KR100610820B1 - Apparatus for Locking Phase - Google Patents

Abstract

The present invention relates to a device for fixing a phase of a transmission signal in a navigation wireless transmission system, comprising: a signal generator (PLL) configured to provide a carrier; A phase shifter for shifting the phase of the signal output from the signal generator; An amplitude modulator for changing the signal output from the phase shifter according to the amplitude of the message signal; A power amplifier for amplifying the signal output from the amplitude modulator; A phase comparator for comparing a phase of a start signal output from the signal generator and a final signal output from the power amplifier; A power divider for branching a portion of the signal output from the signal generator to the phase comparator and branching the remainder to a phase shifter; And a coupler extracting a part of the signal output from the power amplifier and branching the phase comparator to the phase comparator, wherein the phase shifter is input to the amplitude modulator corresponding to a phase difference between the start signal and the final signal detected by the phase comparator. A phase lock is provided for shifting the phase of a signal to be transmitted. According to the present invention, a phase controlled signal is output from a phase shifter by comparing a phase of a start signal and a final signal, and the controlled signal is subjected to an amplitude modulation and amplification process, thereby outputting a phase of a signal transmitted through an antenna. There is an advantage that can be fixed. In particular, the present invention has the advantage that the safe operation of the aircraft by ensuring that the phase fixed signal can be transmitted in the DVOR system exhibiting a sensitivity to the phase change.

AM, radio transmitter, power amplifier, amplitude modulator, phase shifter, phase comparator, phase locked loop (PLL)

Description

Phase lock device {Apparatus for Locking Phase}             

1 is a view showing a circuit configuration of a radio transmitting apparatus for navigation according to the prior art.

2 is a diagram illustrating a circuit configuration of a phase lock device according to an embodiment of the present invention.

3 illustrates a circuit configuration inside a signal generator according to the present invention.

<Description of Major Symbols in Drawing>

100, 200: signal generator 102, 210: amplitude modulator

104, 212: power amplifier 204, 300: phase comparator

206, 302: low pass filter (LPF) 208: phase shifter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase lock device, and more particularly, a phase shifter is disposed in front of a modulator and an amplifier in a DVOR (Doppler Very high frequency Omni directional Range) system, which is used for a marking facility for navigation of an aircraft. The present invention relates to a device capable of providing a stable radio wave quality by allowing a signal having a phase fixed to be transmitted.

In the past, mainly a wired communication method has been used, but in recent years, wireless communication methods using electromagnetic waves have been mainly used due to the development of communication technology.

Wireless communication is performed by modulating and amplifying a message signal, which is an original signal, by a transmitting device, and transmitting the message signal wirelessly, by receiving a remote device receiving the signal and demodulating the received signal.

The area of wireless communication is expanding day by day, and wireless communication has provided direct convenience to human life by promoting the development of wireless mobile phones and wireless Internet.

On the other hand, in recent years, a wireless communication method is also used for the navigation of the aircraft, the representative system is the DVOR (doppler Very high frequency Omni directional Range: Doppler omnidirectional indicator system) system.

The DVOR system is an aircraft guidance system that transmits amplitude-modulated navigation radio signals to an aircraft during operation and provides information on the current position and flight direction of the aircraft.It uses two 30Hz signals, the reference phase signal and the variable phase signal. Perform aircraft guidance functions.

In a DVOR system, the reference phase signal is obtained by a carrier wave modulated with a 30 Hz sinusoidal signal, which is radiated in all directions. In addition, the variable phase signal is obtained by amplitude modulating a carrier wave with a subcarrier having a difference of 10 KHz from an amplitude modulated carrier wave, which is frequency modulated by the spatial synthesis of the upper and lower band signals separated from the side band antenna.

By receiving the reference phase signal and the variable phase signal at the receiver of the aircraft, and determine the phase difference of these signals, it is possible to check the current position, the route and the like of the aircraft.

1 is a diagram illustrating a circuit configuration of a radio navigation apparatus for navigation according to the prior art.

As shown in FIG. 1, the conventional navigation wireless transmitter includes a signal generator, a modulator, a power amplifier, and an antenna.

The signal generator 100 is a device for generating a carrier of a specific frequency to enable the original signal to be transmitted to a remote location. As such, a carrier of a specific frequency is output from the signal generator 100, and a modulation is performed in which a modulator 102 loads a message signal on a carrier of a specific frequency. Thereafter, the modulated signal is amplified through the power amplifier 104, and the amplified signal is sent out through the antenna 106.

In order to communicate with each other, the radio transceivers must transmit and receive signals of a certain frequency. In the conventional radio communication for navigation, only the signal generator 100 is configured in a PLL (phase locked loop) structure to output a phase-locked carrier wave. .

However, as described above, in order to perform wireless communication, a signal is processed, such as modulation and amplification of the signal, and there is a problem in that undesirable phase noise is generated during this processing.

In other words, even if the signal generator 100 outputs a signal whose phase is fixed, the modulator 102 changes according to the phase in the process of amplitude modulation or frequency modulation, and the heat generated in the process of being amplified by the power amplifier 104. This causes a problem that the phase of the signal changes. In addition, when transmitting a periodic signal, a problem occurs that the phase of the signal continuously changes over time.

In general, radio amplitude modulation (AM) transmitters are insensitive to phase noise because they only modulate amplitude and do not adjust frequency, so there is little consideration for such phase noise, i.e., phase sway.

However, as described above, in the DVOR system for navigation of an aircraft, even if a signal is transmitted using amplitude modulation, a variable phase signal composed of subcarriers is obtained by spatial synthesis of upper and lower band signals, and is referred to at the receiver of the aircraft. Since the current position is determined using the phase difference between the phase signal and the variable phase signal, the signal is very sensitive to phase noise. Accordingly, when a radio signal is transmitted while the phase is continuously changed in a navigation wireless transmitter, a fatal accident may occur by incorrectly determining a path at a receiver of an aircraft.

The present invention is to solve the above problems of the prior art, by configuring the navigation wireless transmitter itself in the form of a phase locked loop (PLL), the device capable of fixing the phase of the signal transmitted from the navigation wireless transmission device I would like to propose.

It is another object of the present invention to compare a start signal and a final signal with a phase shifter located in front of an amplitude modulator and a power amplifier to output a phase controlled signal, thereby eliminating any kind of phase noise that may occur in a signal's movement path. It is to propose a device that can be improved.

In order to achieve the above object, according to a preferred embodiment of the present invention, an apparatus for fixing the phase of the outgoing signal in the navigation wireless transmission system, comprising a PLL, a signal generator for providing a carrier; A phase shifter for shifting the phase of the signal output from the signal generator; An amplitude modulator for changing the signal output from the phase shifter according to the amplitude of the message signal; A power amplifier for amplifying the signal output from the amplitude modulator; A phase comparator for comparing a phase of a start signal output from the signal generator and a final signal output from the power amplifier; A power divider for branching a portion of the signal output from the signal generator to the phase comparator and branching the remainder to a phase shifter; And a coupler extracting a portion of the signal output from the power amplifier and branching the phase comparator to the phase comparator, wherein the phase shifter is input from the signal generator corresponding to a phase difference between the start signal and the final signal detected by the phase comparator. A phase lock is provided for shifting the phase of a signal to be transmitted.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the phase lock apparatus according to the present invention.

2 is a diagram illustrating a circuit configuration of a phase lock device according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the phase locker according to the present invention includes a signal generator 200, a power divider 202, a phase comparator 204, a low pass filter (LPF) 206, and a phase shift. Crunch 208, amplitude modulator 210, power amplifier 212, coupler 214, and antenna 216.

In order to more easily understand the circuit configuration of the present invention, the principle of a general signal generator will be described first.

The signal generator 200 is a device for outputting a carrier wave to transmit a message signal, which is an original signal, to a remote location. In order to transmit high quality radio waves, the signal generator 200 needs to output a signal having a fixed phase (and frequency).

Therefore, the signal generator 200 has a PLL (phase locked loop) structure to fix the frequency, that is, to prevent the frequency of the output signal from shaking.

FIG. 3 is a diagram illustrating a circuit configuration inside the signal generator, and as shown in FIG. 3, the signal generator 200 includes a phase detecter 300, a low pass filter 302, and a voltage controlled VCO. oscillator) 304.

It is _assumed that a user wants to output a signal having a frequency f _vco (f _vco is the same value as f _r below), and the VCO 304 outputs a signal having a frequency f _p . Here, the VCO 304 may output a signal having a different frequency according to the voltage applied.

A portion of the f _p signal output from the VCO 304 is input to the phase comparator 300 by a feedback loop.

In addition to the signal output from the VCO 304, the phase comparator 300 receives a reference signal having a frequency f _r . Where f _r is Above It is the same frequency as f _vco .

The phase comparator 300 detects a frequency difference between the input signals and outputs a pulse corresponding to the difference. As the pulse passes through the low pass filter 302, it is converted into a voltage signal that can compensate for the frequency difference between both signals. By applying this voltage signal to the VCO 304, the frequency of the signal output from the VCO 304 can be fixed.

That is, the phase comparator 300 _{outputs from} the VCO 304 by increasing the voltage applied to the VCO 304 when f _p is smaller than f _r (= f _vco ), and decreasing the voltage on the contrary. _Allow the frequency of the signal to be fixed at f _vco .

The present invention introduces the above-described PLL structure inside the signal generator to the entire circuit of the navigation radio transmitter, and its configuration will be described in detail as follows.

As described above, the signal generator 200 has a PLL structure to provide a fixed frequency carrier.

According to the present invention, a signal output from the signal generator 200 (hereinafter referred to as a 'start signal') is evenly distributed through the power divider 202 and input to the phase comparator 204 and the phase shifter 208, respectively. do.

In the above, although the power divider 202 evenly distributes the signal, this is merely an example, and it will be apparent to those skilled in the art that the signal may be distributed at various ratios.

The phase comparator 204 receives not only a start signal output from the signal generator 200 but also a signal that has been processed, such as amplitude modulation and power amplification, as shown in the figure.

As described above, since phase noise may occur in the process of processing the signal, the phase comparator 204 compares the start signal and the final signal and outputs a voltage signal corresponding to the phase difference between the two signals.

The method of detecting the phase difference in the phase comparator 204 will be described in detail below.

A voltage signal representing the phase difference is input to the phase shifter 208 through the low pass filter 206.

The phase shifter 208 receives a start signal branched from the power divider 202 as well as a signal corresponding to the phase difference between the start signal and the final signal as described above.

The phase shifter 208 uses the signal output from the phase comparator 204 to branch directly from the power divider 202 to appropriately change the phase of the input start signal.

The phase shifter 208 can be implemented by various methods. The phase shifter can be phase shifted by adjusting the length of the microstrip line, and the phase shifter can be configured by configuring a circuit such as a zero gain amplifier or an all-pass filter. You might be able to

The signal output from the phase shifter 208 is input to the modulator 210 to perform modulation.

As described above, the present invention can be mainly applied to a DVOR system that provides information such as the current position and flight direction of the aircraft using the phases of the reference phase signal and the variable phase signal, and the reference phase signal is a 30 Hz sinusoidal signal. It consists of an amplitude modulated carrier.

Therefore, according to the present invention, an amplitude modulation process is performed on the signal output from the phase shifter 208.

Thereafter, the modulated signal is input to the power amplifier 212 and amplified so that the modulated signal can be sent to a remote transmission device with high energy.

The power amplifier 212 is a circuit including a transistor for amplifying a signal. The power amplifier 212 sets a bias condition of a transistor so that a desired characteristic is obtained, and then outputs power input by the bias in a form proportional to a change in an input signal. .

That is, the power amplifier 212 does not enlarge the input signal itself, but moves the bias power sensitively to the voltage / current change of the input signal, thereby expanding and copying the input signal.

Although only the case of amplitude modulation has been described above, this is only an example, and it will be apparent to those skilled in the art that a signal may be transmitted by performing frequency modulation.

The signal amplified by the power amplifier 212 passes through a coupler 214. The coupler 214 distributes the amplified signal into two specific signals, and signal energy emitted from adjacent lines to each other. The coupling effect is used to indirectly or indirectly flow into the other track. The signal amplified by the power amplifier 212 is a main signal output from the coupler 214 to the antenna 216 and a coupling signal output from the coupling port (the main signal and the coupling signal correspond to the final signal). Are separated.

The main signal is sent out remotely through the antenna 216 and the coupling signal is fed back to the phase comparator 204.

As described above, the phase change of the signal occurs during the modulation and amplification process. In particular, since the DVOR system uses a large amount of power of 100 Watt or more for power amplification, a large amount of heat is generated during the power amplification process, and phase heat is generated by the heat.

Therefore, there is a phase difference between the unprocessed start signal and the coupled signal after amplitude and modulation.

When two signals having different phases are input to the phase comparator 204, the phase comparator 204 converts each of them into a voltage signal and mixes these signals with each other.

For example, if the start signal is cos (ω1t + θr) and the coupler signal is cos (ω1t + θp), the phase comparator 204 mixes the two signals with each other to obtain a signal represented by the following equation. Will print.

As the above signal passes through the low pass filter 206, the high frequency signal is filtered out and only the low frequency signal remains. That is, the component having a high frequency ω 1 is removed, leaving only cos (θ r -θ p).

In this way, the signal according to the phase difference is input to the phase shifter 208, so that the phase shifter 208 can appropriately change the phase of the start signal.

Although not shown in the figure, the signal passing through the low pass filter 206 may be input to the phase shifter 208 past the analog portion.

The analog unit is composed of an operational amplifier. When a voltage signal proportional to a phase difference is input to the analog unit, the analog unit outputs the signal to the phase shifter 208 after buffering and amplifying the signal.

The analog unit may perform not only buffering and amplification but also summing. For example, if the user wants to manually adjust the phase of the signal, if the appropriate bias voltage is applied to the analog unit, the analog unit may adjust the output signal according to the magnitude of the applied voltage. This configuration may also manually adjust the phase of the start signal.

Comparing the present invention with the PLL structure shown in FIG. 2, it can be seen that the signal generator 200 functions to output a reference signal to the phase comparator 204, and the phase shifter 208 is a conventional PLL. It may correspond to the VCO 304 to compensate for the difference in frequency between the start signal and the final signal.

Therefore, according to the present invention, since the phase shifter 208 already outputs the phase controlled signal in consideration of the phase change by amplitude modulation and power amplification, it is possible to stably transmit the signal having a fixed phase.

For example, suppose a user wants to transmit a signal whose phase is fixed to θ, but the amplitude change and power amplification cause a phase shift of + 60 ° compared to the start signal, as described above. A start signal and a coupler signal having a phase of (θ + 60 °) are input to the phase comparator 204, and pass through a low pass filter 206, whereby a signal corresponding to the + 60 ° phase difference is added to the phase shifter 208. ) Is entered.

At this time, the phase shifter 208 changes the phase of the start signal input from the power divider 202 to the phase shifter 208 to (θ-60) °. When the signal undergoes amplitude modulation and power amplification, a phase change of + 60 ° occurs, and finally, a signal having a phase of a desired θ can be output through the antenna 118.

In particular, the present invention can be applied to a DVOR system for transmitting a periodic signal for flight navigation, according to the present invention, detects the phase difference between the start signal and the coupler signal (final signal), according to the phase difference By shifting the phase of the start signal itself, even if amplitude modulation and amplification are performed, the phase of the final output signal can be fixed, allowing stable communication between the plane and the ground facility.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

As described above, the phase lock apparatus according to the present invention has an advantage of enabling stable navigation wireless communication by appropriately removing phase noise generated during signal modulation and amplification.

In addition, according to the present invention, in a DVOR system for the flight of a plane that periodically transmits and receives a radio signal, the phase is fixed by controlling the phase before input to the amplitude modulator and the power amplifier for the signal output from the signal generator The advantage is that the signal can be sent.

In addition, according to the present invention, since the phase is changed by comparing the start signal output from the signal generator with the final signal that has undergone the modulation and amplification of the start signal, etc., various kinds of phase changes occurring in the movement path of the signal can be avoided. All have the advantage of being able to compensate.

Claims (3)

An apparatus for fixing a phase of a transmission signal in a navigation wireless transmission system, A signal generator comprising a phase locked loop (PLL) and providing a carrier wave; A phase shifter for shifting the phase of the signal output from the signal generator; An amplitude modulator for changing the signal output from the phase shifter according to the amplitude of the message signal; A power amplifier for amplifying the signal output from the amplitude modulator; A phase comparator for comparing a phase of a start signal output from the signal generator and a final signal output from the power amplifier; A power divider for branching a portion of the signal output from the signal generator to the phase comparator and branching the remainder to a phase shifter; And A coupler for extracting a part of the signal output from the power amplifier and branching the phase comparator, And the phase shifter shifts a phase of a signal input from the signal generator corresponding to a phase difference between a start signal and a final signal detected by the phase comparator. delete The method of claim 1, The phase lock device, A low pass filter for filtering out high frequency components of a signal representing a phase difference output from the phase comparator; And an analog unit configured to buffer and amplify the signal output from the low pass filter.

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