JPH0457982B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an improvement in a main bang suppressor circuit for suppressing the main bang of a radar or the like.

[Prior Art] FIG. 4 shows a circuit configuration of a radar including a main bang suppressor according to the prior art. In the figure, a magnetron 3 transmits a transmission signal of a predetermined length in response to a trigger signal from a transmitter 2. This transmission signal is radiated from the antenna 1 via the circulator 4. The reflected wave of the radiated radio wave is detected again by the antenna 1, passes through the circulator 4 and the limiter 5, is amplified by the receiver 6, and is displayed on the display 7. The transmission signal of the magnetron 3 is leaked to the limiter 5 by the circulator 4 even when the antenna 1 between the limiter 5 and the antenna 1 is turned off, and is inputted to the receiving section 6. This signal is called a main bang. The main bang signal is displayed as a brightly shining part, for example, in the center of the cathode ray tube of the display section 7, and even if there is an object to be detected in this part, for example, it cannot be detected. For this reason, general radars are equipped with a main bang suppressor to reduce the output level of the receiver 6 when the magnetron outputs a signal. In FIG. 4, a one-shot multivibrator 15 is triggered by a transmission signal from the magnetron 3 to obtain a pulse signal with a predetermined time width, and the level is adjusted by a level adjustment control circuit 16 and applied to the receiver 6. 5a, 5b, 5c, and 5d show timing charts of waveforms of each circuit shown in FIG. 4. In the figure, FIG. 5a is a transmission trigger output from the transmitter 2. FIG. 5b shows the transmission signal of the magnetron 3. The main bang signal has substantially the same waveform as this transmission signal. FIG. 5c shows the magnetron current flowing through the magnetron 3. FIG. 5d shows the waveform of the main bang suppressor signal transmitted by the one-shot multivibrator 15. The conventional device is configured so that the time from the rise time t2 to the fall time t4 of the waveform shown in FIG. 5d is equal to the time width of the transmission signal shown in FIG. 5b, so as to suppress the received image due to the main bang. ing.

[Problem to be solved by the invention] In the waveform shown in FIG. 5b, from time t2 to time t4
If the time duration is shorter than the time width of the transmission signal shown in FIG. There is a possibility that it will be suppressed by the suppressor signal and cannot be displayed. Therefore, the time width of the main bang suppressor signal, which is a signal for suppressing the main bang, must be equal to the time width of the transmission signal. In the conventional technique shown in FIG. 4, the time width of the main bang suppressor signal is adjusted to be equal to the time width of the main bang by adjusting the constants of the elements of the one-shot multivibrator 15. In practice, this is often done at the site where the radar is installed and is extremely complicated. Further, the time width of the radar transmission signal generally differs depending on the measurement range of the radar, and for example, it differs for each of the short range, the first intermediate range, the second intermediate range, and the long range. Therefore, the time width of the main bang suppressor signal must be adjusted to suit each. However, in the conventional technology, such adjustment is very complicated and is generally adjusted only for the main bang in a short measurement range.

[Means for Solving the Problems] The radar main bang suppressor of the present invention obtains an envelope output of the magnetron output by a first waveform shaping circuit, and obtains an envelope output of the magnetron output from the magnetron output waveform by a second waveform shaping circuit. The configuration is such that a signal having a steep rise characteristic and a gradual fall characteristic is obtained, and the level of the signal is set to a predetermined value by a level setting circuit.

[Operation] The time width of the main bang suppressor signal is proportional to the time width of the magnetron output.

[Embodiment] FIG. 1 shows a block diagram of a radar to which the present invention is applied. The magnetron 3 generates a transmission signal in response to a trigger signal transmitted from the transmitter 2, and the signal is radiated from the antenna 1 via the circulator 4. The reflected wave from the object to be measured is antenna 1.
The signal is detected by the circulator 4 and the limiter 5, is amplified by the receiver 6, and is displayed on the display 7, for example, on a cathode ray tube. The magnetron current flowing through the magnetron 3 is rectified by a magnetron current waveform shaping circuit 8, which is a first waveform shaping circuit, and ringing etc. are removed, resulting in an output with an envelope waveform of the magnetron oscillation output.
This output is input to a second waveform shaping circuit 10 that generates a main bang suppressor signal. The output of the second waveform shaping circuit 10 is the level setting circuit 1
1 and is applied to the receiving section 6 as a main bang suppressor signal. Figure 2 shows the circuit diagram. In the figure, a voltage output waveform corresponding to the magnetron current is detected across an output resistor 17 of a magnetron current waveform shaping circuit 8, which is a first waveform shaping circuit. Next, a rectifier circuit consisting of capacitors 18 and 19 and a diode 20 removes high frequency components to obtain a positive pulse waveform. This output is input to the amplifier 21 of the second waveform shaping circuit 10. The second waveform shaping circuit 10 includes an integrating circuit consisting of a resistor 23 and a capacitor 24 connected to the output terminal of an amplifier 21, and a diode 22 connected in parallel with the resistor 23 and in the forward direction with respect to the output of the amplifier 21. It is configured. The output of the integrating circuit is amplified by an amplifier 25 and input to a second integrating circuit consisting of a resistor 26 and a capacitor 27. The output of the second integrating circuit is applied to the receiving section 6 via the level adjusting circuit 11.

Next, the operation of this embodiment will be explained. The output of the magnetron current waveform shaping circuit 8 applied to the amplifier 21 is turned into a signal having a steep rise characteristic by the diode 22 and is input to the amplifier 25 . The output waveform of the amplifier 25 is made into a falling characteristic with a gentle slope by an integrating circuit consisting of a resistor 26 and a capacitor 27, is adjusted to a predetermined level by a variable resistor VR of a level setting circuit 11, and is applied to the receiver 6. FIG. 3 shows the waveform of the main bang suppressor signal with the level set. In the figure, waveforms 30 and 31 are the main bang suppressor signal waveforms at the minimum level and maximum level, respectively, and are actually adjusted and set to a predetermined level between the two at the time of manufacturing the radar.

[Effects of the Invention] According to the present invention, the main bang suppressor signal applied to the receiving section 6 is a signal obtained by waveform shaping of the magnetron current, and therefore has a time width corresponding to the magnetron current. Moreover, since its rise and fall characteristics are set by the constants of the elements of the integrating circuit, they are always proportional to the time width of the magnetron transmission signal.
Therefore, the time width of the main bang suppressor signal is set at the time of design and does not need to be adjusted. In addition, even if the time width of the transmitted signal changes when the radar measurement range changes, the time width of the main bang suppressor signal also changes accordingly, so that appropriate main bang suppression can be achieved in any range. can get.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a circuit diagram showing the main parts of the invention, Fig. 3 is a waveform diagram showing the output of the level adjustment circuit, and Fig. 4 is a waveform diagram showing the output of the level adjustment circuit.
The figure is a block diagram of a radar according to the prior art, and FIGS. 5a, 5b, 5c and 5d are waveform diagrams showing signals at various parts of the radar block diagram shown in FIG. . 8: Magnetron current waveform shaping circuit, 10: Second waveform shaping circuit, 11: Level setting circuit, 2
2: Diode, 23: Resistor, 24: Capacitor.

Claims (1)

[Claims] 1. A first waveform shaping circuit that obtains a waveform of an envelope output of a magnetron output; A signal having a steep rising characteristic and a gradual falling characteristic is obtained from the output signal of the first waveform shaping circuit. A main bang suppressor for a radar, comprising: a second waveform shaping circuit; and a level setting circuit that sets the output level of the second waveform shaping circuit to a predetermined level to provide an output for main bang suppression. 2. Claim 1, wherein the second waveform shaping circuit includes a diode connected in parallel to the resistor of an integrating circuit consisting of a resistor and a capacitor.
The main bang suppressor of the radar mentioned in section.