JPH0668542B2 - Holographic It Crader - Google Patents

Description

TECHNICAL FIELD The present invention relates to reduction in size and weight of a holographic radar.

[Conventional technology]

Figure 2 shows Abraham E. Announced in IEEE, EASCON-78.
Rubin (ABRAHAM E.RUVIN) and Leonard Weinberg
(LEONARD WEINBERG) 's paper `` Digital multi-beam forming technology for radar (DIGITAL MULTIPLE BEAMFORMING
TECHNIQUES FOR RADAR ")" shows the configuration of the receiving holographic radar, in which 1 is an element antenna, 2 is an antenna array consisting of N element antennas, and 3 is connected to each element antenna An RF amplifier for amplifying the high frequency signal received by the element antenna, a mixer 4 for converting the high frequency signal into an intermediate frequency signal, and an IF amplifier 5 for amplifying the intermediate frequency signal output from the mixer 4,
6 is a phase detector for converting the intermediate frequency signal to a baseband complex video signal while preserving the phase, and 7 is an in phase channel (hereinafter referred to as I channel) and a quadrature channel (hereinafter referred to as Q channel) of the phase detector 6. Low-pass filter (hereinafter referred to as LP) connected to each output of
F), 8 is connected to the LPF 7, and is an A / D converter for A / D converting the complex video signal converted to baseband, and 9 is a weighting for adjusting the side lobe level during beam forming. Output level adjuster 10 to 3
A receiver composed of each part of 9 and a digital signal forming a multibeam corresponding to the number of element antennas by performing a digital operation on the output of the receiver 10 connected to each element antenna 1. It is a multi-beam former.

Next, the operation of this type of conventional device will be described. N
The high frequency signal received by each element antenna 1 is amplified by the RF amplifier 3, converted into an intermediate frequency signal by the mixer 4, and amplified again by the IF amplifier 5. The intermediate frequency signal is phase-detected by the phase detector 6 and converted into a complex video signal composed of I-channel and Q-channel. The complex video signal is band-limited by the LPF 7, converted into a digital complex video signal by the A / D converter 8, and further weighted for side lobe reduction in beam forming by the output level adjuster 9. Then, it is input to the digital multi-beam former 11. At this time, as shown in FIG. 3, the direction in which the N element antennas are arranged is the X axis,
If the angle between the high-frequency signal, that is, the arrival direction of the radio wave and the X axis is the radio wave arrival angle α, the element antenna interval is d, and the wavelength λ, the phase difference between the signals received by the adjacent element antennas is 2πd. Since cos α / λ, the first equation is used in the digital multi-beam former 11. By calculating r = −N / 2, 0, ..., N / 2−1, α _r = cos ⁻¹ (rλ / Nd)
N beams (r = -N / 2, ...,
0, ..., N / 2-1) can be formed. However, in the first expression, W _k is a weighting coefficient for sidelobe suppression, and is given by the output level adjuster 9 in the receiver 10 connected to each antenna element.

At this time, the beam width δ _r of the r-th beam is given by the second equation And the distance Δ between the r-th and the (r-1) th beams
α _r is the third equation Given in. W of the second equation is a constant determined by the weighting factor W _k, is generally set to about 0.88 to 1.3.

In the digital multi-beam former 11, the first equation is Discrete Fourier Transform.
It is an expression showing form; DFT). In the holographic radar, in order to efficiently form a multi-beam within the field of view, that is, the observation range, which is determined by the beam width of the element antenna, Fast Fourier Transform (F) is used.
The FT) algorithm is used.

[Problems to be solved by the invention]

Since the conventional holographic radar is configured as described above, it requires a number of receivers corresponding to the number of element antennas, and compared with a phased array radar that performs analog beam forming at a high frequency stage. There is a problem that a large number of receivers are required, their weight and size are large, and a large amount of electric power is required.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a holographic radar that is small and lightweight.

[Means for solving problems]

A holographic radar according to the present invention is provided with an antenna array consisting of a plurality of element antennas and one element antenna for each of the above K element antennas (K: an integer of 2 or more), and is received by each element antenna. Receiving means for demodulating a received signal to output a digital complex video signal, a plurality of memories provided corresponding to each of the element antennas for storing the digital complex video signal from the receiving means, the element antenna, and the Between the receiver and the first switch, which is provided between the receiver and the first switch for sequentially switching the reception signals of the K element antennas at predetermined intervals and inputting them to the reception means. A second switch provided for switching the output of the receiving means in synchronism with the first switch to sequentially store the outputs in the K memories; Is obtained by the provided a digital multi-beam forming means for forming a multi-beam using the digital complex video signal output.

[Action]

In the holographic radar according to the present invention, as described above, a memory is provided between the receiving means and the digital multi-beam forming means so as to correspond to each element antenna, and the element antenna, the receiving means, the receiving means and the memory are provided. By providing first and second switches for connection switching between them, and switching the second switch at a predetermined interval in synchronization with the first switch, one receiving unit can time-divisionally operate K number of switches. Since the element antenna output is demodulated and the digital complex video signal as the demodulation result is sequentially stored in the memory, it is possible to demodulate K element antenna outputs by one receiving means, and the number of receiving means To reduce the weight and size.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, 12 is a switch for switching the connection between the element antenna 1 and the receiver 10, and 13 is the receiver 10 and the memory 1.
A switch for switching the connection with 4 and a memory 14 for storing the output of the receiver 10. Each of the parts 1 to 11 is the same part or means as the conventional holographic radar.

The operation of the holographic radar according to this embodiment will be described below with reference to the drawings. Since the internal operations of the receiver 10 and the digital multi-beam former 11 are the same as the operations of the conventional holographic radar, the description thereof will be omitted, and the operations of the switches 12 and 13 and the memory 14 newly added in this embodiment will be described in detail. explain.

In this holographic radar, a combination is selected for the number of element antennas N and the number of receivers L such that the ratio K = N / L is a natural number, and one receiver 10 is provided for every K consecutive element antennas. Is assigned. L receivers 1
The operation of 0 and the changeover switches 12 and 13 added to the input / output terminals thereof are all the same.

The switch 12 is switched in synchronism with the start of observation, that is, in synchronization with the first transmission pulse, and the first element antenna out of K consecutive element antennas assigned to each receiver 10 and the receiver 10 are switched. Connect the input terminal and switch 13
Connects the output terminal of the receiver 10 and the K memories allocated to the receiver 10. This state continues until the next transmission pulse, that is, the second transmission pulse is emitted, during which the amplification, detection and A / D conversion of the high frequency signals of all range bins received by the first element antenna are performed. And the digital complex video signal is stored in the first memory 14. Then, the switches 12 and 13 are switched in synchronization with the second transmission pulse, whereby the second element antenna and the receiver 10 are switched.
The input terminal and the output terminal of is connected to the second memory, and the high frequency signal received by the second element antenna is similarly amplified, detected and A / D converted and then stored in the memory. . The above operation is sequentially repeated until the Kth transmission pulse. K memories 1 assigned to each receiver 10
When the digital complex video signal is stored in all four, the K assigned to each of the L receivers 10 is stored.
Digital complex video signals are simultaneously read out from the memory 14 and the number equal to the number N of element antennas, that is, K.
The L digital complex video signals are input to the digital multi-beam former 11.

The digital multi-beam former 11 forms N multi-beams as in the case of the conventional holographic radar using N element antennas and N receivers.

〔The invention's effect〕

As described above, according to the holographic radar of the present invention, an antenna array including a plurality of element antennas and one element antenna for each of the K element antennas (K: an integer of 2 or more) are provided. , Receiving means for demodulating a received signal received by each element antenna and outputting a digital complex video signal, and provided corresponding to each element antenna,
A plurality of memories for storing digital complex video signals from the receiving means are provided between the element antenna and the receiver, and the reception signals of the K element antennas are sequentially switched at predetermined intervals. A first switch for inputting to the means, the receiving means and the memory are provided, and the output of the receiving means is switched in synchronization with the first switch and sequentially stored in the K memory. Second for
Switch and digital multi-beam forming means for forming a multi-beam using the digital complex video signals output from the plurality of memories are provided. Therefore, by switching the first and second switches, The high-frequency signal received by the K element antennas can be processed by the receiving means of the table, the number of receiving means can be reduced to 1 / K as compared with the conventional apparatus, and the apparatus can be made small and lightweight. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a holographic radar according to an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a conventional holographic radar, and FIG. 3 is a diagram for explaining the operating principle of the holographic radar. It is a figure. 1 ... Element antenna, 2 ... Antenna array, 10 ...
... receiver, 11 ... digital multi-beam former, 1
2, 13 ... Switch, 14 ... Memory. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An antenna array comprising a plurality of element antennas, one for each of the K element antennas (K: an integer of 2 or more).
Receiving means which is provided in proportion to the number of units and which demodulates a reception signal received by each element antenna and outputs a digital complex video signal, and a digital complex video signal which is provided corresponding to each element antenna and which is provided from the above receiving means A plurality of memories for storing, and provided between each of the element antennas and the receiving means,
The first switch is provided between the receiving means and the memory, the first switch for sequentially switching the reception signals of the K element antennas at predetermined intervals and inputting them to the receiver.
Switch the output of the receiving means in synchronization with the switch
A plurality of second switches for sequentially storing in the memories, and digital multi-beam forming means for forming a multi-beam by using digital complex video signals output from the plurality of memories. Holographic radar.