JPH11231046A - Tracking receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a phase shift with a temperature difference in a sum and difference wave path between an antenna and a tracking receiver. SOLUTION: A receiver includes an automatically phase correcting circuit 23 for combining a sum signal and a difference signal modulated with a clock signal to obtain a sum and difference signal and frequency conversion the sum and difference signal for phase detection to form a phase synchronizing loop and for detecting maximum and minimum values for the sum and difference signal by changing the phase of the difference signal to detect an error signal corresponding to an antenna angle with synchronous detection and correcting a phase difference between the sum signal and the difference signal in accordance with the maximum and minimum values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking receiver for receiving a transmission wave output from a transmitter or the like and automatically tracking an antenna to a target.

[0002]

2. Description of the Related Art Normally, a tracking receiver is, for example,
As disclosed in Japanese Patent No. 17311, a two-channel system is provided in which a frequency converter and an intermediate frequency band amplifier are provided for each of a sum signal system and a difference signal system, and phase detection of the sum difference signal is performed. This method is good when used near room temperature, but has a problem that a phase shift occurs when there is a temperature difference in the sum-difference waveguide in the tracking receiver.

A tracking receiver that solves this problem is disclosed in, for example, Japanese Patent Laid-Open No. 2-291986.
There is a one-channel system. This tracking receiver is shown in FIG.

[0006] The tracking receiver shown in FIG. 4 is a one-channel system that supports multi-horn. The operation will be described. First, an RF sum signal and an RF sum signal are output from a multi-horn antenna (not shown).
An X-system difference signal and an RFY-system difference signal are received at an RF sum signal input terminal 1, an RFX-system difference signal input terminal 2, and an RFY-system difference signal input terminal 3, respectively. RFX system difference signal and RF
The Y-system difference signal is X
System 0 / PAI modulator (hereinafter simply referred to as “modulator”)
6 and a Y-system 0 / PAI modulator (hereinafter simply referred to as a “modulator”) 7 which are modulated by a clock signal from a clock generator 19, and after being multiplexed by a combiner 8,
Further, it is combined with the RF sum signal. The combined RF sum / difference signal is converted by the frequency converter 9 into an IF sum / difference signal.
The IF sum / difference signal is amplified by the AGC amplifier 11,
The signals are input to the phase detectors 12 and 13. The IF sum signal is phase-detected in the phase detector 13 by the reference signal of the reference signal oscillator 14, and is input to the voltage control oscillator 10 through the PLL loop filter 16 as a phase error signal to form a phase locked loop. On the other hand, the IF difference signal is subjected to homodyne detection in the phase detector 12, converted into a baseband difference signal, synchronously detected in the error signal detector 18 by the clock signal from the clock generator 19, and converted into a DC signal corresponding to the antenna angle. An X-system error signal output terminal 24 and a Y-system error signal output terminal 25 are output as a system error signal and a DC Y system error signal, respectively.

In a general one-channel tracking receiver, since the sum signal and the modulated difference signal coexist in the IF signal band, the locking of the phase locked loop is false-locked to the difference signal which is a modulation signal. There is. Therefore, in the tracking receiver shown in FIG. 4, in order to prevent pseudo-synchronization of the difference signal with the modulated wave, the difference signal system is turned off at the time of the initial acquisition, the PLL is synchronized and acquired with the sum signal, and then the modulation of the difference signal system is turned on. Function is added. That is, the clock generator 1
By providing a switch circuit 20 between the X clock signal and the Y clock signal from the modulator 9 and the modulators 6 and 7 and adding a lock determination circuit 21, and controlling the switch circuit 20 with a phase synchronization signal, the modulation is performed. The difference signals are not output from the devices 6 and 7. As a result, the phase synchronization with the sum signal is performed, and after the lock determination circuit 21 determines that the lock is established, the switch circuit 20 is turned on to output the difference signal. Since this tracking receiver uses a frequency converter and an intermediate frequency amplifier common to the sum-difference signal,
A phase shift between the sum difference signals is unlikely to occur.

[0006]

However, the conventional tracking receiver cannot correct the phase shift due to the temperature difference of the sum-difference waveguide between the antenna and the tracking receiver.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a tracking receiver capable of automatically correcting even if a phase shift occurs due to a temperature difference of a sum-difference waveguide between an antenna and a tracking receiver. It is in.

[0008]

A tracking receiver according to the present invention synthesizes a sum signal and a difference signal modulated by a clock signal to obtain a sum / difference signal, and converts the sum / difference signal into a frequency. Then, in a tracking receiver that forms a phase locked loop by performing phase detection and detects an error signal corresponding to the antenna angle by performing synchronous detection, the sum / difference is changed by changing the phase of the difference signal. An automatic phase correction circuit for detecting a maximum value and a minimum value of the signal and correcting a phase difference between the sum signal and the difference signal based on the maximum value and the minimum value. . ADVANTAGE OF THE INVENTION According to the tracking receiver which concerns on this invention, since the fine adjustment of the phase between the sum difference signals after connection of an antenna and a tracking receiver is possible, the XY error signal caused by the phase shift by the temperature etc. of the sum difference waveguide is obtained. Crosstalk can be eliminated.

In the tracking receiver of the present invention, in order to prevent pseudo-synchronization with the difference signal modulated wave at the time of initial acquisition, the difference signal modulator is temporarily turned off, and the frequency conversion and the PLL are performed using only the sum signal.
Synchronizing. Thereafter, the modulation by the clock signal of the difference signal modulator is not performed, and the clock control signal is latched at HI (in-phase) or LO (out-of-phase) to turn on the difference signal. In this case, the combined sum / difference signals cannot be modulated and separated, so that they become composite waves having the same carrier frequency but different amplitudes and phases. Here, when the phase of the difference signal system is changed, the sum-difference combined wave produces a beat in the amplitude component according to the variable phase. That is, when the phase becomes the same, the amplitude becomes the maximum, and when the phase becomes the opposite, the amplitude becomes the minimum. When the modulator is latched in the in-phase system, if the incoming radio wave comes from the + X direction, the sum-difference signal will be in phase and the sum-difference composite wave will have the maximum amplitude. And the sum-difference combined wave has the minimum amplitude.

Here, if the phase of the sum difference signal is shifted by θ degrees, the output error voltage of the tracking receiver is degraded in sensitivity by cos θ, and crosstalk occurs by sin θ. If the sum difference signal phase correction amount is about ± 45 degrees, the difference signal
When swept by 45 degrees, the sum-difference combined wave shows a maximum value and a minimum value according to the direction of arrival. That is, if the arriving radio wave comes from the + X direction, the differential signal modulator is set to HI (in-phase).
, One maximum value is generated, and when latched in LO (opposite phase), one minimum value is generated. Generally, since the phase sensitivity is higher in the opposite phase than in the same phase, the optimum phase can be detected by detecting the minimum value and fixing the phase shifter phase to that phase. However, at the time of initial capture, the incoming radio wave is + X,
Since it is unclear which direction of the -X, + Y, and -Y components is larger, the difference signal modulators are set to + XHI (in-phase) and-
XLO (negative phase), + YHI (in phase), -YLO (negative phase)
, The minimum value is detected and each X
Perform Y-axis phase correction. The amplitude of the sum-difference signal composite wave is detected using the AGC voltage which is a homodyne detection output which is shifted by 90 degrees from the PLL detector.

[0011]

1 to 3 show an embodiment of a tracking receiver according to the present invention. FIG. 1 is an overall block diagram, FIG. 2 is a block diagram of a main part, and FIG. 3 is a flowchart showing an operation. is there. Hereinafter, description will be made based on these drawings.

The tracking receiver of this embodiment is a multi-horn compatible one-channel system. First, an RF sum signal, an RFX system difference signal, and an RFY system difference signal from a multi-horn antenna (not shown) are input to an RF sum signal input terminal 1, respectively.
The signal is received at the RFX system difference signal input terminal 2 and the RFY system difference signal input terminal 3. The RFX-system difference signal and the RFY-system difference signal pass through the X-system variable phase shifter 4 and the Y-system variable phase shifter 5 for distinction from the RF sum signal. After being modulated by the clock signal and multiplexed by the combiner 8, the signal is further combined with the RF sum signal. The combined RF sum / difference signal is output to the frequency converter 9
Is converted into an IF sum / difference signal. IF sum / difference signal is A
Amplified by the GC amplifier 11, the phase detectors 12, 13
Is input to The IF sum signal is phase-detected by the reference signal of the reference signal oscillator 14 in the phase detector 13 and applied to the voltage controlled oscillator 10 through the PLL loop filter 16 as a phase error signal, thereby forming a phase locked loop. On the other hand, the IF difference signal is
, And is converted into a baseband difference signal.
Synchronous detection is performed by the clock signal from No. 9 and output from the X-system error signal output terminal 24 and the Y-system error signal output terminal 25 as a DC X-system error signal and a DC Y-system error signal according to the antenna angle, respectively.

In this tracking receiver, in order to prevent pseudo-synchronization of the difference signal with the modulated wave, the difference signal system is turned off at the time of initial acquisition, PLL synchronization is performed only with the sum signal, and then modulation of the difference signal system is performed. A function to turn on is added. That is,
A switch circuit 20 is provided between the X and Y clock signals from the clock generator 19 and the modulators 6 and 7, and a lock determination circuit 21 is added to control the switch circuit 20 by a phase synchronization signal. Thus, the difference signal is not output from the modulators 6 and 7.
The above is the basic operation of the tracking receiver.

Next, the automatic phase correction function which is a feature of the present invention will be described.

As an initial sequence of tracking acquisition, the switch circuit 20 is first turned off so that the modulators 6 and 7 do not output a difference signal. In this state, the tracking receiver accepts only the RF sum signal. Here, when the RF signal arrives, the tracking receiver performs
The sum signal is received, and a PLL phase locked loop of the RF sum signal is formed. When the phase synchronization is performed using the RF sum signal, the lock determination circuit 21 determines that the lock is established, and the automatic phase correction circuit 23
The modulator signal to the REF / latch switching circuit 22 is switched to the latch.

Subsequently, a + X-system difference signal sweep is performed.
First, the X-system latch signal from the automatic phase correction circuit 23 is set to H level.
The I (in-phase) and Y-system latch signals are set to 0. This allows
The modulator 6 is set to the in-phase system, and the modulator 7 is turned off. In this case, the multiplexed sum / X-system difference signal cannot be modulated and separated, so that it becomes a composite wave having the same carrier frequency but different amplitude and phase. Here, when the phase of the X-system difference signal is changed by the X-system variable phase shifter 4, the sum-difference signal composite wave produces a beat in the amplitude component according to the phase. That is, when the phase becomes the same, the amplitude becomes the maximum, and when the phase becomes the opposite, the amplitude becomes the minimum.
The AGC voltage output from the homodyne detector (phase detector 12), which is shifted by 90 degrees with respect to the PLL detector (phase detector 13), is used to detect the amplitude of the sum-difference signal composite wave.
The automatic phase correction circuit 23 records the phase value at which the AGC voltage is minimum and the phase value at which the AGC voltage is maximum.

Subsequently, a difference signal sweep of the -X system is performed. That is, the X-system latch signal is set to LO (opposite phase) and the Y-system latch signal is set to 0 from the automatic phase correction circuit 23.
As a result, the modulator 6 is set to the reverse phase system, the modulator 7 is turned off, the phase of the X system difference signal is changed by the X system phase shifter 4, and the AGC voltage is minimized by the automatic phase correction circuit 23. Record the phase value and the maximum phase value. Similar procedure +
This is performed for the difference signal sweep of the Y system and the −Y system.

Subsequently, the phase value is determined. First, the phase value of the X system is confirmed. From the + X system and -X system AGC voltage minimum and maximum values, sweep the phase from -45 degrees to +45 degrees, and select the valley polarity such as maximum, minimum, and maximum,
The phase of the X-system variable phase shifter 4 is fixed so that the phase becomes the minimum value. Similarly, the phase of the Y-system variable phase shifter 5 is fixed for the Y-system in a similar procedure. However, when there is almost no difference between the minimum value and the maximum value of the AGC voltage in any polarity of the + system and the-system, that is, when there is no difference signal of the system,
Default phase of the variable phase shifter of the system (nominal value)
And Thereby, the phase can be automatically corrected.

Finally, the switch circuit 20 is turned on, the REF / latch switching control signal of each X / Y system from the automatic phase correction circuit 23 is set to REF, and the REF / latch switching circuit 22 is switched to the REF mode. Accordingly, each of the modulators 6 and 7 performs a normal modulation operation, processes the difference signal, and outputs an error signal.

In a tracking receiver, the phase between the sum and difference signals is important. That is, when the phase between the sum difference signals is shifted, the normal error signal output is degraded (for cos θ) and the crosstalk error signal output is increased (for sin θ).
Causes of the phase shift between the sum difference signals include a bias shift of the phase in the waveguide from the antenna output to the sum difference signal synthesis in the tracking receiver, and a phase shift due to temperature and frequency.

[0021]

According to the tracking receiver of the present invention, the following effects can be obtained. . If the phase shift between the sum difference signals is within ± 90 degrees at the maximum, the phase can be automatically corrected. . In particular, it is optimal under severe temperature environment conditions, such as for use in a satellite, and in an environment in which phase correction must be performed automatically.

[Brief description of the drawings]

FIG. 1 is an overall block diagram showing an embodiment of a tracking receiver according to the present invention.

FIG. 2 is a main block diagram showing an automatic phase correction circuit and its periphery in the tracking receiver of FIG. 1;

FIG. 3 is a flowchart showing a sequence of tracking acquisition and automatic phase correction in the tracking receiver of FIG. 1;

FIG. 4 is an overall block diagram showing an embodiment of a conventional tracking receiver.

[Explanation of symbols]

 Reference Signs List 1 RF sum signal input terminal 2 RFX system difference signal input terminal 3 RFY system difference signal input terminal 4 X system variable phase shifter 5 Y system variable phase shifter 6 X system 0 / PAI modulator 7 Y system 0 / PAI modulator 8 Synthesis Device 9 Frequency converter 10 Voltage controlled oscillator 11 AGC amplifier 12, 13 Phase detector 14 Reference signal oscillator 15 90 degree phase shifter 16 PLL loop filter 17 AGC detector 18 Error signal detector 19 Clock generator 20 Switch circuit 21 Lock judgment Circuit 22 REF / latch switching circuit 23 Automatic phase correction circuit 24 X-system error signal output terminal 25 Y-system error signal output terminal

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[Procedure amendment]

[Submission date] January 25, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

1. A difference signal modulated by a sum signal and a clock signal.
Signal to obtain a sum / difference signal,
Form phase locked loop by phase detection after wave number conversion
And synchronous detection to detect the error signal according to the antenna angle.
In the tracking receiver configured to detect the sum signal and the difference signal,
Detect the maximum and minimum values, and find the maximum and minimum values
Corrects the phase difference between the sum signal and the difference signal based on
A phase automatic correction circuit, the automatic phase correction circuit, by fixing the phase of the difference signal corresponding to said minimum value, corrects the phase difference between the sum signal and the difference signal, and characterized by tracking receiver.

2. A difference signal modulated by a sum signal and a clock signal.
Signal to obtain a sum / difference signal,
Form phase locked loop by phase detection after wave number conversion
And synchronous detection to detect the error signal according to the antenna angle.
In the tracking receiver configured to detect the sum signal and the difference signal,
Detect the maximum and minimum values, and find the maximum and minimum values
Corrects the phase difference between the sum signal and the difference signal based on
A phase automatic correction circuit, the operation of the automatic phase correction circuit is carried out when it is phase-synchronized only by the sum signal at the time of initial acquisition,
A tracking receiver , characterized in that:

Claims3]Difference signal modulated by sum signal and clock signal
Signal to obtain a sum / difference signal,
Form phase locked loop by phase detection after wave number conversion
And synchronous detection to detect the error signal according to the antenna angle.
In a tracking receiver that detects the signal, By changing the phase of the difference signal,
Detect the maximum and minimum values, and find the maximum and minimum values
Corrects the phase difference between the sum signal and the difference signal based on
Equipped with an automatic phase correction circuit,  To detect the maximum and minimum values, a PLL detector and 90
Use AGC voltage which is the homodyne detection output which is shifted
Yes,Characterized byTracking receiver.

Wherein said difference signal is composed of a X-based difference signal and the Y-difference signals, according to claim 1, 2 or 3 tracking receiver according.

5. is a satellite mounted claims 1
4. The tracking receiver according to 4 .

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

A tracking receiver according to the present invention synthesizes a sum signal and a difference signal modulated by a clock signal to obtain a sum / difference signal, and converts the sum / difference signal into a frequency. Then, in a tracking receiver that forms a phase locked loop by performing phase detection and detects an error signal corresponding to the antenna angle by performing synchronous detection, the sum / difference is changed by changing the phase of the difference signal. An automatic phase correction circuit for detecting a maximum value and a minimum value of the signal and correcting a phase difference between the sum signal and the difference signal based on the maximum value and the minimum value. . In addition,
The tracking receiver according to the present invention has one of the following configurations
I am taking it. . The automatic phase correction circuit calculates the minimum value
By fixing to the phase of the difference signal corresponding to
A phase difference between the sum signal and the difference signal is corrected. . Said
The operation of the automatic phase correction circuit is based on the sum at the time of initial acquisition.
This is performed when the phase is synchronized only by the signal. .
To detect the maximum and minimum values, a PLL detector and 90
Use AGC voltage which is the homodyne detection output which is shifted
I have. ADVANTAGE OF THE INVENTION According to the tracking receiver which concerns on this invention, since the fine adjustment of the phase between the sum difference signals after connection of an antenna and a tracking receiver is possible, the XY error signal caused by the phase shift by the temperature etc. of the sum difference waveguide is obtained. Crosstalk can be eliminated.

Claims (6)

[Claims] 1. A sum signal and a difference signal modulated by a clock signal are combined to obtain a sum / difference signal, and the sum / difference signal is frequency-converted and phase-detected to form a phase locked loop. Along with this, in a tracking receiver configured to synchronously detect and detect an error signal corresponding to the antenna angle, a maximum value and a minimum value of the sum / difference signal are detected by changing a phase of the difference signal. A tracking receiver, comprising: a phase automatic correction circuit that corrects a phase difference between the sum signal and the difference signal based on a maximum value and a minimum value. 2. The tracking device according to claim 1, wherein the automatic phase correction circuit corrects a phase difference between the sum signal and the difference signal by fixing the phase of the difference signal corresponding to the minimum value. Receiving machine. 3. The tracking receiver according to claim 1, wherein the difference signal comprises an X-system difference signal and a Y-system difference signal. 4. The tracking receiver according to claim 1, wherein the operation of the automatic phase correction circuit is performed when the phase is synchronized only by the sum signal at the time of initial acquisition. 5. The detection of the maximum value and the minimum value is performed by PL
The tracking receiver according to claim 1, 2, 3, or 4, wherein an AGC voltage which is a homodyne detection output shifted by 90 degrees from the L detector is used. 6. The method according to claim 1, wherein the antenna is mounted on a satellite.
Or the tracking receiver according to 5.