JP2015145803A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grasp the degradation state of an electronic tube without causing oscillation failure and without specifying a physical quantity that a cathode has lost, and to effectively and economically use the electronic tube taking corrective measures to extend its life.SOLUTION: Provided is a radar device using an electronic tube as an oscillation device for emitting a microwave, the radar device, by a video degradation input switch 10 and an instable oscillation detection/consumption time calculation circuit 15, specifying the degradation state of a transmitted signal, raising the heater voltage of the electronic tube stepwise in accordance with the degradation state, applying a high voltage to the heater of the electronic tube temporarily, and applying, to the electronic tube, a heater voltage having a different change rate that is set for each pulse width of a short to a long pulse.

Description

  The present invention relates to a radar apparatus having an electron tube such as a magnetron, and more particularly to the life of an electron tube that outputs microwave transmission signals having different pulse widths.

  In recent years, the reliability of electron tubes such as magnetron has been greatly increased, and the life of the tubes has been increased. The life of radar tubes used in pleasure boats has been designed to exceed 20,000 hours. In many cases, it has a long life design that exceeds the life of the device itself.

  On the other hand, for radar devices such as ships, airplanes, etc. that travel frequently over long distances, and radar devices that continuously monitor day and night, the operating time of one year may exceed 8500 hours, and the life of the electron tube is radar. It may not be reached by the end of its service life and may need to be replaced. In such radars, regular replacement is often performed, and the exchanged electron tubes are discarded even though they can be used because their actual use time is shortened with respect to the guaranteed lifetime. It was uneconomical. In addition, when the electron tube is used to the end of its lifetime, there is a problem that a risk of reaching the lifetime in an important aspect arises.

  Conventionally, in order to know the accumulated usage time of the electron tube, a configuration as shown in FIG. 7 is used, and when the power source 1 is turned on, the energization time is accumulated by the accumulated hour meter 2, Usage time is managed. However, since the actual consumption time of the electron tube differs depending on various conditions, the effect of the various conditions is not considered in the simple energization time, and the actual consumption time is not shown.

  An electron tube is usually used as a device having an oscillation and amplification function using a cathode that emits electrons, and a material having a lowered work function such as oxide or oxide is used for the cathode that emits electrons. Impregnated metal or the metal itself is used. In either case, exhaustion occurs due to the emission of electrons, and when a certain level of exhaustion occurs, the emission capability decreases and oscillation and amplification become unstable, resulting in a lifetime. Therefore, it is possible to predict the remaining life by knowing this emission capability.

  For example, in a magnetron, which is one of electron tubes, the remaining life can be known from the detection of the emission capability, including those used for heating. That is, it is difficult to directly measure the emission capacity with the electron tube actually mounted on the device, and the equipment for measurement becomes complicated, so the heater voltage is lowered by some means, the cathode temperature is lowered, The emission capability can be determined by detecting unstable oscillation such as mode jump at that time. Even in the examples of Patent Documents 1 to 5 below, the heater voltage is lowered from the normal use condition, the emission capability is lowered, and the stable oscillation voltage is determined as unstable oscillation at a voltage close to the normal use condition. Detecting what will be.

  On the other hand, in the magnetron disclosed in Patent Document 6, an insulating portion whose surface is insulated is arranged to face the cathode, and the cathode receives a material lost during operation by the insulating portion, and the resistance of the material deposited on the insulating portion. From this, the amount of material lost during operation of the cathode is estimated, and the remaining life is predicted.

JP 05-021153 A JP 09-320480 A JP-A-10-223150 Japanese Patent Laid-Open No. 2001-082744 JP 2008-300259 A British patent GB-2447777B

  However, as described in Patent Documents 1 to 5, in an operation that causes an oscillation failure (unstable oscillation), when a mode jump that is an example of unstable oscillation occurs, a frequency component other than the fundamental wave is generated. Oscillation will occur, and in the radar apparatus, it may be radiated from the antenna and cause radio interference in the vicinity.

  In addition, the radar device has a high-sensitivity receiver that can receive extremely weak signals from distant targets. When a frequency component different from the fundamental wave is input due to unstable oscillation, The limiter cannot prevent it, and it has the risk of destroying the receiving system.

  On the other hand, in the case of the above-mentioned Patent Document 6, since a large amount of electron emitting material is accumulated in a large magnetron, if a device for detecting a change in resistance is incorporated in the wall surface in the magnetron, a change in resistance can be easily detected. With a small-sized magnetron for radar, the amount of electron-emitting material deposited is small, and it is impossible to grasp the exact amount of consumption.

  Furthermore, conventionally, an electron tube that has been determined to have a life span is replaced only at an early stage, and the life of the electron tube has not been extended. If measures and measures for this life extension are taken, the electron tube is effective. And can be used economically.

  The present invention has been made in view of the above problems, and its purpose is to grasp the deterioration state of the electron tube without causing a defective oscillation, and without specifying the amount of material lost by the cathode, and to determine the lifetime. An object of the present invention is to provide a radar device that can effectively and economically use an electron tube by taking measures against extension.

In order to achieve the above object, the invention according to claim 1 specifies a deterioration state of a transmission signal (oscillation wave) generated from the electron tube in a radar device using the electron tube as an oscillation device that oscillates a microwave with a pulse. And a control circuit for adjusting the heater voltage of the electron tube based on a deterioration state obtained from the deterioration detection circuit.
The invention according to claim 2 is a deterioration input means for inputting the deterioration state to the control circuit when the image definition on the radar scope is deteriorated as the deterioration detection circuit, and the instability of the electron tube. An unstable oscillation detection circuit that detects oscillation, or a consumption time calculation circuit that determines deterioration based on the consumption time of the electron tube calculated based on the integration time for each pulse width of the transmission signal is provided.

The control circuit according to a third aspect of the invention is characterized in that a high voltage is temporarily applied to the heater of the electron tube in accordance with the deterioration state of the transmission signal.
The control circuit according to a fourth aspect of the invention is characterized in that a heater voltage having a different rate of change (increase rate) set for each pulse width is applied to the electron tube in accordance with a deterioration state of a transmission signal.

  According to the above configuration, for example, when it is determined that the image definition on the scope is visually deteriorated, when the deterioration state of the transmission signal is input by operating a deterioration input unit such as a switch, the control circuit is, for example, a heater for an electron tube Control to increase the voltage. As a result, the ability of the electron tube is restored, and good target capture is maintained by normal transmission signal output.

Further, even when a high voltage is temporarily applied to the heater of the electron tube by the control circuit, the unstable emission is suppressed by improving the electron emission capability.
Further, the electron emission capability (or consumption of the electron emission material of the electron tube as a function of temperature and current) differs depending on the pulse width (short pulse, middle pulse, long pulse, etc.) of the transmission signal used. Therefore, in the heater voltage variably adjusted as described above, it is possible to accurately improve the electron emission capability by applying a voltage with a different rate of change set by the pulse width.

According to the radar device of the present invention, by using a deterioration detection circuit that specifies a deterioration state of a transmission signal generated by an electron tube without causing a defective oscillation and without specifying the amount of material that the cathode has lost. The deterioration state of the electron tube can be grasped, and the life of the electron tube can be extended by adjusting the heater voltage of the electron tube based on the deterioration state obtained from the deterioration detection circuit. It becomes possible to use it.
Furthermore, according to the configuration of claims 3 and 4, even when the transmission signal has deteriorated due to the lifetime of the electron tube, it is possible to extend the lifetime under the transmission signal of an appropriate output with improved electron emission capability. There is an effect of becoming.

It is a circuit block diagram which shows the 1st structure of the radar apparatus based on the Example of this invention. It is a circuit block diagram which shows the 2nd structure of the radar apparatus of an Example. It is a circuit block diagram which shows the structure in the case of detecting unstable oscillation with the 2nd structure of an Example. It is a graph which shows an example which adjusts the heater voltage of an electron tube in an Example. It is a figure which shows the example of a characteristic when the electron emission capability is improved in the electron tube of an Example. It is a graph which shows the heater voltage which changed the rate of change for every different pulse width in the electron tube of an Example. It is a figure which shows the circuit structure which calculates consumption time in the conventional radar apparatus.

  FIG. 1 shows a radar apparatus having a first configuration according to an embodiment. This radar apparatus is an image deterioration input for a judge to input deterioration of a transmission signal (microwave pulse) by electrical on / off. A switch 10 and a control unit 12 that receives a deterioration signal from the switch 10 are provided. In the radar device, the captured target is displayed on the scope, and when a person viewing the scope determines that the video has deteriorated, the video signal is input to the control circuit 12 by operating the video deterioration input switch 10. The degradation state of is input.

  When the deterioration signal is input, the control circuit 12 adjusts the heater voltage of the electron tube. For example, increasing the heater voltage, applying a high heater voltage temporarily, and applying a heater voltage with a different rate of change set for each pulse width are executed.

  FIG. 2 shows a radar apparatus having a second configuration according to the embodiment. This radar apparatus forms and outputs a transmission signal, and performs processing for displaying an image of the target based on the received signal from the target. Received signal processing circuit 14 for detecting unstable oscillation (decrease in detection capability) from the data processed by this received signal processing circuit 14 or an unstable oscillation detection / consumption time calculation circuit for calculating the consumption time of the electron tube 15. A control unit 12 that receives a deterioration signal from the detection circuit 15 is provided. The reception signal processing circuit 14 displays an image of the target captured by processing the reception signal on the scope.

  FIG. 3 shows a configuration when the unstable oscillation detection / consumption time calculation circuit 15 detects unstable oscillation (decrease in detection capability). As shown in FIG. The microwave output thus transmitted passes through the transmission output transmission system 19 and is transmitted from the antenna 20. A coupler 21 that couples to a part of the transmission output transmission system 19 and picks up a part of the signal, an RF output detector 22 that detects the picked-up signal, and compares the detected signal with a comparison reference level. A comparison reference level 23 for outputting the comparison reference level, a trigger input unit 25 for inputting a detection trigger, and a synchronization circuit 26 are provided. Note that the comparison reference level may be linked to each pulse width or anode current. In order to detect a state in which the comparison reference level has decreased at a constant rate with respect to the original output level, You may set so that it may fall to about 70% of a detection level.

  According to the above configuration, the comparison circuit 23 compares the detection signal from the RF output detector 22 with the comparison reference level in the comparison circuit 23, thereby detecting unstable oscillation. That is, since a pulse signal is used in the radar device, the signal from the trigger input unit 25 is shaped by the synchronization circuit 26 and sent to the comparison circuit 23. A drop in level (decrease in detection capability) can be detected, thereby detecting deterioration of the transmitted signal.

As another example of the detection circuit 15, a configuration may be used in which the consumption time (or remaining life) of the electron tube is detected by integrating the use time (use time for each pulse width) of the electron tube. Deterioration of the transmission signal can be detected.
In other words, the radar device is configured so that the measurement distance can be switched by a range (distance range) switch. For example, short pulses are used for short distances, middle pulses are used for medium distances, and long pulses are used for long distances. Is done. When such a short pulse, middle pulse, and long pulse are used, the operating time for each of the short pulse, middle pulse, and long pulse is accumulated, and the coefficient (consumption) is set for each accumulated time for each pulse width. The coefficient according to the speed) is multiplied, and the total can be calculated as the consumption time of the electron tube.

  The deterioration signal detected in this way is output to the control circuit 16. As with the control circuit 12, when the deterioration signal is input, the control circuit 16 adjusts the heater voltage of the electron tube, increases the heater voltage, temporarily applies a high heater voltage, A heater voltage with a different rate of change set in is given.

Next, adjustment of the heater voltage described above will be described.
The control circuits 12 and 16 determine appropriate timing from the deterioration signal and variably control the heater voltage of the electron tube. For example, since the electron emission capability is high at the beginning of use of the electron tube, stable oscillation can be performed even when the cathode temperature is low. If the cathode temperature is increased unnecessarily at the beginning of use, the emission of the electron emission material is severely shortened. . Therefore, in the embodiment, the heater voltage is adjusted in accordance with the input deterioration signal to operate so as to compensate for the emission capability. In the case of FIG. 1, the deterioration signal input by the video deterioration input switch 10 is correct. 2, in the case of FIG. 2, the heater voltage is adjusted when the deterioration signal is input by the detection circuit 15.

FIG. 4 shows an example of adjustment of the heater voltage. As shown in the figure, when a deterioration signal is input at the consumption time (operation time) t ₁ during operation with a heater voltage of 5 V, for example, raised to about 5.5V, when entered into _{t 2,} and so raised to about 5.8 V, is increased stepwise voltage. As a result, the reduced emission capability can be restored.

  Next, even when a high voltage is temporarily applied to the heater voltage, the control circuits 12 and 16 determine an appropriate timing from the deterioration signal and execute the application of the high voltage. That is, in an electron tube, the electron emission ability may be reduced due to a change in the electrical characteristics of the cathode surface used, or the degree of vacuum may deteriorate due to gas generation in the tube. When the heater voltage is temporarily increased, the cathode temperature rises, the cathode is flushed, or the getter effect is generated. Thereby, although the electron emission capability is temporary, it is possible to recover and restore the original characteristics. For radars that need to be detected, if the performance is restored by applying a high heater voltage in a short period of time when life is reached in an important situation, sudden blackout will be eliminated and the reliability of the radar will be increased and guaranteed. The service life can be extended.

  In the embodiment, a voltage that is flushed temporarily higher than the heater voltage that is normally used is applied. By increasing the cathode temperature for only a short time, it is possible to improve the electron emission capability which has been reduced by the lifetime. For example, in the case of an oxide cathode, it is possible to increase the electron emission capability from 150% before application to about 400% just by raising the temperature to about 10 to 35% higher than the normal cathode temperature for about 30 to 120 seconds. It has been. This level of improvement in electron emission capability has a significant effect on electron tubes that have started to cause unstable oscillation, and unstable oscillation is suppressed.

  FIG. 5 shows an example of characteristics when the electron emission capability is improved in the electron tube, that is, an increase in current when a heater voltage 32% higher than usual is applied for 60 seconds. In addition, it can be seen that the current increased to 171% after the application compared to before the application, and the electron emission ability was improved.

Next, as described above, a description will be given of applying a heater voltage having a different rate of change for each pulse width.
As described above, in the radar apparatus, the measurement distance is switched by the range switch, and for example, a short pulse, a middle pulse, and a long pulse are used. That is, in general, a radar device uses a short pulse to shorten the transmission time for short-range target acquisition, detects a reflected signal immediately after the start of pulse transmission, and uses a long pulse for long-range target acquisition. The signal power is increased to detect a reflected signal in the distance.

  When the pulse width of the transmission signal is different as described above, the temperature of the cathode differs depending on the oscillation condition such as the duty ratio (pulse width / cycle), and the electron emission capability differs greatly (the electron tube function as a function of temperature and current). Since the consumption of the electron-emitting substance varies depending on the pulse width), the heater voltage reduction amount is first changed for each signal having a different pulse width to enable stable oscillation. For example, in a radar apparatus with a peak output of 25 kW, assuming that the duty ratios of long pulses, middle pulses, and short pulses are set to 0.001, 0.0005, and 0.0002 in order, the average output is 25 W in order. 12.5W and 5W, which are significantly different. Therefore, when the current flows through a normal cathode, the temperature rise and the cathode temperature rise due to back bombardment differ greatly (the effect of back bombardment increases as the pulse width becomes longer), and the heater voltage is lowered to be appropriate. It turns out that it is better to use temperature.

  However, at the end of the lifetime, the electron emission capability decreases with the consumption of the electron tube, and the effect on the signal oscillation varies depending on the pulse width. Therefore, in the embodiment, the rate of change of the adjusted heater voltage is changed with a different pulse width. As a setting, stable oscillation is realized. The control circuits 12 and 16 determine an appropriate timing from the deterioration signal, and apply a heater voltage increased at different change rates (tilts) set for each pulse width to the electron tube.

  FIG. 6 shows an appropriate heater voltage with respect to the consumption time (deterioration state) in each pulse width of an electron tube with a peak output of 25 kW. As shown in FIG. 6, the pulse width is short pulse, middle pulse, long pulse, and so on. As the value becomes longer, the proper heater voltage decreases, and when the consumption time (operating time) becomes longer, the proper heater voltage gradually increases. In particular, the proper heater voltage becomes a higher voltage when operated with a short pulse. In other words, when the average output power is changed by changing the pulse width, the required voltage for heating by the heater is changed.

  Therefore, in the embodiment, when the deterioration state (consumption time) is detected, the control is performed by changing the increase rate (slope) according to the pulse width so that the proper heater voltage in FIG. 4 is obtained. The most ideal stable oscillation can be obtained and the life can be extended.

  As described above, according to the embodiment, the deterioration state of the electron tube used in the radar is specified, the function of automatically extending the life of the electron tube, and the use can be extended even when the conventional life is reached. A function can be provided. As a result, the radar does not black out due to sudden life, which can contribute to safety such as navigation, and the electron tube can be used to the end of the life, making economic contribution and environmental contribution. It becomes possible.

1 ... Power switch, 2 ... Integrated hour meter,
10 ... Video deterioration input switch,
12, 16 ... control unit, 14 ... received signal processing circuit,
15: Unstable oscillation detection / consumption time calculation circuit,
18 ... Electron tube, 22 ... RF output detector,
23: Comparison circuit.

Claims (4)

In a radar device that uses an electron tube as an oscillation device that oscillates microwaves in pulses,
A deterioration detection circuit for specifying a deterioration state of a transmission signal generated from the electron tube;
And a control circuit for adjusting a heater voltage of the electron tube based on a deterioration state obtained from the deterioration detection circuit.   As the deterioration detection circuit, when it is determined that the video definition on the radar scope has deteriorated, deterioration input means for inputting the deterioration state to the control circuit, unstable oscillation detection for detecting unstable oscillation of the electron tube 2. The radar apparatus according to claim 1, further comprising a consumption time calculation circuit that determines deterioration based on a consumption time of the electron tube calculated based on a circuit or an integration time for each pulse width of a transmission signal.   3. The radar apparatus according to claim 1, wherein the control circuit temporarily applies a high voltage to the heater of the electron tube according to a deterioration state of the transmission signal.   3. The radar apparatus according to claim 1, wherein the control circuit applies a heater voltage having a different rate of change set for each pulse width to the electron tube in accordance with a deterioration state of a transmission signal.

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