JPH0478209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pulse generator used in a transmitter for a pulse radar device, and particularly relates to a technique for generating multiple types of pulses having different pulse widths.

(Prior Art) As is well known, a pulse radar device is required to have a large coverage distance and a small minimum detection distance, but the two have contradictory characteristics. In other words, it is known that the coverage distance is proportional to the fourth root of the transmission power or the transmission pulse width, but since the transmission power depends on the capability of the transmission pipe and it is difficult to obtain the required value, the coverage distance is To extend the distance, it is necessary to increase the transmission pulse width. On the other hand, increasing the transmission pulse width increases the minimum detection distance. Therefore, in recent years, pulse radar devices have been developed and put into practical use that employ a composite method in which the transmitted pulses are composed of pulse trains of various pulse widths.

In other words, this pulse radar device transmits a combination of short pulses for short distances, short pulses for near coverage area, long pulses for long distances, and long pulses for long distances, and optimally combines these reflected signals. It is designed to provide uniform coverage from short distances to long distances. Note that in this case, for long pulses, a pulse compression technique is employed to obtain the required resolution by compressing the received pulse width.

The transmitter used in this type of pulse radar device includes, for example, as shown in FIG. 3, a transmitting tube 31, a beam power source 35, a collector power source 34, a pulse generator 36, an RF exciter 32, and an isolator 33.

The transmitting tube 31 consists of a grid modulation type amplifier tube such as a traveling wave tube (TWT), a klystron (KLYSTRON), or a TWYSTRON which is a combination of a traveling wave tube and a klystron, and the main body 3 is grounded.
1a, a collector 31b, an RF circuit 31c having the same potential as the main body 31a, a grid 31d, and a cathode 31e. RF circuit 31
An RF signal is input to the grid 31d side (input side) via an exciter 32, and an isolator 33 is provided to the collector 31b side (output side).

A required positive DC voltage is applied to the collector 31b by the collector power supply 34, and the cathode 3
A required negative DC voltage (E ₀ ) is applied to 1e by the beam power source 35. And grid 3
1d, a positive voltage (E ₁ ) and a negative bias voltage (E ₂ ) that determine the pulse amplitude based on the potential (E ₀ ) of the cathode 31e are applied by the pulse generation circuit 36 that is the object of the present invention.

As shown in FIG. 4, the pulse generator 36 includes two DC power supplies 41 and 42 connected in series,
It basically consists of a switcher 43, a pulse transformer 45, a drive circuit 46, and a tail biter circuit 47.

The positive terminal of the DC power supply (terminal voltage E ₁ ) 41 is connected to the power input side of the switcher 43, and the output terminal of the switcher 43 is connected to the grid 31d. Further, the negative terminal of the DC power source 41 is connected to the cathode 31e together with the positive terminal of the DC power source (terminal voltage E ₂ ) 42 and the negative terminal of the beam power source 35, and the negative terminal of the DC power source 42 and the switch 43
A resistor 47 is connected between the output terminals of.

Further, a tail biter circuit 48 is connected in parallel to the resistor 47 . The pulse transformer 45 has a plurality of 2
It has a secondary winding, and each switching element 44, 44, . . . constituting the switcher 43 is connected to each secondary winding. Further, the primary winding of the pulse transformer 45 has a drive circuit 4 that energizes the pulse transformer 45.
6 is connected, and a drive signal a is input to the drive circuit 46.

The drive signal a is a signal in which one short pulse and one long pulse repeat at a period T, as shown in FIG. 45 is energized. Therefore, each switching element 44, 44,...
In this case, it is turned on only during the pulse width periods of the short pulse and long pulse of the drive signal a, and turned off during the pulse rest period. Note that each pulse of the drive signal a is generated in synchronization with the RF signal b shown in FIG.

Each switching element 44, 44, . . . usually uses a high voltage transistor, a MOS type field effect transistor, or the like, and a predetermined number of switching elements are connected in series to increase the voltage resistance. Therefore, depending on the required breakdown voltage level, the switching 43 may be composed of one or two switching elements.

Next, the basic operation of the transmitter configured as described above will be explained with reference to FIG. FIG. 6 shows the pulse generator 3 for one pulse in the drive signal a.
6 is shown.

The cathode 31e of the transmitting tube 31 has a reference potential E ₀
is supplied by the beam power source 35, and the switch 43 is in a non-conductive state during the pulse rest period of the drive signal a. Therefore, the terminal voltage _E2 of the DC power supply 42 is applied to the grid 31d via the resistor 47. As a result, the potential of the grid 31d is biased in the negative direction by a voltage _E2 from the potential _E0 of the cathode 31e. As a result, the transmission tube 31 enters a non-conductive state in which the electron beam emitted from the cathode 31e does not reach the RF circuit 31c.

Next, when one pulse (either a short pulse or a long pulse) in the drive signal a is generated in synchronization with the RF signal b, the switch 43 becomes conductive, and the terminal voltage E of the DC power supply 41 is applied to the grid 31d. ₁ is applied via each switching element 44, 44, . . . of the switcher 43.

As a result, while the switch 43 is in the conductive state, the potential of the grid 31d is biased in the positive direction by a voltage _E1 from the potential _E0 of the cathode 31e.
That is, a high voltage grid driving pulse e is applied. As a result, the transmitting tube 31 becomes conductive, and the electron beam emitted from the cathode 31e exchanges energy with the RF signal b while transmitting energy to the RF circuit 31.
c and reaches the collector 31b. In other words,
The RF signal b is power amplified, and the required pulse power (RF signal output) c is outputted to the load side via the isolator 33.

At this time, in the pulse generator 36, the sixth
As shown in the figure, the tail biter circuit 48 is triggered by the trigger signal d generated in response to the falling of the drive signal a.
is driven, and the falling point of the high-voltage grid drive pulse e applied to the grid 31d becomes steep. Note that when the tail biter circuit 48 is not provided, the falling characteristic is shown by the broken line.

(Problems to be Solved by the Invention) Incidentally, in this type of pulse radar device, it is desirable that the waveform of the transmission pulse is a rectangular wave, but the waveform of the transmission pulse is specified by grid modulation type transmission. In this case, it is the waveform (rising edge, falling edge, sag, ripple, etc.) of the grid driving pulse applied to the grid, that is, the output waveform of the pulse generator.

A pulse generator generates multiple types of pulses with different pulse widths, for example, short pulses of several tens of nanoseconds or more.
1μs, and the long pulse is often 100μs or more. Therefore, in order to satisfy the above-mentioned requirements as a pulse generator, it is necessary to provide a means for transmitting a drive signal to a switcher and a wider band for the switcher. However, although there is no problem since the switcher originally has a wide band, it is difficult to make the pulse transformer used as a transmission means wide band. In other words, as a pulse transformer, the rise of a short pulse,
If a high frequency characteristic is emphasized with the main purpose of improving the fall characteristic, sag will occur in long pulses as shown in Figure 7a, and conversely, if a high frequency characteristic is emphasized with the main purpose of improving the falling characteristic If one with emphasized frequency characteristics is used, normal short pulses cannot be obtained as shown in FIG. 7b.

As a result, the characteristics of the pulse transformer cause problems such as deterioration of the transmitting tube and distortion of the transmitted pulses. In view of the problems of the conventional pulse generators described above, an object of the present invention is to generate a plurality of pulses with different pulse widths, such as short pulses for near-coverage and long pulses for far-coverage, even when each pulse is An object of the present invention is to provide a pulse generator for pulse radar that can generate pulses having an optimal waveform.

(Means for Solving the Problems) In order to achieve the above object, the pulse generator for pulse radar according to the present invention has a common A pulse generator for a pulse radar generated by a switching element, a first pulse transformer to which a drive signal for generating the short pulse for the near-coverage region is applied and having the same number of output circuits as the number of the switching elements; A second pulse transformer which is supplied with a drive signal for generating the long pulse for far-reaching and has the same number of output circuits as the number of switching elements, and one output from each of the first and second pulse transformers is inputted. and a plurality of adder circuits that output the plurality of outputs in a time-series manner, and each output of the plurality of adder circuits operates a corresponding one of the plurality of switching elements.

(Operation) The operation of the pulse generator for pulse radar configured as described above will be explained. The first pulse transformer is a drive signal for generating short pulses for the near range,
Further, the second pulse transformers are each driven by a drive signal for generating long pulses for far-covering. The output of each pulse transformer is arranged chronologically in a summing circuit, thereby activating a common switching element.

Here, since the first and second pulse transformers can have frequency characteristics suitable for the transmission of the pulse transformers that are in charge of each, the waveform of each pulse output through the common switching element has a rising edge and a rising edge. It becomes optimal with greatly improved descent, sag, ripple, etc.

(Embodiment) FIG. 1 shows a pulse generator for pulse radar according to an embodiment of the present invention. Components that are the same as those in FIG. 4 are designated by the same reference numerals and their explanations will be omitted.

This pulse generator for pulse radar uses a short pulse drive signal SP for generating short pulses for near coverage and a long pulse drive signal for generating long pulses for far coverage as drive signals for generating the required pulses. LP is input separately, and for each drive signal SP and LP, a short pulse drive circuit 11, a pulse transformer 12, and a long pulse drive circuit 13 are input.
and pulse transformers 14 are provided separately, and each output of the pulse transformers 12 and 14 is connected to a plurality of adder circuits 1.
5, 15, . . . are arranged in chronological order and input to corresponding ones of the plurality of switching elements.

Here, the pulse transformer 12 transmits short pulse signals, and its frequency characteristics emphasize high frequencies, and short pulses with steep rise and fall characteristics are transmitted to each switching element 44, 4.
4,... is input.

The pulse transformer 14 transmits a long pulse signal, and its frequency characteristic is such that the low frequency is emphasized, and the long pulse having a flat portion without sag is transmitted to each switching element 44, 44,
...is input.

Each of the switching elements 44, 44, . . . has extremely wide frequency characteristics as described above.

As a result, the grid driving pulse, that is, the output pulse, applied to the grid 31d of the transmitting tube 31 is
As shown in FIG. 2, short pulses are output as pulses with steep rises and falls, and long pulses are output as pulses with no sag in flat areas.

In the above embodiment, a case has been described in which two pulses, a short pulse for near-coverage and a long pulse for far-coverage, are generated, but the present invention is not limited to this, and it is possible to generate a larger number of pulses. Of course, the summary can also be used when doing so.

(Effects of the Invention) As detailed above, the pulse generator for pulse radar according to the present invention generates at least a plurality of short pulses for near-coverage and long pulses for far-coverage by a common switching element connected in series. In a pulse generator for a pulse radar, a first pulse transformer is provided with a drive signal for generating the short pulse for near coverage and has the same number of output circuits as the number of switching elements; and a first pulse transformer for generating the long pulse for far coverage. A second pulse transformer is provided with a drive signal for generating the switching element and has the same number of output circuits as the number of switching elements, and one output from each of the first and second pulse transformers is input, and the plurality of outputs thereof are outputted in time. The device includes a plurality of adder circuits that sequentially arrange and output outputs, and each output of the plurality of adder circuits operates a corresponding one of the plurality of switching elements, so that the first and second pulses Transformers that have frequency characteristics suitable for transmitting the pulses that they are responsible for can be used, and each output pulse waveform can be made into the optimal waveform, making it possible to significantly improve the pulse characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a pulse generator for pulse radar according to the present invention, and FIG.
FIG. 3 is a block diagram showing the configuration of a grid modulation type transmitter, FIG. 4 is a block diagram showing the configuration of a conventional pulse generator, and FIG. Figure 4 is a waveform diagram showing the drive signal that drives the conventional device, Figure 6 is a waveform diagram to explain the basic operation of the grid modulation type transmitter, and Figure 7 is the output from the conventional device shown in Figure 4. FIG. 3 is a waveform diagram showing pulses. 11, 13...Drive circuit, 12, 14...Pulse transformer, 15...Addition circuit, 43...Switcher, 44...Switching element.

Claims (1)

[Claims] 1. In a pulse radar pulse generator that generates at least a plurality of short pulses for near-coverage range and long pulses for far-coverage range by a common switching element connected in series; a drive signal for generating the short pulse for near-coverage range; a first pulse transformer which is supplied with a drive signal and has the same number of output circuits as the number of switching elements; a first pulse transformer which is supplied with a drive signal for generating the long pulse for far range and has the same number of output circuits as the number of switching elements; a second pulse transformer having; a plurality of adder circuits that receive one output each of the first and second pulse transformers and output the plurality of outputs in a time-series manner; A pulse generator for a pulse radar, characterized in that each output operates a corresponding one of the plurality of switching elements.