JP2004286632A - Circuit for monitoring vswr - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure VSWR by considering leak power from ISO port. <P>SOLUTION: A VSWR monitoring circuit is provided with the means of: (1) adjusting a vector regulator 105 at a detection voltage of the output coupled with reversed phase of the amplified branch signal by way of the vector adjuster 105, the branch signal before amplifying which is branched signal before amplifying the transmission signal progressive wave 121, with the amplified branch signal having branched the signal after amplifying, and the branched signal before amplifying; (2) adjusting the transmission signal advancing wave branched from a part of the output of the vector regulator 105 with a second vector regulator 108; and (3) removing the advancing wave component by making the output of the second vector regulator 108 couple to a reflection branch signal which separated the reflection wave 122 that includs leakage signal of the transmission signal advancing wave 121, with reversed phase. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a VSWR monitor circuit for detecting a reflected wave of a high-frequency transmission signal in a radio communication transmitting / receiving apparatus, particularly a high-frequency transmitting apparatus.
[0002]
[Prior art]
The VSWR monitor circuit extracts the reflected signal of the transmission signal as a branch signal using a circulator, a distributor, a directional coupler, and the like incorporated in the high-frequency transmission circuit, detects a detection voltage using a detector or the like, and detects a transmission signal progression. It is common to measure the voltage of the wave and the magnitude of the voltage of the reflected wave to determine the standing wave ratio (VSWR). Further, since the power (voltage, current) of the traveling wave is uniquely determined, a method for detecting the reflected wave is being studied for its higher accuracy. For example, FIG. 1 of Japanese Patent Application Laid-Open No. H11-27218 discloses a method of measuring a reflected wave generated by a failure in an antenna system of a wireless transmitting and receiving apparatus, and shows a configuration diagram of the measuring circuit. In the figure, 1 is a transmission end-stage amplifier, 2 is a circulator, 3 is an antenna, 4 is a distributor, 5 is a stripline, 6 and 7 are detectors, 8 is a control circuit, and 13 is an antenna connector terminal.
[0003]
Next, the operation will be described. The output of the transmission final stage amplifier 1 is output to the antenna 3 via the antenna connector terminal 13 by the output 1 of the circulator 2. The reflected wave is input from the output 2 of the circulator 2 to the detectors 6 and 7 via the distributor 4 and measures the detection voltages at the respective measurement positions using the strip line 5 and controls the variation in those voltages. In step 8, the averaging process is performed, and finally, an abnormality in the standing wave is detected. FIG. 3 shows a directional coupler 12 for monitoring an output in addition to a circulator 2 for detecting a reflected wave, and detecting these outputs to obtain a VSWR.
[0004]
[Patent Document 1]
JP-A-11-27218 [0005]
[Problems to be solved by the invention]
The circulator disclosed in JP-A-11-27218 is usually formed of a microstrip line or a waveguide circuit. In the case of a Y-type three-aperture (port), a ferrite magnetized in the center of the transmission line in the port is incorporated. , Incident power from any one direction is transmitted to only one direction of the output port. Other output ports are called ISO ports, and incident power is not transmitted in principle. However, the power loss of such an ISO port is at most about 20 dB, and even if the shape of ferrite or the like is optimized, only a power loss of up to 30 dB can be secured. The same applies to a four-terminal directional coupler. Particularly, in a high-frequency circuit of 1 GHz or more transmitted and received by a transmitting device base station or the like, the band of these powers is narrow, and the multiplex communication method (0.8 to 2. In the design of a common transmission circuit such as 0 GHz), power leakage occurs at the ISO port that cannot be ignored. Therefore, there is a problem that the accuracy of the VSWR is reduced due to the influence of the leakage power from the ISO port.
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to precisely measure a VSWR in consideration of leakage power from an ISO port.
[0007]
[Means for Solving the Problems]
A VSWR monitor circuit according to the present invention includes a pre-amplification branch signal obtained by demultiplexing a part of a signal before amplification of a high-frequency transmission signal traveling wave and an amplification branch obtained by demultiplexing a part of a signal after amplification of the high-frequency transmission signal traveling wave. First means for detecting a signal and an output detection voltage obtained by combining the pre-amplification branch signal in an opposite phase to the amplified branch signal via a vector adjuster and adjusting the vector adjuster; and the vector adjuster The output of the second means is input to a second means for adjusting the phase and the amplitude, and the high-frequency signal including the leakage signal after amplification of the high-frequency transmission signal traveling wave is amplified. The output of the reflected branch signal is detected by coupling the reflected branch signal obtained by demultiplexing a part of the reflected wave of the high-frequency transmission signal from the output end of the transmission signal with an opposite phase.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIG. In the figure, 101 is a high frequency transmission signal input terminal, 102 is a first directional coupler for branching a high frequency transmission signal, and unused apertures (ports) are terminated by terminators. 103 is a high-frequency transmission signal amplifier, 104 is a second directional coupler that branches the amplified high-frequency transmission signal, 105 is a first vector adjuster that adjusts the amplitude and phase of the branched high-frequency transmission signal before amplification, 106 is a first distributor, 107 is a first combiner, 108 is a second vector adjuster, 109 is a second combiner, 110 and 111 are detectors, and 112 and 113 are analog / digital (A / D). A converter 114 is a vector adjustment controller, 115 is a digital / analog (D / A) converter, 116 is a VSWR monitor, 117 is a high-frequency signal output terminal (connector terminal), and is connected to an antenna or the like. Reference numeral 118 denotes an internal interface terminal, which sends information about the VSWR to the high-frequency transmitting device.
[0009]
Next, the operation will be described. A high-frequency transmission signal is input to a high-frequency transmission signal input terminal (input terminal) 101, and a traveling wave of the high-frequency transmission signal (transmission signal progression) amplified by a high-frequency transmission signal amplifier (amplifier) 103 via a first directional coupler 102. Wave 121 is output to a high-frequency signal output terminal (also referred to as an output terminal) 117 via the second directional coupler 104. The amplified transmission signal traveling wave 121 is emitted as a radio wave from an antenna (not shown) which is an output end thereof, while the transmission signal reflected wave 122 generated at the antenna or the connector terminal 117 is combined with the transmission signal traveling wave 121. Travels in the opposite direction and is observed as a standing wave between the transmission line and the amplifier 103.
[0010]
A branch signal of the transmission signal traveling wave 121 is output to one branch port (3) of the second directional coupler 104, and a branch signal of the transmission signal reflected wave 122 is mainly output to the other port (4). Is done. At this time, a part of the strong transmission signal traveling wave 121 is output to the other port (4) of the second directional coupler 104 as leakage power. Usually, the power amount may reach the same level as that of the branch signal of the weakly reflected transmission signal 122, and the power having the same phase and the same phase as the branched signal of the reflected transmission signal 122 is superimposed.
[0011]
The branch signal of the transmission signal traveling wave 121 is output to one branch port (3) of the second directional coupler 104, but a part of the branch signal of the transmission signal reflected wave 122 is also output as leakage power. . The power amount is almost negligible because it is the output of the transmission signal reflected wave 122 from the ISO (suppression) port. However, the power amount is superimposed as a slight power having the same direction and a different phase from the branch signal of the transmission signal traveling wave. . This small amount of power will also be described later.
[0012]
These branched signals, which are the outputs of the second directional coupler 104, are transmitted through the first vector adjuster 105 via the first vector adjuster 105 to the transmission signal traveling wave before amplification amplified by the first directional coupler 102. The transmission signal traveling wave further branched by the unit 106 is combined by the first combiner 107. At this time, the first combiner 107 cancels the traveling waves of the transmission signal. That is, by changing the amplitude and phase of the vector adjuster 105, the branch signal output from the second directional coupler 104 and the first directional coupler 102 output from the first vector adjuster 105 are changed. The phase amount of the phase shifter of the first vector adjuster 105 is adjusted so that the phase of the first branch signal is opposite to that of the first branch signal. In this case, the transmission of the branched signal from the first directional coupler 102 is performed in advance so that the amount of delay between the amplified transmission signal traveling wave 121 and the branched signal is within the adjustment range of the phase shifter of the first vector adjuster 105. If necessary for the line, a delay unit or a delay line (not shown) is provided.
[0013]
Further, the amplitude of the attenuator of the first vector adjuster 105 is adjusted. In this case, the degree of branch coupling of the first directional coupler 102 with respect to the transmission signal traveling wave before amplification is set to be within the adjustment range of the attenuator of the first vector adjuster 105.
[0014]
Next, the output of the first coupler 107 is subjected to DC detection by the detector 110, digitized by the A / D converter 112, and transmitted to the vector controller 114. The vector controller 114 adjusts the first vector adjuster 105 with respect to the input detection voltage. The role of the vector controller 114 is to automatically control the output of the first combiner 107 to be minimized, that is, its detection voltage is minimized.
[0015]
First, a control voltage is applied to each of the phase shifter and the attenuator of the vector adjuster 105 based on information from the A / D converter 112. The vector adjuster 105 changes the amount of phase and the amount of amplitude of the transmission signal traveling wave in the line based on the control voltages. The result is reflected on the detection voltage of the output of the first coupler 107. The vector controller 114 operates to set an initial control voltage at first, then sweep the control voltage, change it in steps, and acquire the minimum point of the detection voltage.
[0016]
FIG. 2 shows a control voltage and a detection voltage of the vector controller 114 in the detector 110 by operating the first vector adjuster 105 for this series of operations. The control voltage is initially swept at random, but operates and converges sequentially to approach the minimum point of the detection voltage. Note that the control voltage of the vector controller 114 is a digital signal to be processed by the CPU, but the first vector adjuster 105 transmits the control voltage via the D / A converter 115 because it operates on an analog signal.
[0017]
As described above, the vector controller 114 searches for the minimum point of the output of the first coupler 107, that is, the minimum point of the detection voltage. Here, the minimum point of the detection voltage is a point at which the transmission signal traveling wave which is a branch signal from the first directional coupler 102 and the transmission signal traveling wave which is a branch signal from the second directional coupler 104 cancel each other. Therefore, only the branch signal of the reflected wave of the transmission signal output from the port 3 of the second directional coupler 104, which is a slight voltage, remains in the end. Since this branch signal is an extremely weak voltage, it is insufficient as a monitor signal for the reflected wave, but can be used as a reference control voltage for adjusting the vector adjuster 105, so that the automatic control of the vector adjuster 105 can be performed with high accuracy. There is an effect that can be done.
[0018]
Next, as described above, the branch signal output from the branch port 4 of the second directional coupler 104 is a signal in which the transmission signal reflected wave 122 and the leakage power of the transmission signal traveling wave 121 are superimposed. These signals are obtained by splitting a transmission signal traveling wave before amplification split by the first directional coupler 102 by the first distributor 106 via the first vector adjuster 105 (first coupler 107). ) Is combined with the transmission signal traveling wave by the second combiner 109. At this time, the second coupler 109 cancels the transmission signal traveling waves.
[0019]
In the present embodiment, the amount of phase and attenuation between the first splitter 106 and the second coupler 109 of the transmission line which is a branched transmission signal traveling wave before amplification and which is output from the first vector adjuster 105. A second vector adjuster 108 for adjusting the amount was installed. That is, by changing the phase and amplitude of the vector adjuster 108, the branch signal from the port 4 of the second directional coupler 104 and the branch from the first directional coupler 102 which is the output of the first vector adjuster 105 are changed. The phase amount of the phase shifter of the second vector adjuster 108 is adjusted so that the signal has the opposite phase.
[0020]
What is important is that the transmission signal traveling wave before amplification amplified by the first directional coupler 102 is output from the first distributor 106 via the vector adjuster 105 to the second directional coupler 104 Is a transmission signal traveling wave that has been adjusted in advance by the vector adjuster 105 with reference to the transmission signal traveling wave output from the port 3.
[0021]
This signal has basically a phase opposite to that of the amplified transmission signal traveling wave output from the port 4 of the second directional coupler 104. This is because this signal refers to the output from the port 3 of the second directional coupler 104 by the vector adjuster 105 as described above. The transmission signal traveling wave output at the port 3 of the second directional coupler and the leakage output of the transmission signal traveling wave at the port 4 can be regarded as having the same branch position, so that the leakage power signal of the transmission signal traveling wave which is the output of the port 4 Are basically canceled out in opposite phases in the second coupler 109 except for a slight delay amount between the transmission lines.
[0022]
Therefore, although the second vector adjuster 108 slightly adjusts the phase amount of the second vector adjuster 108, it is sufficient for the main body to adjust only the amplitude amount of the attenuator. FIG. 3 illustrates the relationship between the detection voltage and the control voltage when the transmission signal advancing waves 121 and the transmission signal reflected wave 122 are observed by the detector 111 by operating the attenuator of the second vector adjuster. By applying an analog voltage (approximately 0 to 8 V) as a control voltage to the second vector adjuster 108 in a stepwise manner, the output signals of the second coupler 109 cancel out the transmission signal traveling waves, so that the detection voltage A minimum point appears. In FIG. 3, the minimum point of the detection voltage is the detection voltage of the desired branched transmission signal reflected wave 122.
[0023]
Further, since the branched transmission signal reflected wave 122 does not pass through the attenuator of the second vector adjuster 108 and is inherently an immobile voltage, even if there is interference by the transmission signal traveling wave (traveling wave), even if it deviates from the minimum point. Identification is easy. That is, when the reflected wave power is large as shown in FIG. 3A, the minimum width of the detection voltage in the change of the vector control voltage (control voltage) is widened, and when the reflected wave power is small as shown in FIG. The width is reduced by the influence (interference contribution). In this case, the control voltage applied to the second vector adjuster 108 may be either automatic or manual, and may be a pulse voltage or a DC voltage without any particular problem.
[0024]
Regarding the adjustment of the phase amount of the second vector adjuster 108, for example, a delay line or a delay unit is inserted between the branch port (4) of the second directional coupler 104 and the second coupler 109, and the phase amount is adjusted. The adjustment may be applied to fine adjustment of the second vector adjuster 108. Therefore, in the present embodiment, the second vector adjuster 108 is used, but the vector controller 114 used for adjusting the first vector adjuster 105 is unnecessary, and a general-purpose phase shifter is used instead of the second vector adjuster 108. Alternatively, the adjustment may be performed using individual attenuators.
[0025]
Next, the branch signal (reflected wave) of the transmission signal reflected wave 122 is digitized by the detector 111 and the A / D converter 113 and sent to the VSWR monitor 116 as reflected wave information. The VSWR monitor 116 accurately measures the fluctuation of the detection voltage in the detector 111 or calculates the VSWR (standing wave ratio) itself by transmitting the amplified transmission signal traveling wave 121 through a directional coupler or a circulator. The output is monitored by taking into account the degree of coupling, and is compared with the detection voltage of the VSWR monitor 116 to determine the output. In the VSWR monitor 116, the detection information of the reflected wave of the transmission signal is sent from the internal interface terminal 118 to a processing circuit (not shown) of the high-frequency transmission device, and a system abnormality due to deterioration of the antenna or a mounted component (an amplifier or the like) caused by the reflected wave. ), And changes in the line impedance environment.
[0026]
If there is a limitation on the adjustable range of the vector adjuster, a delay line or a delay unit may be individually inserted in the circuit in advance. Eventually, as the output of the second coupler 109, only the branch signal of the transmission signal reflected wave 122 is transmitted, and the deterioration of the VSWR due to unnecessary superposition of the transmission signal traveling wave 121 is reduced. In addition, since the phase of the transmission signal traveling wave 121 is controlled by the vector adjuster for the measurement variation of the standing wave caused by the detection position, a stable VSWR can be monitored.
[0027]
Embodiment 2 FIG.
In the first embodiment of the present invention, the transmission signal traveling wave 121, the transmission signal reflection wave 122, and the superimposed signal thereof are branched by the second directional coupler 104, but as shown in FIG. The use of the sex couplers 119 and 120 has the same operation and effect. In this embodiment, unused ports of the directional couplers 119 and 120 are terminated as in the case of the first directional coupler 102 of the first embodiment.
[0028]
【The invention's effect】
As described above, in the case of the present embodiment, even in the case of a transmission signal reflected wave including the leakage power of the transmission signal traveling wave in consideration of the performance limit of the directional coupler, the leakage power component of the transmission signal traveling wave is removed and reflected. Since only waves are measured, a highly accurate VSWR monitor circuit can be realized.
[0029]
In addition, since the adjustment is automatically performed using the vector adjuster, the work of adjusting the amount of phase and the amount of attenuation can be omitted, and the fine measurement of the reflected wave can be performed only by fine adjustment, so that only the reflected wave of the transmission signal can be accurately extracted.
[0030]
Further, since automatic control is performed using a vector adjuster, there is no measurement error due to a detection position or the like as in the conventional example.
[Brief description of the drawings]
FIG. 1 is a block diagram of a VSWR monitor circuit according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a relationship between a detection voltage and a control voltage of the vector adjuster according to the first embodiment of the present invention.
FIG. 3 is a diagram showing a relationship between a control voltage of a second vector adjuster and a desired reflected wave detection voltage according to the first embodiment of the present invention.
FIG. 4 is a block diagram of a VSWR monitor circuit according to a second embodiment of the present invention.
[Explanation of symbols]
101 high-frequency transmission signal input terminal, 102 first directional coupler, 103 high-frequency transmission signal amplifier, 104 second directional coupler, 105 first vector adjuster, 106 first distributor, 107 first coupler , 108 second vector adjuster, 109 second combiner, 110, 111 detector, 112, 113 analog / digital converter, 114 vector controller, 115 digital / analog converter, 116 VSWR monitor, 117 high frequency signal output terminal 118 Internal interface terminal, 119, 120 Directional coupler, 121 Traveling wave of high frequency transmission signal (transmission signal traveling wave), 122 Transmission signal reflected wave.

Claims (3)

A pre-amplification branch signal obtained by demultiplexing a part of the signal before amplification of the transmission signal traveling wave, an amplified branch signal obtained by demultiplexing a part of the signal after amplification of the transmission signal progression wave, and First means for detecting a detection voltage of an output coupled in phase with the amplified branch signal via an adjuster to adjust the vector adjuster, and amplifying the signal which is demultiplexed from a part of the output of the vector adjuster; The pre-branch signal is input to a second means for adjusting the phase and the amplitude, and the output of the second means and a reflection obtained by splitting a part of the transmission signal reflected wave including the leakage signal after the amplification of the transmission signal traveling wave is amplified. A VSWR monitor circuit for detecting the output of the reflected branch signal by combining the branch signal with the transmission signal traveling wave in opposite phases. 2. The VSWR monitor circuit according to claim 1, wherein the second means for adjusting the phase is a delay unit or a delay line. 2. The VSWR monitor circuit according to claim 1, wherein the second means for adjusting the phase and the amplitude is a vector adjuster.

Images