JPS60195470A - Stc circuit of radar receiver - Google Patents

Abstract

PURPOSE:To generate a desired STC signal by storing in advance a data of an STC (sensitive time control) signal curve adapted to an input signal to a receiver, reading out a suitable data in accordance with a state, and converting it to an analog. CONSTITUTION:A data of an STC signal adapted to an input signal to a receiver is stored in a memory 1, a stored data on an address of the memory 1 is read out successively by an address control part 2, an address is stepped by receiving a trigger signal, and the stepping is stopped by receiving an STC effective distance range signal. Also, a digital-analog converting part 3 converts a read-out data from the memory 1 to an analog, and executes an adjustment of an STC level. Aubsequently, a control signal which has superposed a DC portion of a gain adjusting signal on the STC signal which is adjusted by an adder 4 is supplied to an amplifier of a receiving part. In such a way, a signal corresponding to a state is selected, and a disturbance of a sea surface reflection can be eliminated.

Description

[Detailed description of the invention]

The present invention provides a radar receiver STO (Sensor IV)
i tyTime 0ontrol) circuit, especially STO
Signal curve? This is related to the ST 0 circuit of the radar receiver that generates the desired 5T (N signal) from the data of this STO signal curve stored in the memory in advance and stored in the memory. fdM in radars used on ships
Depending on the condition of the f-plane, strong reflected interference called sea surface reflected interference occurs. In order to suppress this sea surface reflection disturbance, 870
The circuit is used. The intensity of the reflected signal input to the radar receiver is the fourth or third power of the distance.Example 1. The farther away the

[7. Sensitivity of the receiver? In order to increase the sensitivity of the receiver as the distance increases, one circuit of VCST (VCST) is operated to enable detection of all target signals.In practical use, the receiver intermediate frequency amplifier A signal adjusted by each adjustment signal to the 8 TO signal waveform shown in Fig. 1 is applied as a control signal to the first stage of the control signal.
), Arrow B Minimum profit 1: I range Q (Min gain
duration), arrow 0 slope adjustment (Rec
The conventional 5T (1 circuit is shown in Fig. The part of the slope adjustment shown in
The sensitivity decreases in inverse proportion to the power of As shown in Figure 2, the sensitivity in range D'''C is too low, so even if there is a target in that area, no image is displayed. Therefore, it is necessary to create a sensitivity characteristic curve that is adapted to the input signal. In addition, each time the receiving section of the receiver was changed due to improvements, the STO circuit had to be changed, and furthermore, if you wanted to use all of the STO signal curves that differed depending on the usage situation, you would have to change the STO circuit. The object of the present invention is to solve the above-mentioned drawbacks. The 8TO circuit of the radar receiving section can generate the desired STO signal by storing the data in advance in the memory, extracting appropriate STO signal curve data from the memory according to the usage situation, and converting the curve into analog. The STO circuit of the radar receiver according to the present invention will be explained below with reference to all the drawings. FIG. 3 shows the configuration of an embodiment of the STO circuit of the radar receiver according to the present invention. FIG. 4 is a time chart explaining the operation of FIG. 3 (7), and FIG. , a 2-digit address control section, 3 a digital-to-analog conversion section, and a 4-digit auxiliary device.In the memory 1, data of the STO signal curve adapted to the input signal to the receiver is stored in advance. STO signal curve data is obtained by generating a signal with a waveform that changes in inverse proportion to the fourth power of the distance or the cube of the distance using a generator, etc., and digitizing the generated signal using an all-analog-to-digital converter. The STO signal curve stored in memory 1 is generated using a signal generator, etc., so any STO signal waveform can be stored and Therefore, the STO signal signal curve can be adjusted to suit the input signal to the receiver.The address control section 2 outputs all the addresses of the memory 1.This causes the address control section 2 to output all the addresses of the memory 1. The data of the STO signal curve stored in rl is IIk' (next read IL).The address control section 2 sequentially increments the address by disabling all the trigger signals, and changes the address by receiving the STO effective distance range signal. stop the progress of The digital-to-analog converter 3 reads n from the memory 1.
, 8 'I'' All the data of the O signal curve are converted into analog data.Then, in this digital-to-analog converter 3, the S
TO level;! I14 adjustment, that is, the ST'O level adjustment shown in FIG. The adder 4 is a circuit that outputs the rM flow of the gain adjustment signal to the 8TC signals that have been subjected to level adjustment, and performs gain control adjustment. The signal is added as a control signal to the first stage of the intermediate frequency amplifier in the receiving section. At the same time as the signal is emitted, a trigger signal is sent to the address control unit 2 (Figure 4: =). Through this process, the address control unit 2 increments the address for memory 1. By sending a read memory control signal to (Fig. 4A), memories 1 to 8 TO
Data of the signal curve is read out sequentially. This IL et al.'s S
The data of the TO Ig curve is converted into an analog signal by the digital-to-analog converter 3, and the STO level is adjusted. As time elapses, when the STO effective distance range signal is sent to the address control section 2 (FIG. 4), the incrementing of the addresses in the memory 1 is stopped. Since the read memory control signal is still sent to the memory 1, the data of the STO signal curve at the stopped address is continuously read from the memory 1 (F in FIG. 4). Bladder to memory 1,
When the initial memory control signal is no longer sent (Gl in Figure 4), the address of address control section 2 is cleared. In this way, the voltage for memory 1 is set to L, (7) 1 cycle is completed. However, when transmitting again from the radar antenna and firing all Zels q4, m
At 1 o'clock, a trigger signal is sent to the address control section 2.
The next cycle starts by turning. The STO signal converted into analog and STO level-adjusted by the digital-to-analog converter 3 is converted into a gain focus by the adder 4 (the jH flow of the rectified signal is superimposed on it to Fig. 4), and the gain control is adjusted. A control signal 111 is sent to the first stage of the intermediate frequency amplifier of the receiving section. Figure 5 is an embodiment of the specific circuit shown in Figure 3, and includes the memory 1, address control section 2, and digital circuit shown in Figure 1.
The analog converter 3 and the adder 11 correspond to the four adders shown in FIG. The address control section 2 includes a flip-flop 11, a mono multivibrator 12, a counter 13, and a switching circuit 1.
4. It is composed of 15 pieces of Fritz. Flip-flop 1 to which the trigger signal is input controls the oscillation of the mono multivibrator 12 and the counting of the counter 13.
control each. The mono multivibrator 12 includes a mono multivibrator with a time constant made up of a capacitor 16 and a resistor 18, and a mono multivibrator with a time constant of a capacitor 17 and a switching circuit 140, and a mono multivibrator with a resistor IL of n and resistors 19 to 22 determined by the capacitor 17 and the switching circuit 140. These two mono multivibrators are connected in series to form an oscillator with variable oscillation frequency. Counter 13 is memory 1
The flip-flop 15 controls the entire STO effective distance range shown in FIG. The digital-to-analog converter 3 includes a digital-to-analog converter 24 with a converter. This digital-to-analog converter 24 with a multiplier has a resistor 2
Based on the STO level adjustment signal inputted through 5 sessions, the signal is read out from memory 1 and multiplied by 8T (1 signal curve data by a predetermined factor of 1q 5 times), and the data is all analogized and the STO level is adjusted. An operational amplifier 25 is used in the adder 4, and the S1'0 signal input to the operational amplifier 25, the DC component gain adjustment signal, and the entire operational amplifier 25 are added (7th. The operation in Fig. 5 is the same as the operation explained in Fig. 3. By switching the switch 26, the upper address A7 of the memory 1 changes, and the data of the STO signal curve stored in the memory 1 can be read in two ways. That is, the switch 26 is an STO signal changeover switch, and if the upper address of the memory 1 is changed by this switch 26, the STO signal for the number of sheets can be generated from the memory 1. 1. ST depending on the situation
By generating an O signal, it becomes possible to distinguish between waves occurring on the sea surface and targets. In the above description, the memory 1 in which the data of the STO signal curve is stored usually uses a ROM, but an EBPROM or a RAM can also be used instead of the ROM. In this case, the user has to memorize the data of the STO signal curve, and the STO signal curve with the reception sensitivity characteristics desired by the user is stored.
A signal curve is obtained. Also, is the receiving section usually a linear amplifier? However, it is also compatible with log amplifiers, which have become increasingly practical in recent years, so if you store all the data of the STO signal curve for log amplifiers in memory 1, you can easily connect linear amplifiers and log amplifiers. It can also be easily switched and used. The digital-to-analog converter used in the digital-to-analog converter 3 does not necessarily have to be equipped with a multiplier (it is also possible to adjust the desired 8'PO level with a separate configuration). As explained above, the S of the VC and STO circuit of the present invention
Since the generation of the TO signal curve is realized using digital memory, it can easily correspond to the characteristics of various receivers, and the STO signal curve can be created arbitrarily. All can be selected, thus making it possible to remove interference from sea surface reflections.

[Brief explanation of drawings]

Figure 1 is a diagram of the 5T waveform, Figure 2 is a characteristic curve diagram for clarifying the difference between the sensitivity characteristics of the receiver and the input color signal, and Figure 3 is a diagram of the radar according to the present invention. FIG. 4 shows a time chart for explaining the operation of FIG. 3, and FIG. 5 shows the configuration of an embodiment of the STO circuit of the receiver. 1#''t memory, 2 is address control section,
3 digit digit/l-analog converter% 4 and add 1L
11tj, flip-flop, 12ir, mono multivibrator, 13 is counter, 14Vtν) switching circuit, 1
5 is a flip-flop, 24 is a digital-to-analog conversion circuit with a multiplier, 25 is an amplifier, and 26 is a switch. Patent applicant Anritsu Electric Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] In the 870 circuit of a radar receiver that lowers the receiver sensitivity immediately after the transmission pulse is emitted and completely suppresses the waves reflected from the sea surface at a short distance:
An address control section 2 which stores in advance the data of the 8TO signal curve adapted to the input signal to the receiver and reads out the STO signal curve stored in the memory 1; 870 circuit of a radar receiver, which is characterized in that it has a digital-to-analog converter 3 for converting the data of the STO signal curve extracted from the memory 1 into analog.