JP2579724B2 - Apparatus for correcting close phase error in double sideband Doppler VOR - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near-side phase error in a field monitor for monitoring the radio wave quality of a double side band Doppler VOR system.
A double sideband Doppler VOR that produces a signal that is nearly equivalent to that received at a distance, corrected by a synthesis circuit, etc.
And a close phase error correction device.

[0002]

2. Description of the Related Art The state of radio wave radiation in a double sideband Doppler VOR system is shown in FIG. 7, and a description of the prior art and its problems will be described below with reference to this figure. In FIG. 7, the upper band wave and the lower band wave have a diameter of 5.1.
It rotates 30 times (30 Hz) on the circumference of λ per second.
The angular frequency ω is ω = 2πf _0, where f ₀ is 108 to 118 assigned to the VOR.
One carrier wave in the MHz band. Note that p = 2π · 9960 ρ = 2π · 30 β = 2π / λ r ₃ = 5.1λ = approximately 6.7 m (at 115 MHz)

Here, λ is the wavelength of the carrier, and m is AM30.
Hz modulation degree (usually 0.3), n is FM subcarrier modulation degree (usually 0.3), r ₀ is distance from carrier antenna to receiving point, r ₁ is sideband emitting upper band wave. The distance from the antenna to the receiving point, r ₂ is the distance from the sideband antenna emitting the lower band wave to the receiving point.

However, since it is difficult to physically rotate the sideband antenna, 48 or 50 sideband antennas SA arranged on the circumference have an upper band wave and a lower band wave counterclockwise. Are sequentially switched and fed. In this case, the upper band wave and the lower band wave are respectively located on the side band antennas S facing each other across the carrier antenna CA.
Emitted from A. The three radiation signals are represented by the following equations.

[0005]

(Equation 1) Hereinafter, the received signal waveforms at the far and near receiving points will be described. Equations (4) and (5) are approximated by the following equations for the received signal waveform at a distant reception point where r ₀ >> r _3.

[0006]

(Equation 2)

For the synthesis of the carrier wave, upper band wave, and lower band wave at a distant place, the values of A and B in Expressions (6) and (7) are calculated by Expression (1),
Expressions (1), (2), and (3) are added to the expressions (2) and (3). Therefore, the received signal R _XF is calculated by the following equation.

[0008]

(Equation 3) Becomes Focusing on the FM subcarrier, the envelope of the amplitude of the FM subcarrier becomes a constant n irrespective of the rotation (represented by ρt). FIG. 8 shows the relationship between the envelope of the amplitude of the FM subcarrier and ρt in this case. Next, a received signal waveform and problems in the vicinity will be described.

A monitor antenna for picking up a radiation signal in order to monitor the quality of a radiated radio wave is arranged near a Doppler VOR antenna group due to various restrictions. In this case A,
B is each

[0010]

(Equation 4)

Then, the values of A and B expressed by the equations (10) and (11) are substituted into the equations (2) and (3), and the equations (1), (2) and (3) are substituted. Is a received signal waveform R _XN at a nearby reception point.

[0012]

(Equation 5)

[0013]

(Equation 6) As can be seen from equation (14), the envelope of the amplitude of the FM subcarrier is expressed by the following equation.

[0014]

(Equation 7)

Here, the envelope of the amplitude of the FM subcarrier is calculated by using equation (15) using the distance from the carrier antenna to the monitor antenna installed nearby and ρt as parameters, as shown in FIG. Even in the vicinity installation, the amplitude envelope becomes n regardless of the distance in the azimuth where βr ₁ = βr ₀ and βr ₂ = βr _{0 at} ρt = 90 degrees and 270 degrees.

However, as shown in FIG. 10, ρt = 0
Degrees and 180 degrees the amplitude is 0.2n at a distance of 40m
When the distance is further reduced, the value becomes 0. At a distance of 30 m, the envelope of the amplitude of the FM subcarrier is folded at a certain value of ρt.

Thus, far and ρt = 90 degrees, 270
In degrees, the envelope of the amplitude of the FM subcarrier received at a constant level is the orthogonal direction (ρt = 0 degrees, 180 degrees) starting from the carrier antenna on a straight line connecting the reception point and the carrier antenna in the monitor antenna installed in the vicinity. And the amplitude of the FM subcarrier due to the lower sideband becomes extremely small. For this reason, the double side band Doppler VOR having the FM subcarrier
It becomes difficult to detect a variable phase signal as a system. Next, the change of the envelope of the amplitude of the subcarrier at ρt = 90 degrees and ρt = 0 degrees will be described using an example. (A) Consider a case where r ₀ = 40 m and an upper band wave from ρt = 90 degrees, a lower band wave from ρt = 270 degrees, and a carrier wave are received. βr ₁ = βr ₀ + βr _{3 βr 2} = βr ₀ −βr ₃ βr ₁ + βr ₂ = 2βr ₀ By substituting this into Expression (14), the envelope of the amplitude of the FM subcarrier = ncos ₀ = n. Ρt in FIG.
= 90 ° and 270 °, and the amplitude is n. (B) upper band wave from ρt = 0 degree at r ₀ = 40 m,
Consider a case where a lower sideband wave and a carrier wave from ρt = 180 degrees are received.

[0018]

(Equation 8) FIG. 9 shows the relationship among βr ₁ , βr ₀ , and βr ₃ . The distances r ₁ , r ₀ , and r ₃ are multiplied by β in order to convert the distances into phases. In the vicinity, βr ₁ becomes βr ₀ , βr ₂
Are physically longer than βr ₀ , and are received with a delayed high-frequency phase.

R ₀ = 40 m, ρt = ₀ , β at 180 degrees
r ₁ −βr ₀ = approximately 77 degrees and βr ₂ −βr ₀ = approximately 77 degrees. By substituting these values into Expression (14), ncos
{(77 + 77) / 2} = 0.2n, ρt = 90
0.2 for the amplitude (n) of the signal from the 270 degree azimuth
It becomes twice as small.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to provide a monitoring system for a double sideband Doppler VOR system in which a received signal without a drop in the amplitude of an FM subcarrier is used even in a monitor system installed nearby. An object of the present invention is to provide a close phase error correction device in a double side band Doppler VOR that can be supplied to a circuit.

[0021]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a double sideband Doppler VOR system which radiates from a sideband antenna disposed on a straight line connecting a receiving point and a carrier antenna. With reference to the high-frequency phase of the lower band, the high-frequency phase of the lower band is radiated from the other sideband antenna, and the high-frequency phase of the lower band is advanced on the receiving side.

[0022]

According to the above-mentioned means, on the receiving side, by using a combination of a directional antenna, a combining circuit, an attenuator, a phase correction circuit, and the like, a conventional monitor system in the vicinity can be used.
A received signal without a drop in the amplitude of the FM subcarrier seen in the 0 ρt = 0 degree and 180 degree directions can be supplied to the monitor circuit of the double sideband Doppler VOR system.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the principle of the present invention will be described with reference to examples.

According to the present invention, the high-frequency signals of the upper band (lower band) from ρt = 90 degrees and the lower band (upper band) from 270 degrees are not subjected to the phase correction and the current phase correction amount of 0 is used. Received as is, from ρt = 90 degrees to ρt = 180
Degrees, ρt = 9 for rotation from 270 ° to 0 °
The signal is received by advancing the high-frequency phase relatively gradually as compared with the signal from 0 degrees or ρt = 270 degrees.
The phase advance is maximized at ρt = 180 degrees or ρt = 0 degrees. FIG. 2 illustrates this relationship.

For example, the upper band and the lower band from ρt = 0 ° and 180 ° arrive at the high-frequency phase delayed by x degrees as shown by the equations (16) and (17). To advance x degrees. As a result, the state where the correction amount is 0 → the correction amount according to the present invention−x is added = result (conventional state) βr ₁ = βr ₀ + x → βr ₀ + x−x = βr ₀ βr ₂ = βr ₀ + x → βr ₀ + x −x = βr ₀ βr ₁ + βr ₂ = 2βr ₀ This is substituted into Expression (14). The envelope of the amplitude of the FM subcarrier is n.

That is, r ₀ = 40 m, ρt = 0 degree and 18
At the time of receiving a signal from 0 degrees, if nothing is done, the envelope of the amplitude of the FM subcarrier drops to 0.2n, but by adding the correction amount according to the present invention, the amplitude 0.2n becomes n,
The amplitude is the same as the amplitude n when receiving signals from ρt = 90 degrees and ρt = 270 degrees, and the direction of the extreme drop in the amplitude of the FM subcarrier is eliminated. Next, two embodiments for advancing the phase will be described. Embodiment 1 A method by combining antenna patterns having sharp directivity and flat directivity will be described. FIG. 3 shows an example of an antenna pattern A having a flat directivity and an antenna pattern B having a sharp directivity in a horizontal plane. Figure 1 shows this 2
1 shows a circuit for distributing, synthesizing, and phase correcting signals received using two antenna patterns A and B. p has a phase of 180
Means to change the degree.

Next, a method for advancing the phase of a signal from ρt = 0 and 180 degrees in (a) with respect to a signal from ρt = 0 and 180 degrees in (b) will be described. I do.

(A) The upper band wave is radiated from the ρt = 90 ° direction, and the lower band wave is radiated from the 270 ° direction. Carrier waves are always emitted from the carrier antenna at the center of rotation. The signal S1 is represented by the equation (12). When the signal is decomposed into a carrier wave and upper and lower sidebands, the carrier wave + upper and lower sidebands are

[0029]

(Equation 9)

The signal S1 from the antenna of the antenna pattern A is divided into two by the distributor X1, and one signal S2 is guided to the combiner X3 as a signal S4 through the attenuator ATT2. Level of the signal S4 is adjusted to Z _0/2 times the signal S1 by the attenuator ATT2.

[0031]

(Equation 10) Another signal S3 from the distributor X1 is guided to the combiner X2. The signal S3 is 1/2 ^1/2 of the signal S1. Times (distributor X
1 characteristic).

[0032]

[Equation 11]

Since the signal S5 from the antenna of the antenna pattern B is connected to a sharp directional antenna as compared with the equation (18), n1 of the equation (18) having an antenna gain
(N1 is the gain ratio between antenna pattern B and antenna pattern A).

[0034]

(Equation 12) The carrier wave level of the signal S5 is adjusted by the attenuator ATT1 so as to be the same as the carrier wave level of the signal S3 in the signal S6 input to the combiner X2.

[0035]

(Equation 13)

Since the signals S3 and S6 are combined in the opposite phase by the combiner X2, the level of the output signal S7 of the combiner X2 becomes zero. Therefore, the input signal S8 of the synthesizer X3, which is the output signal of the phase shifter X4 to which the signal S7 is input, also becomes 0. Synthesizer X
1/2 of 3 to the output signal S9 signal S4 ^1/2 Double appears.

[0037]

[Equation 14] At ρt = 90 degrees and 270 degrees, βr ₁ = βr ₀ = βr ₂
Therefore, (C + D) / 2 = 0 Therefore,

[0038]

(Equation 15) Becomes The envelope of the amplitude of the FM subcarrier is n. (B) Upper band wave is from ρt = 0 degree direction, lower band wave is 1
Emitted from the 80 degree azimuth. Carrier waves are always emitted from the center of rotation. The signal S1 is represented by the equation (12). When the signal S1 is decomposed into a carrier wave and upper and lower sidebands, the carrier wave + upper and lower sidebands are

[0039]

(Equation 16)

Although the level is flat, the level of the upper and lower band waves is m ₀ times the above equation in consideration of the directivity of the antenna pattern A. Therefore, strictly speaking, the carrier wave of the signal S1 and the upper and lower sidebands are

[0041]

[Equation 17] Becomes

[0042]

(Equation 18) 1 / n1 · 2 ^1/2 is added to the signal S5 by the attenuator ATT1. Multiplied. Therefore

[0043]

[Equation 19]

The signal S3 and the signal S6 are combined in opposite phases.
Therefore, the signal S7 is 1/2 ^1/2 ｛Equation (28) -Equation (3)
0)｝. Coefficient 1/2 ^1/2 Is due to the characteristics of the synthesizer.

[0045]

(Equation 20) The phase of the signal S7 is changed by y degrees in the phase shifter X4. Therefore, the signal S8 is represented by the following equation.

[0046]

(Equation 21) Signals S4 and S8 are combined by combiner X3. Signal S
9 is 1/2 ^1/2 {Formula (27) + Formula (32)}.

[0047]

(Equation 22) Here, the envelope of the amplitude of the FM subcarrier is shown.

[0048]

(Equation 23) Pay attention to.

[0049]

(Equation 24) When the position (r ₀ ) of the monitor installed nearby in equation (35) is determined, βr ₁ , βr ₂ , βr ₀ , m ₀ , and n ₀ are determined as constants. Therefore, when Z ₀ relating to the amplitude and y relating to the phase are adjusted and set to appropriate values, the equation (35) can be set to 1. As a result

[0050]

(Equation 25) And the amplitude of the FM subcarrier is m ₀ n = n.
Note that m ₀ due to the flat antenna pattern A is 0.99 (when the receiving point is set to 60 m) in a general half-wavelength dipole, and can be regarded as substantially 1.

Also, A, for ^setting e ^jx + Ae ^{jx + y} = 1,
^Describing y, as shown in FIG. 4, A and y may be determined such that ^-ejx cancels ^ejx and 1 to be obtained is vector-combined, that is, ^-ejx + 1 = ^{Aejx + y} . Here, since x is a constant, the values of A and y can be easily determined. Embodiment 2 A method of combining the directivity of a null pattern (becoming 0) in the ρt = 90 degrees and the 270 degrees azimuth and a flat directional antenna pattern will be described.

FIG. 5 shows an example of a flat directional antenna pattern and a null pattern in a horizontal plane. In FIG. 5, A is an antenna pattern having flat directivity,
C is an antenna pattern having a null pattern.

FIG. 6 shows a circuit for synthesizing and phase-correcting signals received using a flat directional antenna pattern and a null pattern. P means that the phase changes by 180 degrees.

Next, a method for advancing the phase of a signal from ρt = 0 and 180 degrees in (a) with respect to a signal from ρt = 90 degrees and 270 degrees will be described with reference to FIG. I do. (A) The upper band wave is emitted from the ρt = 90 ° direction, and the lower band wave is emitted from the 270 ° direction. Carrier waves are always emitted from the carrier antenna at the center of rotation. The signal S11 from the flat directional antenna pattern A is represented by Expression (12), but the carrier wave and the upper and lower sidebands are

[0055]

(Equation 26)

The signal S11 becomes a signal S12 through the attenuator ATT11 and is led to the combiner X12. Signal S12
The levels are adjusted to Z ₀ times the signal S11 by the attenuator ATT 11.

[0057]

[Equation 27]

In the antenna pattern C, the ρt = 90 ° and the 270 ° azimuth become null.
No signal is received by this antenna. That is, the signal S1
3, S14 is 0. Therefore, the output signal S15 has 1/2 ^1/2 of the signal S12. Signal appears. X11 is a phase shifter.

[0059]

[Equation 28] The term of the FM subcarrier is calculated by the equation (23) described in the first embodiment.
Is the same as Therefore, the envelope of the amplitude of the FM subcarrier is n. (B) Upper band wave is from ρt = 0 degree direction, lower band wave is ρ
Radiated from the azimuth at t = 180 degrees. Carrier waves are always emitted from the center of rotation. The signal S11 is represented by the equation (12). When the signal S11 is decomposed into a carrier wave and upper and lower sidebands, the carrier wave + upper and lower sidebands are

[0060]

(Equation 29) Considering the directivity of the flat antenna pattern A, the level of the upper and lower sidebands is m ₀ times the above equation. Therefore, strictly speaking, the signal S11 is

[0061]

[Equation 30] In the antenna pattern C, the carrier antenna falls in the null direction, and is not received. Only the upper band and the lower band are received.

[0062]

(Equation 31) The phase of the signal S13 is considered to be y degrees in the phase shifter X11.

[0063]

(Equation 32) Signals S12 and S14 are combined by combiner X12. The signal S15 is 1/2 ^1/2 {Formula (41) + Formula (43)}.

[0064]

[Equation 33] Here, the envelope of the amplitude of the FM subcarrier is shown.

[0065]

(Equation 34) Pay attention to.

[0066]

(Equation 35) When the position (r ₀ ) of the monitor installed nearby in equation (46) is determined, βr ₁ , βr ₂ , βr ₀ , m ₀ , and n ₀ are determined as constants. Therefore, when Z ₀ relating to the amplitude and y relating to the phase are adjusted and set to appropriate values, the equation (46) can be set to 1. As a result

[0067]

[Equation 36] And the amplitude of the FM subcarrier is m ₀ n = approximately n. Note that m ₀ due to a flat antenna pattern is 0.99 in a general half-wave dipole (when the receiving point is 60 m,
Can be regarded as almost 1).

[0068]

As described above, according to the present invention, it is possible to improve not only the drop of the FM subcarrier in the monitor of the conventional double sideband Doppler VOR system, but also
The distance to the receiving point where the amplitude of the FM subcarrier becomes 0 is eliminated, and the quality of the radio wave of the Doppler VOR can be monitored in the vicinity which has been considered impossible in the past.

The Doppler VOR is installed at a main position on an air route, around an airport, etc., and provides azimuth information to the aircraft. However, due to the drop in the amplitude of the FM subcarrier, the monitor antenna is separated from the carrier antenna to some extent. Had to be installed. According to the present invention, the distance between the monitor antenna and the carrier antenna can be shortened, and the double side band Doppler VOR system can be installed even in a terrain where the installation was impossible in the past. And contribute to efficient operation.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a relationship between a rotation ρt and a phase correction amount according to the present invention.

FIG. 3 is a pattern diagram showing an example of two antenna patterns having flat and sharp directivity according to the first embodiment of the present invention.

FIG. 4 is a vector diagram for explaining the operation of the first embodiment of the present invention.

FIG. 5 is a pattern diagram illustrating an example of two antenna patterns having a flat pattern and a null pattern according to the second embodiment of the present invention.

FIG. 6 is a configuration explanatory view showing a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an example of the state of radio wave radiation in a Doppler VOR system.

FIG. 8 is a characteristic diagram illustrating an example of a relationship between a rotation ρt and an amplitude envelope of an FM subcarrier after detection in a distant reception.

FIG. 9 is an explanatory diagram for explaining an operation in a current Doppler VOR system.

FIG. 10 is a characteristic diagram showing an example of the relationship between the rotation ρt in the vicinity reception and the envelope of the amplitude of the FM subcarrier after detection in the current state.

[Explanation of symbols]

X1: distributor, X2, X3: synthesizer, X4: phase shifter, A
TT1, ATT2 ... Attenuator.

Claims (1)

(57) [Claims] 1. A carrier wave radiated from a carrier antenna in a double side band Doppler VOR system.
Of the upper and lower bands radiated from the sideband antenna
Equivalent to a total of three high-frequency phases obtained at a distant receiving point
Due to the phase relationship, the near receiving point
In the case of a weak directivity antenna and a sharp directivity antenna
Depending on the combination, carry from the antenna with a weak directivity
A wave and upper and lower band waves are received as a signal synthesized in space
This is distributed, partly used as signal A, and
Remaining signals from loose antennas and sharp antennas
Signals from the two antennas in opposite phases
Carrier from the carrier antenna installed in the acquisition direction
Waves are removed, and the antennas of both antennas are
Due to the difference in directivity, only the upper and lower band waves are received,
By passing the signal of only the lower sideband through the phase shifter,
Advances the high-frequency phase of the upper and lower band compared to A,
By combining the advanced signal B and signal A, the reception point and key
Sidebands arranged on a straight line connecting the carrier antennas
The phase is not delayed from the center line, and it is oblique to the receiving point.
And the lower sideband delays its high-frequency phase.
Correction with signal B allows proximity reception but all reception points
Radio waves arrive as if they were parallel from all sideband antennas
The upper and lower band wave phases are corrected as if
Produces a signal similar to that received at a distance but close
A close phase error correction device for a double side band Doppler VOR.