Weather radar equipment

Abstract

The present invention provides a weather radar system capable of preventing the input of a transmit gate signal with a duty cycle greater than a predetermined value. [Solution] A weather radar device 1 that acquires weather information by emitting radar pulse waves when the transmit gate signal is ON, comprising: a gate width detection unit 31 that detects the time the transmit gate signal is ON, where the ratio of the time the transmit gate signal should be ON to the period during which the radar pulse waves should be periodically emitted is a specified duty cycle; and a gate mask unit 32 that blocks the transmit gate signal after it has been turned ON, wherein the gate mask unit 32 blocks the transmit gate signal such that the ratio of the time detected by the gate width detection unit 31 to the sum of the time detected by the gate width detection unit 31 and the time to be blocked is the specified duty cycle.

Description

Technical Field

[0003]

[0001] This invention relates to a weather radar device.

Background Art

[0002] A weather radar device emits radar pulse waves and detects the intensity of reflected waves / echoes from rain clouds and rain to obtain weather information (see, for example, Patent Document 1). In order to detect rain clouds and rain over a wide range (about 400 km), the transmitter that emits radar pulse waves needs to deliver a large amount of power. For example, in a klystron tube, 250 kW is required instantaneously, and in a solid-state pulse radar using the currently mainstream FET device GaN-HEMT (gallium nitride - high electron mobility transistor), 5 kW of transmission power is required instantaneously.

[0003] However, since a weather radar is a pulse radar, it is only necessary to input the power of the device only at the moment when a pulse is sent. Therefore, in a solid-state radar, as shown in FIG. 4, in addition to the pulse signal (seed signal) to be amplified, a transmission gate signal for controlling the gate voltage of the FET is input, and control is performed to apply the gate voltage only at the moment when a pulse is emitted. As a result, power consumption can be reduced and damage to the device can be prevented.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As shown in Figure 5, the duty cycle is defined as the ratio (τ / T) of the time τ during which the transmit gate signal is input and on, relative to the period T during which the transmit gate signal is repeatedly turned on (the repetition period of the radar pulse). Since the transmit gate signal is input from a device other than the transmitter, there is a risk that a signal with an abnormal duty cycle may be input due to malfunction or degradation. Furthermore, if a transmit gate signal with a duty cycle greater than a predetermined value is input, the gate voltage will be applied for a long time, which may cause the device to overheat and be damaged.

[0006] Therefore, the present invention aims to provide a weather radar device that can prevent the input of a transmit gate signal with an abnormally large duty cycle. [Means for solving the problem]

[0007] To achieve the above objective, the invention described in claim 1 is a weather radar device that obtains weather information by emitting radar pulse waves when a transmit gate signal is ON, comprising: a gate width detection unit that detects the time the transmit gate signal is ON, where the ratio of the time the transmit gate signal should be ON to the period during which the radar pulse waves should be periodically emitted is a predetermined duty cycle; and a gate mask unit that blocks the transmit gate signal after the transmit gate signal has been turned ON, wherein the gate mask unit blocks the transmit gate signal such that the ratio of the time detected by the gate width detection unit to the sum of the time detected by the gate width detection unit and the time to be blocked is the predetermined duty cycle.

[0008] The invention described in claim 2 is characterized in that, in the weather radar device described in claim 1, when the time detected by the gate width detection unit reaches a predetermined time, the gate mask unit blocks the transmission gate signal such that the ratio of the predetermined time to the sum of the predetermined time and the blocking time becomes the specified duty cycle. [Effects of the Invention]

[0009] According to the invention described in claim 1, the transmit gate signal is interrupted such that the ratio of the time detected by the gate width detection unit to the sum of the time detected by the gate width detection unit and the interruption time becomes a specified duty cycle. Therefore, the duty cycle of the transmit gate signal can always be kept below a constant (specified duty cycle). In other words, it is possible to prevent the input of a transmit gate signal with a large duty cycle (abnormal), and to prevent the device from being damaged by overheating due to the gate voltage being applied for a long time.

[0010] According to the invention described in claim 2, when the time the transmit gate signal is on reaches a predetermined time, the transmit gate signal is shut off so that the ratio of the predetermined time to the sum of the predetermined time and the shut-off time is less than or equal to a specified duty cycle. In other words, the time the transmit gate signal is on is limited to a predetermined time, and the duty cycle of the transmit gate signal is kept below a certain level (specified duty cycle). This prevents the input of a transmit gate signal longer than the predetermined time, or a transmit gate signal with a large (abnormal) duty cycle, and prevents the device from being damaged by overheating due to the gate voltage being applied for a long time. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic block diagram showing the transmitter side of a weather radar device according to an embodiment of the present invention. [Figure 2] This diagram illustrates the gate mask time of the weather radar transmitter shown in Figure 1. [Figure 3] Figure 1 shows the state in which a long-duration transmit gate signal is input to the weather radar transmitter (a), and Figure 1 shows the state in which the transmit gate signal following this signal is blocked (b). [Figure 4] This diagram shows how radar pulses are output in conventional weather radar systems using a transmit gate signal and a seed signal. [Figure 5]This diagram illustrates the duty cycle in conventional weather radar systems. [Modes for carrying out the invention]

[0012] The present invention will be described below based on the illustrated embodiments.

[0013] Figure 1 is a schematic block diagram showing the transmitter side of a weather radar device 1 according to an embodiment of this invention. This weather radar device 1 emits radar pulse waves to detect the intensity of reflected waves and echoes from rain clouds and rain, and observes and predicts weather conditions (acquires weather information). Here, since the basic configuration of the weather radar device 1 is the same as known and existing weather radar devices, the different configuration (transmitter side) will be mainly described below.

[0014] First, as in conventional systems, when the seed signal (pulse signal) and transmit gate signal are input to the transmitter 3 from the seed signal generator 2, the transmitter emits a radar pulse wave when the transmit gate signal is ON (only for the time it is input and ON). In the case of solid-state radar, as in conventional systems, the amplifier 33 is equipped with a FET (Field Effect Transistor), and when the transmit gate signal is input and ON from the seed signal generator 2, a gate voltage is applied to the FET only for the time it is ON, and an amplified pulse signal (seed signal) is output.

[0015] In addition to this basic configuration, the transmitter 3 is equipped with a gate width detection unit 31 and a gate mask unit 32.

[0016] The gate width detection unit 31 is a circuit that detects the time the transmit gate signal is ON. That is, when the transmit gate signal is input and turned ON from the seed signal generator 2, it detects the length of time the transmit gate signal is ON in real time.

[0017] The gate mask unit 32 is a circuit that blocks the transmission gate signal for a gate mask time Tm, which will be described later, after the transmission gate signal is turned on. That is, after the gate width detection unit 31 detects the input and turn-on of the transmission gate signal, the gate of the transmission gate signal is closed so that an abnormal transmission gate signal, which will be described later, is not input and turned on to the amplifier 33 (the gate voltage is not applied to the FET for a long time).

[0018] At this time, first, for the time obtained by adding the time detected by the gate width detection unit 31 (the time from the rising edge to the falling edge of the on state) and the blocking time, the transmission gate signal is blocked so that the ratio of the time detected by the gate width detection unit 31 is below the specified duty ratio. Here, the specified duty ratio is the ratio of the time during which the transmission gate signal should be input and turned on (the time during which the radar pulse wave should be emitted) to the period during which the radar pulse wave should be periodically emitted. Explained in FIG. 2, for the time T obtained by adding the time τ during which the transmission gate signal is on (the time detected by the gate width detection unit 31) and the gate mask time Tm (the blocking time), the transmission gate signal is blocked so that the duty ratio p, which is the ratio of the time τ during which the transmission gate signal is on, is below the specified duty ratio (a predetermined value). That is, the transmission gate signal is blocked for such a gate mask time Tm.

[0019] For example, in FIG. 3(a), when the specified duty ratio is 1 / 10, during normal times when the gate ON time (the on time of the transmission gate signal) is appropriate, Duty ratio p = gate ON time / (gate ON time + gate OFF time) = 1 / 10 This holds true. On the other hand, when an abnormal gate (a transmission gate signal with a long on time) occurs, if the transmission gate signal is not blocked, the duty ratio p will be as follows and will be longer than the specified duty ratio of 1 / 10. Duty ratio p = abnormal gate time / (abnormal gate time + gate OFF time) In FIG. 3(a), the rising period of the gate ON is constant.

[0020] Therefore, it blocks the transmission gate signal following the transmission gate signal with a long on-time. At this time, Duty ratio p = abnormal gate time τ / (abnormal gate time τ + gate mask time Tm) it blocks the transmission gate signal only for the gate mask time Tm such that the duty ratio becomes the specified duty ratio of 1 / 10. That is, as shown in Fig. 3(b), it blocks the transmission gate signal for the gate mask time Tm = 9τ. As a result, in this figure, the on-inputs of the three transmission gate signals following the transmission gate signal with a long on-time are blocked. In this case, the time (period) from the transmission gate signal with a long on-time to the next transmission gate signal that is on-input becomes longer than normal, but only some periods of a large number of radar pulse waves become abnormal, and the influence on the function of the weather radar device 1 is small.

[0021] By always performing such blocking processing, when the on-time of the transmission gate signal is normal, only the gate OFF is blocked, and the on-input of the transmission gate signal is not blocked and is input to the amplifier 33 at a duty ratio below the specified duty ratio. On the other hand, when the on-time of the transmission gate signal is long, as described above, the transmission gate signal following this transmission gate signal is blocked and is input to the amplifier 33 at a duty ratio below the specified duty ratio. Thus, even if the on-time of the transmission gate signal fluctuates, it is always input to the amplifier 33 at a duty ratio below the specified duty ratio. Therefore, even when the on-time (time width for emitting the radar pulse wave) of the transmission gate signal input from the seed signal generator 2 is changed, it is always possible to input it to the amplifier 33 at a duty ratio below the specified duty ratio.

[0022] Furthermore, when the time detected by the gate width detection unit 31 reaches a predetermined time, the gate mask unit 32 cuts off the transmit gate signal so that the ratio of the predetermined time to the sum of the predetermined time and the cutoff time (gate mask time Tm) becomes the specified duty cycle. In other words, the transmit gate signal is cut off so that the transmit gate signal is not input to the amplifier 33 (FET) for longer than the predetermined time, and the duty cycle p becomes the specified duty cycle. Here, the predetermined time is the time during which the FET may be damaged if the gate voltage is applied to the FET for longer than this predetermined time, and is set to be longer than the on-time of the transmit gate signal that is expected to be input from the seed signal generator 2.

[0023] Specifically, when the time detected by the gate width detection unit 31 (on time of the transmit gate signal) reaches a predetermined time, the transmit gate signal is cut off. Duty cycle p = predetermined time / (predetermined time + gate mask time Tm) The transmit gate signal is blocked for a gate mask time Tm such that the specified duty cycle is met.

[0024] In a weather radar device 1 with this configuration, the transmit gate signal is interrupted such that the ratio of the time detected by the gate width detection unit 31 to the sum of the time detected by the gate width detection unit 31 and the interruption time becomes the specified duty cycle. Therefore, the duty cycle p of the transmit gate signal can always be kept below a constant (specified duty cycle). In other words, it is possible to prevent the input of a transmit gate signal with a large duty cycle p (abnormal), and to prevent the device FET from being damaged by overheating due to prolonged application of gate voltage.

[0025] Furthermore, when the time the transmit gate signal is on reaches a predetermined time, the transmit gate signal is shut off so that the ratio of the predetermined time to the sum of this predetermined time and the shut-off time becomes the specified duty cycle. In other words, the time the transmit gate signal is input and on is limited to a predetermined time, and the duty cycle p of the transmit gate signal is kept below a certain level (specified duty cycle). As a result, it is possible to prevent the input of a transmit gate signal longer than the predetermined time, or a transmit gate signal with a large (abnormal) duty cycle p, and to prevent the device FET from being damaged by overheating due to prolonged application of the gate voltage.

[0026] Although embodiments of this invention have been described above, the specific configuration is not limited to the embodiments described above, and any design changes, etc., that do not depart from the gist of this invention are also included. For example, in the embodiments described above, the case in which the specified duty cycle is unique and constant was described, but the specified duty cycle may be made changeable, in which case the transmit gate signal is interrupted so that the specified duty cycle becomes the changed specified duty cycle. [Explanation of Symbols]

[0027] 1 Weather radar equipment Type 2 signal generator 3 Transmitter 31 Gate width detection unit 32 Gate mask section 33 Amplifier

Claims

1. A weather radar device that emits radar pulse waves when the transmission gate signal is ON to acquire weather information, The duty cycle is defined as the ratio of the time during which the transmit gate signal should be turned on to the period during which the radar pulse wave should be emitted periodically. A gate width detection unit that detects the time during which the transmission gate signal is ON, The system includes a gate mask unit that blocks the transmission gate signal after the transmission gate signal has been turned on, The gate mask section blocks the transmit gate signal such that the ratio of the time detected by the gate width detection section to the sum of the time detected by the gate width detection section and the blocking time becomes the specified duty cycle. A weather radar device characterized by the following features.

2. When the time detected by the gate width detection unit reaches a predetermined time, the gate mask unit blocks the transmit gate signal such that the ratio of the predetermined time to the sum of the predetermined time and the blocking time becomes the specified duty cycle. The weather radar device according to feature 1.

Images