JPH11101828A - Frequency-measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure an electronic wave source frequency in a visual field with a high sensitivity while widely maintaining the instantaneous visual field by forming multi beams from an A/D converter output corresponding to a plurality of element antennas and synthesizing them. SOLUTION: The radiation electronic wave of an electronic wave source being present in a beam width is received by m element antennas 1 and is amplified and is subjected to frequency conversion by m receivers 2 and then is digitized by m A/D converters 3. A multi-beam forming equipment 4 uses the output of each A/D converter 3 and forms multi beams based on an arrangement consisting of the m element antennas 1. M arrangement patterns are obtained in the radiation pattern and the obtained arrangement pattern is synthesized in terms of vector by a synthesizer 5, thus achieving a level that is m times larger than each radiation pattern of the element antennas 1 and making nearly identical in the beam width, which is subjected to frequency measurement by a frequency analyzer 6. Therefore, the frequency of an electronic wave source can be simultaneously measured while widely maintaining a beam width, namely an instantaneous visual field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency measuring device for measuring the frequencies of a plurality of radio sources within an instantaneous field of view with high sensitivity over a wide field of view.

[0002]

2. Description of the Related Art FIG. 5 shows a configuration of a conventional frequency measuring device. In FIG. 5, reference numeral 11 denotes a parabolic antenna for receiving a radio wave from a radio wave source; 12, a high-frequency amplifier for amplifying the radio wave received by the parabolic antenna 11;
Reference numeral 3 denotes a spectrum analyzer that measures the frequency of the radio wave source based on the output of the high-frequency amplifier 12.

Next, the operation will be described. For example, a radio wave radiated from a radio wave source such as an artificial satellite and propagated in the air is received by a parabolic antenna 11, and the received signal is amplified by a high-frequency amplifier 12 to be a spectrum analyzer 13.
To measure the frequency of the radio source.

[0004]

Since the conventional frequency measuring device is configured as described above, if the radio wave source is an artificial satellite, the radio wave on the ground is weak, so that the aperture diameter of the parabolic antenna 11 is reduced. I had to increase the sensitivity by increasing it. Therefore, there is a problem that the instantaneous visual field of the parabolic antenna 11, that is, the antenna beam width becomes narrow, and only the frequency of the radio source within the narrow visual field can be measured.

The present invention has been made to solve the above problems, and has as its object to measure the frequency of a radio wave source within an instantaneous field of view with high sensitivity while maintaining a wide instantaneous field of view.

[0006]

According to a first aspect of the present invention, there is provided a frequency measuring apparatus comprising two or more M element antennas, M receivers connected to the respective element antennas, and M receivers connected to the respective receivers. M A / D converters and A
A multi-beamformer for forming a multi-beam from the outputs of the respective / D converters, a combiner for combining the outputs of the multi-beams obtained by the multi-beamformer, and a frequency analyzer for measuring the frequency from the output of the combiner It is equipped with a vessel.

According to a second aspect of the present invention, there is provided a frequency measuring apparatus according to the first aspect, further comprising a frequency peak detector for detecting a frequency equal to or higher than a predetermined threshold level based on an output of the frequency analyzer. Things.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a block diagram showing a first embodiment of a frequency measuring apparatus according to the present invention.
−2,..., 1-M are M element antennas (M is a positive number of 2 or more) having the same specification, and form one array antenna. , 2-M amplify and frequency convert signals received by the M element antennas 1 (1-1, 1-2,..., 1-M). .., 3-M are A / D converters for converting the analog output of the receiver 2 into digital values,
Uses the output of each of the A / D converters 3 and
A multi-beamformer 5 for forming a multi-beam based on the arrangement of the element antennas 1, 5 is a combiner for adding and combining the outputs of the multi-beamformer 4, and 6 is a frequency based on the output of the combiner 5. Is a frequency analyzer that determines

Next, the operation will be described. It is assumed that all M element antennas 1 are directed in the same direction, and the beam width of these M element antennas 1 is θ _B.

It is assumed that a plurality of radio sources exist within the beam width θ _B.

The radio waves radiated from these radio wave sources are received by the M element antennas 1, amplified and frequency-converted by the receiver 2, and digitized by the A / D converter 3. .

It is assumed that all M A / D converters 3 simultaneously sample the output of the receiver and at a constant period.

The output of the A / D converter 3-1 sampled at a certain time t is S ₁ (t), and the output of the A / D converter 3-2 is S ₂ (t),. The output of the unit 3-M is S
_{As M} (t), these outputs shall be represented by Equation 1 as a vector X (t).

[0014]

(Equation 1)

In this X (t), the DFT
(Discrete FourierTransform
m) to perform multi-beam Y
(T) can be obtained.

[0016]

(Equation 2)

Where P ₁ (t), P ₂
(T),..., P _M (t) represent M beams, and W is
This is the Tiddle Factor given by

[0018]

(Equation 3)

For example, assuming that the aperture of each of the M element antennas 1 is d and the M element antennas 1 are linearly arranged at intervals d, as shown in FIG. M pieces of the interior of the arrangement pattern _{P 1 (t), P 2} (t), ..., can be obtained P _M (t). The obtained P ₁ (t), P ₂
Since the arrangement pattern of (t),..., P _M (t) combines the radiation patterns of the M element antennas 1 in a vector manner, the level is M times larger than the level of the radiation pattern of the element antennas. .

These arrangement patterns P ₁ (t), P ₂
.., P _M (t) are combined by the combiner 5 to calculate Q (t) shown in Equation 4. The obtained Q (t) is M times larger than the radiation pattern level of each element antenna, and the 3 dB beam width of Q (t) is almost the same as the 3 dB beam width of each radiation pattern of M element antennas 1. Becomes

[0021]

(Equation 4)

The sampling period of the A / D converter 3 is Δt
, Q (0), Q (Δt),.
((N−1) Δt) is output.

It is assumed that these outputs are represented as a vector R by Expression 5.

[0024]

(Equation 5)

The vector R is converted by the frequency analyzer 6 into frequency spectra F ₁ , F
₂ , ..., _FN are obtained. FFT (Fast Fourier) is used as a high-speed operation instead of the DFT shown in Expressions 2 and 6.
Transform) can also be used.

[0026]

(Equation 6)

With the above configuration and operation, the M element antennas 1 are divided into M element antennas 1 by the gain based on the arrangement of the plurality of element antennas 1 while maintaining the antenna beam width of each of the M element antennas 1, that is, the instantaneous visual field. It is possible to obtain M times higher sensitivity than when using an antenna alone, and therefore, to obtain the frequencies of these radio sources simultaneously with higher sensitivity than when observing multiple radio sources within the instantaneous field of view with the antenna alone Can be. Further, compared to the case where one antenna having the same aperture area as the arrangement of the M element antennas 1 is used, the instantaneous field of view can be widened and the frequency of the radio wave source within the instantaneous field of view can be obtained simultaneously.

Embodiment 2 FIG. 2 is a block diagram showing a second embodiment of the present invention.
2,..., 7-M are M compensators of the same specification which are connected to the respective A / D converters 3 and supply the respective outputs to the multi-beamformer 4, and the other components are the same as those in FIG. is there.

Next, the operation will be described. The processing from the M element antennas 1 to the A / D converter is the same as in the first embodiment of the present invention.

By the way, in the compensators 7-1, 7-2,..., 7-M, only a single radio wave source is installed in front of the M element antennas 1 and obtained by the respective A / D converters. The output to be output is a _i · exp (jφ _i ) (i = 1, 2,..., M)
In the compensator 7 corresponding to them, (1 / a _i ) · e
xp (−jφ _i ) (i = 1, 2,..., M) is multiplied.

However, _ai · exp (jφ _i ) (i
= 1, 2,..., M) when the signals radiated from the above-mentioned radio wave source installed in each of the M element antennas 1 are received by such distances that the phases of the received signals are considered to be substantially the same. This radio source shall be installed.

As a result, changes in the amplitude and phase of signals output from the M element antennas 1 and generated on the transmission line up to the receiver 2, the A / D converter 3, and the compensator 7, and the receiver In order to compensate for the variation in the gain, it is possible to form a multi-beam with higher accuracy than the frequency measuring device of the first embodiment.

The multi-beamformer 4, the synthesizer 5,
The operation of frequency analyzer 6 is the same as that of the first embodiment of the present invention.

Embodiment 3 FIG. 3 is a block diagram showing a third embodiment of the present invention.
2,..., 8-M are couplers connected to each of the M element antennas 1 and supplying their respective outputs to each of the receivers 2. Reference numeral 9 generates a reference signal. , And the other components are the same as those in FIG.

Next, the operation will be described. The reference signals generated by the reference signal generator 9 are referred to as 8-1, 8-2,.
It is assumed that the signals are input to the M coupler at the same phase and the same level.

However, at this time, the front surfaces of the M element antennas 1 are covered with a radio wave absorber or the like so that radio waves do not enter the M element antennas 1 from an external power supply.

The reference signal input to the M couplers 8 is
The signals are input to the compensator 7 via the corresponding receiver 2 and A / D converter 3, respectively. The compensator 7 performs the same operation as that described in the second embodiment of the present invention. After setting values to be given to the respective compensators 7 in this manner, the M element antennas 1 are directed to external radio wave sources. The rest is the same as the second embodiment of the present invention.

As described above, in order to compensate for attenuation, delay of the transmission line and variations in the gain of the receiver by the compensator by the reference signal output from the reference signal generator, there is a case where calibration is performed using an external radio wave source. In comparison, calibration can be performed without being restricted by time and place.

Embodiment 4 FIG. 4 is a block diagram showing a fourth embodiment of the present invention. In FIG. 4, reference numeral 10 denotes a frequency peak detector connected to the frequency analyzer 6, and the other components are the same as those in FIG.

Next, the operation will be described. The processing from the M element antennas 1 to the frequency analyzer 6 is the same as in the third embodiment of the present invention.

Now, in the frequency peak detector, for the frequencies F ₁ , F ₂ ,..., F _N obtained by the frequency analyzer 6, the absolute values | F ₁ |, | F ₂ |,. F _N |
And a frequency equal to or higher than a predetermined threshold level is detected.

Therefore, by providing the frequency peak detector, it is possible to extract the frequency of the radio wave source having a predetermined reception level or higher among the radio wave sources existing in the instantaneous visual field.

[0043]

According to the first aspect of the present invention, if the antenna beam width of each of the plurality of element antennas, that is, the gain based on the arrangement of the plurality of element antennas while maintaining the instantaneous visual field, is used, for example, M element antennas can be used. , M times higher sensitivity than when the M element antennas are used alone, so that these antennas can be obtained with higher sensitivity than when the plurality of radio sources in the instantaneous field of view are observed using the antenna alone. The frequency of the radio source can be determined. Further, the instantaneous field of view can be widened and the frequency of the radio wave source within the instantaneous field of view can be obtained as compared with the case where one antenna having the same aperture area as the arrangement of the plurality of element antennas is used.

According to the second aspect of the present invention, since the frequency peak detector is provided, it is possible to extract a frequency of a radio source having a predetermined reception level or higher among radio sources existing in the instantaneous visual field.

[Brief description of the drawings]

FIG. 1 is a diagram showing Embodiment 1 of a frequency measuring device according to the present invention.

FIG. 2 is a diagram showing a second embodiment of the frequency measuring apparatus according to the present invention.

FIG. 3 is a diagram showing a third embodiment of the frequency measuring apparatus according to the present invention.

FIG. 4 is a diagram showing a fourth embodiment of the frequency measuring apparatus according to the present invention.

FIG. 5 is a diagram showing a configuration of a conventional frequency measuring device.

FIG. 6 is a diagram showing an example in which M arrangement patterns are formed inside the radiation pattern of the antenna element.

[Explanation of symbols]

Reference Signs List 1 antenna, 2 receiver, 3 A / D converter, 4 multi-beamformer, 5 synthesizer, 6 frequency analyzer, 7
Compensator, 8 coupler, 9 reference signal generator, 10 frequency peak detector, 11 parabolic antenna, 12 high frequency amplifier, 13 spectrum analyzer.

Claims (2)

[Claims] A plurality of element antennas for receiving radio waves from a radio source, a plurality of receivers connected to each of the element antennas, and a plurality of A connected to each of the receivers A / D converter, a multi-beamformer that receives the output of each of the A / D converters to form a multi-beam, a combiner that combines the outputs of the multibeamformer, and an output of the combiner And a frequency analyzer for obtaining a frequency. 2. The frequency measuring apparatus according to claim 1, further comprising a frequency peak detector that detects a frequency equal to or higher than a predetermined threshold level based on an output from the frequency analyzer.