An aircraft on-board DME ranging device

Abstract

The present invention provides an aircraft airborne DME ranging device, including a DME rangefinder. The DME rangefinder includes a CPU, a frequency synthesizer, a transmitter, a receiver, a circulator, an antenna, a feedback circuit, an automatic gain control circuit, and an anti-interference circuit. The CPU is connected to the frequency synthesizer and the automatic gain control circuit. The frequency synthesizer is respectively connected to the transmitter and the receiver. The transmitter is connected to the circulator. The automatic gain control circuit is connected to the feedback circuit. The feedback circuit is connected to the receiver. The antenna is connected to the anti-interference circuit. The anti-interference circuit is connected to the circulator. The circulator is connected to the receiver. The present invention also provides a feedback circuit, an automatic gain control circuit, and an anti-interference circuit, which are used to adjust the gain of the receiver by using the feedback circuit and the automatic gain control circuit, so as to reduce the ranging error and reduce the multipath interference.

Description

Technical Field

[0001] The present invention relates to the technical field of rangefinders, and particularly to an aircraft-borne DME ranging device. Background Art

[0002] A distance measuring equipment (DME) is also known as a pulse short-range ranging navigation system. It is used to provide the straight-line distance information between an aircraft and a ground station. At an airport, it is often installed on one side of a runway together with a Doppler omnidirectional range beacon, sharing the same station. Combining with the azimuth information given by the omnidirectional range beacon, it determines the accurate position of the aircraft, provides medium and short-range navigation information for the aircraft, and cooperates with the instrument landing system to ensure the safe landing of the aircraft.

[0003] For distance measurement, an airborne receiver emits an interrogation pulse. After the ranging device ground station receives the interrogation pulse, after a fixed delay, it emits a reply pulse containing encoded information. After the airborne receiver receives the reply pulse, it calculates the straight-line distance information relative to the ground station through the time interval between the transmitted and received pulses. When the aircraft approaches the port according to the navigation information and is ready to land, the flight altitude will gradually decrease. Objects such as mountains, houses, and parked large aircraft around the airport may cause multipath interference, affecting the pulse waveform emitted by the rangefinder. The distortion of the pulse waveform will cause a deviation in the measured interval time by the airborne receiver. Through practical operation experience, multipath interference is the main reason affecting the DME ranging accuracy. In addition, there are also some other factors that can cause ranging errors, such as: the instability of the fixed delay given by the equipment, the non-fixed signal amplitude received by the transponder, etc. Summary of the Invention

[0004] The purpose of the present invention is to at least solve one of the above technical defects.

[0005] For this reason, the purpose of the present invention is to provide an aircraft-borne DME ranging device that can reduce multipath interference.

[0006] To achieve the above purpose, the present invention provides an aircraft-borne DME ranging device, including a DME rangefinder. The DME rangefinder includes a CPU, a frequency synthesizer, a transmitter, a receiver, a feedback circuit, a circulator, an antenna, a feedback circuit, an automatic gain control circuit, and an anti-interference circuit. The CPU is connected to the frequency synthesizer and the automatic gain control circuit. The frequency synthesizer is respectively connected to the transmitter and the receiver. The transmitter is connected to the circulator. The automatic gain control circuit is connected to the feedback circuit. The feedback circuit is connected to the receiver. The antenna is connected to the anti-interference circuit. The anti-interference circuit is connected to the circulator. The circulator is connected to the receiver;

[0007] The feedback circuit includes a feedback amplifier, a first grounding resistor, and a first resistor. The input terminal of the feedback amplifier is connected to the transmitter through the first resistor. Another input terminal of the feedback amplifier is connected to the output terminal of the automatic gain control circuit, and another input terminal of the feedback amplifier is also connected to the first grounding resistor. The output terminal of the feedback amplifier is connected to the receiver;

[0008] The automatic gain control circuit includes a gain amplifier. The input terminal of the gain amplifier is connected to the CPU, and the output terminal of the gain amplifier is connected to the feedback amplifier.

[0009] In any of the above solutions, preferably, the automatic gain control circuit further includes a gain adjustment circuit. The gain adjustment circuit includes a first secondary winding, a second secondary winding, a first transistor, a second transistor, second resistors to sixth resistors, and first capacitors to third capacitors. The first output terminal of the first secondary winding is connected to one end of the second resistor. The second output terminal of the first secondary winding is connected to one end of the first capacitor, one end of the third resistor, and one end of the fourth resistor. The other end of the second resistor is connected to the base of the first transistor. The collector of the first transistor is connected to the collector of the second transistor, one end of the fifth resistor, one end of the second capacitor, and one input terminal of the second secondary winding. The other input terminal of the second secondary winding is connected to the other end of the second capacitor, the other end of the fifth resistor, and the other end of the fourth resistor. The emitter of the first transistor is connected to the base of the second transistor. The emitter of the second transistor is connected to one end of the sixth resistor and one end of the third capacitor.

[0010] In any of the above solutions, preferably, the other end of the first capacitor is connected to the other end of the third resistor and both are grounded.

[0011] In any of the above solutions, preferably, another input terminal of the gain amplifier is also connected to one end of a seventh resistor and one end of an eighth resistor. The other end of the seventh resistor is connected to the input interface. The other end of the eighth resistor is connected to one end of the sixth resistor and the anode of a diode. The cathode of the diode is grounded.

[0012] In any of the above solutions, preferably, the input terminal of the feedback amplifier is also connected to the output terminal of the feedback amplifier through a ninth resistor.

[0013] In any of the above solutions, preferably, the anti-interference circuit includes a coupler, an inductor, a tenth resistor, a fourth capacitor, and a third transistor. The output terminal of the coupler is connected to one end of the tenth resistor. The other end of the tenth resistor is connected to one end of the inductor. The other end of the inductor is connected to one end of the fourth capacitor and the collector of the third transistor. The other end of the fourth capacitor is connected to the antenna.

[0014] Preferably, in any of the above solutions, the emitter of the third transistor is grounded.

[0015] Preferably, in any of the above solutions, one end of the inductor is also connected to the power supply voltage.

[0016] Preferably, in any of the above solutions, the model of the feedback amplifier is THS3201.

[0017] Preferably, in any of the above solutions, the model of the gain amplifier is VCA824.

[0018] The aircraft airborne DME ranging equipment of the present invention has the following beneficial effects:

[0019] 1. The present invention also provides a feedback circuit, an automatic gain control circuit, and an anti-interference circuit. The feedback circuit and the automatic gain control circuit are used to adjust the gain of the receiver, thereby reducing the ranging error and reducing the multipath interference.

[0020] 2. The present invention combines the automatic gain control circuit with the feedback circuit, so that when the input signal changes greatly, the output signal of the receiver remains basically stable. That is, when the input signal is weak, the gain of the receiver is high; when the input signal is strong, the gain of the receiver is low.

[0021] 3. Since the gain of the amplifier is closely related to the load, the present invention provides a gain adjustment circuit to change the load of the feedback amplifier. Part of the load of the feedback amplifier is output by the combined action of the first transistor and the second transistor in the gain adjustment circuit. By controlling the conduction conditions of the first transistor and the second transistor, part of the load of the feedback amplifier is changed, so as to achieve the purpose of controlling the gain of the amplifier.

[0022] 4. The input interface in the automatic gain control circuit of the present invention can also be connected to the CPU, and the CPU adjusts the signal output by the gain amplifier, thereby adjusting the gain of the receiver.

[0023] 5. The present invention adopts the design of combining a coupler and an inductor, which can further improve the anti-interference ability of the antenna.

[0024] 6. The circuit structures of the automatic gain control circuit and the feedback circuit of the present invention are simple, with relatively few components, low manufacturing cost, and can be widely promoted and used.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0027] Figure 1 is a structural block diagram of the present invention;

[0028] Figure 2 is a circuit schematic diagram of the feedback circuit of the present invention;

[0029] Figure 3 is a circuit schematic diagram of the gain adjustment circuit of the present invention:

[0030] Figure 4 is a circuit schematic diagram of the anti-interference circuit of the present invention

[0031] In the figure, 1. CPU; 2. Frequency synthesizer; 3. Transmitter; 4. Receiver; 5. Feedback circuit; 6. Automatic gain control circuit; 7. Circulator; 8. Anti-interference circuit; 9. Antenna; Detailed Description of the Embodiment

[0032] The following details the embodiments of the present invention. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0033] DME (Distance Measuring Equipment) is a radio navigation equipment signal generator used by aircraft, installed at airports and on air routes, and is the main en-route navigation equipment. Aircraft use DME to measure the distance between themselves and ground transmitters by transmitting and receiving a pair of pulse signals at fixed intervals.

[0034] The present invention provides an aircraft-borne DME ranging device, as Figure 1 shown, including a DME ranging device, the DME ranging device includes a CPU 1, a frequency synthesizer 2, a transmitter 3, a receiver 4, a circulator 7, and an antenna 9. On this basis, the present invention also provides a feedback circuit 5, an automatic gain control circuit 6, and an anti-interference circuit 8. The CPU 1 is connected to the frequency synthesizer 2 and the automatic gain control circuit 6. The frequency synthesizer 2 is respectively connected to the transmitter 3 and the receiver 4. The transmitter 3 is connected to the circulator 7. The automatic gain control circuit 6 is connected to the feedback circuit 5. The feedback circuit 5 is connected to the receiver 4. The antenna 9 is connected to the anti-interference circuit 8. The anti-interference circuit 8 is connected to the circulator 7. The circulator 7 is connected to the receiver 4.

[0035] Among them, the CPU1 uses a tuning input to tune the frequency synthesizer 2, and the frequency synthesizer 2 provides the frequency of the pulse to the transmitter. When the aircraft's on-board DME ranging device transmits a pulse signal to the ground, the CPU1 provides a signal to the transmitter 3 to transmit an interrogation pulse. The transmitted pulse reaches the antenna 9 after passing through a circulator 7, and then the pulse signal is transmitted through the antenna 9. The antenna 9 can also receive the signal transmitted by the ground transmitter, output the pulse signal to the receiver 4 after passing through the circulator 7, and the receiver 4 outputs the signal to the CPU1.

[0036] The ranging error of the DME rangefinder is also related to the distance it measures. This is because the magnitude of the radiation power and the magnitude of the receiver gain directly affect the intersection time of the decision threshold level and the pulse rising edge. Due to their changes, the ranging accuracy can be directly affected. Therefore, the present invention also provides a feedback circuit 5, an automatic gain control circuit 6, and an anti-interference circuit 8, and uses the feedback circuit 5 and the automatic gain control circuit 6 to adjust the magnitude of the receiver gain, thereby reducing the ranging error.

[0037] The principle of automatic gain adjustment in the present invention is as follows: The automatic gain control circuit transmits the input quantity to the feedback circuit. The feedback circuit compares the input quantity with the comparison quantity. When there is a deviation, a correction quantity is generated to adjust the output quantity.

[0038] As Figure 2 shown, the feedback circuit 5 includes a feedback amplifier U21, a first grounding resistor R7, and a first resistor R5. The input end of the feedback amplifier U21 is connected to the transmitter 3 through the first resistor R5. The other input end of the feedback amplifier U21 is connected to the output end of the automatic gain control circuit 6. The other input end of the feedback amplifier U21 is also connected to the first grounding resistor R7. The output end of the feedback amplifier U21 is connected to the receiver 4. The input end of the feedback amplifier U21 is also connected to the output end of the feedback amplifier U21 through a ninth resistor R3. Among them, the ninth resistor R3 is a feedback resistor. Preferably, the model of the feedback amplifier is THS3201.

[0039] The present invention provides the first grounding resistor R7, the first resistor R5, and the ninth resistor R3, and can set the relationships among the input quantity, comparison quantity, output quantity, and correction quantity of the feedback amplifier U21 according to the magnitudes of the resistor values.

[0040] The present invention combines the automatic gain control circuit 6 with the feedback circuit, so that when the input signal changes greatly, the output signal of the receiver is kept basically stable, that is, when the input signal is weak, the receiver gain is high; when the input signal is strong, the receiver gain is low.

[0041] The automatic gain control circuit 6 includes a gain amplifier U22. The input terminal of the gain amplifier U22 is connected to the CPU1, and the output terminal of the gain amplifier U22 is connected to the feedback amplifier U21. The other input terminal of the gain amplifier U22 is also connected to one end of the seventh resistor RDA1 and one end of the eighth resistor RDA2. The other end of the seventh resistor RDA1 is connected to the input interface DA1, and the other end of the eighth resistor RDA2 is connected to one end of the sixth resistor RDA3 and the anode of the diode DDA1. The cathode of the diode DDA1 is grounded. In addition, the input interface DA1 can also be connected to the CPU1, and the CPU1 adjusts the signal output by the gain amplifier U22, thereby adjusting the magnitude of the receiver gain. Preferably, the model of the gain amplifier is VCA824. This circuit provides a differential input to single-ended conversion, does not require an external buffer, and sets the gain change by changing the external resistor value, improving the flexibility of the design.

[0042] In addition, the automatic gain control circuit 6 is also connected to the CPU1 and the receiver 4. It can output an AGC voltage that changes automatically with the change of the CPU1 output voltage to the feedback circuit according to the change of the CPU1 output voltage, and use this AGC voltage to control the gain of certain stages of the receiver, so as to achieve the purpose of automatic gain.

[0043] As Figure 3 shown, the automatic gain control circuit 6 further includes a gain adjustment circuit. The gain adjustment circuit includes a first secondary winding TR1, a second secondary winding TR2, a first transistor Q11, a second transistor Q12, a second resistor R72 - a sixth resistor R76, a first capacitor C71 - a third capacitor C73. The first output terminal of the first secondary winding TR1 is connected to one end of the second resistor R72. The second output terminal of the first secondary winding TR1 is connected to one end of the first capacitor C71, one end of the third resistor R73, and one end of the fourth resistor R74. The other end of the second resistor R72 is connected to the base of the first transistor Q11. The collector of the first transistor Q11 is connected to the collector of the second transistor Q12, one end of the fifth resistor R75, one end of the second capacitor C72, and one input terminal of the second secondary winding TR2. The other input terminal of the second secondary winding TR2 is connected to the other end of the second capacitor C72, the other end of the fifth resistor R75, and the other end of the fourth resistor R74. The emitter of the first transistor Q11 is connected to the base of the second transistor Q12. The emitter of the second transistor Q12 is connected to one end of the sixth resistor R76 and one end of the third capacitor C73. The other end of the first capacitor C71 is connected to the other end of the third resistor R73 and both are grounded.

[0044] Since the gain of the feedback amplifier is closely related to the load, the present invention provides a gain adjustment circuit to change the load of the feedback amplifier U21. Part of the load of the feedback amplifier U21 is output by the combined action of the first transistor Q11 and the second transistor Q12 in the gain adjustment circuit. By controlling the conduction states of the first transistor Q11 and the second transistor Q12, part of the load of the feedback amplifier U21 is changed. Specifically, when the voltage of the output signal of the gain amplifier U22 meets the conduction conditions of the first transistor Q11 and the second transistor Q12, the first transistor Q11 and the second transistor Q12 conduct, and the equivalent resistance value of the automatic gain control circuit 6 changes, that is, the value of part of the load of the feedback amplifier U21 changes, so as to achieve the purpose of controlling the amplifier gain.

[0045] In addition, in order to improve the anti-interference ability of the antenna, the present invention provides an anti-interference circuit, such as Figure 4 shown.

[0046] The anti-interference circuit 8 includes a coupler U30, an inductor L5, a tenth resistor R61, a fourth capacitor C63, and a third transistor Q7. The output end of the coupler U30 is connected to one end of the tenth resistor R61. The other end of the tenth resistor R61 is connected to one end of the inductor L5. The other end of the inductor L5 is connected to one end of the fourth capacitor C63 and the collector of the third transistor Q7. The other end of the fourth capacitor C63 is connected to the antenna E1. The emitter of the third transistor Q7 is grounded. One end of the inductor L5 is also connected to the power supply voltage.

[0047] The present invention adopts the design of combining the coupler U30 and the inductor L5, which can further improve the anti-interference ability of the antenna.

[0048] In summary, when the pulse signal changes, the present invention uses the feedback circuit and the automatic gain control circuit to automatically adjust the gain of the receiver, so as to ensure the stability of the pulse signal, reduce the multipath interference, and thus reduce the ranging error.

[0049] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An aircraft on-board DME ranging device, comprising a DME rangefinder, and the DME rangefinder includes a CPU, a frequency synthesizer, a transmitter, a receiver, a circulator, and an antenna. Characterized in that, it further includes a feedback circuit, an automatic gain control circuit, and an anti-interference circuit. The CPU is connected to the frequency synthesizer and the automatic gain control circuit. The frequency synthesizer is respectively connected to the transmitter and the receiver. The transmitter is connected to the circulator. The automatic gain control circuit is connected to the feedback circuit. The feedback circuit is connected to the receiver. The antenna is connected to the anti-interference circuit. The anti-interference circuit is connected to the circulator. The circulator is connected to the receiver; The feedback circuit includes a feedback amplifier, a first grounding resistor, and a first resistor. The input end of the feedback amplifier is connected to the transmitter through the first resistor. The other input end of the feedback amplifier is connected to the output end of the automatic gain control circuit. The other input end of the feedback amplifier is also connected to the first grounding resistor. The output end of the feedback amplifier is connected to the receiver; The automatic gain control circuit includes a gain amplifier. The input end of the gain amplifier is connected to the CPU. The output end of the gain amplifier is connected to the feedback amplifier; The automatic gain control circuit further includes a gain adjustment circuit. The gain adjustment circuit includes a first secondary winding, a second secondary winding, a first transistor, a second transistor, second resistors - sixth resistors, and first capacitors - third capacitors. The first output end of the first secondary winding is connected to one end of the second resistor. The second output end of the first secondary winding is connected to one end of the first capacitor, one end of the third resistor, and one end of the fourth resistor. The other end of the second resistor is connected to the base of the first transistor. The collector of the first transistor is connected to the collector of the second transistor, one end of the fifth resistor, one end of the second capacitor, and one input end of the second secondary winding. The other input end of the second secondary winding is connected to the other end of the second capacitor, the other end of the fifth resistor, and the other end of the fourth resistor. The emitter of the first transistor is connected to the base of the second transistor. The emitter of the second transistor is connected to one end of the sixth resistor and one end of the third capacitor; The other end of the first capacitor is connected to the other end of the third resistor and both are grounded; The other input end of the gain amplifier is also connected to one end of a seventh resistor and one end of an eighth resistor. The other end of the seventh resistor is connected to an input interface. The other end of the eighth resistor is connected to one end of the sixth resistor and the anode of a diode. The cathode of the diode is grounded; The input end of the feedback amplifier is also connected to the output end of the feedback amplifier through a ninth resistor; The anti-interference circuit includes a coupler, an inductor, a tenth resistor, a fourth capacitor, and a third transistor. The output end of the coupler is connected to one end of the tenth resistor. The other end of the tenth resistor is connected to one end of the inductor. The other end of the inductor is connected to one end of the fourth capacitor and the collector of the third transistor. The other end of the fourth capacitor is connected to the antenna.

2. The aircraft on-board DME ranging device according to claim 1, Characterized in that, The emitter of the third transistor is grounded.

3. The aircraft airborne DME ranging device according to claim 1, characterized in that one end of the inductor is also connected to the power supply voltage.

4. The aircraft airborne DME ranging device according to claim 1, characterized in that the model of the feedback amplifier is selected as THS3201.

5. The aircraft airborne DME ranging device according to claim 1, characterized in that the model of the gain amplifier is selected as VCA824.

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