CN117665804A - Method and system for controlling working time sequence of satellite-borne radar altimeter - Google Patents
Method and system for controlling working time sequence of satellite-borne radar altimeter Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/882—Radar or analogous systems specially adapted for specific applications for altimeters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/08—Systems for measuring distance only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
- G01S13/9021—SAR image post-processing techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
- G01S13/9021—SAR image post-processing techniques
- G01S13/9023—SAR image post-processing techniques combined with interferometric techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/40—Means for monitoring or calibrating
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
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Abstract
The invention discloses a method and a system for controlling working time sequence of a satellite-borne radar altimeter, which relate to the technical field of the satellite-borne radar altimeter, and the method comprises the following steps: acquiring an association relation between pulse transmission starting time and pulse receiving starting time of the satellite-borne radar altimeter in each working mode; when the satellite-borne radar altimeter works in a set working mode, pulse sending and receiving are carried out according to the association relation corresponding to the set working mode, and the altitude is calculated according to the time interval between the sent pulse and the received pulse. The invention can realize the multi-mode and multi-task time sequence control of the spaceborne radar altimeter, so that the spaceborne radar altimeter can be smoothly switched among the multi-mode and multi-task, and the continuous tracking of the altitude can be realized, so that the spaceborne radar altimeter has the capability of adapting to the continuous change of the satellite-to-ground distance.
Description
Technical Field
The invention relates to the technical field of spaceborne radar altimeters, in particular to a method and a system for controlling working time sequence of a spaceborne radar altimeter.
Background
The satellite-borne radar altimeter is an active microwave remote sensor, and can be used for measuring the height, the effective wave height and the backscattering coefficient of a satellite to the sea surface by transmitting electromagnetic waves to the sea surface and receiving echoes returned from the ground, and inverting the sea surface wind speed through the backscattering coefficient. The data measured by the satellite-borne radar altimeter can be further used for researching ocean gravity anomaly, ground level, sea surface topography, submarine topography, ocean tides, storms and ocean dynamics. The spaceborne radar altimeter can perform global ocean observation by utilizing the orbit advantage.
The measurement principle of the spaceborne radar altimeter is as follows: electromagnetic wave pulses (for short, transmitting pulses) are transmitted to the sea surface, the electromagnetic wave pulses propagate in the atmosphere at a speed close to the speed of light, the electromagnetic wave pulses are reflected by the sea surface, the reflected electromagnetic wave pulses (for short, radar echoes) return to the satellite-borne radar altimeter, and the distance h between the radar and the sea surface can be measured by measuring the propagation time (namely, delay time) between the transmitting time of the transmitting pulses and the time when the satellite-borne radar altimeter receives the radar echoes.
In designing the operational timing of a satellite-borne radar altimeter, two challenges are faced:
1) The first difficulty is: as is well known, the earth is an irregular elliptic sphere with slightly flattened equator and slightly bulging two poles, when the satellite-borne radar altimeter is started up in full-time in orbit to measure the distance from the satellite to the sea surface, the satellite-to-ground distance varies by +/-10 km, so the time interval between the electromagnetic wave transmission and the electromagnetic wave reception of the satellite-borne radar altimeter always varies, and the variation amount of about 140us exists, so that the electromagnetic wave transmission and the electromagnetic wave reception are difficult to be correctly carried out, specifically:
the working model of the spaceborne radar altimeter is shown in fig. 1, the spaceborne radar altimeter generally works on a circular orbit, and the delay time of radar echo in the two-pole area is about 140us longer than that in the equatorial area because the earth is an irregular ellipsoid, the equator is slightly raised, the two poles are slightly flat ellipsoids, and the equator radius is 20 kilometers longer than the polar radius. Because the delay time of the electromagnetic wave is continuously changed and the change amount is large, if the satellite-borne radar altimeter does not change the receiving time, the satellite-borne radar altimeter cannot receive the radar echo at the correct time, so that the receiving time of the radar echo of the satellite-borne radar altimeter needs to be dynamically adjusted; moreover, since the spaceborne radar altimeter periodically transmits pulses, radar echoes may overlap with the transmitted pulses in time, the spaceborne radar altimeter cannot distinguish whether the radar echoes or the transmitted pulses are the radar echoes or the transmitted pulses, and safety hazards exist, so that the time of the transmitted pulses also needs to be changed. The design of the transmit and receive timing of the satellite-borne radar altimeter is complicated by adjusting both the transmit time of the transmit pulse and the receive time of the radar echo.
2) A second challenge: it is difficult to correctly realize the timing of electromagnetic wave transmission and reception of various modes, various tasks, in particular:
the on-orbit working of the satellite-borne radar altimeter comprises three working modes, namely a traditional low-resolution mode, a closed-loop synthetic aperture mode and an open-loop synthetic aperture mode, and the on-orbit working needs to be carried out not only by marine telemetry observation tasks but also by external calibration tasks, so that multiple switching of various modes and various tasks can exist during on-orbit operation, and therefore, how to correctly realize the timing sequence of the emission and the reception of radar electromagnetic waves of various modes and various tasks is another problem which is required to be faced in the design of the satellite-borne radar altimeter.
The load of the satellite-borne radar altimeter is different requirements of measurement, external calibration and the like, a measurement task and an external calibration task are designed on the track, the working time sequence of each task is different, for example, the receiving time of the measurement task needs on-track self-adaptive adjustment, and the external calibration task requires the altimeter to work according to set parameters and does not carry out on-track self-adaptive adjustment. The operating timing requirements for each mode also vary considerably, e.g. a pulse repetition frequency of about 2000Hz in the low resolution mode, about 20000Hz in the closed loop synthetic aperture mode, and about 10000Hz in the open loop synthetic aperture mode.
While considering the two problems, the safety of the load of the satellite-borne radar altimeter is also considered. Specifically: because the satellite-borne radar altimeters are all transmitting and receiving common-caliber antennas, the transmitting pulse and the receiving radar echo cannot be carried out simultaneously, and the satellite-borne radar altimeters must avoid each other in time; if the radar echo is received while the pulse is being transmitted, there is a high probability that the radar receiver of the satellite-borne radar altimeter will be damaged, resulting in equipment damage; in the traditional method, the satellite-borne radar altimeter works on the track, the position of a receiving window needs to be continuously adjusted to adapt to echo time change caused by sea surface height change, so that the window for transmitting pulse and receiving radar echo is overlapped in time, and potential safety hazards exist.
In the prior art, only the description of the working time sequence design result of the satellite-borne radar altimeter is obtained mainly by deduction according to the observation requirement, and no description or report of the specific implementation method or control method of the working time sequence of the satellite-borne radar altimeter is found in relevant published materials.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of the prior art, and particularly provides a method and a system for controlling working time sequence of a satellite-borne radar altimeter, which are as follows:
1) In a first aspect, the invention provides a control method for working time sequence of a satellite-borne radar altimeter, which comprises the following specific technical scheme:
acquiring the association relation between the transmission starting time of the transmitting pulse of the satellite-borne radar altimeter and the receiving starting time of the radar echo in each working mode;
when the satellite-borne radar altimeter works in a set working mode, transmitting of transmitting pulses and receiving of radar echoes are carried out according to association relations corresponding to the set working mode, and the altitude is calculated according to the time intervals of the transmitted transmitting pulses and the received radar echoes.
The working time sequence control method of the satellite-borne radar altimeter provided by the invention has the following beneficial effects:
the multi-mode and multi-task time sequence control of the satellite-borne radar altimeter can be realized, so that the satellite-borne radar altimeter can be smoothly switched among the multi-mode and multi-task, and the continuous tracking of the altitude can be realized, so that the satellite-borne radar altimeter has the capability of adapting to the continuous change of the satellite-ground distance, the overlapping of a window for transmitting pulse and receiving radar echo in time is avoided, and the potential safety hazard is reduced.
On the basis of the scheme, the working time sequence control method of the satellite-borne radar altimeter can be improved as follows.
Further, when the working mode of the spaceborne radar altimeter is a low resolution mode and an open loop synthetic aperture mode, the starting moment of the transmission of the nt transmission pulse in the ng group in the nb cluster is as follows: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+NpX (Nt-1/2), wherein Nb, ng and Nt are positive integers, ng is less than or equal to Ng, nt is less than or equal to Nt, and N0 represents: the value of the radar timing counter, nb represents: cluster period count value, nr represents: star-to-ground distance word count value, np represents: pulse repetition period count value, ng represents: number of pulse groups in a cluster, nt represents: number of pulses in a group.
Further, when the working mode of the satellite-borne radar altimeter is a closed-loop synthetic aperture mode, the starting moment of the transmission of the nt transmission pulse in the ng group in the nb cluster is as follows: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+Np X (nt-1).
2) In a second aspect, the invention also provides a working time sequence control system of the satellite-borne radar altimeter, which comprises the following specific technical scheme:
the system comprises an association relation acquisition module and a sending and receiving calculation module;
the association relation acquisition module is used for: acquiring the association relation between the transmission starting time of the transmitting pulse of the satellite-borne radar altimeter and the receiving starting time of the radar echo in each working mode;
the sending and receiving calculation module is used for: when the satellite-borne radar altimeter works in a set working mode, transmitting of transmitting pulses and receiving of radar echoes are carried out according to association relations corresponding to the set working mode, and the altitude is calculated according to the transmitted transmitting pulses and the received radar echoes.
Based on the scheme, the working time sequence control system of the satellite-borne radar altimeter can be improved as follows.
Further, when the working mode of the spaceborne radar altimeter is a low resolution mode and an open loop synthetic aperture mode, the starting moment of the transmission of the nt transmission pulse in the ng group in the nb cluster is as follows: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+NpX (Nt-1/2), wherein Nb, ng and Nt are positive integers, ng is less than or equal to Ng, nt is less than or equal to Nt, and N0 represents: the value of the radar timing counter, nb represents: cluster period count value, nr represents: star-to-ground distance word count value, np represents: pulse repetition period count value, ng represents: number of pulse groups in a cluster, nt represents: number of pulses in a group.
Further, when the working mode of the satellite-borne radar altimeter is a closed-loop synthetic aperture mode, the starting moment of the transmission of the nt transmission pulse in the ng group in the nb cluster is as follows: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+Np X (nt-1).
3) In a third aspect, the present invention further provides a computer device, where the computer device includes a processor, the processor is coupled to a memory, and at least one computer program is stored in the memory, where the at least one computer program is loaded and executed by the processor, so that the computer device implements any one of the above-mentioned method for controlling a working time sequence of a satellite-borne radar altimeter.
4) In a fourth aspect, the present invention further provides a computer readable storage medium, in which at least one computer program is stored, where the at least one computer program is loaded and executed by a processor, so that a computer implements any one of the above-mentioned satellite-borne radar altimeter operation timing control methods.
It should be noted that, the technical solutions of the second aspect to the fourth aspect and the corresponding possible implementation manners of the present invention may refer to the technical effects of the first aspect and the corresponding possible implementation manners of the first aspect, which are not described herein.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the following drawings in which:
FIG. 1 is a schematic diagram of an operational model of a satellite-borne radar altimeter;
FIG. 2 is a schematic flow chart of a method for controlling the working time sequence of the satellite-borne radar altimeter according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a method for controlling the operational timing of the satellite-borne radar altimeter;
FIG. 4 is a second flow chart of a method for controlling the operational time sequence of a satellite-borne radar altimeter according to an embodiment of the present invention;
FIG. 5 is a timing diagram of a conventional mode in a low resolution mode;
FIG. 6 is a timing diagram of a closed loop synthetic aperture mode;
FIG. 7 is a timing diagram of an open loop synthetic aperture mode;
FIG. 8 is a schematic diagram of a control system for operating time sequence of a satellite-borne radar altimeter according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a computer device according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 2, the method for controlling the working time sequence of the satellite-borne radar altimeter according to the embodiment of the invention comprises the following steps:
s1, acquiring an association relation between a transmission starting time of a transmitting pulse of a satellite-borne radar altimeter in each working mode and a receiving starting time of a radar echo;
s2, when the satellite-borne radar altimeter works in a set working mode, transmitting the transmitting pulse and receiving the radar echo according to the association relation corresponding to the set working mode, and calculating the altitude according to the time interval between the transmitted transmitting pulse and the received radar echo.
The working time sequence control method of the satellite-borne radar altimeter provided by the invention can realize the time sequence control of the satellite-borne radar altimeter in a multi-mode and multi-task mode, so that the satellite-borne radar altimeter can be smoothly switched among the multi-mode and multi-task, and the continuous tracking of the altitude can be realized, so that the satellite-borne radar altimeter has the capability of adapting to the continuous change of the satellite-ground distance, the time overlapping of a window for transmitting pulse and receiving radar echo is avoided, and the potential safety hazard is reduced.
Optionally, in the above technical solution, when the working mode of the spaceborne radar altimeter is a low resolution mode and an open loop synthetic aperture mode, the starting moment of the emission of the nt emission pulse in the ng group in the nb cluster is: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+NpX (Nt-1/2), wherein Nb, ng and Nt are positive integers, ng is less than or equal to Ng, nt is less than or equal to Nt, and N0 represents: the value of the radar timing counter, nb represents: cluster period count value, nr represents: star-to-ground distance word count value, np represents: pulse repetition period count value, ng represents: number of pulse groups in a cluster, nt represents: number of pulses in a group.
It will be appreciated that: when the working modes of the satellite-borne radar altimeter are a low resolution mode and an open loop synthetic aperture mode, the incidence relations between the sending starting time of the transmitted pulse and the receiving starting time of the radar echo are:
the transmission start time of the nt-th transmission pulse in the ng group in the nb cluster is: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+Np X (nt-1/2).
Optionally, in the above technical solution, when the working mode of the spaceborne radar altimeter is a closed loop synthetic aperture mode, the starting time of the emission of the nt emission pulse in the ng group in the nb cluster is: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+Np X (nt-1).
It will be appreciated that: when the working mode of the satellite-borne radar altimeter is a closed-loop synthetic aperture mode, the association relation between the transmission starting moment of the transmitted pulse and the receiving starting moment of the radar echo is as follows: the transmission start time of the nt-th transmission pulse in the ng group in the nb cluster is: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+Np X (nt-1).
The invention provides 5 time sequence control parameters, namely a pulse repetition period count value Np, a star-to-ground distance word count value Nr, a cluster period count value Nb, a cluster pulse group number Ng and group pulse numbers Nt, np, nr, nb, ng and Nt which are positive integers, wherein the pulse repetition period count value Np specifically refers to: the number of radar timer counts corresponding to the pulse repetition period, and the satellite-to-ground distance word count value Nr specifically refers to: the number of radar timer counts corresponding to the star-to-ground distance word, and the cluster period count value Nb specifically refers to: the number of radar timer counts corresponding to the radar cluster period, and the number of pulse groups in the cluster Ng specifically refers to: the number of radar transmitting pulse groups in each cluster, and the number Nt of the pulses in the group specifically refers to: the number of radar transmit pulses in each group:
1) When the operation mode of the spaceborne radar altimeter is the low resolution mode, np, nr, nb, ng and Nt are set as shown in table 1.
Table 1:
taking a certain satellite-borne radar altitude as an example, nt is set to be 5, the starting moment of a 1 st transmission pulse of a certain cluster is taken as the cluster to start, and the value of a radar timing counter is recorded as N0. The values of the radar timing counter corresponding to the start time of the transmission pulse, the start time of the reception window, the start time of the next cluster, and the like are shown in table 2 below.
Table 2:
2) When the operation mode of the spaceborne radar altimeter is a closed loop synthetic aperture mode, np, nr, nb, ng and Nt are set up as shown in table 3.
Table 3:
the start time of the 1 st transmission pulse of a certain cluster is taken as the cluster, and the value of the radar timing counter is recorded as N0. The values of the radar timing counter corresponding to the start time of the transmission pulse, the start time of the reception window, the start time of the next cluster, and the like are shown in table 4.
Table 4:
3) When the operation mode of the spaceborne radar altimeter is an open loop synthetic aperture mode, np, nr, nb, ng and Nt are set up as shown in table 5.
Table 5:
the start time of the 1 st transmission pulse of each cluster is taken as the cluster, and the value of the radar timing counter is recorded as N0. The values of the radar timing counter corresponding to the start time of the transmission pulse, the start time of the reception window, the start time of the next cluster, and the like are shown in table 6.
Table 6:
in another embodiment, the clock source of the radar digital system timer is an 80MHz reference signal, the digital system counts the reference signal, and the reference signal passes through a period (12.5 ns), and then the pulse repetition period counter, the satellite-to-ground distance word counter and the cluster period counter are respectively increased by 1. When the three counters reach the set count value, the counter is cleared, and the counting is restarted as shown in fig. 3.
In the programming of the radar digital system, two counters are designed to record the number of transmitted pulses and the number of groups of transmitted pulses, respectively. When the radar transmits 1 pulse, the pulse count in the group is increased by 1, and when the pulse counter in the group reaches the set pulse count in the group, the pulse counter in the group is cleared, and the transmitted pulse count is increased by 1; when the transmitted pulse group count counter reaches the set value of the pulse group count in the cluster, the pulse group count counter is cleared, as shown in fig. 4.
And (3) circularly running: in order to ensure the circular operation of the radar system, when the cluster period counter reaches the cluster period count value, the work of the cluster is completed. At this point the counters for these 5 parameters are all cleared and the radar starts a new cluster of operations as shown in figure 4.
Taking a conventional low resolution mode as an example, as shown in fig. 5, in order to adapt to the altitude variation range of 120km, the conventional radar timing control method needs to be designed as follows:
1) The satellite-ground distance of 440-560 km, the transceiving time interval is 2.94-3.74 ms, and after the pulse is sent out, the radar echo returns to the satellite after 5-7 pulse repetition periods, so in the design, ground staff is required to send command packets according to the satellite-ground distance, and the pulse delay number of the radar is set (namely, echo acquisition is carried out after a few pulse repetition periods).
2) After the satellite orbit is determined, because the earth is an ellipsoid, the satellite-to-earth distance change range is 490-510 km, and the transceiving time interval is 3.27-3.4 ms (about 130us change), in the design, the load is required to be calculated in real time and the arrival time of the echo is pre-judged, and the sampling starting time is correspondingly adjusted so as to ensure that the sea echo of the radar can be acquired.
3) The satellite-ground distance of 440-560 km, the receiving and transmitting time interval is 2.94-3.74 ms, after the pulse is sent out, 5-7 pulse repetition periods can be passed, and at certain heights, the arrival time of the radar echo and the radar pulse transmitting time are overlapped, so in the design, ground personnel are required to transmit an instruction packet according to the satellite-ground distance, the pulse repetition period of the radar is modified, so that the arrival time of the radar echo and the radar pulse transmitting time are not overlapped, and the radar receiver has safety risks.
In the conventional radar time sequence control method, 3 parameters need to be adjusted to meet the requirement of normal functions of a radar system in the face of the change of track height.
With the present invention, as shown in fig. 6 and 7, in order to adapt the altimeter load to the altitude variation range of 120km, the radar timing control method is designed as follows:
1) The satellite-ground distance of 440-560 km, the transceiving time interval is 2.94-3.74 ms, and after the pulse is sent out, the radar echo returns to the satellite after 5-7 pulse repetition periods possibly, so in the design, the pulse delay number of the radar is designed to be 5 according to the minimum value of the orbit, namely the number Nt=5 of each group of radar transmitting pulses in the mode is set, and no adjustment is needed on orbit.
2) After the satellite orbit is determined, because the earth is an ellipsoid, the satellite-ground distance change range is 490-510 km, and the receiving and transmitting time interval is 3.27-3.4 ms (about 130us change), in the design, the load is required to calculate the satellite-ground distance word in real time, namely the number Nr of radar timer counts corresponding to the satellite-ground distance word, and the sea echo of the radar can be ensured to be acquired by adjusting the value Nr in an on-orbit self-adaptive manner.
3) The satellite-ground distance of 440-560 km, the receiving and transmitting time interval is 2.94-3.74 ms, after the pulse is sent out, 5-7 pulse repetition periods can be passed, by utilizing the method, the radar echo arrival time and the radar pulse transmitting starting time can be separated by Np/2 by adaptively adjusting the value of Nr in an on-orbit manner, and the radar echo arrival time and the radar pulse transmitting time cannot be overlapped because the radar pulse width is always smaller than Np/2, and the radar receiver is always safe and has no risk.
The radar time sequence control method provided by the invention can meet the requirement of the normal function of a radar system by only adjusting 1 parameter in the face of the change of the track height.
In the above embodiments, although steps S1, S2, etc. are numbered, only specific embodiments of the present invention are given, and those skilled in the art may adjust the execution sequence of S1, S2, etc. according to the actual situation, which is also within the scope of the present invention, and it is understood that some embodiments may include some or all of the above embodiments.
As shown in fig. 8, a satellite-borne radar altimeter operation time sequence control system 200 according to an embodiment of the present invention includes an association relationship acquisition module 201 and a transmission and reception calculation module 202;
the association relation acquisition module 201 is configured to: acquiring the association relation between the transmission starting time of the transmitting pulse of the satellite-borne radar altimeter and the receiving starting time of the radar echo in each working mode;
the transceiver module 202 is configured to: when the satellite-borne radar altimeter works in a set working mode, transmitting of transmitting pulses and receiving of radar echoes are carried out according to association relations corresponding to the set working mode, and the altitude is calculated according to the time intervals of the transmitted transmitting pulses and the received radar echoes.
Optionally, in the above technical solution, when the working mode of the spaceborne radar altimeter is a low resolution mode and an open loop synthetic aperture mode, the starting moment of the emission of the nt emission pulse in the ng group in the nb cluster is: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+NpX (Nt-1/2), wherein Nb, ng and Nt are positive integers, ng is less than or equal to Ng, nt is less than or equal to Nt, and N0 represents: the value of the radar timing counter, nb represents: cluster period count value, nr represents: star-to-ground distance word count value, np represents: pulse repetition period count value, ng represents: number of pulse groups in a cluster, nt represents: number of pulses in a group.
Optionally, in the above technical solution, when the working mode of the spaceborne radar altimeter is a closed loop synthetic aperture mode, the starting time of the emission of the nt emission pulse in the ng group in the nb cluster is: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+Np X (nt-1).
It should be noted that, the beneficial effects of the operation time sequence control system 200 of the satellite-borne radar altimeter provided in the above embodiment are the same as those of the operation time sequence control method of the satellite-borne radar altimeter described above, and are not repeated here. In addition, when the system provided in the above embodiment implements the functions thereof, only the division of the above functional modules is used as an example, in practical application, the above functional allocation may be implemented by different functional modules according to needs, that is, the system is divided into different functional modules according to practical situations, so as to implement all or part of the functions described above. In addition, the system and method embodiments provided in the foregoing embodiments belong to the same concept, and specific implementation processes thereof are detailed in the method embodiments and are not described herein again.
As shown in fig. 9, in a computer device 300 according to an embodiment of the present invention, the computer device 300 includes a processor 320, the processor 320 is coupled to a memory 310, at least one computer program 330 is stored in the memory 310, and the at least one computer program 330 is loaded and executed by the processor 320, so that the computer device 300 implements any one of the above-mentioned spaceborne radar altimeter operation timing control methods, specifically:
the computer device 300 may include one or more processors 320 (Central Processing Units, CPU) and one or more memories 310, where the one or more memories 310 store at least one computer program 330, and the at least one computer program 330 is loaded and executed by the one or more processors 320, so that the computer device 300 implements any of the method for controlling the working time sequence of the satellite-borne radar altimeter provided by the above embodiment. Of course, the computer device 300 may also have a wired or wireless network interface, a keyboard, an input/output interface, and other components for implementing the functions of the device, which are not described herein.
The embodiment of the invention relates to a computer readable storage medium, at least one computer program is stored in the computer readable storage medium, and the at least one computer program is loaded and executed by a processor, so that a computer realizes any one of the above-mentioned satellite-borne radar altimeter operation time sequence control methods.
Alternatively, the computer readable storage medium may be a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a compact disc Read-Only Memory (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, and the like.
In an exemplary embodiment, a computer program product or a computer program is also provided, the computer program product or computer program comprising computer instructions stored in a computer readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions so that the computer device performs any of the above-described satellite-borne radar altimeter operation timing control methods.
It should be noted that the terms "first," "second," and the like in the description and in the claims of the present application are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. The order of use of similar objects may be interchanged where appropriate so that embodiments of the present application described herein may be implemented in other sequences than those illustrated or described.
Those skilled in the art will appreciate that the invention may be embodied as a system, method or computer program product, and that the invention may therefore be embodied in the form of: either entirely hardware, entirely software (including firmware, resident software, micro-code, etc.), or entirely software, or a combination of hardware and software, referred to herein generally as a "circuit," module "or" system. Furthermore, in some embodiments, the invention may also be embodied in the form of a computer program product in one or more computer-readable media, which contain computer-readable program code.
Any combination of one or more computer readable media may be employed. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium can be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (8)
1. The method for controlling the working time sequence of the satellite-borne radar altimeter is characterized by comprising the following steps of:
acquiring the association relation between the transmission starting time of the transmitting pulse of the satellite-borne radar altimeter and the receiving starting time of the radar echo in each working mode;
when the satellite-borne radar altimeter works in a set working mode, transmitting the transmitting pulse and receiving the radar echo according to the association relation corresponding to the set working mode, and calculating the altitude according to the time interval between the transmitted transmitting pulse and the received radar echo.
2. The method for controlling the operation time sequence of the satellite-borne radar altimeter according to claim 1, wherein when the operation mode of the satellite-borne radar altimeter is a low resolution mode and an open loop synthetic aperture mode, the starting time of the emission of the nt emission pulse in the ng group in the nb cluster is: n0+nb× (Nb-1) +nr× (ng-1) +np× (nt-1), and the reception start time of the radar echo corresponding to the nt-th transmission pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+NpX (Nt-1/2), wherein Nb, ng and Nt are positive integers, ng is less than or equal to Ng, nt is less than or equal to Nt, and N0 represents: the value of the radar timing counter, nb represents: cluster period count value, nr represents: star-to-ground distance word count value, np represents: pulse repetition period count value, ng represents: number of pulse groups in a cluster, nt represents: number of pulses in a group.
3. The method for controlling the operation time sequence of the satellite-borne radar altimeter according to claim 2, wherein when the operation mode of the satellite-borne radar altimeter is a closed-loop synthetic aperture mode, the starting time of the emission of the nt emission pulse in the ng group in the nb cluster is: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+Np X (nt-1).
4. The satellite-borne radar altimeter working time sequence control system is characterized by comprising an association relation acquisition module and a sending and receiving calculation module;
the association relation acquisition module is used for: acquiring the association relation between the transmission starting time of the transmitting pulse of the satellite-borne radar altimeter and the receiving starting time of the radar echo in each working mode;
the sending and receiving calculation module is used for: when the satellite-borne radar altimeter works in a set working mode, transmitting the transmitting pulse and receiving the radar echo according to the association relation corresponding to the set working mode, and calculating the altitude according to the time interval between the transmitted transmitting pulse and the received radar echo.
5. The operation time sequence control system of a satellite borne radar altimeter according to claim 4, wherein when the operation modes of the satellite borne radar altimeter are a low resolution mode and an open loop synthetic aperture mode, the starting time of the emission of the nt emission pulse in the ng group in the nb cluster is: n0+nb× (Nb-1) +nr× (ng-1) +np× (nt-1), and the reception start time of the radar echo corresponding to the nt-th transmission pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+NpX (Nt-1/2), wherein Nb, ng and Nt are positive integers, ng is less than or equal to Ng, nt is less than or equal to Nt, and N0 represents: the value of the radar timing counter, nb represents: cluster period count value, nr represents: star-to-ground distance word count value, np represents: pulse repetition period count value, ng represents: number of pulse groups in a cluster, nt represents: number of pulses in a group.
6. The operation time sequence control system of a satellite-borne radar altimeter according to claim 5, wherein when the operation mode of the satellite-borne radar altimeter is a closed loop synthetic aperture mode, the starting moment of the emission of the nt emission pulse in the ng group in the nb cluster is: N0+NbX (Nb-1) +NrX (ng-1) +Np X (nt-1), and the starting time of receiving the radar echo corresponding to the nt transmitting pulse in the ng group in the Nb cluster is: N0+NbX (Nb-1) +NrXng+Np X (nt-1).
7. A computer device comprising a processor coupled to a memory, the memory having stored therein at least one computer program, the at least one computer program being loaded and executed by the processor to cause the computer device to implement a method of controlling operation timing of a satellite borne radar altimeter according to any one of claims 1 to 3.
8. A computer-readable storage medium, in which at least one computer program is stored, which is loaded and executed by a processor, to cause the computer to implement a method of controlling the operational timing of a satellite-borne radar altimeter according to any one of claims 1 to 3.
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