Device for receiving linearly polarized satellite signals
阅读说明:本技术 用于接收线性偏振的卫星信号的设备 (Device for receiving linearly polarized satellite signals ) 是由 约亨·贝克 安德烈亚斯·劳尔 奥利弗·利奇克 卢茨·文德利希 西蒙·奥托 于 2018-11-15 设计创作,主要内容包括:本发明涉及一种用于接收线性偏振的卫星信号的设备(10;100),该设备具有至少一个第一和第二耦出探头(14、16)和信号处理装置(13),耦出探头相互成角度取向,并且伸入到空心导体(12)中,并且分别提供线性偏振的输入信号,信号处理装置用于处理两个输入信号。为了改进设备(10;100),使得其能够实现偏振误差角的不易发生干扰的电子修正,根据本发明提出的是,信号处理装置(13)具有第一组合元件(22),第一组合元件从线性偏振的输入信号产生彼此反向的椭圆偏振的高频信号,并且信号处理装置(13)具有能控制的信号转化系统(32、38),信号转化系统将椭圆偏振的高频信号转化为椭圆偏振的中频信号,其中,中频信号相对彼此具有可预设的相移,并且信号处理装置(13)具有第二组合元件,借助第二组合元件能够将椭圆偏振的中频信号组合为线性偏振的输出信号。(The invention relates to a device (10; 100) for receiving linearly polarized satellite signals, comprising at least one first and one second coupling-out probe (14, 16) which are oriented at an angle to one another and project into a hollow conductor (12) and each provide a linearly polarized input signal, and a signal processing device (13) for processing the two input signals. In order to improve the device (10; 100) such that it can be used to carry out an electronic correction of the polarization error angle that is not susceptible to interference, it is proposed according to the invention that the signal processing device (13) has a first combination element (22) which generates elliptically polarized high-frequency signals that are opposite to one another from the linearly polarized input signals, and that the signal processing device (13) has a controllable signal conversion system (32, 38) which converts the elliptically polarized high-frequency signals into elliptically polarized intermediate-frequency signals, wherein the intermediate-frequency signals have a predefinable phase shift relative to one another, and that the signal processing device (13) has a second combination element by means of which the elliptically polarized intermediate-frequency signals can be combined into the linearly polarized output signals.)
1. Device for receiving linearly polarized satellite signals, having at least one first and one second outcoupling probe (14, 16) which are oriented at an angle to one another and project into a hollow conductor (12), wherein the first outcoupling probe (14) provides a linearly polarized first input signal, and wherein the second outcoupling probe (16) provides a linearly polarized second input signal, and having a signal processing device (13) for processing the two input signals, characterized in that the signal processing device (13) has a first combination element (22) which generates a left-handed and a right-handed elliptically polarized high-frequency signal from the two linearly polarized input signals, and in that the signal processing device (13) has a controllable signal conversion system (32) for each of the two elliptically polarized high-frequency signals, 38) Wherein the high-frequency signals are converted by means of two controllable signal conversion systems (32, 38) into elliptically polarized intermediate-frequency signals which are opposite to one another, wherein the intermediate-frequency signals have a phase difference which can be predetermined relative to one another, and the signal processing device (13) has a second combination element (66), wherein the two elliptically polarized intermediate-frequency signals can be combined into a linearly polarized output signal by means of the second combination element (66).
2. Device according to claim 1, characterized in that a left-handed circularly polarized high-frequency signal and a right-handed circularly polarized high-frequency signal can be generated from two linearly polarized input signals by means of the first combination element (22).
3. The device according to claim 1 or 2, characterized in that the signal processing means (13) have a control unit (50) for controlling the signal conversion system (32, 38).
4. Device according to claim 3, characterized in that the control unit (50) is designed as a microprocessor (52).
5. Device according to one of the preceding claims, characterized in that the controllable signal conversion system (32, 38) is designed as a buck converter (33, 40), wherein at least one signal conversion system (32, 38) has a phase-locked loop (37, 43) which can be supplied with a phase control signal.
6. The device according to claim 5, characterized in that the controllable signal conversion system (32, 38) is designed as an integrated circuit.
7. Device according to claim 5 or 6, characterized in that the phase-locked loop (37, 43) is connected to an oscillation circuit (46) which supplies an oscillation signal to the phase-locked loop (37, 43), and in that the phase-locked loop (37, 43) has a loop filter (47, 53) which can be loaded with a phase control current, wherein the phase control current is a phase control signal.
8. Device according to claim 5, 6 or 7, characterized in that a controllable current supply element (54, 58) is assigned to the phase-locked loop (37, 43), which current supply element supplies a phase control current to a loop filter (47, 53) of the phase-locked loop (37, 43).
9. Device according to claim 8, characterized in that the current supply element (54, 58) is designed as a current pulse sensor or as a digital-to-analog converter.
10. Device according to claim 5 or 6, characterized in that the controllable signal conversion systems (32, 38) each have a phase-locked loop (37, 38), wherein the phase-locked loops (37, 43) are connected to a controllable DDS synthesis circuit (102) which supplies the phase-locked loops (37, 43) with a phase control signal in the form of a reference clock signal, wherein the frequencies of the reference clock signals are identical and the phases of the reference clock signals have a phase difference that can be predetermined from one another.
11. The device according to one of claims 5 to 10, characterized in that the buck converters (33, 40) each have a mixing element (35, 41), wherein the frequency of the elliptically polarized high-frequency signals can be converted into an intermediate frequency by means of the mixing elements (35, 41).
12. Device according to any of the preceding claims, characterized in that the signal processing means (13) have a controllable amplifier (18, 24) for each linearly polarized input signal.
13. The device according to claim 12, characterized in that the controllable amplifier (18, 24) is connected to an amplifier control element (96).
14. The apparatus according to claim 13, characterized in that the amplifier control element (96) is provided with a control signal by a control unit (50).
15. Device according to any of the preceding claims, characterized in that the signal processing means (13) have a controllable level adjuster (62, 68) for each intermediate frequency signal.
16. Device according to claim 15, characterized in that the level regulators (62, 68) can be provided with control signals, respectively, by a control unit (50).
17. Device according to any of the preceding claims, characterized in that the level of the intermediate frequency signal can be adjusted to the same value.
18. Device according to any one of the preceding claims, characterized in that a filter element (74) is provided after the second combination element (66).
19. Device according to claim 18, characterized in that the filter element (74) is designed as a band pass (76).
20. The device according to one of the preceding claims, characterized in that the signal processing device (13) has a power detector (90) which can be loaded by the second combination element (66) with a signal to be measured which corresponds to the output signal of the second combination element (66), wherein the power detector (90) supplies a measured value corresponding to the measured power to the control unit (50).
Technical Field
The invention relates to a device for receiving linearly polarized satellite signals, having a first and a second outcoupling probe, which are oriented at an angle to one another and project into a hollow conductor, wherein the first outcoupling probe supplies a linearly polarized first input signal, and wherein the second outcoupling probe supplies a linearly polarized second input signal, and having signal processing means for processing the two input signals.
Background
Such a device is intended to receive linearly polarized signals transmitted by satellites that are stationary with respect to the earth, in particular in the frequency range from 10.7GHz to 12.75 GHz. The satellite signals are linearly polarized, wherein two different signals in two polarization planes oriented perpendicular to one another are transmitted by a satellite stationary relative to earth, usually in the same frequency range, in particular at the same carrier frequency. One of the planes of polarization is commonly referred to as the vertical plane of polarization and the other plane of polarization is commonly referred to as the horizontal plane of polarization. The satellite signals are received by means of two coupling-out probes which project into the hollow conductor and are oriented at an angle to one another, preferably perpendicular to one another.
A difficulty in receiving linearly polarized satellite signals is that the outcoupling probe provided for this purpose should ideally be oriented in the polarization plane of the desired satellite signal. Furthermore, the outcoupling probe can absorb only a small part of the energy used by the receiving site, and the outcoupling probe receives not only the desired fraction of the satellite signal but also the fraction of the miniature signal transmitted in the other polarization plane. This results in a deterioration of the signal-to-noise ratio of the signal provided by the coupled-out probe.
The angular deviation between the plane of polarization of the desired satellite signal and the plane in which the coupled-out probe arranged for receiving the satellite signal is oriented is generally referred to as the polarization error angle.
In order to keep the polarization error angle as small as possible and ideally to obtain a polarization error angle of 0 °, receiving apparatuses are known in which the coupling-out probe together with the hollow conductor (into which the coupling-out probe projects) can be mechanically rotated about the longitudinal axis of the hollow conductor. This enables mechanical calibration of the receiving device. If the receiving device is operating stationary and only signals of a single satellite, which is stationary relative to the earth, should be received, this calibration can be performed once when the receiving device is installed. Under normal circumstances, no further calibration is then necessary.
Difficulties arise if the signals of different satellites that are stationary relative to the earth should be received alternately by the receiving device. For this purpose, the receiving device must be aligned with the respective satellite, wherein a correction of the polarization error angle must also be carried out, since the satellite that is stationary relative to the earth occupies different orbital positions, which lead to different polarization error angles.
Additional difficulties arise in the case of receiving devices which are not installed in a fixed position, but which are operated alternately at different locations. It has been shown that different polarization error angles occur at different locations even with respect to the same satellite, which is relatively stationary with respect to the earth, and these polarization error angles have to be corrected separately. If the receiving device is mechanically adjusted each time a location or satellite is changed, this will lead to significant failures based on the mechanical loading of the receiving device.
Particular difficulties arise in the case of receiving devices which are mounted on land or marine vehicles and which are in motion during operation. A continuous correction of the polarization error angle is necessary when the receiving device is in continuous motion, which cannot be realized in practice by mechanical adjustment.
Instead of mechanically rotating the receiving device, for example by means of an electric motor, it is proposed in US5,568,158 to electronically correct the polarization error angle. The input signals provided by the two coupling-out probes oriented perpendicular to one another are processed by means of a signal processing device. The input signals are amplified and attenuated by means of controllable attenuation elements and then combined, wherein additionally the phase of one of the input signals can be shifted by 180 ° by means of a phase shifter. The frequency of the combined signal resulting from the combination of the processed input signals is then reduced by means of a buck converter, so that an output signal with an intermediate frequency is present, which can then be fed to a receiver via a coaxial cable.
The problems caused by mechanically adjusting the receiving device are eliminated by electronic correction of the polarization error angle. It has been found, however, that the electronic correction by means of a controllable damping element, known from US5,568,158, is often disturbing in practice and is difficult to control.
Disclosure of Invention
The object of the invention is therefore to improve a device of the type mentioned at the outset such that it enables a simple and interference-free electronic correction of the polarization error angle.
This object is achieved according to the invention in a device of the generic type in that the signal processing device has a first combination element which generates, from two linearly polarized input signals, left-handed and right-handed elliptically polarized high-frequency signals, and the signal processing device has a controllable signal conversion system for each elliptically polarized high-frequency signal, wherein the high-frequency signals can be converted by means of the signal conversion system into elliptically polarized intermediate-frequency signals which are opposite to one another, wherein the intermediate-frequency signals have a predeterminable phase difference with respect to one another, and the signal processing device has a second combination element, wherein the two elliptically polarized intermediate-frequency signals can be combined into a linearly polarized output signal by means of the second combination element.
An elliptically polarized high-frequency or intermediate-frequency signal is understood to mean a signal which corresponds to an electromagnetic wave and whose deflection from the rest position revolves in an ellipse in a plane oriented perpendicularly to the propagation direction of the wave. The semi-axes of the ellipses can be identical or different, so that elliptical polarization also includes circular polarization as a special case in the present case, in which the deflection of the electromagnetic wave revolves in a circle in a plane oriented perpendicular to the propagation direction. Thus, the term "elliptical polarization" also includes circular polarization at the present time.
The concept of the present invention is that a linearly polarized satellite signal can be obtained completely from a received signal, which is provided by two coupling-out probes oriented at an angle to one another, by combining the linearly polarized input signals of the coupling-out probes into a left-handed elliptically polarized, in particular circularly polarized, high-frequency signal and into a right-handed elliptically polarized, in particular circularly polarized, high-frequency signal, and converting these oppositely elliptically polarized, in particular circularly polarized, signals into intermediate-frequency signals with a predefinable phase difference, and then combining the converted elliptically polarized, in particular circularly polarized, intermediate-frequency signals again into a linearly polarized output signal. The required phase difference of the elliptically, in particular circularly, polarized intermediate frequency signals can be determined by optimizing the signal-to-noise ratio of the output signal.
The device according to the invention enables an electronic correction of the polarization error angle that is less prone to interference. In a first step, the two linearly polarized input signals exiting the probe are converted into two elliptically polarized, in particular circularly polarized, high-frequency signals which are opposite to one another. For this purpose, the signal processing device has a first combination element. In order to generate an elliptically polarized, in particular circularly polarized, first high-frequency signal, for example a left-handed elliptically polarized, in particular circularly polarized, high-frequency signal, the first combination element performs a phase shift of 90 ° of the first input signal and subsequently forms a weighted sum of the 90 ° phase-shifted first input signal and the second input signal unchanged in its phase. In order to generate an elliptically polarized, in particular circularly polarized, second high-frequency signal, i.e. an elliptically polarized, in particular circularly polarized, high-frequency signal, for example with a right-hand rotation, the first combination element performs a phase shift of the second input signal by 90 ° and subsequently forms a weighted sum of the 90 ° phase-shifted second input signal and the first input signal unchanged in its phase. The first and second input signals, which are phase-shifted by 90 ° and unchanged in their phase, can be weighted in the sum formation, so that signals with the same weight or also with different weights are combined. Equal weighting of the signals leads to the special case of circular polarization of the sum signal, while different weighting leads to non-circular elliptical polarization of the sum signal.
Subsequently, the elliptically, in particular circularly, polarized high-frequency signals which are opposite to one another are converted by means of a controllable signal conversion system into elliptically, in particular circularly, oppositely polarized intermediate-frequency signals which have a phase difference which can be set in advance. For this purpose, the at least one signal conversion system can also perform a predefinable phase shift in addition to the frequency conversion, so that the intermediate frequency signals have a predefinable phase difference with respect to one another.
Preferably, the two signal conversion systems perform a phase shift in addition to the frequency conversion. For example, a first controllable signal conversion system can be supplied with a left-handed elliptically polarized, in particular circularly polarized, high-frequency signal, which is converted by the first signal conversion system into a left-handed elliptically polarized, in particular circularly polarized, intermediate-frequency signal with a changed phase, and a second controllable signal conversion system can be supplied with a right-handed elliptically polarized, in particular circularly polarized, high-frequency signal, which is converted by the second signal conversion system into a right-handed elliptically polarized, in particular circularly polarized, intermediate-frequency signal with a changed phase.
In a further step, elliptically, in particular circularly, polarized intermediate frequency signals which are opposite to one another are combined into a linearly polarized output signal by means of a second combination element.
It has now been demonstrated that the signal-to-noise ratio of a linearly polarized output signal can be optimized by varying the phase shift performed by at least one controllable signal conversion system, wherein the output signal corresponds to a satellite signal transmitted in a first polarization plane, for example to a satellite signal transmitted in a horizontal polarization plane. The output signal has practically no share of the satellite signal transmitted in a second plane of polarization, e.g. a vertical plane of polarization, orthogonal to the first plane of polarization. The addition of the oppositely elliptically, in particular circularly, polarized intermediate signals eliminates the proportion of the interfering second satellite signal, wherein the elimination can be recognized by the fact that the output signal has the best signal-to-noise ratio.
In an electrically rotatable receiving device, the polarization error angle can be corrected in such a way that the signal-to-noise ratio of the output signal provided by the receiving device is optimized by the mechanical rotation of the device. In the device according to the invention, no mechanical rotation is necessary, rather the signal-to-noise ratio of the output signal can be optimized by changing the phase difference of the oppositely elliptically polarized, in particular circularly polarized, intermediate frequency signal.
As already mentioned, the first combination unit is configured in such a way that a left-handed elliptically polarized high-frequency signal and a right-handed elliptically polarized high-frequency signal can be generated from the two linearly polarized input signals. It is particularly advantageous if, by means of the first combination element, a left-handed circularly polarized high-frequency signal and a right-handed circularly polarized high-frequency signal can be generated from the two linearly polarized input signals. As already mentioned, this can be achieved by performing equal weighting when summing first and second input signals that are phase-shifted by 90 ° and that have not changed in their phase.
For controlling the signal conversion system, the signal processing device advantageously has a control unit.
Preferably, the use of a control unit is allowed to provide the at least one signal conversion system with a special phase control signal.
Advantageously, the two signal conversion systems each perform a phase shift, wherein the first signal conversion system can be supplied with a first phase control signal corresponding to a first phase shift angle, and wherein the second signal conversion system can be supplied with a second phase control signal corresponding to a second phase shift angle.
The phase shift angles are not necessarily the same. In particular, it can be provided that the two phase shift angles differ only in their sign, but do not differ in their absolute value, so that a left-handed circularly polarized signal is shifted in its phase by, for example, a phase angle + Φ, while a right-handed circularly polarized signal is shifted by a phase angle- Φ, where Φ can assume values between 0 ° and 90 °.
Preferably, a microprocessor can be used as the control unit.
The controllable signal conversion system is preferably designed as a buck converter, wherein at least one signal conversion system has a phase-locked loop (phase-locked loop) which can be supplied with a phase control signal. Buck converters with a phase-locked loop (also referred to as phase-locked loop) are known to those skilled in the art. Standard circuits are involved, which are produced inexpensively in large numbers for completely different purposes of use. The phase control signal can be used to shift the phase of the signal converted by the buck converter.
Preferably, the two controllable signal conversion systems have a phase-locked loop (phase-locked loop) which can be supplied with the phase control signal.
Advantageously, the signal conversion systems are each formed with a single integrated circuit. Integrated circuits can constitute a compact set of electrical structures that can be inexpensively manufactured in large quantities.
For example, it can be provided that the phase-locked loop of the at least one signal conversion system is connected to an oscillating circuit, which supplies an oscillating signal to the phase-locked loop, and that the phase-locked loop has a loop filter, which can be loaded with a phase control current. Phase locked loops with loop filters are well known to those skilled in the art and therefore need not be elaborated upon. The phase control current is a phase control signal by means of which a phase shift can be obtained. The phase control current is loaded, that is to say introduced into the loop filter, to cause a phase shift of the oscillator signal and this in turn causes a phase shift of the intermediate frequency signal provided by the buck converter.
Advantageously, a controllable current supply element is associated with the phase-locked loop, which supplies the phase-controlled current to the loop filter of the phase-locked loop.
Preferably, the current providing element is controllable by a control unit of the signal processing device.
It can be provided that the current supply element is designed as a current pulse sensor or as a digital/analog converter, which is acted upon by the control unit for controlling the signal.
In an advantageous embodiment of the invention, the controllable signal conversion systems each have a phase-locked loop (phase-locked loop), wherein the phase-locked loop is connected to a controllable DDS synthesis circuit (Direct digital synthesis-synthesis) which supplies a reference clock signal to the phase-locked loop, wherein the frequencies of the reference clock signals are identical and the phases of the reference clock signals have a phase difference (phase offset) that can be set. Controllable DDS synthesis circuits are known per se to the person skilled in the art and therefore do not need to be elaborated on at present. With the aid of a controllable DDS synthesis circuit, two phase control signals can be generated in the form of two reference clock signals having the same frequency and a predefinable phase offset. One of the two reference clock signals may be supplied to the phase-locked loop of the first buck converter, while the other reference clock signal may be supplied to the phase-locked loop of the second buck converter. This results in the buck converter providing an intermediate frequency signal which differs in its phase in a predefinable manner.
Preferably, the DDS synthesis circuit is controllable by a control unit of the signal processing device.
The buck converters preferably each have a mixing element, with the aid of which the frequency of the elliptically, in particular circularly, polarized high-frequency signal can be converted into an intermediate frequency.
The intermediate frequency is preferably 0.95GHz to 2.15 GHz.
Advantageously, the signal processing device has an amplifier with a controllable degree of amplification for each linearly polarized input signal. This allows amplifying the linearly polarized input signals provided by the coupled-out probe independently of one another in a predefinable manner. The amplifiers may be alternately turned off for testing purposes.
Advantageously, the signal processing device has an amplifier control element for controlling the amplifier.
Preferably, the control signal may be provided by the control unit to the amplifier control element.
In an advantageous embodiment of the invention, the signal processing device has a controllable level controller for each elliptically polarized, in particular circularly polarized, intermediate frequency signal. The level controller can be designed, for example, as a controllable damping element or also as a controllable amplification element. The undesired level differences of the two intermediate frequency signals can be eliminated by means of the level adjuster. In particular, it can be ensured by means of a controllable level regulator that the level of the intermediate frequency signal supplied to the second combination element is equally high, so that the same input level is present at the input of the second combination element. This in turn leads to an optimum amplitude of the output signal, wherein undesired signal contributions are suppressed.
Advantageously, the level regulator can be provided with a control signal by the control unit.
As mentioned, it is advantageous that the level of the elliptically, in particular circularly, polarized intermediate frequency signal can be adjusted to the same value, since an output signal with a high amplitude and a small proportion of undesired signals can thereby be obtained.
In an advantageous embodiment of the invention, a filter element is arranged downstream of the second combination element. Undesired spectral components of the output signal can be removed by means of the filter element.
The filter element is preferably designed as a low-pass or band-pass filter.
In order to be able to supply the individual components of the signal processing device with control signals which are dependent on the power of the output signal, it is advantageous if the signal processing device has a power detector which can be acted upon by the second combination element with the signal to be measured which corresponds to the output signal of the device, and the power detector supplies the control unit of the signal processing device with measured values which correspond to the measured power. The power detector can be used to control the aforementioned level regulator, for example, in such a way that the amplitude of the intermediate frequency signal present at the input of the combination element is equally large.
Drawings
The following description of advantageous embodiments is provided to illustrate the invention in detail with reference to the accompanying drawings. Wherein:
FIG. 1: a block diagram of an advantageous first embodiment of an apparatus for receiving linearly polarized satellite signals is shown;
FIG. 2: a block diagram of an advantageous second embodiment of an arrangement for receiving linearly polarized satellite signals is shown.
Detailed Description
An advantageous first embodiment of the device according to the invention for receiving linearly polarized satellite signals is shown in fig. 1 and generally takes the
The
In order to generate a left-handed elliptically polarized, in particular circularly polarized high-frequency signal, the
In order to generate a right-handed elliptically polarized, in particular circularly polarized, high-frequency signal, the
In the summation formation, the first and second input signals, which are phase-shifted by 90 ° and which have not been changed in their phase, can be weighted such that signals having the same weight or also different weights are summed. Equal weighting of the signals leads to the special case of circular polarization of the high-frequency signals, while different weighting leads to non-circular elliptically polarized high-frequency signals.
The
The controllable first
The controllable second
The intermediate frequency of the elliptically, in particular circularly, polarized intermediate frequency signal is 0.95GHz to 2.15 GHz.
To obtain the first phase shift, the first phase control current provided at the
To obtain the second phase shift, the second phase control current provided at the
The phase shift by the controllable first
The control of the
The
In a corresponding manner, the
As already mentioned, the second phase shift angle is not the same as the first phase shift angle. Preferably, the second phase shift angle is inversely equal to the first phase shift angle.
The left-handed elliptically polarized, in particular circularly polarized, intermediate frequency signal provided by first
The
The signal-to-noise ratio of the output signal can be maximized by varying the phase shift angle Φ. The output signal optimized by a suitable choice of the phase shift angle Φ corresponds to a linearly polarized satellite signal which is transmitted in the polarization plane and is received in portions by the two
If an output signal corresponding to the linearly polarized second satellite signal should be provided, the phase angle Φ only needs to be increased by 90 °.
The change of the phase shift angle Φ to optimize the output signal is effected by means of a
A
A control signal can be transmitted from a receiver, not shown in the figures, via a
Second combining
In consideration of the measured values provided by the
An advantageous second embodiment of the device for receiving linearly polarized satellite signals according to the invention is schematically illustrated in fig. 2 and generally takes the
The
In the
The
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