Radar equipment

Abstract

This prevents saturation of the amplification circuit within the radar device's receiving section. [Solution] The radar device of the present invention comprises a transmitting unit, a circulator, an antenna, a receiving unit, and a control unit that instructs the transmitting unit on the timing for transmitting a transmission signal. The receiving unit has an amplification circuit for amplifying a received signal and a variable voltage circuit that supplies a voltage to the amplification circuit for amplifying the received signal. The control unit instructs the timing for supplying a voltage to the variable voltage circuit so that the amplification circuit does not obtain a predetermined amplification gain when transmitting the transmission signal.

Description

Technical Field

[0001] The present invention relates to a radar device including a transmission unit, a circulator, an antenna, and a reception unit.

Background Art

[0002] Generally, a radar device includes a transmission unit, a circulator, an antenna, and a reception unit. The transmission unit outputs a transmission signal, the circulator sends the transmission signal to the antenna, the antenna transmits the transmission signal and receives the reflected wave of the transmitted signal as a reception signal, the circulator sends the reception signal to the reception unit, and the reception unit acquires the reception signal. The circulator is a component for sharing the antenna for transmission and reception. Most of the transmission signal is transmitted to the antenna, but a part of it leaks from the circulator to the reception unit. In addition, a part of the transmission signal transmitted to the antenna is reflected by the antenna and input to the reception circuit. The leakage of the circulator and the transmission signal reflected by the antenna are high-power inputs to the reception unit, which cause saturation of the output of the amplification circuit in the reception unit. When saturation occurs in the reception unit, there is a problem that it takes about several microseconds until the gain of the amplification circuit recovers (until it recovers to a state where the reflected wave can be normally amplified).

[0003] In order to address the above problems, techniques such as providing a variable attenuation circuit in the subsequent stage of a limiter circuit to reduce the saturation of the reception circuit, and providing a parallel circuit of a high-power circuit and a low-power circuit are known. Further, in Patent Document 1, the abstract states that '... an STC (Sensitivity Time Control) variable attenuator 4a is inserted into the reception system, and the maximum attenuation amount of this variable attenuator 4a is set to a value that does not saturate the reception system even when a signal of the maximum level is input to the reception system, and the attenuation amount of the variable attenuator 4a is maximized during the transmission period to prevent the saturation of the reception system due to the leakage of the transmission signal.' In Patent Document 2, the abstract states that '... by controlling the AGC to prevent the saturation of the reception signal in the receiver, the dynamic range of the reception system can be effectively utilized.' [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-174542 [Patent Document 2] Japanese Patent Publication No. 2010-230461 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, conventional technology has the following problems: (1) If a variable attenuation circuit is provided before the amplification circuit of the receiving section, insertion loss increases. (2) If a parallel circuit of a high-power circuit and a low-power circuit is provided in the receiving section, the circuit becomes complex. (3) Patent document 1 has a variable attenuator for the STC in the receiving section, which increases insertion loss, making it difficult to reduce noise and simplify the circuit. (4) In patent document 2, if an excessive input is input to the receiving section, the amplification circuit saturates even if the AGC is controlled, making it difficult to sufficiently prevent the saturation of the received signal. Therefore, even if the above-mentioned conventional technology is used, if the output saturates, the problem that occurs during the period when the small reflected wave cannot be received, while the transmission signal is still present even after transmission has stopped, until the gain of the amplification circuit gradually recovers over a period of several microseconds, is not sufficiently solved.

[0006] In view of the above circumstances, the present invention aims to prevent saturation of the amplification circuit in the receiving section of a radar device. [Means for solving the problem]

[0007] The radar system of the present invention comprises a transmitter, a circulator, an antenna, and a receiver. The transmitter outputs a transmission signal, the circulator sends the transmission signal to the antenna, the antenna transmits the transmission signal and receives the reflected wave of the transmission signal as a received signal, the circulator sends the received signal to the receiver, and the receiver acquires the received signal. The radar system of the present invention also comprises a control unit that instructs the transmitter on the timing of transmitting the transmission signal. The receiver has an amplification circuit that amplifies the received signal and a voltage variable circuit that supplies a voltage to the amplification circuit to amplify the received signal. The control unit instructs the timing of supplying voltage to the voltage variable circuit so that the amplification circuit does not obtain a predetermined amplification gain when transmitting the transmission signal. [Effects of the Invention]

[0008] According to the radar device of the present invention, the supply voltage is controlled so that the amplification circuit does not amplify the received signal as intended when the transmitting unit transmits the transmission signal. Therefore, it is possible to prevent the amplification circuit from becoming saturated. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram showing an example of a radar system configuration. [Figure 2] A diagram showing an example of the receiver's configuration. [Figure 3] A diagram showing a first example configuration of an amplifier circuit and a variable voltage circuit. [Figure 4] A diagram showing a second example configuration of an amplifier circuit and a variable voltage circuit. [Figure 5] A diagram showing a third configuration example of an amplifier circuit and a variable voltage circuit. [Figure 6] A diagram showing a fourth configuration example of an amplifier circuit and a variable voltage circuit. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described in detail below. Components having the same function will be given the same number, and redundant explanations will be omitted. [Examples]

[0011] Figure 1 shows an example of the radar system configuration. Figure 2 shows an example of the receiver configuration. Figure 3 shows a first configuration example of the amplifier circuit and voltage variable circuit, Figure 4 shows a second configuration example of the amplifier circuit and voltage variable circuit, Figure 5 shows a third configuration example of the amplifier circuit and voltage variable circuit, and Figure 6 shows a fourth configuration example of the amplifier circuit and voltage variable circuit.

[0012] The radar system 100 comprises a transmitter 110, a circulator 130, an antenna 140, a receiver 120, a control unit 150, and a waveguide 160. The transmitter 110 outputs a transmission signal. The circulator 130 sends the transmission signal to the antenna 140 via the waveguide 160. The antenna 140 transmits the transmission signal and also receives the reflected wave of the transmission signal as a received signal, sending it to the circulator 130 via the waveguide 160. The circulator 130 sends the received signal to the receiver 120. The receiver 120 acquires the received signal. However, the transmission signal leaking from the circulator 130 and the transmission signal reflected by the antenna 140 are generated at the same time that the transmitter 110 transmits the transmission signal, and are input to the receiver 120.

[0013] The receiving unit 120 includes an amplification circuit 200, a variable voltage circuit 300, a mixer 400, a local oscillator 500, and the like. The amplification circuit 200 amplifies the received signal. The variable voltage circuit 300 supplies voltage (power) to the amplification circuit 200 for amplification of the received signal based on a voltage control signal described later. The internal signal, which is the output of the amplification circuit 200, is an amplified received signal while the variable voltage circuit 300 is supplying voltage to the amplification circuit 200 for amplification of the received signal. On the other hand, when the variable voltage circuit 300 is not supplying voltage to the amplification circuit 200 for amplification of the received signal, the internal signal is an attenuated received signal or a received signal that is not sufficiently amplified. The mixer 400 and the local oscillator 500 are configured to obtain an intermediate frequency (IF) output from the high-frequency internal signal, and existing technology can be used.

[0014] The control unit 150 instructs the transmitter unit 110 on the timing to transmit a transmission signal. The control unit 150 also instructs the voltage variable circuit 300 on the timing to supply voltage to the amplifier circuit 200 so that it does not achieve a predetermined amplification gain. More specifically, the control unit 150 instructs the voltage variable circuit 300 to stop supplying voltage before the transmitter unit transmits the transmission signal. For example, the control unit 150 can instruct the voltage variable circuit 300 to stop supplying voltage at the time when the reception of the reflected wave of the previously transmitted transmission signal is complete. The control unit 150 then instructs the voltage variable circuit 300 to start supplying voltage a predetermined amount of time before the end of transmission of the transmission signal. "Definite amplification gain" refers to the amplification gain when the amplifier circuit 200 is operating normally. "Definite time" is basically the time from when the voltage supply begins until the amplifier circuit 200 reaches the predetermined amplification gain, which is usually several hundred nanoseconds (for example, around 200 nanoseconds). The time can be determined appropriately for each amplifier circuit 200 used. However, since reflected waves from nearby targets have high power, it may be possible to obtain a sufficient IF output even if the amplification gain does not reach the "predetermined amplification gain". The "predetermined time" may also be determined taking into account the power of the reflected wave. The time from when the voltage variable circuit 300 stops supplying voltage until the amplifier circuit 200 can no longer obtain the predetermined amplification gain is about 100 to 300 microseconds. Generally, there is an interval of several hundred microseconds or more between the time when the reception of the reflected wave of the previously transmitted signal is completed and when the next transmission signal is transmitted, so this does not cause any problems.

[0015] In the example shown in Figure 3, the voltage supplied by the variable voltage circuit 300 is the voltage supplied to the output side of the amplification circuit 200. The amplification circuit 200 includes an amplifier 210 that is powered by applying a voltage to its output terminal. For example, the amplifier 210 may contain a fixed-bias field-effect transistor circuit, or it may contain a self-bias field-effect transistor circuit. The amplification circuit 200 also includes a capacitor 220 for inputting only the AC component to the amplifier 210. The variable voltage circuit 300 includes, for example, a NOT gate 320, a field-effect transistor 310, capacitors 330 and 340, and an inductor 360. Capacitor 330 is a capacitor for DC-isolating the output side of the amplification circuit 200 from ground, and capacitor 340 is a capacitor for outputting only the AC component. The inductor 360 is provided to prevent the AC component contained in the output from the amplification circuit 200 from flowing to the drain power supply side.

[0016] For example, the transmit control signal is set to High when the transmit signal is sent and Low when it is not sent. Similarly, the voltage control signal is set to High when no voltage is supplied (similar to the transmit control signal's transmission timing) and Low when voltage is supplied (similar to the transmit signal's non-transmission timing). The NOT gate plays the role of converting the input to High when voltage is supplied in such cases. If the voltage control signal is Low when no voltage is supplied and High when voltage is supplied, the NOT gate 320 is unnecessary. When High is input to the gate of the field-effect transistor 310, voltage is supplied to the output side of the amplifier circuit 200. The same applies to the examples shown in Figures 4 to 6 below.

[0017] In the example of FIG. 4, the voltage supplied by the voltage variable circuit 301 is the power supply voltage that supplies power to the amplifier circuit 201. The amplifier circuit 201 includes an amplifier 211 having a terminal for supplying power, capacitors 220 and 230, and a coil 260. The amplifier 211 is of a type that operates by inputting the power supply voltage to the terminal for supplying power. The capacitor 220 is a capacitor for inputting only the AC component, and the capacitor 230 is a capacitor for outputting only the AC component. The coil 260 is provided to AC-isolate the terminal for supplying power of the amplifier 211 from the drain power supply. The voltage variable circuit 301 includes, for example, a NOT circuit 320, a field effect transistor 310, and a capacitor 330. The functions of the NOT circuit 320, the field effect transistor 310, and the capacitor 330 are the same as those of the voltage variable circuit 300.

[0018] In the example of FIG. 5, the amplifier circuit 202 has a field effect transistor 210 with its gate as the input side, its drain as the output side, and its source grounded, a capacitor 220, and a coil 270. The voltage supplied by the voltage variable circuit 300 is the voltage supplied to the drain side of the field effect transistor 210. A bias voltage is applied to the gate of the field effect transistor 210 via the coil 270. The coil 270 is provided to prevent the AC component of the received signal from flowing to the gate bias power supply side. The circuit formed by the field effect transistor 210 may be a fixed bias with its source grounded. This is because a fixed bias is preferable for amplifying high-frequency low-noise signals of several GHz or more. The voltage variable circuit 300 is the same as that in FIG. 3.

[0019] In the example of FIG. 6, the amplifier circuit 203 has a field effect transistor 210 with its gate on the input side, drain on the output side, and source grounded, a capacitor 230, and a coil 280. The voltage supplied by the voltage variable circuit 303 is a bias voltage supplied to the gate side of the field effect transistor 210. In the amplifier circuit 203, a voltage is supplied to the drain of the field effect transistor 210 from the drain power supply via the coil 280. The coil 280 is provided to prevent the AC component of the amplified received signal from flowing to the drain power supply side. In this example, the characteristic that the field effect transistor 210 cannot obtain a predetermined amplification gain unless an appropriate bias voltage is supplied to the gate is utilized. The voltage variable circuit 303 includes, for example, a NOT circuit 323, a field effect transistor 313, resistors 341, 342, 343, a capacitor 350, and a coil 360. The capacitor 350 is a capacitor for inputting only the AC component of the received signal. The coil 360 is provided to prevent the AC component included in the received signal from flowing to the source power supply side or the like. When the field effect transistor 313 is OFF, the potential difference between the positive voltage power supply and the negative voltage power supply is divided by the resistors 341, 342, 343, and the bias voltage supplied to the gate side of the field effect transistor 210 is set so that the amplifier circuit 203 cannot obtain a predetermined amplification gain. When the field effect transistor 313 is ON, the potential difference between the positive voltage power supply and the negative voltage power supply is divided by the resistors 342, 343, and the bias voltage supplied to the gate side of the field effect transistor 210 is set so that the amplifier circuit 203 can obtain a predetermined amplification gain. The voltages of the positive voltage power supply and the negative voltage power supply and the resistors 341, 342, 343 may be appropriately determined in consideration of the bias voltage supplied to the gate side of the field effect transistor 210. The circuit formed by the field effect transistor 210 may be a fixed bias with its source grounded. This is because a fixed bias is preferable for high-frequency low-noise amplification of several GHz or more.

[0020] According to the radar device 100, at the timing when the transmitting unit 110 transmits a transmission signal, the supply voltage is controlled so that the amplification circuits 200, 201, 202, and 203 do not enter the state where they are amplifying the received signal as intended. Therefore, it is possible to prevent the amplification circuits 200, 201, 202, and 203 from becoming saturated.

[0021] The effects will be explained in more detail. The control unit 150 controls the voltage supplied to the amplification circuits 200, 201, 202, and 203, and controls them to be turned OFF during transmission and ON when transmission stops. With this method, the period until the original amplification gain of the amplification circuits 200, 201, 202, and 203 is obtained is short, and control can be performed in conjunction with the cessation of transmission. It is preferable to place a limiter before the amplification circuits 200, 201, 202, and 203 in the receiver unit 120, but since it is not necessary to place a variable attenuation circuit as in conventional technology, insertion loss can be reduced. The number of components in the receiver unit 120 can be reduced, and the circuit can be simplified. The radar device 100 can also obtain these effects. [Explanation of symbols]

[0022] 100 Radar system 110 Transmitter 120 Receiver 130 Circulator 140 Antenna 150 Control Unit 160 Waveguide 200, 201, 202, 203 Amplifier Circuit 210,211 Amplifier 210, 310, 313 Field-effect transistors 220, 230, 330, 340, 350 Capacitors 260, 270, 280, 360 coils 300, 301, 303 Variable Voltage Circuit 320,323 NOT circuit 341, 342, 343 resistors 400 Mixer 500 Local Oscillators

Claims

1. It comprises a transmitting unit, a circulator, an antenna, and a receiving unit. A radar device comprising: a transmitting unit that outputs a transmission signal; a circulator that sends the transmission signal to the antenna; the antenna that transmits the transmission signal and receives the reflected wave of the transmission signal as a received signal; the circulator that sends the received signal to the receiving unit; and the receiving unit that acquires the received signal. The transmitting unit also includes a control unit that instructs the timing for transmitting the transmission signal, The receiving unit includes an amplification circuit for amplifying the received signal and a variable voltage circuit that supplies a voltage to the amplification circuit for amplifying the received signal. The control unit instructs the timing for supplying the voltage to the variable voltage circuit such that the amplification circuit does not obtain a predetermined amplification gain when transmitting the transmission signal. A radar device characterized by the following features.

2. A radar device according to claim 1, The control unit instructs the variable voltage circuit to start supplying the voltage a predetermined amount of time before the end of transmission of the transmission signal. A radar device characterized by the following features.

3. A radar device according to claim 1 or 2, The aforementioned voltage is the voltage supplied to the output side of the amplification circuit. A radar device characterized by the following features.

4. A radar device according to claim 1 or 2, The aforementioned voltage is the power supply voltage that supplies power to the amplification circuit. A radar device characterized by the following features.

5. A radar device according to claim 1 or 2, The aforementioned amplification circuit has a field-effect transistor with its gate as the input, its drain as the output, and its source grounded. The voltage mentioned above is the voltage supplied to the drain side. A radar device characterized by the following features.

6. A radar device according to claim 1 or 2, The aforementioned amplification circuit has a field-effect transistor with its gate as the input, its drain as the output, and its source grounded. The voltage is the bias voltage supplied to the gate side. A radar device characterized by the following features.

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