JPH0730414A - Phase locked loop circuit and in-phase synthesizer and antenna device using the same - Google Patents

Abstract

(57) [Summary] [Configuration] In the phase-locked loop circuit PLL1, the multiplier FC
At 1, the input reception signal B1 and the output signal of the voltage controlled oscillator VCO1 are mixed. The output signal of the multiplier FC1 is input to the phase comparator PC1 after the high-frequency component is removed by the low-pass filter LPF1 and the signal-to-noise ratio is improved by the comb-teeth filter KF1.
The phase comparator PC1 compares the phase of the signal from the comb filter KF1 with the reference signal from the line 60. The output signal is converted into a control voltage to be given to the voltage controlled oscillator VCO1 in the loop filter LF1. [Effect] Since the signal-to-noise ratio of the input signal of the phase comparator PC1 is improved, the noise in the loop can be reduced. Therefore, the loop gain can be increased and the capture range and the lock range can be increased. As a result, it is possible to favorably compensate the influence of fluctuations in the oscillation frequency of the voltage controlled oscillator VCO1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase locked loop circuit used in an electronic tracking type antenna device to be mounted on a moving body, an in-phase synthesizing device using the same, and an antenna device.

[0002]

2. Description of the Related Art On a roof of a vehicle, a moving body such as a train or a bus receives satellite broadcasting and a television receiver installed in the vehicle can broadcast an image from the broadcasting satellite. It has been proposed to install an antenna for receiving satellite broadcasts. In such an antenna device, it is necessary to reduce the height of the entire device so as not to hinder the traveling of the vehicle, and a tracking function for directing the antenna to the direction of the broadcasting satellite regardless of the direction of the vehicle is provided. Must be equipped.

The height of the device is largely determined by the height of the antenna. Therefore, there has been proposed an antenna device in which a plurality of horizontally long planar antenna elements are installed in parallel and the antenna area is secured so that the radio waves of a broadcasting satellite can be received with a sufficient image quality as a whole. The outputs of the planar antenna elements are superposed as if they were received by a single planar antenna. A circuit that realizes this superposition is called an in-phase synthesis circuit.

The general configuration of the in-phase synthesis circuit is shown in FIG. A plurality of planar antenna elements a1, a2, ...
., An received signals are respectively BS converters c1, c
2, ..., Cn, and the signals of the frequencies of the radio waves of satellite broadcasting are converted into low-frequency signals that are easy to process. This frequency conversion is performed by, for example, the BS converters c1 and c.
2, ..., Output signals of a local oscillator (not shown) provided inside cn and antenna elements a1, a2 ,.
This is done by mixing the input signal from an. The signal after the frequency conversion is input to the in-phase synthesis circuit 1.

The in-phase synthesis circuit 1 includes a BS converter c1,
A plurality of phase locked loop circuits p1, p2, ..., P to which the signals from c2, ...
(N-1). The signal from the BS converter cn is a plurality of phase locked loop circuits p1, p2, ...
It is input to the reference system circuit pn for synchronizing (n-1).

The reference system circuit pn includes a BS converter cn.
The multiplier mn to which the signal from is input is provided.
The multiplier mn is supplied with a signal from a fixed frequency oscillator 3 that generates a signal having a constant frequency. In the multiplier mn, the two input signals are mixed, and the frequency conversion is achieved by this mixing. The frequency-converted signal is input to the power combiner 7 via the low-pass filter fn and the automatic gain control type amplifier agcn.

The signal from the BS converter cn is mixed with a signal obtained by delaying the phase of the signal from the fixed frequency oscillator 3 by 90 degrees in the phase delay unit 5 in a multiplier 9 different from the multiplier mn. This mixed signal has a high-frequency component removed by a low-pass filter 11 and then a line 13
, A plurality of phase-locked loop circuits p1, p2, ...
It is supplied to p (n-1) as a reference signal.

Phase locked loop circuits p1, p2, ..., P
All of (n-1) have the same configuration. Therefore, the configuration will be described taking the phase locked loop circuit p1 as an example. The phase-locked loop circuit p1 includes a BS converter c1.
Is provided with a multiplier m1 for mixing the signal from VCO1 with the signal from the voltage controlled oscillator vco1. Multiplier m
The output of 1 is input to the power combiner 7 through the automatic gain control type amplifier agc1 after the high frequency component is removed by the low pass filter f1.

The output of the multiplier m1 is further input to the phase comparator pc1. In the phase comparator pc1, a reference signal given from the reference system circuit pn via the line 13 and
A phase comparison is performed with the signal from the low-pass filter f1, and an output signal corresponding to the comparison result is output. This output signal is converted into a control voltage by the loop filter ff1, and this control voltage is input to the voltage controlled oscillator vco1.

For the phase comparator pc1, for example, a multiplication circuit is used. In this case, the phase locked loop circuit p
1 is the reference signal from the line 13 and the low-pass filter f
It operates so that the phase difference from the signal from 1 is maintained at 90 degrees. Therefore, the signal input to the power combiner 7 through the automatic gain control type amplifier agc1 is the reference system circuit pn1.
Through the automatic gain control type amplifier agcn to the power combiner 7
It has the same phase as the signal input to.

The same operation is performed by another phase locked loop circuit p.
2, ..., P (n-1). As a result, these phase locked loop circuits p2, ..., P (n-
1) to automatic gain control type amplifier agc2, ...
The signal amplified by agc (n-1) and input to the power combiner 7 has the same phase as the signal output by the automatic gain control amplifier agcn.

As a result, a plurality of input signals are power-combined in the power combiner 7, whereby in-phase combination of output signals of the plurality of antenna elements a1, a2, ..., An is achieved.

[0013]

The oscillating frequency of the voltage controlled oscillator in the phase locked loop circuit and the oscillating frequency of the local oscillator in the BS converter fluctuate as the ambient environmental temperature fluctuates. In this case, the compensation for the fluctuation of the oscillation frequency is imposed on the synchronization function of the phase locked loop circuit.

As is well known, the measures of the synchronization function are the capture range (frequency pull-in range) and the lock range (synchronization holding range). If these are made large, the above-mentioned fluctuation of the oscillation frequency can be favorably compensated. To increase the capture range and lock range, the loop gain should be increased. But,
If the loop gain is large, the output signal of the voltage-controlled oscillator will have a large degree of frequency modulation due to noise in the loop. When the degree of this frequency modulation becomes large, for example, when the received radio wave is a frequency modulated wave, there arises a problem that noise during demodulation becomes large.

Therefore, the loop gain cannot be increased indefinitely. Therefore, an object of the present invention is to provide a phase-locked loop circuit capable of increasing the loop gain by reducing the noise in the loop and consequently improving the capture range and the lock range. Is to provide.

Another object of the present invention is to provide an in-phase combiner capable of satisfactorily in-phase combining a plurality of signals regardless of environmental changes. Still another object of the present invention is to provide an antenna device capable of satisfactorily performing in-phase synthesis of signals from a plurality of antenna elements regardless of environmental changes so that radio waves can be received well in any environment. Is to provide.

[0017]

A phase-locked loop circuit of the present invention for achieving the above object comprises a voltage-controlled oscillator and a signal having a frequency corresponding to the frequency of the output signal of the voltage-controlled oscillator. And a predetermined reference signal are input, the phases of these two signals are compared, a phase comparator that outputs a signal corresponding to the comparison result, and the output of this phase comparator are converted into voltage signals, A loop filter that supplies this voltage signal to the voltage controlled oscillator as a control voltage, and a signal to be input to the phase comparator is filtered so that only a signal in a predetermined frequency band is passed to the phase comparator. Filter means for improving the signal-to-noise ratio of the input signal (claim 1).

According to this structure, the signal to be input to the phase comparator is filtered by the filter means,
The signal to noise ratio is improved. That is, only the signal in the predetermined frequency band from which noise has been removed is input to the phase comparator. As a result, signals other than the required frequency can be removed, and noise in the loop can be reduced. as a result,
Since the loop gain can be increased, the capture range and lock range can be increased.

When the frequency of the required signal exists in a discrete frequency band, the filter means may have a plurality of discretely set frequency bands, as described in claim 2. A material having a comb-shaped pass frequency characteristic that allows signals to pass may be applied. Further, the in-phase combiner of the present invention is an in-phase combiner for aligning the phases of a plurality of input signals and performing power combining, capable of inputting a plurality of signals, and combining the input plurality of signals with a power combiner. Means for mixing, a predetermined reference input signal, which is one of the plurality of input signals, and a predetermined reference frequency signal, and means for supplying the signal obtained by this mixing to the power combining means. A reference signal creating means for creating a predetermined reference signal by mixing the reference input signal with the predetermined reference frequency signal; and input signals other than the reference input signal among the plurality of input signals. , A signal having the same phase as a signal obtained by mixing the reference input signal and the reference frequency signal based on the reference signal created by the reference signal creating means, and giving the signal to the power combining means 1
One or more phase-locked loop circuits, wherein the phase-locked loop circuit mixes a voltage-controlled oscillator, an output signal of the voltage-controlled oscillator and the input signal, and outputs the signal obtained by the mixing. The frequency mixing means supplied to the power synthesizing means, the output signal of the frequency mixing means, and the reference signal from the reference signal generating means are input, and these 2
A phase comparator that compares the phases of two signals and outputs a signal corresponding to the comparison result, and the output of this phase comparator is converted into a voltage signal, and this voltage signal is applied to the voltage-controlled oscillator as a control voltage. Is provided between the frequency mixing means and the phase comparator, and the output signal of the frequency mixing means is filtered to pass only a signal in a predetermined frequency band, thereby the phase A first filter means for improving a signal-to-noise ratio of a signal input to the comparator (claim 3).

In this configuration, a phase locked loop circuit is used to combine a plurality of input signals in phase. In the phase-locked loop circuit, noise in the loop is reduced by the action of the first filter means, so that the loop gain can be increased and the capture range and lock range can be increased. As a result, even if the oscillation frequency of the voltage-controlled oscillator fluctuates due to environmental changes such as ambient temperature, such fluctuations in the oscillation frequency should be well compensated for in the phase-locked loop circuit. You can Therefore, a plurality of signals can be favorably in-phase combined regardless of changes in the environment.

When the frequency of the input signal exists in a discrete frequency band, a plurality of discretely set frequencies are used as the first filter means as described in claim 4. It is preferable to apply a material having a comb-shaped pass frequency characteristic that allows signals in the band to pass.
Further, as described in claim 5, the reference signal which is interposed between the reference signal generating means and the phase comparator and which is output from the reference signal generating means is filtered to obtain a predetermined frequency band. By passing only the signal,
By further providing the second filter means for improving the signal-to-noise ratio of the signal input to the phase comparator, the noise in the loop can be further reduced.

In this case, when the frequency of the input signal exists in a discrete frequency band, a plurality of discretely set plurality are used as the second filter means as described in claim 6. It is preferable to apply a material having a comb-shaped pass frequency characteristic that allows signals in the frequency band of 1. Further, the antenna device of the present invention is capable of inputting a plurality of antenna elements and a plurality of signals, and a power combining means for performing power combination of the plurality of input signals, and one of the plurality of antenna elements. Means for mixing a predetermined reference reception signal which is a reception signal corresponding to the antenna element and a predetermined reference frequency signal, and inputting the signal obtained by this mixing to the power combining means, and the predetermined reference reception signal Reference signal creating means for creating a predetermined reference signal by mixing with the reference frequency signal, and received signals other than the reference received signal among the received signals corresponding to the plurality of antenna elements are input, and the reference signal On the basis of the reference signal created by the creating means, a signal having the same phase as the signal obtained by mixing the reference received signal and the reference frequency signal is created to create the power combining means. And one or more phase-locked loop circuits for providing the voltage-controlled oscillator, the output signal of the voltage-controlled oscillator being mixed with the received signal, and the signal obtained by the mixing. Is input to the power combining means, the output signal of the frequency mixing means, and the reference signal from the reference signal generating means are input, the phases of these two signals are compared, and the comparison result is obtained. A phase comparator that outputs a signal corresponding to, and the output of this phase comparator is converted to a voltage signal,
A loop filter that supplies this voltage signal to the voltage controlled oscillator as a control voltage, and is interposed between the frequency mixing means and the phase comparator, and filters the output signal of the frequency mixing means to a predetermined frequency. A first filter means for improving the signal-to-noise ratio of the signal input to the phase comparator by allowing only the signal in the band to pass therethrough (claim 7).

With this configuration, the loop gain of the phase-locked loop circuit can be increased to increase the capture range and the lock range, so that the received signals corresponding to the plurality of antenna elements can be changed in the environment. In-phase synthesis can be satisfactorily performed without depending. Therefore,
Radio waves can be favorably received by an antenna device using a plurality of antenna elements.

As described in claim 8,
It is preferable that the first filter means supplies only a signal in a predetermined frequency band corresponding to a frequency band of a signal to be received by the antenna element to the phase comparator. By doing so, noise in the phase locked loop circuit can be effectively removed. Further, when the frequency of the received signal exists in a discrete frequency band, as described in claim 9, as the first filter means,
It is preferable to apply a material having a comb-shaped pass frequency characteristic that allows signals in a plurality of discretely set frequency bands to pass.

Further, according to a tenth aspect of the present invention, the reference signal which is interposed between the reference signal generating means and the phase comparator and which is output from the reference signal generating means is filtered to obtain a predetermined signal. By further providing the second filter means for improving the signal-to-noise ratio of the signal input to the phase comparator by passing only the signal in the frequency band, the noise in the phase locked loop can be more effectively It can be reduced.

In this case, as described in claim 11, the second filter means causes only the signal in the predetermined frequency band corresponding to the frequency band of the signal to be received by the antenna element to have the phase. It is preferably supplied to a comparator. Further, when the frequency of the received signal exists in a discrete frequency band, as described in claim 12, as the second filter means, signals of a plurality of discretely set frequency bands are provided. It is preferable to apply a filter having a comb-shaped pass-frequency characteristic that allows to pass through.

[0027]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 6 is a plan view showing the configuration of an antenna device to which an embodiment of the present invention is applied, and FIG. 7 is a front view thereof. The antenna device is used by being installed on the roof of a vehicle or the like, and includes a base 20 fixed to the roof of the vehicle. This base 2
A turntable 22 supported by a rotary shaft 21 is provided on the position 0. The turntable 22 can rotate around an axis line 23 extending in the vertical direction.

A gear is formed on the peripheral surface of the turntable 22, and a gear 24 is meshed with this gear. The rotating force of a motor 25, which is a drive unit, is transmitted to the gear 24 by bevel gears 26 and 24A. On the upper surface of the turntable 22, a plurality of antenna elements A1, A2, ...
.., A10 are fixed so as to be parallel to each other via a support member 27 or the like. That is, the antenna element A1
The directions of the main radiation lobes of ~ A10 are parallel to each other. The antenna element A1 and the antenna element A2 are antenna elements that are used for both tracking of a radio wave source in the azimuth direction along the horizontal plane and reception of a radio wave. Also, the antenna element A3
A10 are used exclusively for receiving radio waves.

Each component arranged on the base 20 is covered with a radome 30 shown in phantom in FIG.
However, the illustration of the radome 30 is omitted in FIG. For example, the antenna elements A1 to A10 are fixed so that the elevation angle θ is about 38 degrees. This is the median value of the elevation angle in the direction of the broadcasting satellite in each region when the satellite broadcasting is received in Honshu, Japan, since it is in the range of about 32 to 44 degrees. As a result, the receiving antenna elements A1 to A that are associated with the differences in elevation angle at each receiving point
The gain reduction of 10 is minimal. These antenna elements A1 to A10 are set such that the half-power width in a plane substantially perpendicular to the horizontal plane is 20 to 90 degrees.

In order to reduce the height of the entire device,
Planar antennas are used for the antenna elements A1 to A10, and these antenna elements A1 to A10 are arranged in a plane on the turntable. In this case, the height of the antenna elements A1 to A10 is, for example, about 40 mm or less, and the height of the entire antenna device is, for example, about 130 mm.

FIG. 1 is a block diagram showing the electrical configuration of the above antenna device. The reception signals of the antenna elements A1 to A10 are input to the BS converters BC1 to BC10, and the frequency of the radio wave of satellite broadcasting (about 11.7 to 12 GHz).
Signal is a low frequency signal (about 1.03 ~
1.33 GHz). That is, the signals from the antenna elements A1 to A10 and the BS converters BC1 to BC are
Frequency conversion is performed by frequency mixing with the output signal of the local oscillator provided inside 10.
BS converter B corresponding to antenna elements A3 to A10
The output signals of C3 to BC10 are given to the in-phase synthesizing circuit 40 as the in-phase synthesizing device of the embodiment of the present invention.

On the other hand, the output signals of the BS converters BC1 and BC2 corresponding to the antenna elements A1 and A2 are distributed to the distributor 4
It is distributed at 1,42. One of the signals respectively distributed by the distributors 41 and 42 is applied to the in-phase combining circuit 40 and is in-phase combined with the signals from the BS converters BC3 to BC10. The in-phase combined signal VT obtained by the in-phase combining is given to the BS tuner (not shown).

The respective other signals distributed by the distributors 41 and 42 are given from the attenuators 43 and 44 to the hybrid circuit 45 and combined. The hybrid circuit 45 converts the input signals a and b having the phase difference δ given to the two input terminals P1 and P2 into the two signals c and d having the phase difference δ ± 90 ° and outputs them to the output terminals P3 and P4. To derive. That is, the input signals a and b are respectively expressed by the following equation (1) and
If it is expressed by equation (2), a and b of this input signal are converted into output signals c and d shown in equations (3) and (4) below. A and B are signal amplitudes, ω is angular frequency, and δ ′ and δ ″ are constants.

[0034]

(1) b = Bcos (ωt + δ) ・ ・ ・ ・ (2) c = Acos (ωt + δ ′) + Bcos (ωt + δ ′ + δ + 90 °) ··· (3) d = Acos (ωt + δ ″) + Bcos (ωt + δ ″ + δ−90 °) (4) The output signals Sc and Sd of the hybrid circuit 45 are supplied to the level difference detection unit 46, and the level difference VM is detected. The detected level difference VM is input to the control unit 47. The control unit 47 is also based on the output of a geomagnetic sensor (not shown in FIGS. 6 and 7) 48 fixedly arranged at a predetermined position of the turntable 22 (see FIGS. 6 and 7). Antenna elements A1 to A10
The output of the azimuth detecting section 49 for detecting the azimuth angle of the main radiation lobe and outputting the azimuth detection signal ΦG corresponding thereto is also given.

In this embodiment, the azimuth detected by the geomagnetic sensor 48 is 0 degree (corresponding to true north) when the turntable 22 is placed horizontally in an environment that is not affected by magnetization or the like. The relative relationship between the geomagnetic sensor 48 and the antenna elements A1 to A10 is set so that the projection of the main radiation lobes of the antenna elements A1 to A10 on the azimuth plane in the state indicates magnetic north. By setting like this,
The projection of the main radiation lobes of the antenna elements A1 to A10 on the azimuth plane is directed to the detection direction of the geomagnetic sensor 48. In other words, the azimuth detection signal ΦG output from the azimuth detection unit 49 based on the output VG of the geomagnetic sensor 48 is
It is a signal indicating the azimuth angle of the main radiation lobes of the antenna elements A1 to A10.

The control unit 47 gives a control signal corresponding to the azimuth detection signal ΦG from the azimuth detection unit 48 and the level difference VM to the motor drive circuit 50. As a result, the motor 25 is energized by the electric power from the motor drive circuit 50, and the turntable 22 rotates. When the signals from the antenna elements A1 and A2 are processed by the hybrid circuit 45, two radiation lobes are formed. For example, the antenna element A1,
The antenna element A has the same radiation lobe and the same gain as A2, and the axis connecting the centers is perpendicular to the radiation lobe and is in a plane parallel to the turntable 22.
1 and A2 are arranged, and the BS converters and cables from the antenna elements A1 and A2 to the hybrid circuit 45 have the same characteristics and lengths. In this case, for example, if the distance between the centers of the two antenna elements A1 and A2 is 1.6 wavelengths and the half-power width for turning the turntable 22 of the two antenna elements A1 and A2 is selected to be about 44 degrees, the above two values will be obtained. The projection of the direction of the radiation lobe on the azimuth plane is at an angle of about 12 degrees with respect to the projection of the receiving antenna elements A1 to A10 on the azimuth plane and is on the opposite side. Come to do.

Therefore, by selecting each condition as described above, the projection of the receiving antenna elements A1 to A10 in the direction of the main radiation lobe onto the azimuth plane is formed by the action of the hybrid circuit 45. It can be accommodated between each projection of the direction of the radiation lobe onto the azimuthal plane.
If the antenna gains of the receiving antenna elements A1 and A2, the conversion gains of the BS converters BC1 and BC2, or the distribution ratios of the distributors 41 and 42 have some variations in characteristics, attenuation by the attenuators 43 and 44 is performed. By setting the value appropriately, the amount can be compensated.

With the above configuration, the control unit 47 roughly controls the directions of the antenna elements A1 to A10 by driving and controlling the motor 25 based on the azimuth detection signal ΦG corresponding to the azimuth detected by the geomagnetic sensor 48. . Specifically, the control until the radio waves from the broadcasting satellite can be received by the main lobes of the two radiation lobes formed by the action of the hybrid circuit 45 is performed by the geomagnetic sensor 4.
It is performed based on the output of 8. Then, in order that the level difference VM detected by the level difference detection unit 46 becomes zero,
The motor 25 is drive-controlled. As a result, the main radiation directions of the antenna elements A1 to A10 can be accurately oriented toward the broadcasting satellite. In this manner, the attitude control of the antenna with respect to the azimuth angle can be accurately performed, and the tracking of the radio wave source can be achieved.

FIG. 2 is a block diagram showing a detailed structure of the in-phase synthesis circuit 40. The signals B1 to B10 from the BS converters BC1 to BC10 are input to the in-phase combining circuit 40. Then, in-phase combining processing is performed using the signal B10 from the BS converter BC10 as a reference reception signal. More specifically, phase locked loop circuits PLL1 to PLL9 are provided corresponding to the signals B1 to B9. Further, the signal B10 is given to the reference system circuit REF.

The reference system circuit REF is provided with a fixed frequency oscillator OSC for generating a signal having a constant reference frequency. The signal B10 is input to the multiplier FC10 and mixed with the output signal of the fixed frequency oscillator OSC. As a result, frequency conversion is performed. The frequency converted signal is
After the high-frequency component is removed by the low-pass filter LPF10, the level is adjusted by the automatic gain control amplifier AGC10 and the signal is input to the power combiner 52 as the signal C10.

The signal B10 is also the phase-locked loop circuit P.
It is also input to a multiplier 53 as a reference signal creating means for creating a reference signal to be given to LL1 to PLL9. That is, the signal B10 is
The phase of the reference frequency signal generated by the fixed frequency oscillator OSC is mixed with the signal obtained by delaying the phase of the reference frequency signal by 90 degrees by the phase delay device 51, and frequency conversion is performed. The frequency-converted signal has its high-frequency component removed by the low-pass filter 55, and is then provided to the comb-teeth filter KF10 as the second filter means. Comb tooth filter KF1
0 is a filter having a comb-shaped pass frequency characteristic. The frequency characteristic of the comb-shaped filter KF10 will be described later.

The output signal of the comb filter KF10 is
The reference signal is distributed from the line 60 to the plurality of phase locked loop circuits PLL1 to PLL9. The phase locked loop circuits PLL1 to PLL9 have similar configurations and functions. For example, the phase locked loop circuit PLL1
Then, the input signal B1 is a multiplier F as a frequency mixing means.
At C1, the signal is mixed with the signal from the voltage controlled oscillator VCO1 and frequency converted. This signal is a low pass filter L
After the high frequency component is removed by PF1, the level is further adjusted by the automatic gain control type amplifier AGC1 and is input to the power combiner 52 as the signal C1.

The output signal of the LPF1 also has a pass frequency characteristic similar to that of the above comb-teeth filter KF10,
Comb-tooth filter K functioning as first filter means
Given to F1. And, this comb filter KF
The output of 1 is given to the phase comparator PC1. In this phase comparator PC1, the signal from the comb filter KF1 and the reference signal from the line 60 are compared in phase. Then, the output signal is converted into a control voltage by the loop filter LF1, and the control voltage is converted into the voltage controlled oscillator VCO1.
Given to.

For example, when a multiplication circuit is used as the phase comparator PC1, the phase locked loop circuit PLL1 is
The signal provided from the comb-teeth filter KF1 and the line 6
It operates so that the phase difference from the reference signal from 0 is held at 90 degrees. The other phase locked loop circuits PLL2 to PLL9 corresponding to the signals B2 to B9 are the phase locked loop circuit P.
It has the same configuration as LL1. Therefore, from each of the phase locked loop circuits PLL2 to PLL9, the line 60
The signals C2 to C9 having a constant phase difference (for example, 90 degrees) from the reference signal appearing in the line are automatically gain controlled amplifier AGC2.
Through AGC 9 to power combiner 52.

Due to the function of the phase delay device 51, the signal C10 provided from the automatic gain control type amplifier AGC10 to the power combiner 52 becomes a signal whose phase is delayed by 90 degrees from the signal derived on the line 60. Therefore, after all, the signal C
The signal 10 has the same phase as the signals C1 to C9. As a result, the power combiner 52 outputs a plurality of received signals B1 to B1.
A signal VT in which 0 is in-phase combined is output.

FIG. 3 shows phase locked loop circuits PLL1 to P1.
The comb-shaped filters KF1 to KF9 and KF provided in the LL9 (hereinafter, collectively referred to as “phase locked loop circuit PLL”) and the reference system circuit REF, respectively.
10 (hereinafter, when collectively referred to, "comb-shaped filter K
"F". 3] is a block diagram showing a configuration example of FIG. The input signal is first divided into a plurality of signals in the power divider 71. In the example of FIG. 3, eight distributions are made. Each of the distributed signals has a plurality of (eight in the example of FIG. 3) band pass filters BPF1 and B having different pass frequency bands.
Input to PF2, ..., BPF8. The signals after being filtered by the band pass filters BPF1, BPF2, ..., BPF8 are power-combined by the power combiner 73. The output signal of this power combiner 73 is
It is an output signal of the comb-shaped filter KF.

FIG. 4 is a characteristic diagram showing the pass frequency characteristic of the above comb-shaped filter. Each band pass filter BPF
1, BPF2, · · · ·, BPF 8, respectively the central frequencies f _1, f _2, having a pass frequency band the bandwidth of Δf centered on · · · · f _8. As a result, the comb filter KF
Has a comb-shaped pass frequency characteristic as a whole.

FIG. 5 shows the frequency distribution of each channel of satellite broadcasting.
FIG. 3 is a diagram showing a relative relationship between the positions of the BS converter and
And frequency changes in multipliers FC1 to FC10 (see FIG. 2)
The frequency constellation corresponding to the converted signal is shown.
There is. The satellite broadcasting channel currently used is BS
1, BS3, BS5, BS7, BS9, BS11, BS1
8 channels of 3, BS15. Each satellite channel
Is a predetermined value f _S(= 27MHz) apart
Center frequency f₁, F₂, F₃, ..., f₈Centered on
Predetermined width f_BOccupies the band of (= 38.36MHz)
It And, with 8 channels of BS1 to BS15, 29
It occupies a frequency band with a bandwidth of 5.52 MHz.

That is, each of the band pass filters BPF1, BPF2, ..., B constituting the comb-teeth filter KF.
The PF 8 has a pass frequency band in a bandwidth of Δf around the center frequency of each channel of satellite broadcasting. The bandwidth Δf is set to 5 MHz, for example. This is because about 90% of the signal power of each channel of satellite broadcasting is concentrated within a bandwidth of about 5 MHz centered on the center frequency of each channel.

With the above configuration, only the signal within the bandwidth of 5 MHz centering on the center frequency of each channel of satellite broadcasting is supplied to the phase comparator of the phase locked loop circuit PLL in the comb tooth filter KF. To be done. Therefore, the noise input to the phase comparator becomes extremely small compared to the conventional case, and the signal-to-noise ratio (S / N ratio) of the signal input to the phase comparator can be increased. As a result, the loop gain can be increased.

A more specific description will be given. In satellite broadcasting,
As can be seen in FIG. 5, a frequency bandwidth of about 300 MHz is used. Therefore, normally, the BS converters BC1 to BC
The C10 is equipped with a filter that passes a signal having a bandwidth of about 300 MHz used in satellite broadcasting. In this case, in the conventional configuration in which the comb-teeth filter KF is not used in the phase-locked loop circuit PLL forming the in-phase combining circuit 40, noise over a bandwidth of about 300 MHz is input to the phase comparator. On the other hand, in the configuration of this embodiment,
The total additional bandwidth of the comb-shaped filter KF is 40 MHz.
(= 5 MHz × 8). Therefore, naturally, the power of noise is reduced to about 1 / 7.5 (= 40/300). Therefore, the loop gain of the phase locked loop circuit PLL can be increased up to about 7.5 times.

On the other hand, as described above, in satellite broadcasting, about 90% of the signal power is concentrated in the frequency band of about 5 MHz centering on the center frequency of each channel. Therefore, after all, the gain for the signal is 6.75 (= 7.5 × 0.
9) It can be doubled. As a result, the capture range and the lock range can be increased about 6.75 times within the oscillating frequency range of the voltage controlled oscillator.

By thus increasing the capture range and lock range, the BS converter BC
1 to BC 10 even if the oscillation frequency of the local oscillator or the voltage-controlled oscillator in the in-phase synthesis circuit 40 changes due to the influence of environmental changes such as changes in ambient temperature, such oscillation frequencies Can be favorably compensated for in the phase locked loop circuit PLL in the in-phase combining circuit 40.

As a result, the in-phase synthesizing process in the in-phase synthesizing circuit 40 can be satisfactorily performed regardless of environmental changes, and the radio waves from the broadcasting satellite can be satisfactorily received. On the contrary, BS converters BC1 to BC
Since the requirements for fluctuations in the oscillation frequency of the local oscillator in 10 and the voltage-controlled oscillator in the in-phase synthesis circuit 40 are alleviated, an inexpensive local oscillator or voltage-controlled oscillator with relatively low accuracy can be used. Therefore, the total cost of the antenna device can be reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above embodiment, a comb filter is used, but when the frequency of the received radio wave is concentrated in a relatively narrow frequency band centered on a certain frequency, for example, A bandpass filter may be used instead of the comb filter.

Further, in the above embodiment, the antenna device used for receiving the satellite broadcast is taken as an example, but the antenna device of the present invention may be used for purposes other than the reception of the satellite broadcast. Furthermore, although a plurality of phase-locked loop circuits are provided in the above embodiment, for example, when there are two antenna elements, only one phase-locked loop circuit needs to be provided.

In the above embodiment, the signal filtered by the comb filter KF10 is supplied to the phase comparator of the phase-locked loop circuit as a reference signal. However, noise is eliminated without using the comb filter. If a small number of reference signals can be created, filtering on the reference signals is not always necessary. In addition, various design changes can be made without changing the gist of the present invention.

[0058]

As described above, according to the present invention, a signal to be input to the phase comparator in the phase locked loop circuit is filtered, and a signal having an improved signal-to-noise ratio is supplied to the phase comparator. Is entered. Therefore, noise in the loop can be reduced, and as a result, the loop gain can be increased and the capture range and the lock range can be increased. As a result, even if the oscillation frequency of the voltage controlled oscillator or the like fluctuates due to environmental changes such as ambient temperature changes, this fluctuation of the oscillation frequency can be well compensated for in the phase-locked loop circuit.

As a result, when a plurality of signals are in-phase combined using the phase-locked loop circuit, in-phase combination can be performed regardless of changes in the environment. Further, in the antenna device in which the reception signals of the plurality of antenna elements are combined in phase, a good reception state can be maintained regardless of changes in the environment. On the other hand, since the influence of the fluctuation of the oscillation frequency of the voltage controlled oscillator or the like can be favorably compensated by the phase locked loop circuit, it is not always necessary to use the voltage controlled oscillator or the like having a small fluctuation of the oscillation frequency.
That is, since it is possible to use relatively inexpensive parts with low accuracy, it is possible to reduce the cost of the antenna device and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of an antenna device to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a configuration of an in-phase combining circuit.

FIG. 3 is a block diagram showing a configuration example of a comb-shaped filter.

FIG. 4 is a characteristic diagram showing a pass frequency characteristic of a comb filter.

FIG. 5 is a diagram for explaining an arrangement of frequency bands used in satellite broadcasting.

FIG. 6 is a plan view showing an internal configuration of the antenna device.

FIG. 7 is a front view showing an internal configuration of the antenna device.

FIG. 8 is a block diagram showing an electrical configuration of a conventional antenna device.

[Explanation of symbols]

 A1 to A10 Antenna elements BC1 to BC10 BS converter 40 In-phase combining circuit 52 Power combiner 53 Multiplier REF Reference system circuit PLL1 to PLL9 Phase locked loop circuit OSC Frequency fixed oscillator FC1, FC10 Multiplier KF1, KF10 Comb filter LF1 loop Filter PC1 Phase comparator VCO1 Voltage controlled oscillator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H03L 7/08

Claims (12)

[Claims] 1. A voltage-controlled oscillator, a signal having a frequency corresponding to the frequency of an output signal of the voltage-controlled oscillator, and a predetermined reference signal are input, the phases of these two signals are compared, and the comparison is performed. A phase comparator which outputs a signal corresponding to the result, a loop filter which converts the output of the phase comparator into a voltage signal and supplies the voltage signal to the voltage controlled oscillator as a control voltage, and the phase comparator By filtering the signal to be input to and passing only the signal in the predetermined frequency band,
A phase-locked loop circuit comprising: filter means for improving a signal-to-noise ratio of a signal input to the phase comparator. 2. The filter means has a comb-shaped pass frequency characteristic of passing signals in a plurality of discretely set frequency bands.
The described phase-locked loop circuit. 3. An in-phase synthesizing device for synthesizing power by aligning the phases of a plurality of input signals, the power synthesizing means capable of inputting a plurality of signals and power synthesizing the plurality of input signals. Means for mixing a predetermined reference input signal, which is one of the plurality of input signals, and a predetermined reference frequency signal, and supplying the signal obtained by this mixing to the power combining means; A reference signal creating means for creating a predetermined reference signal by mixing a signal and the predetermined reference frequency signal, and an input signal other than the reference input signal among the plurality of input signals is input to create the reference signal. One or more phase-locked loops for generating a signal having the same phase as a signal obtained by mixing the reference input signal and the reference frequency signal based on the reference signal generated by the means, and giving the power combining means. The phase-locked loop circuit mixes a voltage-controlled oscillator, an output signal of the voltage-controlled oscillator and the input signal, and supplies the signal obtained by this mixing to the power combining means. The frequency mixing means, the output signal of the frequency mixing means, and the reference signal from the reference signal creating means are input, the phases of these two signals are compared, and a signal corresponding to the comparison result is output. Between the phase comparator, a loop filter that converts the output of the phase comparator into a voltage signal and supplies this voltage signal to the voltage controlled oscillator as a control voltage, between the frequency mixing means and the phase comparator. The signal pair of the signals input to the phase comparator by filtering the output signal of the frequency mixing means and passing only the signal in the predetermined frequency band. Phase combination and wherein the one having a first filter means for improving the sound ratio. 4. The first filter means has a comb-shaped pass frequency characteristic that allows signals in a plurality of discretely set frequency bands to pass therethrough. In-phase synthesizer. 5. A reference signal which is interposed between the reference signal generating means and the phase comparator and which filters the reference signal output by the reference signal generating means to pass only a signal in a predetermined frequency band, The in-phase combiner according to claim 3 or 4, further comprising second filter means for improving a signal-to-noise ratio of a signal input to the phase comparator. 6. The second filter means has a comb-shaped pass frequency characteristic that allows signals in a plurality of discretely set frequency bands to pass therethrough. In-phase synthesizer. 7. A plurality of antenna elements, a power combining means capable of inputting a plurality of signals and power combining the input plurality of signals, and one antenna element of the plurality of antenna elements. Means for mixing a predetermined reference reception signal which is a received signal and a predetermined reference frequency signal, and inputting the signal obtained by this mixing to the power combining means, the predetermined reference reception signal and the reference frequency signal And a reference signal creating means for creating a predetermined reference signal, and a received signal other than the reference received signal among the received signals corresponding to the plurality of antenna elements is input and created by the reference signal creating means. One or more signals which have the same phase as the signal obtained by mixing the reference reception signal and the reference frequency signal based on the generated reference signal and which are provided to the power combining means. A phase-locked loop circuit, wherein the phase-locked loop circuit mixes a voltage-controlled oscillator, an output signal of the voltage-controlled oscillator and the received signal, and a signal obtained by this mixing is used as the power combining means. To the frequency mixing means, the output signal of the frequency mixing means, and the reference signal from the reference signal generating means are input, the phases of these two signals are compared, and a signal corresponding to the comparison result is obtained. A phase comparator for outputting, a loop filter for converting the output of the phase comparator into a voltage signal and supplying the voltage signal to the voltage controlled oscillator as a control voltage, the frequency mixing means and the phase comparator. And is input between the phase comparator by filtering the output signal of the frequency mixing means and passing only the signal in a predetermined frequency band. Antenna apparatus characterized by those having a first filter means to improve the signal-to-noise ratio of No.. 8. The first filter means supplies to the phase comparator only a signal in a predetermined frequency band corresponding to a frequency band of a signal to be received by the antenna element. Item 7. The antenna device according to item 7. 9. The method according to claim 8, wherein the first filter means has a comb-shaped pass frequency characteristic that allows signals in a plurality of discretely set frequency bands to pass therethrough. Antenna device. 10. A reference signal which is interposed between the reference signal generating means and the phase comparator and which filters the reference signal output by the reference signal generating means to pass only a signal in a predetermined frequency band, The antenna device according to any one of claims 7 to 9, further comprising second filter means for improving a signal-to-noise ratio of a signal input to the phase comparator. 11. The second filter means supplies to the phase comparator only a signal in a predetermined frequency band corresponding to a frequency band of a signal to be received by the antenna element. Item 10. The antenna device according to item 10. 12. The second filter means has a comb-shaped pass frequency characteristic that allows signals in a plurality of discretely set frequency bands to pass therethrough. Antenna device.