JPS60190881A - Gain control apparatus - Google Patents

Abstract

PURPOSE:To achieve the improvement of an approximate value, the security of maintenance capacity, the enhancement of temp. characteristics and reproducibility and presettable capacity while making the information of a specific distance clear, in redar, by combining an STC circuit with a D/A converter and a calculator. CONSTITUTION:A pre-trigger pulse is obtained from a transmitter and used as a signal for start and a clock allows an address counter 10 to count. An arbitrary STC wave form is preliminarily written in the n-address of ROM8 corresponding to the distance R(n) at the time of the n-th clock pulse from the pre- trigger pulse and the address of ROM8 is indicated by the counter 10 to read the content thereof while this content is converted by a D/A converter 9 to control a receiving level. As a result, a repeated same STC wave form can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a radar gain control device for detecting targets such as aircraft or ships.

Now, let T be the time from when the transmitter is emitted, until it reaches the target, is reflected once, and returns.
The distance R to the target object is expressed by .Since (2) is known, the distance R can be obtained by knowing 9 hours T. By the way, the reflected signal from the target has the property of being strong at short distances and weak at long distances, so the gain control device uses a temporal sensitivity adjustment (temporal sensitivity adjustment) that changes the reception level according to the distance. Sensitivity Tim = C
ontrol:5TC) to keep the receiver level within an appropriate range.

[Prior art]

FIG. 1(a) is a diagram showing an example of a conventionally used STC circuit, and (1) is an STC amplitude volume.

(2a) (2b) is an amplifier, (3) is a transistor, (
4) is the STC slope Boriuno'+(5) is Kano (Sita), (61 (71 is resistance).

In Figure 1 (a), the DC voltage generated by varying the 8TC amplitude volume (1) is amplified by the amplifier (2a), and the transistor (3) is used to control the STC slow volume (4). is varied to change the discharge time constant CR of the capacitor (5) and resistor (7), and the amplifier (
2b) to obtain 8TC waveform ports. Turning the STC amplitude volume (1) changes the strength of the STC, and turning the 8TC slope volume (4) changes the distance covered by the STC. In addition, Fig. 1(b) shows the pre-trigger generated from the transmitter and synchronized with the transmitted pulse, and the ST obtained from this.
It is a waveform diagram of C waveform.

By the above operation, the STC circuit shown in FIG. 1(a) can control the reception level and avoid saturation of the receiver.

By the way, the intensity of the radar reflected signal is R-4 of the distance R.
Depending on the object, it may be proportional to R-3, R',
In the above STC circuit, the waveform is approximated by the resistors +61' and +71 and the discharge time constant of the canister (5).

Since the waveform is changed using two controls: the STC amplitude volume (1) and the STC slope volume (4), the influence of temperature is large, and reproducibility tends to be lacking, making adjustment difficult.

The approximation was not good. Furthermore, R-4, R-3, R-
The drawback was that nine circuits had to be complicated in order to prepare a 7° curve and multiple waveforms.

[Summary of the invention]

By using a ROM and a D/A converter, the present invention improves reproducibility, approximation, and temperature characteristics, which are the problems of conventional gain control devices.

And any waveform can be preset.

Furthermore, by adding a computer, the reception level at a specific distance is optimized, and by prioritizing only information at this distance, it is possible to reduce the amount of information to be processed and simplify the test.

[Embodiments of the invention]

FIG. 2(a) shows a block configuration of the present invention.

Similar to the conventional STC circuit, the signal is obtained from the transmitter and used as a signal to start the clock.

The address counter 00) is counted. With the length of one cycle of this clock pulse, the distance R(n) from the reciprocating trigger pulse to the nth clock pulse is R(n) - 22 (where V is the speed of the radio wave). Therefore, in advance, an arbitrary STC waveform is set at a distance R
(n), write it to address n of ROM+81, read the contents by specifying the address of ROM181 using the address counter, and then write the contents to the D/A converter (9).
) performs D/A conversion, and the reception level is controlled by this output port. The above operation makes it possible to repeatedly generate the same STC waveform. 9 For example, when setting multiple waveforms such as R-4 (c), R-3), and R-' (e), ROM +1υ, yen, (13
Prepare 1.

Just switch this.

As described above, the present invention provides the STC circuit of the gain control device with ROM+81 and 4. By using the converter (9), a step-like waveform is created that steps every ILSB.9For example, if the full scale F8 of the D/A converter is 5V and the number of bits is 8, the ILSB becomes FS/
2g, and the maximum error is expressed as I L8 B/2, so the error with respect to the ideal curve at any point is 10 mV.
Guaranteed within. Furthermore, since the number of bits can be increased by increasing the number of bits, it is possible to generate an STC waveform with a better approximation than the conventional method.

Further, it is possible to change the waveform according to the waveform simply by switching the ROM+81. Furthermore, since there is no need to adjust the volume like in the past, maintainability is ensured, and the influence of temperature changes is reduced, which improves reproducibility.

Figure 3 (,) is the result of adding a computer circle to Figure 2 (,) above. From this computer, a constant that does not change over time, at any time nt, other R4, R3 , Rho, and a signal G that controls switching to the above constants.

In addition, the settings of the above constants and the settings of distance R(n) are
By inputting externally using a keyboard, etc.

Information on a specific distance can be easily obtained at the optimum level.

〔Effect of the invention〕

As described above, according to the present invention, by storing the s'i'c waveform in advance in the ROM+8+ and further adding the computer 04), compared to the conventional circuit.

In addition to improving approximation, ensuring maintainability, improving temperature characteristics and reproducibility, and being presettable, it has the advantage of being able to clarify information at a specific distance where information is most needed.

[Brief explanation of the drawing]

FIG. 1(a) is a circuit diagram showing an example of a conventional STC circuit. Figure 1(b) is a waveform diagram for explaining the operation of Figure 2(a), and Figure 2(a) and ? p: Figure 3 (a) is a block diagram showing this invention, Figures 2 (b) and 3 (b) are
FIG. 3 is an operation waveform diagram of the present invention. In the figure, (1) is the STC amplitude poly, (2a)
, (2b) is an amplifier, (3) is a transistor, (4)
is the STC slope volume, (5) is the capacitor, (6
) is the resistance of the STC amplitude volume i71 is the resistance of the STC slow volume, (8) (I3) hI? OM, +
91 is D/A: 17 converter, (10) is address counter, (xB is R waveform, ttaun'' waveform,
Q4) is a calculator. Note that in FIG. 1, the same or corresponding parts are designated by the same reference numerals. Agent Masuo Oiwa Figure 1 (cL) Figure 2: R (n) E Shi S Talk ≦ F Minister Shig Gi Cao Chu Tomi Official Sky Wealth - Acupuncture Dause Yu Wu Enemy Japan Conflict - 4 - Day Q Salmon Endurance
Ku〈−＜−〈−←〈− = 9 S, s, ridge ku 6 groan

Claims (1)

[Claims] Lower the receiver level for reflected waves from short-range targets,
In addition, in a gain control device having an STC circuit that controls the receiver level according to the target distance so as to raise the receiver level for reflected waves from a long-range target, an arbitrary STC waveform is preset over a distance R ( R which is stored corresponding to n)
OM and a computer that outputs constants to optimize the receiver level at a specific distance, control switching with the ROM output, and set the specific distance and the constant, and a transmitter buri trigger. an address counter that counts clock pulses and specifies the address of the ROM for the distance R(n) at the time of the nth clock pulse; and storage information of the address specified by the address counter that is output information of the ROM. D to convert to analog
1. A gain control device characterized in that the above STC circuit is constructed from a /A converter.