JP5700571B2 - Tracking antenna device and initial phase difference compensation method - Google Patents

Description

  The present invention relates to a tracking antenna device and an initial phase difference compensation method in an earth station device for mobile satellite communication.

  Since satellite communication is the only broadband communication means provided on the ocean, reliability against failure of the earth station device for satellite communication on board is required. As a technique for realizing this at a low cost, a tracking antenna apparatus using a plurality of antennas has been studied (Non-patent Document 1). Here, the tracking antenna device has a function of mechanically controlling the directivity direction (elevation angle and azimuth angle) of the antenna by detecting the directivity direction estimation and the directivity direction error amount from various sensor information and signals received from the other party of communication. I have.

FIG. 3 shows a configuration example of a conventional tracking antenna apparatus using a plurality of antennas.
In FIG. 3, the tracking antenna device includes N (N is an integer of 2 or more) transmission / reception devices 50-1 to 50 -N, a phase control device 60, and a modem device 70.

FIG. 4 shows a configuration example of a conventional transmission / reception device 50-k (k = 1 to N).
In FIG. 4, the transmission / reception device 50-k includes an antenna unit 51 and a frequency up-converter (UC) 52. The UC 52 includes a local oscillator that outputs a local signal LO _k having a frequency f _LO and a frequency converter. The frequency converter mixes the transmission IF signal S _IF-k having the frequency f _IF and the local signal LO _k that are input from the modulation / demodulation device 70 via the phase control device 60, and has the frequency f _RF (= f _IF + f _LO ). The transmission RF signal S _RF-k is output to the antenna unit 51. Note that the configuration of the reception system in the transmission / reception device 50-k is omitted.

  In such a tracking antenna device, the transmission RF signal from each transmission / reception device 50-k is controlled to be transmitted in a predetermined phase (for example, in-phase) to the satellite station, thereby improving the reliability and the pointing accuracy. , EIRP (effective radiation power) and G / T (reception performance) are improved.

  However, in order to control so that each transmission RF signal is transmitted in a predetermined phase (for example, in-phase), it is necessary to compensate for the phase fluctuation generated in each transmission / reception device 50-k. For this purpose, the transmission RF signal output from the UC 52 is converted into a low-frequency FB (feedback) signal using the multiplied wave of the transmission IF signal or the low-frequency reference signal, and fed back to the phase controller 60. A method for compensating for phase fluctuations occurring in each transceiver 50-k has been proposed (Non-Patent Document 2).

  However, in order to realize this method, it is necessary to first compensate the initial phase characteristics of each transmitting / receiving device. As an initial phase characteristic compensation method, the element electric field vector rotation method (REV method: Rotating Element Electric Field Vector Method) is used to shift the phase of each transmitting / receiving device, and the return of the own signal via the satellite is maximized. There is a method of performing compensation so as to satisfy (Non-Patent Document 3). Also, a method for compensating for non-uniform components of amplitude and phase by controlling the transmission RF signals output from the antennas of the respective transmitting and receiving apparatuses to be orthogonal using a synchronous orthogonal code and performing inverse FFT conversion on the received signal. (Non-Patent Document 4).

Susaki, Suzuki, Yamashita, Kobayashi, "Study on a tracking antenna for a shipboard earth station using multiple antennas", 2010 IEICE Society Conference, B-3-19, 2010 Susaki, Suzuki, Kobayashi, "Method for compensating phase variation of shipboard earth station distributed array antenna and experimental verification", IEICE Technical Report SAT2011-3, pp.11-16, May 2011 Mano, Katagi, "Element Amplitude Phase Measurement Method for Phased Array Antenna-Element Electric Field Vector Rotation Method", IEICE Transactions B, Vol.J65-B, No.5, pp.555-560, 1982 May Odo, Miura, "Transmission Array Antenna Calibration Using Synchronous Orthogonal Codes", IEICE Techniques A / P99-121, RCS99-118, October 1999

The local oscillator included in the UC 52 of each transmission / reception device 50-k shown in FIG. 4 oscillates at the same frequency (13.05 GHz in the Ku band) by a common reference signal (for example, 10 MHz reference signal). Here, since the frequency difference between the frequency f _{LO of the} local signal output from the local oscillator and the reference signal is more than 1000 times, a slight phase shift Δθ _k (t) due to frequency division between the local oscillators is accumulated. Then, the relative phase varies with time. FIG. 5 shows a time variation example of the relative phase difference generated between the transmitting and receiving apparatuses with respect to the same input signal (transmission IF signal). When such a relative phase difference occurs, problems such as a decrease in gain and a shift in the directivity direction occur.

  Since these phase shifts have different values every time each transmitting / receiving apparatus is activated, it is necessary to perform initial phase correction of the transmission signal using means such as the REV method. However, since the REV method sees the change in the reception level of the satellite return signal of the local station signal, a delay of 250 ms occurs until the correction is reflected in the reception level, and each phase is increased as the number of transmission / reception devices increases. It takes time to adjust and monitor. In addition, in order to perform calibration with high accuracy when using a synchronous orthogonal code, it is necessary to know the satellite direction in advance, which is not suitable for the system to be applied.

  It is an object of the present invention to provide a tracking antenna apparatus and an initial phase difference compensation method that can detect and compensate for an initial phase difference between a plurality of transmission / reception apparatuses in a short time.

In the first invention, a transmission IF signal is input to a plurality of transmission devices via a cable from a phase control device that controls the phase of a transmission IF signal of an intermediate frequency, and the frequency f obtained by frequency-converting the transmission IF signal by each transmission device. _In a tracking antenna device that transmits RF transmission RF signals from an antenna unit in a predetermined phase, the transmission device includes a first reference signal S _REF1 having a frequency f _{ref1 that} is f _d lower than the frequency f _RF of the transmission RF signal, and f a second reference signal S _REF2 of _d higher frequency f _ref2 is input from the phase control unit via a cable, first obtained by frequency converting the transmitted RF signal by using the first reference signal and a second reference signal of the feedback signal S _FB1 and the second feedback signal S _FB2 comprises means for feedback to the phase control unit via a cable, the phase control unit, reference from the transmitter comprising A first feedback signal S _FB1-1, the phase difference between the first feedback signal S _FB1-k from the transmitter of the k detected, a second feedback signal S from a reference transmitter device _FB2-1 And the second feedback signal S _FB2-k from the k-th transmission device, and since the absolute values of the phase differences are equal, the initial phase difference in each transmission device is detected, and the initial position In this configuration, the phase of the transmission IF signal transmitted to each transmission device is controlled so that the phase difference between the first feedback signal and the second feedback signal is constant based on the phase difference.

  In the tracking antenna device of the first invention, the phase control device causes the phase of the first reference signal and the second reference signal to follow the phase change of the transmission IF signal, and the first reference signal is input. The difference between the phase difference between the first feedback signal and the second feedback signal and the value obtained by inverting the sign of the phase difference between the first feedback signal and the second feedback signal when the second reference signal is input. The phase of the transmission IF signal is controlled so as to be minimized.

According to a second aspect of the present invention, a transmission IF signal is input to a plurality of transmission devices via a cable from a phase control device that controls the phase of a transmission IF signal having an intermediate frequency, and a frequency f obtained by frequency-converting the transmission IF signal by each transmission device. _In the initial phase difference compensation method for a tracking antenna apparatus that transmits an _RF transmission RF signal from an antenna unit in a predetermined phase, the transmission apparatus uses a first reference of a frequency f _{ref1 that} is f _d lower than the frequency f _RF of the transmission RF signal. the signal S _REF1, f _d greater and the second reference signal S _REF2 frequency f _ref2 is input from the phase control unit via a cable, transmission RF signal by using the first reference signal and a second reference signal a first feedback signal S _FB1 and the second feedback signal S _FB2 obtained by frequency conversion via the cable back to the phase controller, a phase controller, a primary transmission instrumentation A first feedback signal S _FB1-1 from the phase difference between the first feedback signal S _FB1-k from the transmitter of the k detected, a second feedback signal S from the transmitter as a reference The phase difference between _FB2-1 and the second feedback signal S _FB2-k from the kth transmitter is detected, and since the absolute value of each phase difference is equal, the initial phase difference in each transmitter is detected, Based on the initial phase difference, the phase of the transmission IF signal transmitted to each transmission apparatus is controlled so that the phase difference between the first feedback signal and the second feedback signal is constant.

  In the initial phase difference compensation method for the tracking antenna device according to the second aspect of the invention, the phase control device causes the phase of the transmission IF signal to follow the phases of the first reference signal and the second reference signal, and the first reference signal The phase difference between the first feedback signal and the second feedback signal when the signal is input and the phase difference between the first feedback signal and the second feedback signal when the second reference signal is input are inverted. The phase of the transmission IF signal is controlled so that the difference from the measured value is minimized.

The present invention uses a first reference signal S _REF1 having a frequency f _{ref1 that} is f _d lower than the frequency f _RF of the transmission RF signal and a second reference signal S _REF2 having a frequency f _ref2 that is f _d higher than the frequency f _RF. Controls the phase of the transmission IF signal transmitted to each transmission device so that the phase difference between the signal and the second feedback signal is constant, thereby detecting and compensating for the initial phase difference between the plurality of transmission / reception devices. can do.

It is a figure which shows the Example structure of the tracking antenna apparatus of this invention. It is a figure explaining the example of control which makes the phase of reference signals _SREF1 and _SREF2 follow the phase change of transmission IF signal _SIF-k . It is a figure which shows the structural example of the conventional tracking antenna apparatus which uses a some antenna. It is a figure which shows the structural example of the conventional transmission / reception apparatus 50-k. It is a figure which shows the example of a time fluctuation of the relative phase difference which arises between transmission / reception apparatuses.

FIG. 1 shows the configuration of an embodiment of the tracking antenna apparatus of the present invention.
In FIG. 1, the tracking antenna apparatus according to the present embodiment includes a transmission / reception apparatus 10-k (k = 1 to N, N is an integer of 2 or more), a phase control apparatus 20, and a modulation / demodulation apparatus 30. The transmission / reception device 10-k and the phase control device 20 are connected via a cable 40-k having a cable length l _k . In FIG. 1, the configuration of the transmission system related to the initial phase control is shown, and the configuration of the reception system and others is omitted.

  The transmission / reception device 10-k includes an antenna unit 11, a frequency up-converter (UC) 12, a frequency converter 13, a duplexer 14, and a multiplexer / demultiplexer 15.

The phase control device 20 includes a reference signal generator 21, a phase control unit 22-k corresponding to each transmission / reception device 10-k, and an initial phase control unit 23. The phase control unit 22-k controls the phase of the transmission IF signal S _IF of the frequency f _IF output from the modem device 30 with the transmission phase control signal output from the initial phase control unit 23, the reference signal The phase shifters 222 for controlling the phases of the reference signals S _REF1 and S _REF2 of the frequencies f _ref1 and f _ref2 output from the generator 21 by the reference phase control signal output from the initial phase control unit 23 are respectively phase-controlled. An adder 223 for adding the transmission IF signal S _IF-k and the reference signals S _REF1 and S _REF2 , a D / A converter 224 for converting the addition output to an analog signal and sending it to the cable 40-k, and a multiplexer / demultiplexer 225, an A / D converter 226 that converts the FB signals S _FB1-k and S _FB1-k input from the cable 40-k via the multiplexer / demultiplexer 225 into digital signals and outputs them to the initial phase controller 23. Constitution It is.

The transmission IF signal S _IF-k and the reference signals S _REF1 and S _REF2 input from the phase control device 20 to the transmission / reception device 10-k via the cable 40-k are transmitted by the branching filter 14 via the _multiplexer / demultiplexer 15. The transmission IF signal S _IF-k is input to the UC 12 and the reference signals S _REF1 and S _REF2 are input to the frequency converter 13. The UC 12 mixes the transmission IF signal S _IF-k and the local signal LO _k and converts the frequency into a transmission RF signal S _RF-k having a frequency f _RF . The transmission RF signal S _RF-k is transmitted from the antenna unit 11 and input to the frequency converter 13. The frequency converter 13 mixes the transmission RF signal S _RF-k and the reference signals S _REF1 and S _REF2 and converts the frequency into FB signals S _{x1 -k} and S _{x2 -k} . The FB signals S _x1-k and S _x2-k are transmitted from the multiplexer / demultiplexer 15 to the phase controller 20 via the cable 50-k, and are demultiplexed by the multiplexer / demultiplexer 225 of the corresponding phase controller 22-k. The FB signals S _FB1-k and S _FB2-k are input to the initial phase control unit 23.

Here, the frequencies f _ref1 and f _ref2 of the reference signals S _REF1 and S _REF2 are
f _RF −f _ref1 = f _ref2 −f _RF = f _d
Is set to be

When the dielectric constant of the cable 40-k is ε, the propagation velocity v is represented by v = c / √ε (c is the speed of light of 3 × 10 ⁸ [m / s]). The phase difference resulting from the cable length difference between each transceiver 10-k when the transceiver 10-1 is used as a reference is obtained as follows. When the phase coefficient α of the cable length difference L _k (= l _k −l ₁ ) of each cable 40-k with respect to the cable length l ₁ of the cable 40-1 is set to α = 2πL _k √ε / c, the cable length difference L _The phase added to the transmission IF signal S _IF-k at _k is αf _IF , and the phases added to the reference signals S _REF1 and S _REF2 in the same section are αf _ref1 and αf _ref2 . Further, the phase added to the FB signals S _{x1, k} and S _{x2, k} in the same section is αf _d , which are set as FB signals S _{FB1 -k} and S _{FB2 -k} . In addition, an initial phase generated in the _UC 12 of the transmission / reception device 10-k is assumed to be θ _UC-k .

First, the transmission RF signal S _RF-k at the input end (the output end of the UC 12) of the antenna unit 11 subjected to frequency conversion by transmitting the transmission IF signal S _IF from the phase control device 20 to the transmission / reception device 10 _-k is the cable length. The phase αf _{IF corresponding} to the difference L _k and the initial phase generated by the _{UC 12} are added to θ _UC-k , and S _RF-k = sin (2π (f _RF ) t + αf _IF + θ _UC-k ) (1)
It is expressed.

A frequency converter 13 for mixing the transmission RF signal S _RF-k and the reference signal S _REF1 transmitted from the phase control device 20 to the transmission / reception device 10-k and added with the phase αf _{fef1 corresponding} to the cable length difference L _k. The FB signal S _{x1, k} at the output of
S _{x1, k} = sin (2π (f _RF −f _ref1 ) t + αf _IF + θ _UC−k −αf _ref1 ) (2)
Represented, further FB signal S _FB1-k phase .alpha.f _d inputs are added to the phase control unit 22-k of the cable length difference L _k min and,
S _{FB1, k} = sin (2π (f _RF −f _ref1 ) t + αf _IF + θ _UC−k −αf _ref1 + αf _d ) (3)
It is expressed. Therefore, the phase A of the FB signal S _FB1-k is
A = αf _IF + θ _UC−k −αf _ref1 + αf _d (4)
It is expressed.

Similarly, the frequency conversion for mixing the transmission RF signal S _RF-k and the reference signal S _REF2 transmitted from the phase control device 20 to the transmission / reception device 10-k and added with the phase αf _ref2 for the cable length difference L _k is added. The FB signal S _{x2, k} at the output end of the device 13 is
S _{x2, k} = sin (2π (f _RF −f _ref2 ) t + αf _IF + θ _UC−k −αf _ref2 ) (5)
It is expressed. Since this signal has a negative frequency, the phase is inverted. Therefore, FB signal S _FB2-k cable length difference L _k of the phase .alpha.f _d is added to the input to the phase control unit 22-k is
S _FB2−k = sin (2π (f _RF −f _ref1 ) t−αf _IF −θ _UC−k + αf _ref2 + αf _d ) (6)
It is expressed. Therefore, the phase B of the FB signal S _FB2-k is
B = −αf _IF −θ _UC−k + αf _ref2 + αf _d (7)
It is expressed.

In the initial phase control unit 23, when the phase A of the FB signal S _{FB1-k in} Expression (4) and the phase B of the FB signal S _{FB2-k in} Expression (7) are added,
A + B = −αf _ref1 + αf _ref2 + 2αf _d = −α (f _RF −f _d ) + α (f _RF + f _d ) + 2αf _d = 4αf _d (8)
Thus, the phase coefficient α of the cable length difference L _k can be calculated.

If this phase coefficient α is calculated, other phases are also found, so that the initial phase θ _UC-k generated in the _{UC 12} can be calculated. The transmission phase control signal corresponding to the initial phase θ _UC-k is output to the phase shifter 221 of the phase control unit 22-k, and the initial phase θ _UC-k is delayed from the phase of the transmission IF signal S _IF-k . By performing the correction, the initial phase correction in the transmission / reception device 10-k is completed.

Further, from the equations (4) and (7), A−αf _d = αf _IF + θ _UC−k −αf _ref1 (9)
_{B-αf d = - (αf} IF + θ UC-k -αf ref2) ... (10)
However, it can be seen that the rotation of the phase is reversed when αf _ref1 or αf _ref2 increases. When the frequencies f _ref1 and f _ref2 are high frequencies, an error with a small value of α may greatly affect the calculated phase amount. For this reason, it is conceivable that the control is performed by depending on the phase change of the transmission IF signal S _{IF-k so that} the phases of the reference signals S _REF1 and S _REF2 have the following relationship. A specific procedure will be described with reference to FIGS. 2 (1) to (4).

FIG. 2 (1) shows the initial state expressed by the equations (4) and (7). From this initial state, the initial phase αf _d of the FB signals S _{FB1 -k} and S _{FB2 -k} is subtracted to obtain the states of equations (10) and (11). This state is shown in Fig. 2 (2). Further, as shown in FIG. 2 (3), the phases of the transmission IF signal S _IF-k and the reference signal S _REF1 are f _d : f _ref1 , and the phases of the transmission IF signal S _IF-k and the reference signal S _REF2 are f _d. : The phase may be rotated so as to be f _ref2, and control may be performed so that the phase difference between A−αf _d and − (B−αf _d ) is minimized. That is, the reference phase control signal applied to the phase shifter 222 is simultaneously moved by xαf _d (x <1), and the transmission phase control signal applied to the phase shifter 221 is simultaneously moved by xαf _ref1 . Similarly for the reference signal S _REF2 , the reference phase control signal is simultaneously moved by xαf _d equivalent to the phase amount moved by the reference signal S _REF1 , and the transmission phase control signal is simultaneously moved by xαf _ref2 . By alternately switching the reference signals, the phase of the transmission IF signal is changed little by little with high accuracy. As shown in FIG. 2 (4), the phase difference between the two FB signals S _FB1-k and S _FB2-k By searching for a point (θ _UC−k ) that minimizes the error of the phase coefficient α, the influence of the error can be reduced.

The above description is an example of transmitting RF signal S _RF-k frequency conversion by the reference signal S _REF1, S _REF2, and inputs the reference signal S _REF1, S _REF2 to the frequency converter 13 and M multiplied In the case of the configuration, the phase control amounts of the reference signals S _REF1 and S _REF2 are 1 / M times.

10, 50 Transceiver 11, 51 Antenna unit 12, 52 Frequency up-converter (UC)
13 frequency converter 14 demultiplexer 15 multiplexer / demultiplexer 20, 60 phase control device 21 reference signal generator 22 phase control unit 23 initial phase control unit 221, 222 phase shifter 223 adder 224 D / A converter 225 combination Demultiplexer 226 A / D converter 30, 70 Modulator / Demodulator 40 Cable

Claims (4)

A transmission IF signal is input to a plurality of transmission devices via a cable from a phase control device that controls the phase of the transmission IF signal of the intermediate frequency, and a transmission RF signal of frequency f _RF obtained by frequency-converting the transmission IF signal by each transmission device is transmitted. In the tracking antenna device that transmits each from the antenna unit at a predetermined phase,
The transmission apparatus includes a first reference signal S _REF1 of the transmission RF signal of frequency f _RF than f _d lower frequency f _ref1, said second reference signal S _REF2 of f _d higher frequency f _ref2 phase control device The first feedback signal S _FB1 and the second feedback signal S _FB2 that are input through the cable and frequency-converted the transmission RF signal using the first reference signal and the second reference signal are connected to the cable. Means for feeding back to the phase control device via
The phase control device detects a phase difference between the first feedback signal S _FB1-1 from the reference transmission device and the first feedback signal S _FB1-k from the kth transmission device, and Because the phase difference between the second feedback signal S _FB2-1 from the transmitting device and the second feedback signal S _FB2-k from the kth transmitting device is detected, and the absolute value of each phase difference becomes equal The transmission IF that detects an initial phase difference in each of the transmission devices and transmits the phase difference between the first feedback signal and the second feedback signal to each of the transmission devices based on the initial phase difference. A tracking antenna device, characterized by being configured to control the phase of a signal. The tracking antenna device according to claim 1,
The phase control device causes the phase of the first reference signal and the second reference signal to follow the phase change of the transmission IF signal, and the first feedback signal when the first reference signal is input. And the difference between the phase difference between the second feedback signal and the value obtained by inverting the sign of the phase difference between the first feedback signal and the second feedback signal when the second reference signal is input. A tracking antenna apparatus, wherein the phase of the transmission IF signal is controlled to be minimized. A transmission IF signal is input to a plurality of transmission devices via a cable from a phase control device that controls the phase of the transmission IF signal of the intermediate frequency, and a transmission RF signal of frequency f _RF obtained by frequency-converting the transmission IF signal by each transmission device is transmitted. In the initial phase difference compensation method of the tracking antenna device that transmits each of the antenna units at a predetermined phase,
The transmission apparatus includes a first reference signal S _REF1 of the transmission RF signal of frequency f _RF than f _d lower frequency f _ref1, said second reference signal S _REF2 of f _d higher frequency f _ref2 phase control device The first feedback signal S _FB1 and the second feedback signal S _FB2 that are input through the cable and frequency-converted the transmission RF signal using the first reference signal and the second reference signal are connected to the cable. Feedback to the phase control device via
The phase control device detects a phase difference between the first feedback signal S _FB1-1 from the reference transmission device and the first feedback signal S _FB1-k from the kth transmission device, and Because the phase difference between the second feedback signal S _FB2-1 from the transmitting device and the second feedback signal S _FB2-k from the kth transmitting device is detected, and the absolute value of each phase difference becomes equal The transmission IF that detects an initial phase difference in each of the transmission devices and transmits the phase difference between the first feedback signal and the second feedback signal to each of the transmission devices based on the initial phase difference. An initial phase difference compensation method for a tracking antenna device, characterized by controlling a phase of a signal. In the initial phase difference compensation method of the tracking antenna device according to claim 3,
The phase control device causes the phase of the first reference signal and the second reference signal to follow the phase change of the transmission IF signal, and the first feedback signal when the first reference signal is input. And the difference between the phase difference between the second feedback signal and the value obtained by inverting the sign of the phase difference between the first feedback signal and the second feedback signal when the second reference signal is input. A method of compensating for an initial phase difference of a tracking antenna device, wherein the phase of the transmission IF signal is controlled to be minimized.

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