Antenna phase center measurement device and method based on attitude data

Abstract

The present invention discloses an antenna phase center measurement device and method based on attitude data, which relates to the field of antenna measurement and satellite navigation positioning, including a satellite system, an angle test system and a multi-frequency receiver; the satellite system includes a satellite antenna, a swing rod and a telescopic rod, the satellite antenna is installed on the upper end of the swing rod, the swing rod is movably connected to the telescopic rod, and the telescopic rod is arranged at the lower end of the swing rod; a lightning surge protector is arranged between the satellite system and the angle test system; the multi-frequency receiver is communicatively connected with the angle test system. The satellite simulator and the multi-frequency receiver in the present invention use the same reference clock module, which eliminates the clock difference between the receiver and the satellite, multipath error, tropospheric error, ionosphere error and other errors.

Description

Technical Field

[0001] The present invention relates to the field of antenna measurement and satellite navigation positioning, and in particular to an antenna phase center measurement device and method based on attitude data. Background Art

[0002] The antenna phase center refers to the position of the equivalent point source of the antenna's electromagnetic radiation. At present, the calibration of the antenna phase center mainly adopts the rotating antenna method similar to the QJ1729A standard, or the short baseline measurement method similar to BD420003. These two methods can complete the calibration and correction of the antenna phase center deviation. At present, IGS CB will fully use the absolute phase center correction model to replace the relative phase center correction model to address the impact of antenna phase center changes on positioning. For example, "Chen Tao, Hu Zhigang, Li Tao. Experimental study on accurate detection of GPS antenna phase center changes [J]. Seismology and Geology, 2013, 35(2): 8." This type of method basically completes compensation for positioning scenarios. In the scenario of antenna sensing for precise angle measurement, the change of the antenna's own attitude causes the change of its own input signal strength and altitude angle, as well as the change of the distribution position and orientation of the satellites in the sky, which causes the change of the antenna phase center. In order to achieve the same level of measurement accuracy as the laser measurement system, the correlation data between the antenna phase center and attitude change is difficult to obtain using existing methods.

[0003] Currently, only a simple multi-antenna system is used for field observation, and the receiver performs differential processing on the phase observation data: There may be several problems: First, although the multipath error can be reduced, it is necessary to use multiple days of measurement data in the same test environment to establish a priori model, and precision ranging equipment such as Invar baseline rulers and laser length meters are required for relative length calibration, which is time-consuming and complex to operate manually. Second, the initial phase values ​​of the receiver and satellite oscillator at the beginning of the observation are unknown, and the phase integer of the starting epoch is also unknown, that is, the integer ambiguity, which requires long-cycle observation code measurement or multiple days of measurement data to establish a priori models to narrow the value range.

[0004] Chinese patent CN110658537A belongs to the field of antenna measurement technology and satellite positioning and navigation, and relates to a method for high-precision calibration of the absolute phase center of a GNSS receiver antenna in a microwave darkroom. This method aims to solve the problem that outdoor GNSS observations are easily affected by errors such as multipath and the BDS satellite constellation structure is not complete, and it is impossible to obtain a high-precision receiver absolute antenna phase center correction model. The influence of errors such as multipath is eliminated by absorbing materials in the microwave darkroom, and the GNSS transmission signal is simulated by a vector network analyzer. The incident direction of the received signal of the antenna to be tested is controlled by the movement of a high-precision rotating turntable and a computer control system. The phase pattern covering the hemisphere of the antenna is obtained by the measurement system, and a three-dimensional model of the phase pattern is established to separate the antenna phase center deviation PCO and the antenna phase center variation PCV. Finally, the PCO is solved by the least squares algorithm and the observation value residual is fitted by polynomials and spherical harmonics to calculate PCV. However, this patent is applicable to microwave darkrooms, and its usage scenarios are limited. It cannot solve the problem of phase deviation caused by the influence of the outdoor environment. Summary of the invention

[0005] In order to solve the existing problems of measurement errors caused by only using a simple multi-antenna system for field observation, the present invention provides a phase center measurement device and method based on antenna attitude.

[0006] In order to achieve the purpose of the phase center measurement device based on antenna attitude in the present invention, the technical solution adopted by the present invention is as follows:

[0007] An antenna phase center measurement device based on attitude data, comprising a satellite system, an angle test system and a multi-frequency receiver;

[0008] The satellite system comprises a satellite antenna, a swing rod and a telescopic rod, wherein the satellite antenna is mounted on the upper end of the swing rod, the swing rod is movably connected to the telescopic rod, and the telescopic rod is arranged at the lower end of the swing rod;

[0009] A lightning surge protector is arranged between the satellite system and the angle test system; and the multi-frequency receiver is communicatively connected with the angle test system.

[0010] Furthermore, the satellite system, the lightning surge protector and the angle test system are all connected via transmission cables, and the lightning surge protector is connected to the active connection between the swing rod and the telescopic rod in the satellite system via cables.

[0011] Furthermore, the vertical projection direction angle range of the swing rod is 0-2π, and the horizontal projection pitch angle range of the swing rod is 0-π / 3.

[0012] Furthermore, the telescopic length of the telescopic rod ranges from 0.5m to 1.5m.

[0013] Furthermore, the satellite antenna includes a first satellite antenna and a second satellite antenna, wherein the first satellite antenna is a standard antenna, the second satellite antenna is an antenna to be tested, and one end of the standard antenna and the antenna to be tested are both connected to a lightning surge protector.

[0014] In order to achieve the purpose of the phase center measurement method based on antenna attitude in the present invention, the technical solution adopted by the present invention is as follows:

[0015] A method for measuring an antenna phase center based on attitude data, the steps comprising:

[0016] Step S1: In the initial state, the antenna elevations of the antenna arrays are the same, the pendulum angles are adjusted to be perpendicular to the ground, and the initial antenna coordinates are set to (xi, yi, zi);

[0017] Step S2: adjusting the telescopic rod and the swing rod of the standard antenna so that the antennas are in parallel;

[0018] Step S3: recording the field signal through the standard antenna and the antenna to be tested, and setting the center deviation of the standard antenna;

[0019] Step S4: according to the recorded field signals, the constellation diagram of the satellite simulator output signal is set in the order of fixed satellite serial numbers;

[0020] Step S5: The multi-frequency receiver receives the phase center deviation of each frequency antenna transmitted by the satellite simulator through communication, and records the received signal;

[0021] Step S6: Combine the data records of the phase center deviations of the antennas to obtain a data set of the phase center of the antenna to be tested as the angle changes.

[0022] Further, the telescopic rod in step S2 is adjusted, and the phase center deviation of the standard antenna is at the corresponding angle of the antenna to be tested for comparison. The conversion formula between the earth rectangular coordinates (X, Y, Z) and the antenna rectangular coordinates (x, y, z) is: Among them, B is the geodetic latitude, L is the geodetic longitude, H is the satellite orbit altitude, N is the radius of curvature of the ellipsoid, and e is the eccentricity of the ellipsoid.

[0023] Furthermore, the field signals recorded in step S3 and step S4 at least include satellite serial number, satellite angle, satellite time and signal frequency.

[0024] Furthermore, the standard antenna phase observation equation of the multi-frequency receiver is:

[0025]

[0026] Among them, P1 is the standard antenna phase center offset, t 1 is the clock difference between the receiver and the satellite, Q 1 is the multipath error, ρ T is the flow layer error, ρ I is the ionospheric error, N 1 is the integer ambiguity, t r is the receiver hardware delay error, f is the carrier frequency, c is the speed of light, l 1 It is the pseudo-range value from the satellite signal to the receiver through the standard antenna.

[0027] Furthermore, the phase observation equation of the antenna to be measured is:

[0028]

[0029] Among them, P 2 is the phase center offset of the antenna to be tested, t 2 is the clock difference between the receiver and the satellite, Q 2 is the multipath error, ρ T is the flow layer error, ρ I is the ionospheric error, N 3 is the integer ambiguity, t r is the receiver hardware delay error, f is the carrier frequency, c is the speed of light, l 2 It is the pseudo-range value from the satellite signal passing through the antenna to be tested to the receiver.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] The satellite simulator and the multi-frequency receiver in the present invention use the same reference clock module, eliminating the clock difference between the receiver and the satellite, multipath error, tropospheric error, ionosphere error and other errors. And this full-time adopts direct transmission self-loop measurement and then outputs the information to the standard receiver, thereby achieving the effect of eliminating the receiver hardware delay error. And the present invention records the field signal through a test device; sets the constellation diagram according to a fixed satellite number sequence, and the test system adopts direct transmission self-loop measurement and then outputs it to the standard receiver; the test system obtains the phase center deviation of the antenna at each frequency point through wireless transmission; uses a turntable combined with the phase center deviation of each antenna to perform data comparison, and obtains the data set of the antenna phase center changing with the angle, etc., which is not only closer to the daily working environment of the equipment to be tested, but also has stronger compatibility, wider applicability and high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the present invention;

[0033] The reference numerals are as follows: 1. Satellite antenna; 11. Standard antenna; 12. Antenna to be tested; 2. Pendulum rod; 3. Telescopic rod; 4. Lightning surge protector; 5. Cable. DETAILED DESCRIPTION

[0034] To make the purpose and technical solution of the embodiments of the present invention clearer, the following will be combined with the embodiments of the present invention.

[0035] The technical solution of the present invention is described clearly and completely.

[0036] In the description of this application, it is necessary to understand that the terms "length", "upper", "lower",

[0037] "Vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate the direction or position

[0038] The position relationship is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description.

[0039] does not indicate or imply that the device or element referred to must have a specific orientation, be in a specific position

[0040] The structure and operation thereof should not be construed as limiting the present application.

[0041] Example 1

[0042] according to Figure 1 The antenna phase center measurement device based on attitude data shown in the figure includes a satellite system, an angle test system and a multi-frequency receiver, wherein the satellite system provides a test signal, the angle test system is used to eliminate errors, and the multi-frequency receiver is used to record data; the satellite system includes a satellite antenna 1, a swing rod 2 and a telescopic rod 3, wherein the satellite antenna 1 is installed on the upper end of the swing rod 2, the swing rod 2 is movably connected to the telescopic rod 3, and the telescopic rod 3 is arranged at the lower end of the swing rod 2; a lightning surge protector 4 is arranged between the satellite system and the angle test system, wherein the lightning surge protector 4 is to ensure that the signal strength and signal-to-noise ratio received by the antenna are good, and needs to be set up in an open and unobstructed place, and there is a possibility of being struck by lightning on the roof or open plain, so the device is needed to protect the test system and the receiver, and the lightning surge protector 4 is well grounded. The multi-frequency receiver is communicatively connected to the angle test system.

[0043] The satellite system, the lightning surge protector 4 and the angle test system are all connected via a transmission cable 5, and the lightning surge protector 4 is connected to the active connection between the swing rod 2 and the telescopic rod 3 in the satellite system via a cable 5.

[0044] The maximum telescopic length of the telescopic rod 3 is close to the horizontal distance between the two antennas, and the typical telescopic length range is 0.5m-1.5m.

[0045] A method for measuring an antenna phase center based on attitude data, the steps comprising:

[0046] Step S1: In the initial state, the antenna elevations of each antenna array are the same, the angle of the pendulum 2 is adjusted to be perpendicular to the ground, and the initial antenna coordinates are set to (xi, yi, zi), i = 1, 2, ..., n, n ≥ 3; the microbending of the rod caused by the lever effect is taken into account here, the telescopic rod 3 and the pendulum 2 are designed separately, and the length of the pendulum 2 is much smaller than the telescopic rod 3. At this time, the lever effect is taken into account. If the pendulum 2 and the telescopic rod 3 are designed as an integrated whole, the pendulum 2 / telescopic rod 3 is not perpendicular to the horizontal plane when the posture is changed, and the gravity is perpendicular to the horizontal plane. At this time, the pendulum 2 / telescopic rod 3 will be slightly bent, which introduces new uncertainty to the attitude angle measurement. It can only be avoided by increasing the rigidity of the pendulum 2 / telescopic rod 3 using consumables, but it will waste the test cost. The split design of the pendulum 2 is much smaller than the telescopic rod 3, which greatly weakens the lever effect of the pendulum 2 and reduces the design cost.

[0047] Step S2: Adjust the telescopic rod 3 and the swing rod 2 of the standard antenna 11 so that the antennas are parallel to each other, and set the center deviation of the standard antenna 11; specifically, the center deviation of the standard antenna 11 is known, and adjust the lifting rod of the standard antenna 11 so that the antennas are parallel to each other. When the phase center deviation corresponding angle of the standard antenna 11 is compared with the antenna 12 to be tested, the mechanical deflection angle range meets the requirement of better than 0.3°, and will be corrected by the x, y, and z values ​​later. The multi-frequency receiver obtains the antenna phase center deviation coefficient of each frequency point of the antenna 12 to be tested through wireless transmission, where the conversion formula between the earth rectangular coordinates (X, Y, Z) and the antenna rectangular coordinates (x, y, z) is: Among them, B is the geodetic latitude, L is the geodetic longitude, H is the satellite orbit altitude, N is the radius of curvature of the ellipsoid, and e is the eccentricity of the ellipsoid.

[0048] The pendulum 2 is adjusted so that the vertical projection direction angle range of the pendulum 2 is 0-2π, and the horizontal projection pitch angle range of the pendulum 2 is 0-π / 3.

[0049] Specifically, the standard antenna 11 refers to an antenna that has been calibrated for antenna phase center deviation. The antenna to be tested 12 refers to an antenna for which the change between the antenna attitude and the antenna phase center needs to be obtained.

[0050] Step S3: Recording the on-site signal through the standard antenna 11 and the antenna to be tested 12; specifically, a signal recording module is provided in the angle test system, and the signal is recorded here to extract the key parameters of the on-site satellite signal into the GNSS simulator for error elimination.

[0051] Step S4: According to the recorded field signal, the constellation diagram of the satellite simulator output signal is set in the order of fixed satellite serial numbers; wherein the satellite simulator and the multi-frequency receiver use the same reference clock module, thereby eliminating the clock error between the receiver and the satellite, multipath error, tropospheric error, and ionosphere errors. And the test device uses direct transmission self-loop measurement and outputs to the standard receiver to eliminate the receiver hardware delay error. Here, the receiver hardware delay error is a type of error, and the standard receiver is a multi-frequency receiver.

[0052] Specifically, the field signals recorded in step S3 and step S4 include at least information such as satellite serial number, satellite angle and satellite time, the recorded frequencies include at least GPS-L1 and BDS-B1, and the multi-frequency receiver is set to a single-frequency differential working mode.

[0053] Step S5: The multi-frequency receiver receives the phase center deviation of each frequency antenna transmitted by the satellite simulator through communication, and records the received signal;

[0054] Step S6: Combine the data records of the phase center deviations of the antennas to obtain a data set of the phase center of the antenna 12 to be tested changing with the angle.

[0055] Among them, the phase observation equation of the standard antenna 11 of the multi-frequency receiver is:

[0056]

[0057] Where P1 is the phase center offset of the standard antenna 11, t 1 is the clock difference between the receiver and the satellite, Q 1 is the multipath error, ρ T is the flow layer error, ρ I is the ionospheric error, N 1 is the integer ambiguity, t r is the receiver hardware delay error, pseudo carrier frequency, and c is the speed of light.

[0058] The phase observation equation of the antenna to be tested is:

[0059]

[0060] Among them, P 2 is the phase center offset of the antenna 12 to be tested, t 2 is the clock difference between the receiver and the satellite, Q 2 is the multipath error, ρ T is the flow layer error, ρ I is the ionospheric error, N 3 is the integer ambiguity, t r is the receiver hardware delay error, f is the carrier frequency, and c is the speed of light.

[0061] Specifically, the initial states of steps S1, S2 and S3 are:

[0062]

[0063] Step S4: The GNSS simulator performs simulation based on the actual satellite signal parameters (satellite number, satellite angle, satellite time, etc.) transmitted by the signal playback module. The simulated signal completes a self-loop internally. At this time, the standard phase value τ 0 Contains only pseudorange values ​​(converted directly from positioning information), system noise ε (an empirical constant not associated with the sample to be measured)

[0064]

[0065]

[0066]

[0067] Step S5: The simulator combines S2 to obtain The value is then reset to zero at the receiver, with the antennas in a stationary state.

[0068]

[0069] Step S6: The antenna phase center deviation of the standard antenna 11 is known, and the phase center deviation δ of the antenna to be tested 12 is obtained after compensation and saved as the phase center deviation correction coefficient. The angle of the antenna to be tested 12 is changed, and the phase τ of the antenna to be tested 12 of the receiver is θ for:

[0070]

[0071] Where Δl is the dual-antenna pseudorange difference.

[0072] In conventional RF direction test projects, the accuracy of the relationship between amplitude-related parameters such as power and level and attitude is generally 5° to 10°. In the precision angle measurement scenario, the equipment is easily affected by non-standard signals or stray signals during daily work. Even if calibrated with existing equipment, the data set will often fail during work. In order to meet practicality and accuracy requirements, a multi-frequency receiver is used to record each phase parameter to obtain the relationship between phase difference and angle change:

[0073] Where f is the carrier frequency, c is the speed of light, Δl is the pseudorange difference, δ is the correction coefficient of the antenna phase center deviation, and is the current angle value. For example, the relationship between the rotation angle and the coordinates provided by the simulator under vertical projection is: d is the distance between the antennas, and the antenna phase center change test is completed at each angle. In the pseudo-range measurement process, since any measuring device has signal jitter, in order to achieve measurement accuracy, a multi-frequency receiver is used to record the pseudo-range difference of each antenna to eliminate the measurement error of the measuring instrument itself in this parameter.

[0074] The above is only an embodiment of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection of the present invention.

Claims

1. A method for measuring the phase center of an antenna based on attitude data, characterized in that: A device for measuring the phase center of an antenna based on attitude data is provided, and the steps include: Step S1: In the initial state, the antenna elevations of the antenna arrays are the same, the pendulum angles are adjusted to be perpendicular to the ground, and the initial antenna coordinates are set to (xi, yi, zi); Step S2: adjusting the telescopic rod and the swing rod of the standard antenna so that the antennas are in parallel; Step S3: recording the field signal through the standard antenna and the antenna to be tested, and setting the center deviation of the standard antenna; Step S4: according to the recorded field signal, the constellation diagram of the satellite simulator output signal is set in the order of fixed satellite serial numbers; wherein the satellite simulator and the multi-frequency receiver use the same reference clock module; Step S5: The multi-frequency receiver receives the phase center deviation of each frequency antenna transmitted by the satellite simulator through a communication method, and records the received signal; Step S6: combining the data records of the phase center deviations of each antenna to obtain a data set of the phase center of the antenna to be tested changing with the angle; Among them, the standard antenna phase observation equation of the multi-frequency receiver is: Where P1 is the standard antenna phase center offset, t1 is the clock difference between the receiver and the satellite, Q1 is the multipath error, and ρ T is the flow layer error, ρ I is the ionospheric error, N1 is the integer ambiguity, t r is the receiver hardware delay error, f is the carrier frequency, c is the speed of light, and l1 is the pseudorange value from the satellite signal to the receiver through the standard antenna; Phase observation equation of the antenna to be measured: Among them, P2 is the phase center offset of the antenna to be tested, t2 is the clock difference between the receiver and the satellite, Q2 is the multipath error, and ρ T is the flow layer error, ρ I is the ionospheric error, N3 is the integer ambiguity, t r is the receiver hardware delay error, f is the carrier frequency, c is the speed of light, and l2 is the pseudorange value from the satellite signal passing through the antenna to be tested to the receiver; Among them, in step S6, the antenna phase center deviation of the known standard antenna is compensated to obtain the phase center deviation δ of the antenna to be tested and save it as the phase center deviation correction coefficient. The angle of the antenna to be tested is changed, and the phase center deviation of the antenna to be tested of the receiver is τ θ for: Among them, Δl is the dual-antenna pseudorange difference, δ is the antenna phase center deviation correction coefficient, and θ is the current angle value.

2. The method for measuring the antenna phase center based on attitude data according to claim 1, characterized in that: Adjust the telescopic rod in step S2, and compare it with the antenna to be tested at the corresponding angle of the phase center deviation of the standard antenna. The conversion formula between the earth rectangular coordinates (X, Y, Z) and the antenna rectangular coordinates (x, y, z) is: Among them, B is the geodetic latitude, L is the geodetic longitude, H is the satellite orbit altitude, N is the radius of curvature of the ellipsoid, and e is the eccentricity of the ellipsoid.

3. The method for measuring the antenna phase center based on attitude data according to claim 1, characterized in that: The field signals recorded in step S3 and step S4 at least include satellite serial number, satellite angle, satellite time and signal frequency.

4. An antenna phase center measurement device based on attitude data, characterized in that: Using the antenna phase center measurement method based on attitude data as described in any one of claims 1 to 3, the device includes a satellite system, an angle test system and a multi-frequency receiver; The satellite system comprises a satellite antenna, a swing rod and a telescopic rod, wherein the satellite antenna is installed at the upper end of the swing rod, the swing rod is movably connected to the telescopic rod, and the telescopic rod is arranged at the lower end of the swing rod; A lightning surge protector is provided between the satellite system and the angle test system; The multi-frequency point receiver is communicatively connected with the angle testing system.

5. The antenna phase center measurement device based on attitude data according to claim 4, characterized in that: The satellite system, the lightning surge protector and the angle test system are all connected via transmission cables, and the lightning surge protector is connected to the active connection between the swing rod and the telescopic rod in the satellite system via cables.

6. The antenna phase center measurement device based on attitude data according to claim 4, characterized in that: The vertical projection direction angle range of the pendulum rod is 0-2π, and the horizontal projection pitch angle range of the pendulum rod is 0-π / 3.

7. The antenna phase center measurement device based on attitude data according to claim 4, characterized in that: The telescopic length range of the telescopic rod is 0.5m-1.5m.

8. The antenna phase center measurement device based on attitude data according to claim 4, characterized in that: The satellite antenna comprises a first satellite antenna and a second satellite antenna, wherein the first satellite antenna is a standard antenna, the second satellite antenna is an antenna to be tested, and one end of each of the standard antenna and the antenna to be tested is connected to a lightning surge protector.

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