JP2013165418A - Radio wave environment measurement device, radio wave environment measurement method, and control program thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of realizing accurate VSWR abnormality determination and observation of peripheral frequency environment.SOLUTION: A radio wave environment measurement device measures a reflection wave of a transmission signal reflected from an antenna side and an interference wave input from the antenna. It includes a control circuit for controlling a control voltage, a voltage variable filter which, in order to observe frequency components of the interference wave and the reflection wave of the transmission signal, is swept at an arbitrary control voltage while center frequency is changed based on the control voltage that is controlled by the control circuit, and a detector which detects frequency components of the interference wave and the reflection wave of the transmission signal extracted through the voltage variable filter, for monitoring an output voltage, thereby allowing detection of a voltage standing wave ratio and observation of frequency component of unnecessary wave.

Description

  The present invention monitors a VSWR (Voltage Standing Wave Ratio) such as a cable or an antenna connected to an antenna end of a base station radio unit apparatus without being affected by an interference wave, and an ambient frequency environment. The present invention relates to a radio wave environment measuring apparatus, a radio wave environment measuring method, and a control program thereof that provide a function for monitoring a radio wave.

  An example of a conventional VSWR monitoring device 1 'is shown in FIG. The VSWR monitoring device 1 'shown in FIG. 6 is for monitoring only the reflected power and causing an alarm (ALM) to be activated when the reflected power becomes a value equal to or greater than a threshold value. In the VSWR monitoring apparatus 1 ′ illustrated in FIG. 6, the transmission signal of the base station passes through the power amplifier (PA) 10, the isolator (ISO) 20, and the coupler (CPL) 30 and is output toward the antenna 40. When the transmission signal output in the direction of the antenna 40 is reflected due to the damage of the antenna 40 or the cable reaching the antenna 40, the reflected wave reflected through the coupler 30 is extracted, and the detector (DET ) By detecting at 60, abnormalities such as damage can be monitored.

  However, the reflected wave (desired wave) reflected from the antenna 40 includes not only the transmitted signal but also various frequency components depending on the surrounding base station environment. Therefore, if the power of the frequency component other than the desired wave is close to the reflected power of the desired wave, an error in the measured value of the reflected power of the desired wave becomes large. Further, if the power of the frequency component other than the desired wave is larger than the reflected power of the desired wave, there is a possibility that an alarm malfunctions. In order to avoid this, a band pass filter (BPF) 100 is disposed in FIG. The bandpass filter 100 has a frequency characteristic that allows only the desired wave to pass, and is thus less susceptible to the influence of frequency components other than the desired wave.

  By the way, in recent years, base station apparatuses are becoming more multi-carrier signals and wider bands, and the desired wave band required for the band-pass filter 100 is also required to have a wide band characteristic. There is. In addition, the influence of frequency components other than the desired wave often affects not only the VSWR detection but also other functions and operations of the base station apparatus. At that time, in order to observe what kind of frequency component interference wave is input via the antenna 40 for analysis, once the base station is stopped, a measuring instrument is connected again. It is cumbersome because it is necessary to have an advanced mechanism for performing a Fourier transform by digitally capturing a signal so that the operation can be started and observed or the frequency component of the interference wave can be detected in the base station apparatus.

  As an example of such a conventional technique, Patent Document 1 detects a transmission signal output via an output terminal 92 and a transmission signal output via an output terminal 95, and transmits the transmission signal output via the output terminal 92. An output voltage is calculated on the basis of the voltage value based on and the voltage value based on the transmission signal output via the output terminal 95 so that the power of the high-frequency signal reaches a predetermined transmission power level based on the calculated output voltage. A transmission power control method for controlling the power amplifier 61 is disclosed.

  In Patent Document 1, in order to control the transmission power to be constant without depending on the load of the antenna, the transmission signal from the output terminal 92 and the transmission signal from the output terminal 95 are used to control the maximum transmission power. The traveling wave component is prevented from being added to the detected power as the value of the detected power.

JP 2011-30101 A

  However, Patent Document 1 is intended to prevent deterioration in output accuracy due to reflected power, and the portable terminal includes a voltage variable filter for observing frequency components of reflected waves and interference waves. Therefore, it was necessary to realize it with an expensive filter. Moreover, the influence of frequency components other than the desired wave could not be observed.

  Also, recent transceiver devices such as mobile base stations have become highly functional, and as one of the functions, a function for determining the normality of the cable connected to the antenna terminal or the antenna body by VSWR is often required. . Depending on the surrounding environment, the base station apparatus may operate abnormally due to the interference wave input to the base station antenna.

  When the interference wave input to the base station antenna exists in the immediate vicinity of the desired transmission wave due to the surrounding environment, it was necessary to detect it after attenuating other than the desired signal by attaching an expensive filter to the VSWR detector. .

  Furthermore, when the VSWR judgment accuracy is greatly deteriorated due to the interference wave input to the base station antenna due to the surrounding environment, the base station operation is stopped and the surrounding environment is observed with a measuring instrument for the analysis. Therefore, it is necessary to incorporate an expensive analysis mechanism into the base station apparatus.

  In order to solve the above problems, an object of the present invention is to realize an accurate VSWR abnormality determination by adding a minimum circuit and to observe an ambient frequency environment.

  In view of the above-described problems, an embodiment of the present invention provides a control circuit that controls a control voltage in a radio wave environment measurement apparatus that measures a reflected wave of a transmission signal reflected from an antenna side and an interference wave input from the antenna; In order to observe the frequency component of the reflected wave and the interference wave of the transmission signal, a voltage variable filter that is swept with an arbitrary control voltage while changing the center frequency based on the control voltage controlled by the control circuit; By detecting the reflected wave of the transmission signal extracted through the voltage variable filter and the frequency component of the interference wave and monitoring the output voltage, the voltage standing wave ratio is detected and the frequency component of the unwanted wave is observed. And a radio wave environment measuring apparatus comprising:

  Another aspect of the present invention relates to a radio wave environment measurement method for measuring a reflected wave of a transmission signal reflected from an antenna side and an interference wave input from the antenna, wherein a frequency component of the reflected wave of the transmission signal and the interference wave is calculated. In order to observe, sweeping with an arbitrary control voltage while changing the center frequency based on the control voltage, detecting the reflected wave of the transmission signal and the frequency component of the interference wave, and monitoring the output voltage, The present invention relates to a radio wave environment measurement method that enables detection of a voltage standing wave ratio and observation of frequency components of unnecessary waves.

  According to another aspect of the present invention, there is provided a control program for a radio wave environment measurement method for measuring a reflected wave of a transmission signal reflected from an antenna side and an interference wave input from the antenna, In order to observe the frequency component of the interference wave, based on the control voltage, sweeping with an arbitrary control voltage while changing the center frequency, detecting the reflected wave of the transmission signal and the frequency component of the interference wave, The present invention relates to a control program that causes a computer to execute processing that enables detection of a voltage standing wave ratio and observation of frequency components of unnecessary waves by monitoring an output voltage.

  According to the present invention, it is possible to inexpensively realize a function of monitoring a VSWR such as a cable or an antenna connected to an antenna end of a base station radio unit apparatus without being affected by an interference wave and monitoring a surrounding frequency environment. It becomes possible.

  Further advantages and embodiments of the present invention are described in detail below using the description and the drawings.

1 is a block diagram of a radio wave environment measuring apparatus according to an embodiment of the present invention. It is a figure which shows the example of a filter (10 MHz width) which has 3 dB bandwidth equivalent to a transmission signal band. It is a figure which shows the example of a characteristic of the voltage variable filter provided in the electromagnetic wave environment measuring apparatus by embodiment of this invention. It is a figure which shows the frequency component and detection level of the desired wave and interference wave which are input from the antenna side. It is a figure which shows the frequency component and detection level which were detected with the detector provided in the electromagnetic wave environment measuring apparatus by embodiment of this invention. It is a block diagram of the VSWR monitoring apparatus by a prior art example.

  Embodiments of the present invention will be described below with reference to the drawings. However, the technical scope of the present invention is not construed as being limited by the embodiments described below.

  FIG. 1 is a block diagram of a radio wave environment measuring apparatus 1 according to an embodiment of the present invention. The radio wave environment measuring apparatus 1 according to the present embodiment realizes not only the detection of VSWR abnormality but also the function of monitoring the interference wave of the frequency component other than the desired wave by an inexpensive method.

  A radio wave environment measuring apparatus 1 according to this embodiment shown in FIG. 1 includes a power amplifier 10, an isolator 20, a coupler 30, an antenna 40, a voltage variable filter 50, a detector 60, an analog / digital converter 70, and a digital / analog converter. 80 and an output end 90. The transmission signal of the base station is radiated from the antenna 40 through the power amplifier 10, the isolator 20, and the coupler 30. Further, general-purpose devices can be used as the analog / digital converter 70 and the digital / analog converter 80 to be used.

  In the radio wave environment measuring apparatus 1, if there is an impedance mismatch between the output end 90 and the antenna 40, part of the power to be radiated from the antenna 40 is reflected back as a reflected wave. When the antenna 40 or the coaxial cable up to the antenna 40 is abnormal and becomes completely open, it returns with total reflection. The reflected signal (reflected wave) is extracted through the coupler 30 and detected by the detector 60 through the voltage variable filter 50. The voltage variable filter 50 is a voltage control type variable filter and has a mechanism capable of changing the center frequency using a control voltage controlled by a digital / analog converter (DAC) 80.

  In addition, when performing VSWR detection of the transmission signal band or when it is desired to accurately observe frequency components other than the desired wave, it is necessary to narrow the 3 dB bandwidth of the voltage variable filter 50. For example, in the case of a filter having a 3 dB bandwidth equivalent to the transmission signal band as shown in FIG. 2, even if the frequency is varied, it is possible to identify the frequency components of unnecessary waves with an interval narrower than the bandwidth of the voltage variable filter 50. become unable. Therefore, when accurately monitoring the frequency components of unnecessary waves, it is desirable to use a filter with a 3 dB bandwidth narrower than the transmission signal bandwidth as shown in FIG.

  When the reflected wave of the desired wave and the interference wave component other than the desired wave as shown in FIG. 4 are input from the antenna 40 side, the output voltage of the detector 60 is swept by the digital / analog converter 80. Is monitored, the frequency component and the detection level shown in FIG. 5 are observed. In the case of the present embodiment, the center frequency of the voltage variable filter 50 is swept from 2020 MHz to 2180 MHz at 1 MHz intervals. Thereby, not only the reflected power of the desired wave but also frequency components other than the desired wave can be detected.

  A similar monitor takes in the output of the detector 60 into the baseband without arranging a filter for band limitation between the coupler 30 and the detector 60, and then performs Fourier transform, or directly captures the signal with a down converter. Although it is possible, the bandwidth of the high-speed detector 60 and the analog / digital converter (ADC) 70 to be incorporated into the baseband must be selected in accordance with the bandwidth to be monitored, and the monitor apparatus is expensive. turn into. Therefore, by using the voltage variable filter 50 as in the embodiment of the present invention, it is possible to use an inexpensive filter and detector configuration.

  Sweeping at fine frequency steps requires a certain amount of sweep time, but for applications such as VSWR measurement and interference wave observation, even if the 200 MHz band is swept 10 times at 1 MHz step and 1 step 100 us, it takes 1 second on average Because the measurement is finished within, quick measurement is possible.

  As described above, in the radio wave environment measuring apparatus 1 according to the embodiment of the present invention, the center frequency can be changed by the voltage between the coupler 30 that takes in the signal reflected from the antenna 40 side and the detector 60 that detects the reflected power. A voltage variable filter (VCF) 50 is added. This voltage variable filter 50 has a 3 dB bandwidth of about 1/10 of the desired signal band. By monitoring the detection voltage output of the detector 60 while controlling the control voltage of the voltage variable filter 50 to change the center frequency, the reflected power of the desired wave and the frequency of the interference wave other than the desired wave as shown in FIG. When a component is input, its frequency component and detection level can be detected as shown in FIG. When it is desired to detect VSWR, it is possible to eliminate the influence of the interference wave that exists in the immediate vicinity of the desired wave by using the result of sweeping with the control voltage only in the frequency band where the desired wave exists. Further, by sweeping the control voltage in a wide band other than the frequency band in which the desired wave exists, it becomes possible to observe frequency components other than the desired wave (unnecessary wave) input via the antenna 40. .

  Next, the operation of the radio wave environment measuring apparatus 1 according to the embodiment of the present invention will be described.

  In the embodiment of the present invention, the “desired wave” in FIGS. 4 and 5 means the reflected power of the desired wave, and the interference waves A to D mean the interference wave component jumped from the antenna 40. The transmission signal of the base station is radiated from the antenna 40 through the power amplifier 10, the isolator 20 and the coupler 30. If there is an impedance mismatch between the output end 90 and the antenna 40, a part of the power to be radiated from the antenna 40 is reflected and returned. This is expressed as “desired wave” in FIGS. A signal input from the antenna 40 is extracted through the coupler 30 and detected by the detector 60 through the voltage variable filter 50. The voltage variable filter 50 is a voltage control type variable filter, and has a mechanism capable of changing the center frequency by controlling the control voltage by the digital / analog converter 80. The voltage variable filter 50 can be set to an arbitrary frequency within the resolution range of the digital / analog converter 80. In the present embodiment, a desired wave with a 10 MHz bandwidth is assumed, and the 3 dB bandwidth of the voltage variable filter 50 has a characteristic of about 1 MHz so that an interference wave immediately above the desired wave band can be detected.

  When the reflected wave of the desired wave and the interference wave component other than the desired wave as shown in FIG. 4 are input from the antenna 40 side, the output voltage of the detector 60 is swept by the digital / analog converter 80. Is monitored, frequency components and detection levels as shown in FIG. 5 are observed. In the case of the present embodiment, the center frequency of the voltage variable filter 50 is swept from 2020 MHz to 2180 MHz at 1 MHz intervals. Thereby, not only the reflected power of the desired wave but also frequency components other than the desired wave can be detected. In FIG. 5, the boundary between the desired wave and the interference wave D is difficult to understand, but the boundary can be made clearer by further narrowing the 3 dB bandwidth of the voltage variable filter 50. However, it is not necessary to use a filter with such a high Q value as long as the VSWR and the interference wave around the desired wave are monitored. When calculating as the VSWR value, the detection result of the lower half of the 10 MHz bandwidth of the desired wave may be used to convert to the 10 MHz bandwidth. Further, even if this monitor is swept 10 times every 100 us and averaged, the sweep time in the 200 MHz band is 200 ms, which is a sufficiently short time for the VSWR monitor.

  Furthermore, since the radio wave environment measuring apparatus 1 according to the present embodiment can accurately observe frequency components other than the desired wave as shown in FIG. 5, analysis using high-speed and expensive sampling and Fourier transform, and once stopping the base station. It is possible to monitor the interference wave component input to the output terminal 90 of the apparatus without connecting the measuring device. If the device can be remotely controlled, it is possible to provide an environment for observing the interference wave component remotely without going to the site where the base station is installed.

  In this way, an interference wave near the desired wave can be obtained without using a configuration using an expensive crystal filter / SAW filter or a configuration using an inexpensive voltage variable filter and detector without using frequency analysis using high-speed sampling and Fourier transform. VSWR detection in a certain environment is possible, and a function of monitoring unnecessary wave components around the base station using the apparatus 1 can be realized.

  As described above, the present invention has the following effects.

  The first effect is that VSWR measurement using the reflected power of the desired wave can be performed even in an environment where an interference wave exists in the vicinity.

  The second effect is that it is possible to observe frequency components other than the desired wave band without having an expensive device. Therefore, an environment in which data necessary for the surrounding environment investigation and troubleshooting can be acquired remotely. It can be realized at low cost.

  A control program that causes a computer to execute the radio wave environment measuring method according to the above-described embodiment is also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Radio wave environment measuring apparatus 10 Power amplifier 20 Isolator 30 Coupler 40 Antenna 50 Voltage variable filter 60 Detector 70 Analog / digital converter 80 Digital / analog converter 90 Output end

Claims (7)

In the radio wave environment measuring device that measures the reflected wave of the transmission signal reflected from the antenna side and the interference wave input from the antenna,
A control circuit for controlling the control voltage;
In order to observe the frequency component of the reflected wave and the interference wave of the transmission signal, based on the control voltage controlled by the control circuit, a voltage variable filter that is swept with an arbitrary control voltage while changing the center frequency;
By detecting the frequency component of the reflected wave and the interference wave extracted through the voltage variable filter and monitoring the output voltage, the voltage standing wave ratio is detected and the frequency component of the unwanted wave is observed. A radio wave environment measuring device comprising:   2. The radio wave environment measuring apparatus according to claim 1, wherein the voltage variable filter has a resonance peak sharp enough to monitor a voltage standing wave ratio and an interference wave around a desired wave.   2. The radio wave environment measuring apparatus according to claim 1, wherein the voltage variable filter is a filter having a narrower bandwidth than a transmission signal band.   The reflected wave of the transmission signal reflected from the antenna side is a desired wave in which a part of the power to be radiated from the antenna is reflected due to impedance mismatch between the output end and the antenna. The radio wave environment measuring device according to any one of claims 1 to 3.   The radio wave environment measuring apparatus according to any one of claims 1 to 4, wherein the radio wave environment measuring apparatus is a remotely controllable apparatus and provides an environment for remotely observing an interference wave component. . In the radio wave environment measurement method for measuring the reflected wave of the transmission signal reflected from the antenna side and the interference wave input from the antenna,
In order to observe the frequency component of the reflected wave and the interference wave of the transmission signal, based on the control voltage, sweeping with an arbitrary control voltage while changing the center frequency,
By detecting the frequency component of the reflected wave and the interference wave of the transmission signal and monitoring the output voltage, it is possible to detect the voltage standing wave ratio and observe the frequency component of the unnecessary wave. Environmental measurement method. In a control program for a radio wave environment measuring method for measuring a reflected wave of a transmission signal reflected from an antenna side and an interference wave input from an antenna,
In order to observe the frequency component of the reflected wave and the interference wave of the transmission signal, based on the control voltage, sweeping with an arbitrary control voltage while changing the center frequency,
Performs processing that enables detection of the voltage standing wave ratio and observation of frequency components of unnecessary waves by detecting the frequency components of the reflected wave and the interference wave of the transmission signal and monitoring the output voltage. Control program to make.

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