JP2988386B2 - CW interference wave canceler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground DME (Dista
CW for removing a continuous wave (CW) signal from a CW radar or the like mixed into a receiver of the nce measuring equipment) and normally receiving an interrogation pulse when a CW interference wave exists.
The present invention relates to a W interference wave removing device.

[0002]

2. Description of the Related Art Conventionally, VOR in air traffic control systems
(VHF Omnidirectional Range) and the like are provided with a DME system. This DME system consists of an onboard DME (interrogator) mounted on an aircraft and this onboard DM
It consists of a transponder (terrestrial DME) for receiving the interrogation pulse from E and returning a response pulse after a delay to measure heading and distance with the onboard DME. In this on-board DME, the round-trip elapsed time in radio wave propagation of the interrogation pulse and the response pulse is obtained, and a prescribed delay time in the terrestrial DME, for example, a delay time of 50 μsec is subtracted to obtain an inclination distance from the terrestrial DME. I'm asking. In this case, in order to define the time measurement in the DME system, the distance measurement processing is performed based on the half-amplitude point at the leading edge of the interrogation pulse.

FIG. 4 is a block diagram showing a main configuration of a receiver in a conventional terrestrial DME, and FIG. 5 is a timing chart of processing signals in operation. 4 and 5, the reception signal (interrogation pulse) from the antenna 10 is amplified by the preamplifier 11 and detected by the detector 12.
This detection signal is input to the delay unit 13 and the attenuation unit 14 to detect a half-amplitude point at the leading edge of the interrogation pulse. Delay unit 1
The output signal from 3 is negatively offset by the voltage offset unit 15 and input to the comparator 17. The attenuating unit 14 attenuates the detection signal by, for example, 6 dB and outputs the signal to the comparator 17.

The comparator 17 compares the attenuated detection signal S18 from the attenuating unit 14 with the delayed offset signal S19 from the voltage offset unit 15, and finds the half-amplitude point at the leading edge of the interrogation pulse required for the distance measurement operation. It is detected as the rising point (a) of the output signal S16 of the voltage 5 / 0V.

In such a terrestrial DME receiver, an interrogation pulse is received from an onboard DME mounted on an aircraft. At the same time, when a continuous wave (CW) of a strong electric field strength is received from a CW radar or the like, the interrogation pulse is received. Cannot be received normally. In other words, FIG. 5A shows a case where the CW is not interrupted, but as shown in FIG.
The phase of the interfering CW signal and the interrogation pulse are in phase (0 °)
In the case of (1), since there is no intersection between the attenuation detection signal S18 from the attenuation unit 14 and the delay offset signal S19 from the voltage offset unit 15, a rising point cannot be obtained in the output signal S16.

Also, as shown in FIG. 5C, when the phase of the CW signal and the interrogation pulse is 90 °, the attenuation detection signal S18 from the attenuation unit 14 and the delay offset signal from the voltage offset unit 15 Since there is no intersection with S19, a rising point cannot be obtained in the output signal S16.

Further, as shown in FIG. 5D, when the phases of the CW signal and the interrogation pulse are opposite phases (180 °), that is, the attenuated detection signal S18 from the attenuator 14 and the voltage offset unit 15 Also, when the delayed offset signal S19 is out of phase, the rising point cannot be obtained.

Japanese Patent Publication No. Sho 63-4 discloses this type of distance measuring technique.
Techniques described in Japanese Patent Publication No. 3716 and Japanese Patent Publication No. Hei 2-20075 are known, but all of them enable high-accuracy distance measurement, but cannot cope with removal of CW interference waves.

[0009]

As described above, in the above-mentioned conventional example, when receiving the CW interference wave, it is impossible to normally receive the interrogation pulse from the onboard DME. That is, since the half-amplitude point at the leading edge of the interrogation pulse as a reference for defining the time measurement in the DME system cannot be obtained, the on-machine DM
There is a disadvantage that accurate distance measurement in E becomes impossible.

[0010] The present invention is to solve such a problem in the prior art, and a CW signal mixed into a receiver of a terrestrial DME is effectively removed, and a question is asked even when a CW interference wave exists. Pulse can be received normally,
Provided is a CW interference wave elimination device that enables accurate ranging.

[0011]

According to a first aspect of the present invention, there is provided a CW interference wave removing apparatus for outputting a reception signal which receives a target radio wave and a CW interference wave. A phase-locked oscillation means for transmitting a high-frequency signal phase-locked to a CW signal in a reception signal from the reception means, and a high-frequency signal from the phase-locked oscillation means for passing the reception signal from the reception means A directional coupler for canceling the CW signal by performing high-frequency coupling in opposite phases and at the same level to cancel each other, a DC level detection unit that detects only a DC component in a signal received from the reception unit, and a DC level detection unit. A CW erasure level generator for generating a signal for setting a signal level necessary for erasing the CW signal based on the DC component to be output; and a CW erasure level generator based on the signal from the CW erasure level generator. An attenuation unit for attenuating a high-frequency signal from said phase synchronization oscillation means to the CW signal and the same level have, moved and sends it to the directional coupler the signals from the attenuation section and phase to phase opposite to CW signal and a phase vessels, construction and a damping phase shifting means for the high-frequency signal Soshi shift in opposite phase and the same level in the CW signal is supplied to the directional coupler attenuated from the phase synchronization oscillation means There is.

[0012] CW interference wave removal apparatus according to claim 2, wherein the 請
The CW interference wave removing apparatus according to claim 1, wherein, as the phase-locked oscillation means, a limiter that performs a level limit for reducing a phase detection error with respect to a signal received from a reception means;
The CW signal in the received signal from the limiter and the CW signal
Comparing means for comparing the phase with the high-frequency signal corresponding to the signal, a low-pass filter for smoothing the comparison output signal from the comparing means, and C based on the voltage from the low-pass filter.
Configuration and a voltage controlled oscillator to lock to the phase of the W signal and outputs to the comparing means a high-frequency signal oscillated entirety in
You.

According to a third aspect of the present invention, there is provided a CW interference wave canceling apparatus.
The CW interference wave removing apparatus according to claim 1 or 2,
This is a configuration provided in the ground DME in the system .

According to a fourth aspect of the present invention, there is provided a CW interference wave canceling apparatus.
The configuration of the CW jammer removing apparatus according to claim 1 or 2,
Defines time measurement for distance measurement in DME system.
The half-amplitude point at the leading edge of the interrogation pulse
Detecting delay, attenuation, voltage offset, and comparator
It has a configuration with a radiator.

[0015] The CW interference wave canceling device having such a configuration is as follows.
Question pal from on-board DME through antenna, amplifier, etc.
Receive the target radio wave of the satellite and the CW jammer from the CW radar.
Is supplied to the directional coupler. This place
From the voltage controlled oscillator locked to the phase of the CW signal.
High-frequency signal is attenuated and phase-shifted, and the phase is opposite to CW signal
To the same level and supply it to the directional coupler,
Cancel the CW signal by coupling and output the interrogation pulse
ing.

That is, the CW erase level generating section is provided in the direction
Degree of coupling of sexual coupler, and from attenuator to directional coupler
Is stored in advance, and the CW signal is deleted.
To calculate the level required for this. The attenuator has a CW erasure level.
Phase-locked oscillation based on the signal from the bell generator
The oscillation signal from the means is attenuated and output to the phase shifter.

In this phase shifter, the CW signal is erased.
The phase of the signal from the attenuator to
Phase shift so that the phase is exactly opposite (180 °)
Output to the sex coupler.

Therefore, the CW signal mixed into the receiver of the terrestrial DME is effectively removed, and the interrogation pulse is normally received even when the CW interference wave exists. In this case, the intersection of the waveforms of the delay detection signal in the delay section, the attenuation section, the voltage offset section, the comparator, and the delay offset signal from the voltage offset section can be reliably obtained.

As a result, the half-amplitude point of the leading edge of the interrogation pulse, which serves as a reference for defining the time measurement for distance measurement in the DME for detecting the half-amplitude point of the front edge of the interrogation pulse, is reliably detected. Accurate ranging with on-board DME is possible.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a CW interference wave removing apparatus according to the present invention will be described in detail with reference to the drawings. FIG.
FIG. 1 is a block diagram showing a configuration of an embodiment of a CW interference wave removing apparatus of the present invention. In FIG. 1, a CW interference wave removing apparatus 18 is an antenna for receiving an interrogation pulse from an onboard DME mounted on an aircraft (not shown) together with a phase locked oscillator 19 and wirelessly transmitting a response pulse to the onboard DME. 20 and a preamplifier 21 that outputs an amplified reception signal S21 obtained by amplifying the reception signal from the antenna 20.

The CW interference wave removing apparatus 18 stores a DC level in the amplified received signal S21 based on the DC level detected by the DC level detecting section 22 and the DC level detected by the DC level detecting section 22 in advance. C that generates a signal set to the amount of attenuation (the level required to cancel the CW signal)
And a W erase level generator 23. Furthermore, CW
An attenuator 24 for attenuating a signal for erasing the CW signal (oscillation signal from the phase locked oscillator 19) to the same level as the CW signal based on a signal from the erasure level generator 23, and an attenuator 24. And a phase shifter 25 for shifting the phase of the signal from the CW signal so as to match the phase of the CW signal in the opposite phase and outputting the same.

Further, the CW interference wave removing device 18 allows the amplified reception signal S21 from the preamplifier 21 to pass therethrough, and
A directional coupler 26 that suppresses the CW signal in the amplified received signal S21 with an opposite-phase signal from the phase shifter 25 and outputs a received signal S21a, and a detector that detects and outputs the received signal S21a 27 are provided.

Next, the phase-locked oscillator 19 includes, in the amplified reception signal S21 from the preamplifier 21, a limited reception signal S2 whose level has been limited in order to reduce a phase detection error.
2 and a limiter 37 for outputting the limited reception signal S22.
And a phase comparator 38 that compares the phase of the oscillation signal of the voltage-controlled oscillator and outputs a voltage error signal S23, and a low-pass filter (LPF) 39 that outputs a control voltage S24 obtained by smoothing the voltage error signal S23. Have been. Further, there is provided a voltage controlled oscillator (VCO) 40 for outputting an oscillation signal in which the phase of the oscillation signal is locked to the phase comparator 38 and the attenuator 24 in accordance with the control voltage S24 from the LPF 39.

The CW interference wave removing device 18 includes a delay unit 43 and an attenuation unit 44 for detecting the half-amplitude point at the leading edge of the interrogation pulse from the detection signal from the detector 27, and a delay unit 43.
And a voltage offset unit 45 for negatively offsetting the output signal from the output unit. Further, the attenuation section 44
A comparator 47 that compares the attenuation detection signal S28 from the input signal and the delay offset signal S29 from the voltage offset unit 45 and outputs an output signal S26 for detecting a half-amplitude point at the leading edge of the input interrogation pulse is connected. Have been.

Next, the operation of this embodiment will be described. FIG. 2 is a waveform diagram of a processing signal in the operation of this embodiment, and FIG. 3 is a diagram for explaining an output signal in the embodiment. The signal received by the antenna 20 is amplified by the preamplifier 21. In the amplified reception signal S21 shown in FIG. 2A, the CW wave received from the CW radar, that is, the CW signal received as an interference wave is superimposed on the interrogation pulse. The amplified received signal S21 is supplied to the directional coupler 26, the DC level detector 22, and the limiter 3 in the phase locked oscillator 19.
7 is input.

In the limiter 37, the level of the amplified reception signal S21 is limited in order to reduce the error in the phase detection, and the limited reception signal S22 shown in FIG.
Output to The phase comparator 38 compares the phase of the limited reception signal S22 from the limiter 37 with the phase of the oscillation signal of the voltage controlled oscillator (VCO) 40, and converts the voltage error signal S23 shown in FIG. Output.

The voltage error signal S23 includes a fluctuation component caused by the interrogation pulse. That is, the interrogation pulse has a pulse width of, for example, 3.4 μsec, and a fluctuation component synchronized with the pulse width is generated. Since this fluctuation is extremely short with respect to the time of the CW signal, LP
It is smoothed by F39. The smoothed control voltage S24 shown in FIG. 2D is input to the control terminal of the VCO 40.

The VCO 40 outputs an oscillation signal whose phase is controlled in accordance with the control voltage S24 from the LPF 39 to the phase comparator 38 and the attenuator 24. By these closed loop controls, the phase of the oscillation signal of the VCO 40 is locked to the phase of the CW signal.

In the amplified received signal S21 input to the DC level detector 22, only the DC component is detected here. Therefore, the output signal of the DC level detector 22 is
The effect of the received interrogation pulse is removed to generate a voltage corresponding to the level of the CW signal, and the CW erase level generator 2
3 is input.

In the CW erasure level generator 23, the degree of coupling of the directional coupler 26 and the amount of attenuation between the attenuator 24 and the directional coupler 26 are stored in advance, and the CW signal is eliminated. To calculate the level required for this. Damping part 2
4 attenuates the oscillation signal of the VCO 40 to a level based on the signal from the CW erasure level generator 23 and outputs the signal to the phase shifter 25. In the phase shifter 25, the phase of the signal (oscillation signal of the VCO 40) from the attenuating section 24 for canceling the CW signal is exactly opposite to the CW signal (180 °). And outputs it to the directional coupler 26.

In the directional coupler 26, the amplified received signal S21 from the preamplifier 21 and the signal from the phase shifter 25 are combined (high-frequency coupling). Here, the CW signal in the amplified reception signal S21 and a signal (VCO4
Since the levels of the 0 oscillation signals are the same and opposite in phase, the high frequency coupling by the directional coupler 26 cancels the CW signal. Therefore, the reception signal S21a shown in FIG. 2E input to the detector 27 has the CW signal removed, and only the interrogation pulse is supplied to the detector 27 and detected.

The detection signal of the detector 27 is processed in the same manner as in the conventional example. That is, the detection signal from the detector 27 is
Delay unit 43 for detecting a half-amplitude point at the leading edge of the interrogation pulse
, And input to the attenuation unit 44. The output signal from the delay unit 43 is input to the comparator 47 after being negatively offset by the voltage offset unit 45. The attenuating section 44 attenuates the detection signal by, for example, 6 dB and outputs the signal to the comparator 47.

The comparator 47 outputs an output signal S26 having a voltage of 5/0 V obtained by comparing the attenuation detection signal S28 from the attenuation unit 44 with the delay offset signal S29 from the voltage offset unit 45, and the output signal S26 rises. Point (b) is detected as the half-amplitude point at the leading edge of the interrogation pulse.

As described above, in this embodiment, the half-amplitude point at the leading edge of the interrogation pulse serving as a reference for defining time measurement for distance measurement in the DME system is accurately and reliably detected.

[0035]

As is apparent from the above description, according to the CW jammer removing apparatus of the present invention, the CW when the target radio wave of the interrogation pulse from the onboard DME and the CW jammer from the CW radar are received. The signal is supplied to the directional coupler. In this case, the high-frequency signal from the voltage-controlled oscillator locked to the phase of the CW signal is attenuated and shifted to the opposite phase, and the CW signal is canceled by the high-frequency coupling in the directional coupler, and only the interrogation pulse is output. .

Therefore, the CW signal mixed into the receiver of the terrestrial DME is effectively removed, and the interrogation pulse is normally received even when the CW interference wave exists. As a result, DM
The half-amplitude point at the leading edge of the interrogation pulse, which is a reference for defining the time measurement for distance measurement in E, can be reliably detected, and accurate distance measurement can be performed with the onboard DME.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a CW interference wave removing apparatus of the present invention.

FIG. 2 is a waveform diagram of a processing signal in the operation of the embodiment.

FIG. 3 is a waveform chart for explaining detection of a half-amplitude point in the embodiment.

FIG. 4 is a block diagram showing a receiver in a conventional terrestrial DME.

FIG. 5 is a waveform chart for explaining detection of a half-amplitude point in a conventional example.

[Explanation of symbols]

 Reference Signs List 18 CW interference wave removing device 19 Phase locked oscillator 20 Antenna 21 Preamplifier 22 DC level detection unit 23 CW cancellation level generation unit 24 Attenuation unit 25 Phase shifter 26 Directional coupler 27 Detector 37 Limiter 38 Phase comparator 39 LPF Reference Signs List 40 voltage controlled oscillator 43 delay unit 44 attenuating unit 45 voltage offset unit 47 comparator S21 amplified reception signal S21a reception signal S22 limited reception signal S23 voltage error signal S24 control voltage S26 output signal S28 attenuation detection signal S29 delay offset signal

Continuation of the front page (56) References JP-A-62-277720 (JP, A) JP-A-61-258884 (JP, A) JP-A-62-249087 (JP, A) JP-A-56-109882 (JP, A) JP-A-62-77719 (JP, A) JP-A-63-48018 (JP, A) JP-A-2-285725 (JP, A) JP-A-2-5088 (JP, U) Patent 2645557 ( JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01S 7/00-7/42 G01S 13/00-13/95 H04B 1/10

Claims (4)

(57) [Claims] 1. A receiving means for outputting a reception signal having received a target radio wave and a CW interference wave, a phase-locked oscillation means for transmitting a high-frequency signal phase-locked to a CW signal in a reception signal from the receiving means , A directional coupler for passing a reception signal from the means, and for canceling the high-frequency signal from the phase-locked oscillating means by performing high-frequency coupling with the CW signal in opposite phase and at the same level, and canceling the reception signal from the reception means. A DC level detection unit for detecting only a DC component in the CW signal, and a CW erasing level for generating a signal for setting a signal level necessary for erasing a CW signal based on the DC component output from the DC level detection unit a generator, a high-frequency signal from said phase synchronization oscillation means on the basis of a signal from the CW erase level generator CW
Comprising a damping unit for damping the signal in the same level, and a phase shifter to be sent to the directional coupler the signals from the attenuation section and phase to phase opposite to the CW signal, from said phase synchronization oscillation means A phase-shifting means for shifting the high-frequency signal to the CW signal in the opposite phase and to the same level, attenuating the same, and supplying the same to the directional coupler. 2. A limiter for performing a level limit for reducing a phase detection error with respect to a reception signal from the reception unit, a CW signal in a reception signal from the limiter, Comparison means for comparing the phase with a high-frequency signal corresponding to the CW signal; a low-pass filter for smoothing a comparison output signal from the comparison means; and a phase-locked CW signal based on a voltage from the low-pass filter. The CW interference wave removing apparatus according to claim 1, further comprising: a voltage-controlled oscillator that outputs the oscillated high-frequency signal to the comparing unit. 3. A CW interference wave eliminator according to claim 1 or 2, wherein the CW interference wave eliminator is provided on a terrestrial DME in a DME system. 4. A CW jammer removing apparatus according to claim 1, wherein a half-amplitude point at a leading edge of an interrogation pulse serving as a reference for defining time measurement for performing distance measurement in a DME system is detected. A CW interference wave removing device comprising a delay unit, an attenuation unit, a voltage offset unit, and a comparator.