azimuth interval between macro cycles. A smaller equivalent azimuth interval ΔΨ is achieved, while the azimuth interval between macrocycles is As the antenna's dwell time (i.e., integration time) increases, the number of macrocycles M experienced during one antenna scan decreases. When the dwell time (i.e., integration time) in the along-track region increases, although the corresponding macrocycle length increases, the number of macrocycles M decreases. Therefore, the antenna's scan time can still be kept short, i.e., a high rotational speed can be maintained. Overall, the technical solution of the present invention can maintain a high antenna rotational speed while increasing the along-track integration time.

[0039] Example 1

[0040] In this embodiment, the beams transmitted within a macrocycle are, in order, a 0° beam, an 8° beam, a 10° beam, an 8° beam, and a 10° beam. The transmission azimuth angles of the macrocycle are {0°, 8°, 10°, 8°, 10°}, and both the 8° beam and the 10° beam are reused. In the original SWIM beams, 6°, 8°, and 10° are "spectral beams," primarily used to detect the directional spectrum and wave parameters of ocean waves. Reducing the azimuth spacing of the spectrum beams helps improve the accuracy of ocean wave spectrum detection. The wave spectrum measurement value of the 6° beam is significantly lower than the buoy value. Therefore, the 8° or 10° beam is selected as the reused beam.

[0041] Specifically, in the first macrocycle, the starting azimuth angle of the first 8° beam is 3°, the azimuth angle of the first 10° beam is 135°, the starting azimuth angle of the second 8° beam is 45°, and the azimuth angle of the second 10° beam is 273°. The relative positions of the starting positions of each beam are as follows: Figure 1 After the last beam detection in the first macrocycle is completed, the spectrometer adjusts the antenna pointing direction according to the 12° azimuth interval between macrocycles and performs the second macrocycle. After several macrocycles, the azimuth angle of any nth beam in the macrocycle is consistent with the initial azimuth angle of the beam, and the azimuth angle then begins the next round of adjustment according to the same rule.

[0042] Table 1 below shows a periodic set of azimuth angles experienced by the first 8° beam, the first 10° beam, the second 8° beam, and the second 10° beam when the antenna scans one circle.

[0043] Table 1

[0044]

[0045]

[0046] As can be seen, the azimuth interval within a macrocycle is 12°, and one scan cycle involves 30 macrocycles, 360° / 12°. That is, during one antenna scan, the first 8° beam, the first 10° beam, the second 8° beam, and the second 10° beam each scan 30 different azimuths. By the 31st macrocycle, the first 8° beam, the first 10° beam, the second 8° beam, and the second 10° beam have returned to their respective initial azimuths. Because the 8° beam is reused twice within one macrocycle, the combined azimuths of the two 8° beams mean that the 8° beam scans 60 different azimuths during one antenna scan, with an effective interval of 6° between adjacent azimuths. Similarly, because the 10° beam is also reused twice within one macrocycle, the combined azimuths of the two 10° beams mean that the 10° beam scans 60 different azimuths during one antenna scan, with an effective interval of 6° between adjacent azimuths. The azimuth angles for the 8° beam during along-track detection are 3°, 9°, 15°, 165°, 171°, 177°, 183°, 189°, 195°, 345°, 351°, and 357°. The azimuth angles for the 10° beam during along-track detection are also 3°, 9°, 15°, 165°, 171°, 177°, 183°, 189°, 195°, 345°, 351°, and 357°.

[0047] In the above embodiment, since the 2°, 4° and 6° beams are removed and beam multiplexing is performed, when the equivalent azimuth angle interval of 6° is achieved, the number of macrocycles required for one scan is reduced to 30, so a higher rotation speed can be maintained while increasing the integration time of the along-track area.

[0048] Moreover, in the same macrocycle, the azimuth angles of the beams are at least 42° apart, that is, the azimuth angles within one macrocycle are relatively dispersed.

[0049] For example, the 0° beam starts working first. The working time (integration time) of the 0° beam in one macrocycle is 55.4ms. The 8° and 10° beams work (observe) twice each. The integration time of the 8° and 10° beams varies with the azimuth angle. The specific time is as follows: Figure 2 、 Figure 3 As shown. Figure 4The figure shows the trajectory of the beam center in this embodiment. The blue circle is the 0° beam, the green arrow is the first 8° beam, the dark blue arrow is the first 10° beam, the red arrow is the second 8° beam, and the yellow arrow is the second 10° beam. The direction of the arrow represents the observation direction, and the position of the arrow represents the position of the beam center. The figure shows the result of rotating 4 circles. Since the working time of the 0° beam is 55.4ms, when the equivalent azimuth angle interval is 6°, it takes 30 macrocycles to scan one circle. Therefore, when scanning one circle, the 0° beam takes about 1.66s. Figure 2 and Figure 3 The times used for the 8° and 10° beams are calculated to be 4.348 s and 4.7770 s, respectively. Therefore, the total time for one scan is about 10.78 s, and the rotation speed is about 5.6 rpm, which is close to the rotation speed of the azimuth angle interval of 7.5° in the traditional SWIM scheme. However, the scheme of the present invention greatly improves the integration time of the along-track area.

[0050] Example 2

[0051] In this embodiment, the transmitted beams within a macrocycle are, in order, a 0° beam, a 2° beam, a 10° beam, a 10° beam, a 10° beam, and a 10° beam. The transmit azimuth angles of the macrocycle are {0°, 2°, 10°, 10°, 10°, 10°}, and the 10° beam is multiplexed.

[0052] Specifically, in the first macrocycle, the starting azimuth angle of the 2° beam is 279°, the starting azimuth angle of the first 10° beam is -1°, the starting azimuth angle of the second 10° beam is 64°, the starting azimuth angle of the third 10° beam is 149°, and the starting azimuth angle of the fourth 10° beam is 214°. The azimuth rotation interval is The azimuth equivalent spacing of the 10° beam is ΔΨ=5°. The relative positions of the starting positions of each beam are as follows: Figure 5 After the last beam detection in the first macrocycle is completed, the spectrometer adjusts the antenna pointing direction according to the 20° azimuth interval between macrocycles and performs the second macrocycle. After several macrocycles, the azimuth angle of any nth beam in the macrocycle is consistent with the initial azimuth angle of the beam, and the azimuth angle then begins the next round of adjustment according to the same rule.

[0053] Table 2 below shows a periodic set of azimuth angles experienced by the 2° beam, the first 10° beam, the second 10° beam, the third 10° beam, and the fourth 10° beam when the antenna scans one circle.

[0054] Table 2

[0055]

[0056]

[0057] As can be seen, the azimuth interval within a macrocycle is 20°, and one scan cycle involves 360° / 20° = 18 macrocycles. That is, during one antenna scan, the 2° beam, the first 10° beam, the second 10° beam, the third 10° beam, and the fourth 10° beam each scan 18 different azimuths. By the 31st macrocycle, the 2° beam, the first 10° beam, the second 10° beam, the third 10° beam, and the fourth 10° beam have returned to their initial azimuths. Because the 10° beam is reused four times within one macrocycle, the azimuths of the four 10° beams are combined, and during one antenna scan, the 10° beam scans 72 different azimuths, with an effective interval of 5° between adjacent azimuths. The 2° beam detects along-track at azimuths of 19°, 179°, 199°, and 359°. The azimuth angles of the 10° beam when detecting in the along-track area are 4°, 9°, 14°, 19°, 164°, 169°, 174, 179°, 184°, 189°, 194°, 199°, 344°, 349°, 354°, and 359°.

[0058] In the above embodiment, since the 4°, 6°, and 8° beams are removed and beam multiplexing is performed, when the equivalent azimuth angle interval of 5° is achieved, the number of macrocycles experienced in one scan is reduced to 18. Therefore, a higher rotation speed can be maintained while increasing the integration time of the along-track area.

[0059] Moreover, in the same macrocycle, the azimuth angles of the beams are at least 65° apart, that is, the azimuth angles within one macrocycle are relatively dispersed.

[0060] For example, the 0° beam starts working first, and the working time of the 0° beam in one macrocycle is 55.4ms. Then the 2° beam starts working, and the working time is 22.6ms. The 10° beam works (observes) four times. The integration time changes with the azimuth angle as follows: Figure 6 As shown, Figure 7 The figure shows the trajectory of the beam center in this embodiment. The blue circle is the 0° beam, the rose-red circle is the 2° beam, the green arrow is the first 10° beam, the dark blue arrow is the second 10° beam, the red arrow is the third 10° beam, and the yellow arrow is the fourth 10° beam. The direction of the arrow represents the observation direction, and the position of the arrow represents the position of the beam center. The figure shows the result of rotating 4 times. Since the working time of the 0° and 2° beams are 55.4ms and 22.6ms respectively, when the equivalent azimuth angle interval is 5°, it takes 18 macrocycles to scan one circle. Therefore, when scanning one circle, the 0° beam and the 2° beam take about 0.9972s and 0.4068s respectively. In this solution, the integration time of the 10° beam is as follows: Figure 6Therefore, the time required for the 10° beam is 9.2453 s, and thus the time required for a full scan is about 10.6 s, and the rotation speed is about 5.6 rpm, which is close to the rotation speed in the conventional SWIM scheme in which the azimuth angle interval is 7.5°, but the scheme greatly improves the integration time in the along-track region.

[0061] In an embodiment, the spectrometer controls the antenna pointing by using a phased array, and in the current macro period, the azimuth angle of the current beam remains unchanged when the beam emits a pulse.

[0062] The application also provides a sea wave spectrum measurement system, which comprises the spaceborne ocean wave spectrometer and a ground receiver used in cooperation with the spaceborne ocean wave spectrometer.

[0063] The spaceborne ocean wave spectrometer is configured to receive echo signals reflected by the sea surface after emitting pulses to the sea surface, perform on-board processing on the echo signals, obtain spaceborne signals, and transmit the spaceborne signals to the ground receiver.

[0064] When the along-track region is detected, the ground receiver is configured to remove speckle noise by using a cross-spectrum method or a post-integration method. When the along-track region is detected, the total number of independent pulses is affected by the sea surface condition, and the speckle noise spectrum needs to be measured in real time. Two observations are performed in one wave position, two spaceborne signals are transmitted, and the cross-spectrum method or the post-integration method is applied to the two signals to solve the speckle noise spectrum. Specifically, the detection signals of the same macro period, the same incident angle, and different pulses are divided into two parts according to time, and the two parts are averaged, respectively. The two averaged signals are transmitted back to the ground, and the cross-spectrum method or the post-integration method is used to remove the speckle noise. When the along-track region is detected, compared with the empirical formula method, the cross-spectrum method or the post-integration method can more accurately calculate the speckle noise, and the sea wave spectrum inversion accuracy is improved.

[0065] For the non-along-track region, the speckle noise can be accurately estimated by using the empirical formula method, and thus, when the on-board processing is performed, the detection signals of the same macro period, the same incident angle, and different pulses are all averaged to obtain an averaged signal, and the signal is transmitted back to the ground, and the empirical formula method is used to calculate the speckle noise.

[0066] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict each other, they should be considered as falling within the scope of the present application. It should be noted that the “in an embodiment of the present application”, “for example”, “for instance” and the like in the present application are intended to illustrate the present application, but are not used to limit the present application.

[0067] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A spaceborne ocean spectrometer, characterized in that: The spectrometer transmits beams in sequence within a macrocycle and keeps the transmission azimuth angle fixed each time the beam is transmitted, and the residence time in the along-track area is greater than the residence time in the non-along-track area; when the last beam detection of the current macrocycle is completed, the spectrometer adjusts the antenna pointing and enters the next macrocycle, and the transmission azimuth angles of beams with the same transmission sequence number between the two adjacent macrocycles have a fixed azimuth interval is the default value, The value of satisfies the periodicity of the set of transmission azimuth angles of beams with the same serial number in different macrocycles; wherein, the type of the first beam in the macrocycle is a 0° beam, and the types of the remaining beams are selected from 2° beams, 4° beams, 6° beams, 8° beams, and 10° beams; the intervals between adjacent azimuth angles in all transmission azimuth angles of the same type of multiplexed beams are fixed azimuth equivalent intervals ΔΨ, k≥2 is the number of times this type of beam is reused.

2. The spaceborne ocean spectrometer according to claim 1, wherein: The transmitted beams within the macro cycle are 0° beam, 8° beam, 10° beam, 8° beam, and 10° beam.

3. The spaceborne ocean spectrometer according to claim 2, wherein: In the first macrocycle, the starting azimuth angle of the first 8° beam is 3°, the azimuth angle of the first 10° beam is 135°, the starting azimuth angle of the second 8° beam is 45°, the azimuth angle of the second 10° beam is 273°, and the azimuth interval is The azimuth equivalent spacing of the 8° beam is ΔΨ=6°, and the azimuth equivalent spacing of the 10° beam is ΔΨ=6°.

4. The spaceborne ocean spectrometer according to claim 1, wherein: The transmitted beams within the macro cycle are 0° beam, 2° beam, 10° beam, 10° beam, 10° beam, and 10° beam.

5. The spaceborne ocean spectrometer according to claim 4, wherein: In the first macrocycle, the starting azimuth of the 2° beam is 279°, the starting azimuth of the first 10° beam is -1°, the starting azimuth of the second 10° beam is 64°, the starting azimuth of the third 10° beam is 149°, and the starting azimuth of the fourth 10° beam is 214°. The azimuth interval is The azimuth equivalent spacing of the 10° beam is ΔΨ=5°.

6. The spaceborne ocean spectrometer according to claim 1, wherein: The spectrometer uses a phased array to control the antenna direction, so as to keep the transmission azimuth angle fixed when transmitting a beam each time.

7. The spaceborne ocean spectrometer according to claim 1, wherein: Increase the integration time of the along-track area to ensure that the signal-to-spot ratio in the along-track area is greater than 1.

8. A wave spectrum measurement system, characterized in that: Including spaceborne ocean spectrometer and ground receiver; The satellite-borne ocean spectrometer is a satellite-borne ocean spectrometer according to any one of claims 1 to 7, configured to transmit pulses to the sea surface, receive echo signals reflected from the sea surface, and process the echo signals onboard to obtain satellite-borne signals and transmit the signals back to the ground receiver. The ground receiver is used to receive the satellite-borne signal and remove speckle noise to invert the ocean wave spectrum. When detecting along-track areas, the ground receiver uses a cross-spectrum method or a post-integration method to remove speckle noise.

9. The ocean wave spectrum measurement system according to claim 8, wherein: When detecting off-track areas, the ground receiver uses an empirical formula method to remove speckle noise.

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