RU2247408C1 - Radar signal processing device - Google Patents

Abstract

FIELD: radar engineering; systems for searching and tracking airborne targets.

SUBSTANCE: proposed device has rotary directivity pattern receiver, azimuth sensor, amplitude-to-code converter unit, and secondary processing unit; output of rotary directivity pattern receiver is connected to input of amplitude-to-code converter unit and group of azimuth sensor outputs is connected to group of secondary processing unit inputs. Newly introduced in device are parallel delay line unit, subtracter, coder, and adder; group of amplitude-to-code converter unit outputs is connected to second group of subtracter inputs and through parallel delay line unit, to first group of subtracter inputs; subtracter also has group of outputs connected through coder to first group of adder inputs; second group of adder inputs and group of outputs are respectively connected to group of azimuth sensor outputs and to second group of secondary processing unit inputs.

EFFECT: enhanced precision of finding target direction.

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Description

The invention relates to the field of radar and the layout can be used in search and tracking systems for airborne objects.

A device for processing radar signals is described in the book "Radio Engineering Systems" by Yu. M. Kazarinov, 1991, Moscow, p. 383. In it, by analyzing the maximum envelope, the direction to the object is determined using a single-channel receiver with a rotating radiation pattern. However, with an increase in the viewing speed, two or one signal can be received, which can also be elongated. while the accuracy of determining the direction decreases.

A device for processing radar signals is known, which is part of the radar set forth in the aforementioned source on pages 194-197. In it, after signals from objects are extracted in a single-channel receiver with a rotating radiation pattern, the determination of the envelope maximum can occur, as shown in the aforementioned analogue. during the initial processing. This can be done by determining the amplitudes of the signals using the amplitude to code conversion unit. The angular position corresponding to the maximum envelope along with the azimuth code from the azimuth sensor enters the secondary processing unit, where the construction of the object's motion paths is carried out. However, with an increase in the viewing speed, two or one signal can be received, which can also be elongated. In this case, the accuracy of determining the direction decreases.

Using the proposed device increases the accuracy of determining the direction in the presence of two or one elongated signal.

This is achieved by introducing a block of parallel delay lines, a subtractor, an encoder and an adder, while the group of outputs of the amplitude-to-code conversion block is connected to the second group of inputs of the subtractor and, through the block of parallel delay lines, is connected to the first group of inputs of the subtractor having a group of outputs connected via an encoder with the first group of inputs of the adder, the second group of inputs of which and the group of outputs are respectively connected to the group of outputs of the azimuth sensor and to the second group of inputs of the secondary processing unit.

In figure 1 and in the text the following notation:

1 - receiver with a rotating radiation pattern;

2 - azimuth sensor;

3 - block conversion of the amplitude in the code;

4 - block parallel lines of delays;

5 - subtractor;

6 - encoder;

7 - adder;

8 - secondary processing unit,

wherein the output of the receiver with the rotating radiation pattern 1 is connected to a separate input of the amplitude conversion unit into code 3 having an output group connected to the second group of inputs of the subtractor 5 and through the parallel delay line unit 4 connected to the first group of inputs of the subtractor 5 having the group of outputs connected through an encoder 6 to the first group of inputs of the adder 7, the second group of inputs of which and the group of outputs are respectively connected to the group of outputs of the azimuth sensor 2 and the second group of inputs of the secondary image block quipment 8 having a first input group connected to the group of the aforementioned azimuth sensor 2 outputs.

The operation of the device is as follows.

In the receiver with a rotating radiation pattern 1, electromagnetic signals are converted into electrical signals and selected according to characteristics corresponding to airborne objects. The extracted signals are sent to the amplitude conversion block into code 3, where the amplitude is converted to code, which then goes to the second group of inputs of the subtractor 5 and, through the block of parallel delay lines 4, goes to the first group of inputs of this subtractor. The value of each delay line is, for example, the maximum delay time of the reflected signal or the time equal to determining the duration of the elongated signal, if it is single, and the number of delay lines is equal to the bits of the parallel code. The difference from the subtraction of the amplitude codes enters the encoder 6, which determines the angular position of the object in the field of view of the receiver with a rotating radiation pattern 1. The value of this angular position is added to the current value of the azimuth code from the azimuth sensor 2 in adder 7, and the true value of the direction to the object arrives in the secondary processing unit 8, which implements the construction of the trajectory of the movement of objects. The azimuth code also enters the first group of inputs of the secondary processing unit for its use in the presence of other devices. The execution of the azimuth sensor with an angular resolution, for example, one minute, outputting information in the form of a code, is presented in the aforementioned source on page 414. For a more detailed explanation of the principle of determining the direction using a single-channel receiver, we use the envelope shown in Fig. 2, where the following notation :

9 - the first amplitude;

10 - line passing through the maximum radiation pattern of the receiver;

11 - the second amplitude.

Consider two options.

The first option, when during the intersection of the object with the radiation pattern of the receiver 1, one signal is reflected, and in the second option, during the same intersection time, two signals are reflected.

In the first embodiment, the signals can be elongated, and each can occupy part of the envelope area, namely, a section limited by amplitudes 9 and 11.

In the second embodiment, we assume conditionally that the shortened signals occupy the same position inside the envelopes in figure 2. In both cases, the value of the parallel delay lines in block 4 corresponds to the length of the segment a-c.

As can be seen from figure 2, each difference in amplitudes determined in the subtractor 5 will correspond to a certain position inside the envelope, and therefore, inside the radiation pattern of the receiver 1 relative to line 10. Therefore, each position corresponds to a strictly defined position of the second amplitude 11 relative to line 10, passing through the maximum envelope.

In figure 2, this position is characterized by a segment m.

The elongated signal in the first embodiment can also be used in early warning radars. Thus, each value of the difference in amplitudes from the output of the subtractor 5 corresponds to a certain code in the encoder 6, characterizing the angular position of the second amplitude relative to the equal-signal vertical plane, dividing the radiation pattern of the receiver into two equal parts. Inside this plane there is line 10. If amplitude 11 is to the right of line 10, this angular position will be positive, and if it is left, it will be negative, and, as noted earlier, it will add up in adder 7 with the azimuth of the vertical signal of the rotating plane receiver.

As noted in the aforementioned source on page 383, the maximum envelope value also depends on the magnitude of the signal amplitudes. However, the difference of the two amplitudes, limiting the same section of the envelope, does not depend on this maximum value, since when shortening the segments 9, 11 (see figure 2), their difference does not change. The accuracy of determining the direction depends on the presence of two signals from their fluctuation and can be a value equal to 0.05-0.15 of the width of the diagram. We give an example of a specific implementation.

Let two signals reflected from the object have a duration of 20 μs and arrive at the receiver as a result of the emission of two probe pulses during the rotation time of the combined transmitting and receiving radiation patterns by the value of their own width. Then, with a maximum width of the diagrams in azimuth of 2 degrees, an elevation angle of 30 degrees and a detection range of 300 km, the viewing time will be 0.7 seconds, and the accuracy of determining the direction is 6-18 minutes.

Another variant of the example is possible when one elongated signal is received for a duration of 2 ms, with a maximum range of 1200 km. Then the time of the circular survey will be 1.5 seconds, and fluctuations will not affect the accuracy of determining the direction, which can be 5 minutes. Thus, increasing the accuracy of determining the direction while reducing the viewing time improves the quality of the construction of the trajectories of rapidly changing objects. The device can be used in systems for determining the height and systems of sector review in the radar according to patent 2161807, including those with an increased signal repetition rate, where instead of a two-channel receiver, it is possible to use a single-channel one.

At the same time, a narrower emitter beam that spasmodically rotates with a phased antenna array emits two short or one elongated signal, which is received by a receiver with a synchronously continuously rotating wider radiation pattern, which can be rotated with respect to a narrow transmitting pattern to reduce the influence of local objects. In this case, to determine the range, the direction of arrival of the reflected signal is fixed, which coincides with the direction at the time of its emission.

The device can also be used in passive locators, where the value of the delay lines should be adjusted depending on the characteristics of the signals.

Claims (1)

A device for processing radar signals, consisting of a receiver with a rotating radiation pattern, an azimuth sensor, an amplitude to code conversion unit and a secondary processing unit, where the output of a receiver with a rotating radiation pattern is connected to the input of an amplitude to code conversion unit and an output group of an azimuth sensor is connected to a group of inputs a secondary processing unit, characterized in that a block of parallel delay lines, a subtractor, an encoder and an adder are introduced, while the group of outputs of the block is converted The amplitude in the code is connected to the second group of inputs of the subtractor and through a block of parallel delay lines connected to the first group of inputs of the subtractor having a group of outputs connected via an encoder to the first group of inputs of the adder, the second group of inputs of which and the group of outputs are respectively connected to the group of outputs of the azimuth sensor and with the second group of inputs of the secondary processing unit.

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