Single-point command and measurement complex

Abstract

FIELD: space technology; command and measurement complexes.SUBSTANCE: single-point command and measurement complex contains a main antenna, a transmitter-receiver, a command and telemetry radio link unit, a range and radial velocity measurement unit, and a computer. In addition, it contains an interferometric measurement system, including three smaller antennas (located on the sides of a right angle), three receivers, three digital correlators and a common local oscillator, with the outputs of the correlators connected to the computer.EFFECT: increase in the accuracy of measuring the direction of the spacecraft and an increase in the accuracy of trajectory measurements are achieved.1 cl, 1 dwg

Description

[0001] The invention relates to the field of astronautics, to systems of trajectory measurements of spacecraft.

[0002] Command and measurement systems used to control spacecraft (SC) and measure their locations are known [1, Chapter 6]. A common drawback of known command and measurement systems is the low accuracy of measuring the direction to the SC. To improve the accuracy of trajectory measurements, phase direction finders are often used [1, Section 5.4.1]. This navigation technology is called quasi-single-point navigation.

[0003] A method for simultaneously determining six parameters of spacecraft motion during trajectory measurements by one tracking station and a system for its implementation are known (RU Patent No. 2555247, 2015), which is an analogue.

[0004] Analogue contains:

[0005] - a large main antenna and two smaller antennas, which form, together with the main antenna, two orthogonal bases for interferometric measurements;

[0006] - interferometric measurement unit;

[0007] - equipment that exchanges information necessary for controlling the spacecraft (issuing control commands, receiving telemetry and other information);

[0008] - equipment for measuring the range and radial velocity of the spacecraft;

[0009] - blocks for disclosing the ambiguity of angle measurements.

[0010] A disadvantage of this analog is the difficulty of calibrating the hardware phase characteristics and monitoring the interferometric baselines, as the antenna system contains antennas of different sizes. To achieve the stated accuracy of 1-4 arc seconds, it is necessary to ensure a baseline distance measurement accuracy of tenths of a millimeter.

[0011] A generalized command and measurement system [1, pp. 213, 217, 223] was selected as a prototype. It contains a main antenna, the input / output of which is connected to the first input / output of the transceiver unit, the second input / output of which is connected to the input / output of the command and telemetry radio link unit, the third input / output of the transceiver unit is connected to the input / output of the range and radial velocity measurement unit, the output of which is connected to the first input of the computer, and the second input of the computer receives information from the antenna position sensors. Based on the measurements of range, radial velocity and direction, the trajectory of the spacecraft is calculated. A disadvantage of the prototype is the low accuracy of measuring the direction to the spacecraft, which is about 3 arc minutes.

[0012] The features of the invention, which coincide with the features of the prototype, are the main antenna, the transmitting and receiving unit, the command-telemetry radio line unit, the range and radial velocity measuring unit, and the computer.

[0013] The technical result of the claimed invention consists in increasing the accuracy of measuring the direction of the spacecraft, and, as a consequence, in increasing the accuracy of trajectory measurements.

[0014] The technical result is achieved by the fact that the command and measurement system of the prototype includes an interferometric measurement system consisting of three antennas of a smaller size than the main antenna, three receivers and three digital correlators connected in series with them, respectively, a heterodyne, the output of which is connected to the second inputs of the receivers, the second inputs of the digital correlators are connected to the third output of the transmit-receive unit, the outputs of the digital correlators are connected to the inputs of the computer, respectively.

[0015] The essence of the invention is explained by the description and drawing shown in Fig. 1.

[0016] The functional diagram of the single-point command and measurement complex contains (Fig. 1) three antennas 1, 2, 3, located on the sides of a right angle, wherein antenna 2 is located at the top of this angle, three receivers 5, 6, 7 and three digital correlators 9, 10, 11 connected in series with them, a heterodyne 8, the output of which is connected to the second inputs of the receivers, a fourth antenna 4, of a larger size, the input / output of which is connected to the first input / output of the transmitting and receiving unit 12, the second input / output of which is connected to the input / output of the command and telemetry radio line unit 13, the third input / output of the transmitting and receiving unit 12 is connected to the input / output of the range and radial velocity measuring unit 14, the output of which is connected to the first input of the computer 15, the second inputs of the digital correlators are connected to the fourth output of the unit transmission and reception, and the outputs are connected to the inputs of the computer 15, respectively.

[0017] The single-point command and measurement complex operates as follows.

[0018] Antenna 4, via transceiver unit 12, transmits a request signal and receives a response signal from the spacecraft. The response signal is processed in command and telemetry radio link unit 13, and the spacecraft's operability is assessed. The response signal is also processed in range and radial velocity measurement unit 14. After processing, the received information on the distance to the spacecraft and its velocity is sent to computer 15. The response signal is also frequency-converted in transceiver unit 12 to an intermediate frequency corresponding to the intermediate frequency of receivers 5-7, and is sent to the fourth output of transceiver unit 12.

[0019] The response signal from the spacecraft, received by antennas 1-3, after frequency conversion, amplification and filtering using receivers 5-7, is fed to the first inputs of digital correlators 9-11. The signal from the fourth output of the transceiver unit 12 is fed to the second inputs of digital correlators 9-11. The digital correlators, after multiplying and averaging the signals received by antennas 1-3 and antenna 4, form quadrature components of the form - I i4 =A i A4cos(φ i -φ4), Q i4 =A i A4sin(φ i -φ4), A i and φ i - the amplitude and phase of the signals, where i corresponds to the antenna number 1-3. Calculator 15 calculates the phase difference of the received signals Δφ i4 =arctgQ i4 / I i4 .

[0020] Thus, according to the signals of the digital correlators we have: correlator 9 - Δφ 14 =φ1-φ4, correlator 10 - Δφ 24 =φ2-φ4, correlator 11 - Δφ 34 =φ3-φ4, where the phase index corresponds to the antenna number.

[0021] The energy potential of the measuring channels is determined by multiplying the signal received by antenna 4 with the signals received by antennas 1-3. The size of antenna 4 is limited only by technical feasibility. This allows, by selecting the largest possible size for antenna 4, to ensure high sensitivity for a single-point command and measurement system.

[0022] Based on the measured phase differences, the calculator 15 calculates the phase differences of the signals received by antennas 1.2 and 3.2, according to the following algorithm:

[0023] Δφ 12 =Δφ 14 -Δφ 24 =φ1-φ2, Δφ 32 =Δφ 34 -Δφ 24 =φ3-φ2. In this case, the phase shifts introduced by the equipment of measuring channel 4 do not affect the accuracy of the phase measurements of the interferometric system, since they are compensated.

[0024] The cosines of the direction angles in two orthogonal planes are calculated using calculator 15 using the formulas cosθ1=Δφ 12 λ / 2πd12 and cosθ2=Δφ 32 λ / 2πd 32 where λ is the signal wavelength, d is the base of the interferometric measurement system, θ1 is the angle between the direction to the spacecraft and the base 1.2, θ2 is the angle between the direction to the spacecraft and the base 3.2. Using information about the cosines of the direction angles, the distance to the spacecraft and its speed, measured by the range and radial speed measurement unit 14, the spacecraft trajectory is calculated.

[0025] Unlike its analog, the use of an interferometric measurement system with antennas of the same size and a classical antenna field design ensures reliable calibration of the phase characteristics of the receiving equipment and control of baseline distances [1, Section 3.1.4, Fig. 3.8]. Moreover, the command and measurement system and the interferometric measurement system are combined not only functionally but also structurally. Using the energy of a large main antenna allows for a nearly halving of the size of additional antennas and, consequently, a reduction in the cost of a single-point command and measurement complex.

[0026] The ambiguity of interferometric measurements is resolved by implementing the analog mode of operation at two different frequencies. However, the proposed command-measurement system does not utilize the specialized signal used in analog systems; rather, it organizes the operation of the command-telemetry radio link and the radio rangefinder at different frequencies.

[0027] Literature.

[0028] 1. Urlichich Yu.M., Ezhov S.A., Zhodzishsky A.I. et al. “Modern technologies of navigation of geostationary satellites”, Moscow: FIZMATLIT, 2006. - 271 p.

Claims

A single-point command and measurement complex comprising a main antenna, the input / output of which is connected to the first input / output of a transmitting-receiving unit, the second input / output of which is connected to the input / output of a command and telemetry radio link unit, the third input / output of the transmitting-receiving unit is connected to the input / output of a range and radial velocity measuring unit, the output of which is connected to the first input of a computer, characterized in that an interferometric measurement system is introduced into it, consisting of three antennas of a smaller size than the main antenna, located on the sides of a right angle, wherein the second antenna is located at the vertex of the angle, three receivers and three digital correlators connected in series with them, respectively, a heterodyne, the output of which is connected to the second inputs of the receivers, the second inputs of the digital correlators are connected to the fourth output of the transmitting-receiving unit, the outputs of the digital correlators are connected to the inputs of the computer, respectively.

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