JPH02161380A - Radio wave distance detecting device - Google Patents

Abstract

PURPOSE:To correct an error and to understand a true value by modulating a transmission wave by a prescribed frequency, varying a frequency of the transmission wave itself between prescribed values, calculating an obtained value and deriving a distance. CONSTITUTION:An oscillator 12 is brought to oscillation by frequencies (f0 - f1) based on a carrier wave frequency adjusting signal outputted from a data processor 13, and brought to AM modulation by a modulator 15 by a signal fm of a modulation signal generator 14. The modulated signal is sent out of a transmission antenna 10, reflected by the ground and reaches a reception antenna 11 by being delayed by the time (2l/c second, (c) denotes a velocity of light) determined by altitude (distance (l)) of an unmanned helicopter 1. An output signal passes through an amplifier 16 and detected by a detector 17, and only a modulation component is fetched. Subsequently, phases of the detected signal and a signal from the generator 14 are compared by a detector 18, inputted to the processor 13, and the distance (l) is derived by calculating it. By varying and measuring the wavelength lambda and averaging all the measured values, the true value can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a radio distance detection device that uses radio waves to measure distance based on the phase difference between a transmitted wave and a received wave reflected from an object to be measured.

[Prior art] A method of measuring distance using radio waves involves modulating a transmitted wave at a predetermined frequency, and using the time delay caused by propagation along a path twice the distance to the object to be measured to reduce the modulated frequency. It is known that the phase of the received wave signal is delayed and the distance can be calculated based on the phase difference between the transmitted and received modulated waves.

[Problems to be Solved by the Invention] By the way, when detecting the phase of a received wave, in addition to the received wave signal reflected from the object to be measured, radio waves directly input from the transmitting antenna to the receiving antenna and other signals within the transmitting/receiving circuit are detected. Due to the electromagnetic coupling, it is difficult for a receiver that receives reflected received waves to completely eliminate the input of the transmitted signal, and instead detects a received wave that is a combination of the transmitted signals.

In this case, depending on the phase of the transmitted waves, if they are in the same phase, it will be strong.
In the case of opposite phases, they cancel each other out. Therefore, as shown in Figure 6, the distance 1 is λ/2 for the wavelength λ of the transmitted wave.
Phase information that can be detected every time it changes (λ in round trip distance) causes a repeat error.

The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a radio wave distance detection device that corrects errors and makes it possible to grasp the true value.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a radio distance detection device that measures distance based on a phase difference between a transmitted wave and a received wave,
It is characterized in that the transmitted wave is modulated at a predetermined frequency, the frequency of the transmitted wave itself is also varied between predetermined values, and the obtained value is calculated to determine the distance.

[Function] In the radio distance detection device of the present invention, distance is measured based on the phase difference between the transmitted wave and the received wave. At this time, since the error is caused by the synthesis of sine waves, the frequency of the transmitted wave is adjusted by a predetermined amount. The error itself when changed also becomes a sine curve. Therefore, the true value can be found by calculating the average of the maximum and minimum values in this sine curve, the average of all data in one wavelength, or the average of the starting and ending points of a half wavelength. be able to.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a side view of a remote-controlled helicopter equipped with the present invention, and FIG. 2 is a view of the remote-controlled mulberry vertical helicopter seen from the rear.

In the figure, reference numeral 1 denotes a radio-controlled unmanned helicopter for dispersing medicine, and a body 2 of the helicopter 1 is provided with legs 3 for landing.

The support portion 3a of the leg portion 3 extends downward from the body 2 by being curved on both sides, and a landing portion 3b is attached to the support portion 3a. This landing portion 3b extends in the longitudinal direction of the aircraft body 2.

An engine, a receiver, a control device, a servo mechanism, etc. (not shown) are arranged inside the front part of the fuselage 2. A main rotor 5 is attached to an output shaft 4 extending substantially vertically upward from the engine, and a tail rotor 6 is attached to the rear end of the fuselage 2. This tail rotor 6 is for canceling the reversal torque produced by the main rotor 5, and is provided toward the rear of the fuselage 2 via a rotating shaft 7 that extends horizontally and to the left in the direction of travel.

A tail fin 8 is provided on the fuselage 2 between the main rotor 5 and the tail rotor 6 below the fuselage.

A mooring body (not shown) made of wire, rope, etc. is fixed to the rear of the body 2, and the other end of the mooring body is connected to a rope winding device (not shown) provided on the ground.

A radio range detection device 9 is provided between the legs 3 at the lower part of the bridge body 2. This radio wave distance detection device 9 has a transmitting antenna 10 and a receiving antenna 11, for example, a transmitting antenna on the front side! 0, a receiving antenna 11 is provided on the rear side.

A circuit diagram of this radio wave distance detection device 9 is shown in FIG.
The figure shows the waveform opening of this circuit, altitude 1 of helicopter 1.
A device that measures altitudes from 5 m to 15 m will be explained.

First, the oscillator 12 emits an image at a frequency (fo to f+) based on the carrier frequency adjustment signal output from the data processing device 13, and the modulator 15 uses the signal fm from the modulation signal generator 14 to
M modulates. The modulated signal is sent out from the transmitting antenna 10 and reflected on the ground for a time determined by the altitude (distance L) of the unmanned helicopter 1 (2j2/C seconds C: speed of light)
The signal reaches the receiving antenna 11 with a delay. Since the received signal has very low power, it is amplified by the amplifier 16 and then sent to the detector 17.
Detect and extract only the modulated signal component.

The phase of the detected signal and the modulated signal generator 14 are compared by a transfer detector 18 and output. In this way, when the carrier wave is changed from f0 to f1, the error caused by carrier wave interference changes from an increasing state to a decreasing state, and the minimum value θ0 and maximum value θ1 of the phase output are obtained as shown in Fig. 4. .

In this way, the measurement error is distance +! 1J2 and carrier wavelength λ
This is caused by a specific relationship with You will be able to measure without any problems. For this reason, the wavelength λ is set to 21λon≧λ,
λ that has a relationship of (n+1). At this time, λ is varied from λ1 to λ1 and measured. n! If the relationship λ,'(n+1) is established, the average of all measured data is taken as the measured value, and λ. When n>λ1 (n+1), the average of the maximum value and minimum value may be used as the measured value.

The output value is θ. and θ1, and θ−(θ.

+θl)/2, and an output without errors caused by interference can always be obtained.

Here, fl is fo from the maximum measurement altitude of 15 m, and f+ is from the minimum measurement altitude of 1.5 m. First, if fo is 10 GHz (n is an integer) f 410. By setting the frequency to 1 GHz, measurements can be made in the range of 1.5 m to 15 m.

Furthermore, measurement errors are caused by a specific relationship between the distance 1 and the wavelength λ of the carrier wave, and the error caused by a 0 phase difference that can change the phase state of transmission and reception by changing λ is the error caused by the sine wave. Since it is generated by synthesis, the error also becomes a sine curve depending on the phase difference, and the true value can be obtained by calculating the average of all data for one wavelength.

In addition, one way to reduce the error is to change the frequency of the carrier wave by one wavelength or more and take the average of the maximum and minimum data, but at short distances, unless the frequency change is large, one wavelength Because it does not shift, it may be difficult in practice. Therefore, the error caused by the phase difference is caused by the synthesis of sine waves, and the error also forms a sine curve depending on the phase difference. Therefore, if the phase difference is changed from φ to φ+π, the information at φ , φ+π, the central value of the data can be obtained.

Therefore, the wavelength λ is 2jl−λ according to the distance aIi. nl1Ilλ, (n+1/2) λ0
As shown in FIG. 5, by varying the information from .theta. to .lamda.

The relationship between carrier waves f0 and fl is (n is an integer) Eliminating n and finding fl f+ = fo + (0, sc7'2Jl).

Define f with the initial value of 1 measured at any time, and
Phase information θ8 when o and f. θ. , and θ=(
θ. When outputting as 10I)/2, the maximum error may be the maximum or minimum in Fig. 6, but the distance 11J2 changes continuously and the phase difference can be detected in a short time.
Further, even if the maximum error is set as the initial value, the phase difference error of the carrier wave is only the error percentage of the initial value, so the measured data will converge to the true value by repeated measurements.

As described above, it is possible to perform measurements with few errors using a relatively small number of carrier wave frequencies.

[Effects of the Invention] As described above, the radio distance detection device of the present invention modulates the transmitted wave at a predetermined frequency, changes the frequency of the transmitted wave itself between predetermined values, and modulates the obtained value. Since the distance is determined by calculation, the error is caused by the synthesis of sine waves, and the error itself when the frequency of the transmitted wave is changed by a predetermined amount also becomes a sine curve. Therefore, the true value can be determined by calculations such as calculating the average of the maximum and minimum values in this sine curve, the average of all data in one wavelength, and the average of the start and end points of half frequencies.

[Brief explanation of the drawing]

Figure 1 is a side view of a remote-controlled helicopter equipped with this invention, Figure 2 is a view of the remote-controlled helicopter seen from the rear, Figure 3 is a circuit diagram of the radio range detection device, and Figures 4 and 5.
The figure is a waveform diagram of the circuit of the radio wave distance detection device, and FIG. 6 is a diagram showing the relationship between distance and phase. In the figure, 1 is a helicopter, 2 is a fuselage, 3 is a leg, 9 is a radio range detection device, 10 is a transmitting antenna, 11 is a receiving antenna, 12 is an oscillator, 13 is a data processing device, and 14 is a modulation signal generator , 15 is a modulator, 16 is an amplifier, and a phase detector. 17 is a detector, 18 is a scale diagram, a diagram, and a relaxation diagram.

Claims (1)

[Claims] In a radio distance detection device that measures distance based on the phase difference between a transmitted wave and a received wave, the transmitted wave is modulated at a predetermined frequency, and the frequency of the transmitted wave itself is also varied between predetermined values. A radio distance detection device characterized by calculating distance.