JP2546373B2 - Radar signal transmission system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radar signal transmission system, and more particularly to a nonlinear quantization transmission system for radar signals.

(Prior Art) As is well known, in a non-linear quantization method, the quantization step width is uneven, and a fine quantization step width is used in a region where the signal amplitude level is small, and the quantization step width increases as the signal amplitude level increases. This is a method of increasing the width and performing coarse quantization. The quantization step interval is generally increased logarithmically. Therefore, a conventional radar signal transmission system for nonlinearly quantizing and transmitting a radar signal is, for example, as shown in FIG. That is, on the transmitting side, the radar signal as shown in FIG. 4 (a) has a nonlinear quantization step as shown in FIG. 4 (b).
Non-linear quantization is performed by the A / D conversion circuit to obtain a non-linear quantized signal as shown in FIG. Then, the non-linear quantized signal (FIG. 4 (c)) transmitted from the receiving side is non-linear
Analogized by D / A conversion circuit (Fig. 4 (d)),
Reproduce the radar signal.

(Problems to be Solved by the Invention) In the conventional radar signal transmission system described above, for example,
When the target signal is superimposed on the ground clutter signal as shown in FIG. 5A, all the signal changes within the coarse quantization step width are quantized as the same level as shown in FIG. 5B. As a result, the target signal often enters the quantization unit, resulting in the problem that the target signal disappears as shown in FIG. 5 (c).

The present invention has been made in view of such a conventional problem, and its object is to reliably non-linearly quantize the target signal even if a specific signal such as a ground clutter signal is superimposed on the receiving side. It is to provide a radar signal transmission system capable of reproducing the target signal.

(Means for Solving the Problems) In order to achieve the above object, the radar signal transmission system of the present invention has the following configuration. That is, the radar signal transmission system of the present invention includes: an A / D conversion circuit for linearly quantizing an input radar signal on the transmission side; a first pattern memory storing a specific pattern for each angle unit; A subtraction circuit for taking a difference between the output of the D conversion circuit and the signal pattern read from the first pattern memory; a non-linear conversion circuit for converting the output of the subtraction circuit into a non-linear quantized signal;
A linear conversion circuit for converting the non-linear quantized signal into a linear quantized signal on the receiving side; a second pattern memory storing the same pattern of a specific signal as the transmitting side; and an output of the linear conversion circuit. An addition circuit for adding the signal pattern read from the second pattern memory; and a D / A conversion circuit for converting the output of the addition circuit into a radar signal. is there.

(Operation) Next, the operation of the radar signal transmission system of the present invention configured as described above will be described.

On the transmission side, the difference between the linearly quantized radar signal and the signal of a specific pattern (that is, ground clutter component, etc.) is obtained, that is, the ground clutter component, etc. is removed from the radar signal, and the residual signal component is nonlinearly quantized. To do. Here, of the remaining signal components, the signal component superposed on the ground clutter signal or the like has a low amplitude level, and therefore, in the non-linear quantization of this, it is converted in the fine conversion range of the non-linear conversion. Therefore, if the target signal component is present there, the nonlinear quantization is surely performed. And
On the receiving side, a radar signal is reproduced by adding a ground clutter component or the like after linearly converting the nonlinear quantized signal.

Therefore, even if the target signal is superimposed on the ground clutter signal or the like, the target signal can be reliably transmitted and reproduced.

(Examples) Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the configuration of a radar signal transmission system according to an embodiment of the present invention. In FIG. 1, the transmitting side, as shown in FIG. 1 (a), has an A / D conversion circuit 1 and a subtraction circuit 2
A pattern ROM (Read Only Memory) 3 and a non-linear conversion circuit 4 are basically provided.

The radar signal 9 input to the A / D conversion circuit 1 is, for example, as shown in FIG. 2A, the target signal a superimposed on the ground clutter signal and the target signal located outside the ground clutter signal area. And b. The A / D conversion circuit 1 linearly quantizes the radar signal 9 in a linear quantization step as shown in FIG. 2B, and outputs the quantized radar signal 10 to one input of the subtraction circuit 2. In the pattern ROM 3, a signal of a specific pattern such as a ground clutter component in the radar range is stored in advance in units of angles. That is, the signal stored in the pattern ROM 3 is a linear quantized signal, and the pattern signal 11 composed of the quantized signal is output to the other input of the subtraction circuit 2 according to the angle information 12. In the ground clutter signal area (FIG. 2 (a)) of the radar signal 9, the pattern signal 11 is as shown in FIG. 2 (c). Since the subtraction circuit 2 calculates the difference between the quantized radar signal 10 and the pattern signal 11, the subtraction result difference signal 13 is as shown in FIG. 2 (d). The target signal a, which was superimposed on the ground clutter signal, exists at a low amplitude level,
It is shown that the nonlinear transformation is performed at a narrow width of the nonlinear quantization step. That is, the nonlinear conversion circuit 4
The differential signal 13 is subjected to non-linear quantization and a non-linear quantized signal 14 as shown in FIG. 3 (e) is output. This is transmitted to the receiving side.

As shown in FIG. 1B, the receiving side has a linear conversion circuit 5, an addition circuit 6, a pattern ROM 7, and a D / A conversion circuit 8.
Basically equipped with. The linear conversion circuit 5 includes a memory for storing a pattern signal in which the polarity of a specific pattern signal stored in the pattern ROM 7 is inverted, and a multiplier. 15 is formed and is output to one input of the adder circuit 6. In the pattern ROM7, the same pattern signal as that of the pattern ROM3 is similarly stored in the angle unit, and the pattern signal having the same contents as the pattern signal 11 according to the angle information 12 is stored.
Output 16 Therefore, the pattern signal 16 is shown in FIG.
And is output to the other input of the adder circuit 6.

As a result, the addition signal 17 which is the output of the addition circuit 6 becomes as shown in FIG. 3 (f), and it is recognized that the target signal a exists together with the target signal b. Therefore, the reproduced radar signal 18 obtained by analogizing this with the D / A conversion circuit 8 becomes as shown in FIG. 3 (g), and the target signal B is not erased and is superimposed on the ground clutter signal. Is played.

(Effects of the Invention) As described above, according to the radar signal transmission system of the present invention, the transmitting side removes the specific signal component such as the ground clutter component before the nonlinear conversion, and nonlinearly quantizes the remaining signal component. . In other words, the target signal superimposed on the ground clutter signal has a low amplitude level,
Non-linear conversion is performed with a fine conversion range. Then, on the receiving side, the nonlinear quantized signal sent is linearly converted and the ground clutter component is added to it to reproduce the radar signal, so that even if the target signal is superimposed on the ground clutter signal, etc. The target signal can be reliably transmitted and reproduced by the non-linear quantization.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a radar signal transmission system according to an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of the operation of the present invention, and FIG. The figure is an explanatory diagram of the operation of the conventional method when the target signal is superimposed on the ground clutter signal. 1 ... D / A conversion circuit, 2 ... subtraction circuit, 3 ... Pattern R
OM, 4 ... Non-linear conversion circuit, 5 ... Linear conversion circuit, 6 ...
… Addition circuit, 7 …… Pattern ROM, 8 …… D / A conversion circuit,
9 ... Radar signal, 10 ... Quantized radar signal, 11 ... Pattern signal, 12 ... Angle information, 13 ... Difference signal, 14 ...
Non-linear quantized signal, 15 …… Linear quantized signal, 16 …… Pattern signal, 17 …… Addition signal, 18 …… Reproduced radar signal.

Claims (1)

(57) [Claims] 1. An A / D conversion circuit for linearly quantizing an input radar signal at a transmitting side; a first pattern memory in which a specific pattern is stored for each nuclear degree unit; and an output of the A / D conversion circuit. And a non-linear conversion circuit that converts the output of the subtraction circuit into a non-linear quantized signal; and a subtraction circuit that takes the difference between the signal pattern read from the first pattern memory and the non-linear quantized signal. A linear conversion circuit for converting a signal into a linear quantized signal; a second pattern memory storing the same specific signal pattern as the transmission side; an output of the linear conversion circuit and a signal read from the second pattern memory A radar signal transmission system comprising: an adder circuit for adding a pattern; and a D / A converter circuit for converting the output of the adder circuit into a radar signal.