JP2007158759A - Radio communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise quality in radio communication even when the reception electric wave is at a weak electric field level. <P>SOLUTION: Synthetic reception level generating portions 20a, 20b amplify intermediate frequency signals IF1, IF2 after the frequency conversion of radio signals RF1, RF2, which are respectively received from first and second antennas so as to detect reception levels L1, L2, detect a noise level so as to generate inversion noise levels N1, N2 by inverting the polarity of the detected noise level, synthesize the inversion noise levels N1, N2, which appear in a weak electric field level area, with the weak electric field level portions of the reception levels L1, L2, and respectively generate synthetic reception levels C1, C2. A comparing portion 30 compares the synthetic reception level C1 with C2. An antenna switching portion 40 performs switching by selecting the antenna at the higher synthetic reception level. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio communication apparatus, and more particularly to a radio communication apparatus that performs radio communication by performing diversity reception.

  In wireless communications, signal waves propagate through multiple paths (multipath) due to reflections from mountains, buildings, etc., and are mixed together. Fading in which the level of reception appears depending on the location where the signal is received (multipath fading) The phenomenon called is generated.

  In multipath fading, for example, when two radio waves of a direct wave and a reflected wave are mixed, if the delay of the reflected wave is exactly one cycle, the two radio waves strengthen each other, but when they are out of phase by half a cycle, they cancel each other It will be.

  In other words, if the distance difference between the propagation paths of two radio waves is received at a position that is an even multiple of 1/2 wavelength, the radio waves will suddenly weaken (thus, if the radio is moving, If the strength of the radio waves is frequently repeated), fading causes an increase in the information transmission error rate.

  Therefore, in order to avoid such multipath fading and perform good radio wave reception, a reception method called diversity reception is widely used in the field of wireless communication. In this method, radio waves are received using a plurality of antennas, and an antenna having the best reception state is selected and switched to perform stable reception.

  As a method for avoiding multipath fading, it is possible to simply change the propagation distance of radio waves by moving the position of the antenna (it may be within a slight range of about ½ wavelength). Thereby, since the phase difference is adjusted, it is possible to escape from the phase point where the reception level falls.

  Therefore, if diversity reception is performed with two antennas installed in the receiver, the antennas should be installed with an interval of about ½ wavelength so that radio waves can be received by both antennas, and the sensitivity should be improved as needed. Try to switch.

  In this way, diversity reception is performed by placing two antennas spatially apart, comparing the reception levels of radio waves received by both antennas, and receiving field strength index (RSSI: Received Signal Strength) of one antenna. When (Indicator) decreases, it is switched to one of the antennas for reception to prevent the RSSI from decreasing, and this is also called space diversity reception.

  Diversity reception also has a method of combining the signals received by multiple antennas in phase, but in this case, it is necessary to shift the phase of either received radio wave, which is simpler than the antenna switching method described above. It is not a simple method.

As a conventional diversity reception technique, a technique has been proposed in which an antenna is switched in a section where there is no communication control data, a reception level is measured, and antenna switching is performed while preventing loss of communication control data (for example, Patent Document 1). .
Japanese Patent Laying-Open No. 2005-203958 (paragraph numbers [0018] to [0025], FIG. 1)

  In recent wireless communication, there is an increasing number of cases in which a digital signal is also superimposed on an analog FM (Frequency Modulation) wave, and improvement in communication quality is required. For this reason, in the antenna reception type diversity reception, a stable reception level can be obtained with a simple circuit configuration, and therefore it can be utilized for improving communication quality even in FM multiplexed communication.

  On the other hand, in antenna switching type diversity reception, each received signal from two antennas is IF amplified by an FM-IF (Intermediate Frequency) amplifier, and the two received levels after amplification are detected and compared, and the detection level is high. Select the other antenna.

  However, since a stable IF amplification could not be expected at a weak electric field level (−100 dBm or less), a stable voltage level could not be detected when the received wave became a weak electric field level (to the IF amplifier). If the input level is too low, a stable amplified output cannot be obtained. For this reason, in a weak electric field level region, level comparison is performed with unstable amplification output, so that antenna switching fluctuates violently or the switching function does not operate, causing deterioration in reception quality. There was a problem.

  Also, in this case, when a mobile body having an antenna switching type diversity reception function enters an area with a weak electric field level, the clarity of communication (call) deteriorates, and as a result, the call area is reduced. become.

  For this reason, especially in self-operated wireless systems (wireless systems for public works such as firefighting / emergency, gas and water, or general-purpose wireless systems that support corporate activities such as home delivery services), the sensitivity is weak around 6 dBμ or less. Even in the case of an electric field, it is necessary to widen the dynamic range, and there is a strong demand for a system that can perform stable wireless signal communication even in such a region.

  The present invention has been made in view of these points, and provides a wireless communication apparatus that performs stable wireless communication and improves wireless communication quality even when a received radio wave is at a weak electric field level. With the goal.

  In the present invention, in order to solve the above-described problem, in the wireless communication device 1 that performs wireless communication as shown in FIG. 1, the first antenna, the second antenna, and the wireless signal RF1 received from the first antenna. Is converted into the intermediate frequency signal IF1, and the frequency converter 10 that converts the radio signal RF2 received from the second antenna into the intermediate frequency signal IF2, and the intermediate frequency signal IF1 is amplified, and then the reception level L1 for the radio signal RF1 is set. An intermediate frequency amplifying unit 21a for detecting, a noise level detecting unit 22a for detecting a noise level with respect to the radio signal RF1, an inverted noise level generating unit 23a for generating an inverted noise level by inverting the polarity of the detected noise level, The inversion noise level N1 in the weak electric field level region of the radio signal RF1 is combined with the weak electric field level portion of the reception level L1, and combined reception A combined reception level generation unit 20a composed of a level synthesis unit 24a that generates the bell C1, an intermediate frequency amplification unit 21b that amplifies the intermediate frequency signal IF2 and then detects the reception level L2 for the radio signal RF2, and a radio A noise level detection unit 22b that detects a noise level for the signal RF2, an inversion noise level generation unit 23b that inverts the polarity of the detected noise level to generate an inversion noise level, and a weak electric field level region of the radio signal RF2. A composite reception level generation unit 20b configured by combining a certain inversion noise level N2 with a weak electric field level portion of the reception level L2 to generate a composite reception level C2, and a composite reception level C1 Is compared with the combined reception level C2 and outputs a comparison signal indicating the comparison result, and based on the comparison signal. A radio communication apparatus 1 comprising: an antenna switching unit 40 that selects and switches either the first antenna or the second antenna having a higher reception level L1 or reception level L2 as a reception antenna. Is provided.

  Here, the frequency converter 10 converts the radio signal RF1 received from the first antenna into the intermediate frequency signal IF1, and converts the radio signal RF2 received from the second antenna into the intermediate frequency signal IF2. The intermediate frequency amplifier 21a amplifies the intermediate frequency signal IF1, and then detects the reception level L1 for the radio signal RF1. The noise level detector 22a detects the noise level for the radio signal RF1. The inverted noise level generation unit 23a generates the inverted noise level N1 by inverting the polarity of the detected noise level. The level combining unit 24a combines the inverted noise level N1 in the weak electric field level region of the radio signal RF1 with the weak electric field level portion of the reception level L1 to generate a combined reception level C1. The intermediate frequency amplifier 21b amplifies the intermediate frequency signal IF2 and then detects the reception level L2 for the radio signal RF2. The noise level detector 22b detects the noise level for the radio signal RF2. The inverted noise level generator 23b inverts the polarity of the detected noise level to generate an inverted noise level N2. The level combining unit 24b combines the inverted noise level N2 in the weak electric field level region of the radio signal RF2 with the weak electric field level portion of the reception level L2 to generate a combined reception level C2. The comparison unit 30 compares the combined reception level C1 and the combined reception level C2 and outputs a comparison signal indicating the comparison result. Based on the comparison signal, the antenna switching unit 40 selects and switches either the first antenna or the second antenna having the higher reception level L1 or reception level L2 as the reception antenna.

  The wireless communication device of the present invention has two antennas, amplifies the intermediate frequency signal after frequency conversion of the wireless signal from each antenna, detects the reception level, and detects the noise level, and is detected. The inverted noise level is generated by inverting the polarity of the noise level. Then, the inversion noise level appearing in the weak electric field level region is combined with the weak electric field level portion of the reception level to generate a combined reception level, and the antenna with the higher combined reception level is selected as the reception antenna. It was set as the structure switched. As a result, even if the received radio wave is at a weak electric field level, the dynamic range can be expanded and stable antenna switching can be performed, and the wireless communication quality can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a principle diagram of a wireless communication apparatus. The wireless communication device 1 includes two antennas, a first antenna and a second antenna, and includes a frequency conversion unit 10, a combined reception level generation unit 20a (first combined reception level generation unit), and a combined reception level generation. This is an apparatus that includes a unit 20b (second combined reception level generation unit), a comparison unit 30, and an antenna switching unit 40, and performs antenna switching diversity reception. Hereinafter, the first antenna is referred to as an MN antenna (MN is Main), and the second antenna is referred to as an SD antenna (SD is Space Diversity).

  The frequency converter 10 converts the radio signal RF1 (first radio signal) received from the MN antenna into an intermediate frequency signal IF1 (first intermediate frequency signal), and receives the radio signal RF2 (second radio signal) received from the SD antenna. Wireless signal) is converted into an intermediate frequency signal IF2 (second intermediate frequency signal).

The combined reception level generation unit 20a includes an intermediate frequency amplification unit 21a, a noise level detection unit 22a, an inverted noise level generation unit 23a, and a level combination unit 24a.
The intermediate frequency amplifier 21a amplifies the intermediate frequency signal IF1 and detects the reception level L1 for the radio signal RF1. The noise level detection unit 22a detects a noise level (described later in FIG. 3) that increases when the radio signal RF1 is at a weak electric field level.

  The inverted noise level generation unit 23a generates the inverted noise level N1 by inverting the polarity of the detected noise level. The level combining unit 24a combines the inverted noise level N1 in the weak electric field level region with the weak electric field level portion of the reception level L1 to generate a combined reception level C1.

The combined reception level generation unit 20b includes an intermediate frequency amplification unit 21b, a noise level detection unit 22b, an inverted noise level generation unit 23b, and a level combination unit 24b.
The intermediate frequency amplifier 21b amplifies the intermediate frequency signal IF2 and detects the reception level L2 for the radio signal RF2. The noise level detector 22b detects a noise level that increases when the radio signal RF2 is at a weak electric field level.

  The inverted noise level generator 23b inverts the polarity of the detected noise level to generate an inverted noise level N2. The level combining unit 24b combines the inverted noise level N2 in the weak electric field level region with the weak electric field level portion of the reception level L2 to generate a combined reception level C2.

  The comparison unit 30 compares the combined reception level C1 and the combined reception level C2 and outputs a comparison signal indicating the comparison result. The antenna switching unit 40 selects and switches either the MN antenna or the SD antenna having the higher reception level L1 or reception level L2 as the reception antenna based on the comparison signal.

  Next, operations of the combined reception level generation units 20a and 20b will be described. Note that the MN antenna system combined reception level generation unit 20a and the SD antenna system combined reception level generation unit 20b perform the same operation, and therefore only the MN antenna system will be described.

  FIG. 2 is a diagram showing the characteristics of the reception level L1. The vertical axis represents the reception level L1 (V), and the horizontal axis represents the reception electric field level (dBm) of the radio signal RF1. The reception level L1 corresponds to an amplified voltage obtained by amplifying the intermediate frequency signal IF1 after the intermediate frequency amplification unit 21a frequency-converts the radio signal RF1. The reception electric field level is a level voltage at the time of radio signal antenna reception.

  When the received electric field level of the radio signal RF1 received by the MN antenna exceeds −100 dBm, the intermediate frequency signal IF1 is an input level sufficient for the amplification function of the intermediate frequency amplifier 21a to operate stably. In the intermediate frequency amplifier 21a, stable IF amplification can be performed. Accordingly, as shown in the figure, the received level L1 (amplified voltage) increases as the received electric field level increases (however, the saturation level is reached when the received electric field level exceeds −20 dBm).

  On the other hand, when the reception electric field level of the radio signal RF1 received by the MN antenna is −100 dBm or less, the intermediate frequency amplification unit 21a cannot perform stable IF amplification because the level of the intermediate frequency signal IF1 is too low. For this reason, the reception level L1 (amplified voltage) is indefinite within the range of the reception electric field level where the radio signal RF1 is −100 dBm or less. Since it is indefinite, the graph of the reception level in this weak electric field level range (−100 dBm or less) is not shown in the figure.

  FIG. 3 is a diagram showing the characteristics of the noise level. The vertical axis represents the peak-to-peak noise level (V) detected by the noise level detector 22a, and the horizontal axis represents the received electric field level (dBm) of the radio signal RF1.

  Here, the noise level detection unit 22a detects a noise level that increases when the radio signal RF1 is not received. In general, in a radio receiver, noise is reduced when there is a desired incoming radio wave, but when there is no incoming radio wave, a large noise is generated at the speaker output. Control for suppressing this noise is called noise squelch. The noise detected by the noise level detection unit 22a refers to the noise to be suppressed by this noise squelch.

  Therefore, as shown in the figure, in the region where the reception electric field level of the radio signal RF1 is small (−120 dBm), it means that the desired incoming radio wave is not received, and therefore the noise level increases (2.0 V or more). ) As the reception electric field level of the radio signal RF1 increases (when the radio signal RF1 is tuned), the noise level decreases.

  FIG. 4 is a diagram showing the inverted noise level N1. The vertical axis represents the inverted noise level N1 (V), and the horizontal axis represents the received electric field level (dBm). The inversion noise level generation unit 23a inverts the polarity of the graph of the noise level with the downward slope shown in FIG. 3 to generate the inverted noise level N1 of the graph with the upward slope of the right.

  FIG. 5 is a diagram showing the combined reception level C1. The vertical axis represents the combined reception level C1 (V), and the horizontal axis represents the reception electric field level (dBm). The level combining unit 24a combines the inverted noise level N1 in the region of −120 dBm to −100 dBm with the portion of −120 dBm to −100 dBm of the radio signal RF1 to generate a combined reception level C1.

  By performing such processing, the indefinite region of the reception level L1 can be eliminated, and the dynamic range is expanded to the weak electric field level. At the time of generating the inverted noise level N1, the inverted noise level generation unit 23a performs DC conversion (DC conversion) on the inverted noise level N1 and then combines it with the reception level L1, thereby -120 dBm to -120 dBm of the combined reception level C1. Provide linearity in the weak electric field level region of 100 dBm (by providing linearity, it is easy to perform the combining process, and the comparison unit 30 in the subsequent stage sets the combined reception levels C1 and C2 in the weak electric field level region. It is easy to detect the comparison difference value when comparing each other). In addition, the combined reception level generation unit 20b of the SD antenna system performs similar processing to generate a combined reception level C2.

  On the other hand, since the comparison unit 30 at the subsequent stage receives the combined reception levels C1 and C2 having no indefinite region even when the radio signals RF1 and RF2 are at a weak electric field level, both levels can be compared stably. . Further, the antenna switching unit 40 switches the antenna with high accuracy even if the radio signals RF1 and RF2 are at the weak electric field level based on the comparison signal indicating the result of comparing the combined reception levels C1 and C2 by the comparison unit 30. It becomes possible to execute.

  Next, a detailed configuration of the wireless communication device 1 will be described. 6 and 7 are diagrams illustrating the configuration of the wireless communication device 1. FIG. The wireless communication device 1 includes an MN antenna, an SD antenna, a frequency conversion unit 10, a combined reception level generation unit 20a, a combined reception level generation unit 20b, a comparison unit 30, an antenna switching unit 40, display units 50a and 50b, a demodulation unit 60, The pilot signal detector 70 is configured.

(Frequency converter 10)
The frequency converter 10 includes RF amplifiers 11a and 11b, mixers 12a and 12b, IF amplifiers 13a and 13b, mixers 14a and 14b, bandpass filters 15a and 15b, and local oscillators 16 and 17. The

  In the processing of the MN antenna system, the RF amplifier 11a amplifies the radio signal RF1 of the VHF (Very High Frequency: 30 MHz to 300 MHz) band or UHF (Ultra High Frequency: 300 MHz to 3 GHz) band received via the MN antenna. .

  The local oscillator 16 outputs a local oscillation signal LO1 having the same frequency as the local oscillation signal when transmitting the radio signal RF1 on the transmission side, and the mixer 12a mixes the output of the RF amplifier 11a and the local oscillation signal LO1. Then, the signal is returned to the first intermediate frequency signal (for example, 10.7 MHz or 21.4 MHz).

  The IF amplifier 13a amplifies the first intermediate frequency signal. The local oscillator 17 outputs a local oscillation signal LO2 having the same frequency as the local oscillation signal when transmitting the radio signal RF1 on the transmission side, and the mixer 14a mixes the output of the IF amplifier 13a and the local oscillation signal LO2. Then, the signal is returned to the second intermediate frequency signal (for example, 455 KHz, corresponding to the intermediate frequency signal IF1).

  The band pass filter 15a performs filtering processing of the intermediate frequency signal IF1 to remove interference waves and nearby waves (this filter is preferably narrowband, but if there is multiplexed information in the baseband, the bandpass filter 15a has a necessary band. It needs to be widened and used properly according to the application). Since the operation of each component in the frequency conversion unit 10 of the SD antenna system is exactly the same as described above, the description thereof is omitted.

(Synthetic reception level generation unit 20a, 20b)
The combined reception level generation unit 20a includes an FM / IF amplifier 21a (corresponding to the intermediate frequency amplification unit 21a), a noise level detection unit 22a, an inverted noise level generation unit 23a, and a level combination unit 24a.

  The FM / IF amplifier 21a amplifies the intermediate frequency signal IF1 output from the bandpass filter 15a and outputs a reception level L1. The noise level detection unit 22a detects the noise level from the reception level L1.

  The inverted noise level generation unit 23a generates the inverted noise level N1 by inverting the polarity of the noise level. Here, when the inverted noise level generation unit 23a is configured, it can be easily configured using a diode. In this case, the cathode side of the diode is connected to the output end of the noise level detection unit 22a, and the anode side is connected to the input end of the level synthesis unit 24a.

  When an AC signal is output from the noise level detection unit 22a, if a negative signal of the AC signal is input to the cathode of the diode, a current flows from the cathode to the anode. At this time, the greater the AC signal swings to the negative side, the more current flows, and the less current flows where it swings smaller.

  In the graph of FIG. 3, the more the AC signal swings to the negative side (the smaller the value on the vertical axis of the graph), the more current flows from the cathode to the anode and the smaller the AC signal negative side swing ( The smaller the value on the vertical axis of the graph, the less current flows from the cathode to the anode. That is, a signal that rises to the right (inverted noise level signal) obtained by converting the signal output from the noise level detector 22a into a direct current is output from the inverted noise level generator 23a.

  The level combining unit 24a combines the inverted noise level N1 appearing in the weak electric field level region with the weak electric field level portion of the reception level L1 to generate a combined reception level C1. The operation of each component in the combined reception level generation unit 20b of the SD antenna system is exactly the same as described above, and the description thereof is omitted.

(Comparator 30)
When receiving the pilot detection signal, the comparison unit (comparator) 30 performs a comparison process between the combined reception level C1 and the combined reception level C2, and outputs a comparison signal indicating the comparison result to the antenna switching unit 40. As a comparison control, for example, when C1> C2 and the level on the MN antenna side is large, “H” is output as a comparison signal. When C1 <C2 and the level on the SD antenna side is large, “L” is output as a comparison signal. Output is assumed. When the pilot detection signal is not received, the comparison signal becomes high impedance and the antenna switching control is stopped.

(Antenna switching unit 40)
The antenna switching unit 40 includes two FETs (Field Effect Transistors) 41 and 42. The drain of the FET 41 is connected to the output terminal of the bandpass filter 15a and the input terminal of the FM / IF amplifier 21a, and the drain of the FET 42 is connected to the output terminal of the bandpass filter 15b and the input terminal of the FM / IF amplifier 21b. The sources of the FETs 41 and 42 are both connected to the input terminal of the demodulator 60.

  Further, the gate of FET 41 (positive logic) and the gate of FET 42 (negative logic) are connected, and both gates receive a comparison signal. When the comparison signal is “H”, the FET 41 is switched on and the FET 42 is switched off. When the comparison signal is “L”, the FET 41 is switched off and the FET 42 is switched on.

  The antenna switching unit 40 has an analog switch structure for branching to the FM / IF amplifiers 21a and 21b and switching to the demodulating unit 60. Since the branch point and the switching point are the same part, there is almost no level difference. It does not seem to occur. In addition, since the antenna switching unit 40 imagines a transfer type switch and is always connected to either one, by using an analog switch or FET to realize this, there is no contact, no switching timing In addition, it is easy to align between the stages.

(Display 50a, 50b)
The display units 50a and 50b display the level values of the combined reception levels C1 and C2, respectively (metering display or the like). Also, an indication of whether the radio wave is being received by the MN antenna or the SD antenna (for example, if radio waves are being received by the MN antenna, the LED on the display unit 50a side is lit, and the display unit 50b side is illuminated. LED goes off).

(Demodulator 60)
The demodulator 60 receives a signal that flows from the FET 41 or the FET 42 that is turned on, temporarily amplifies the signal, and then performs a demodulation process to output a demodulated signal.

(Pilot signal detector 70)
The pilot signal detector 70 detects a pilot signal transmitted from the base station from the demodulated signal. When a pilot signal is detected, the pilot detection signal is output to the comparison unit 30.

  As described above, according to the present invention, with respect to a weak electric field level region that is not stably amplified and output by the amplifying unit of the intermediate frequency signal, a noise level that increases when the radio signal is at a weak electric field level. An inversion noise level is generated by detection, and the inversion noise level is combined with the weak electric field level portion of the reception level to expand the dynamic range. Accordingly, even when the radio signal is at a weak electric field level, the reception level comparison process and the antenna switching control can be operated with high accuracy, and the reception quality can be improved.

In addition, even for VHF band and UHF band private mobile communication, by using the present invention, it is possible to suppress a rapid deterioration of the bit error rate even if the reception level is lowered.
In addition, by operating the antenna switching function only when a pilot signal is detected, it is possible to receive and process useless noise signals in adverse environments where pilot signals cannot be detected, or to receive interference waves from other systems. It is possible to avoid such processing.

It is a principle figure of a radio | wireless communication apparatus. It is a figure which shows the characteristic of a reception level. It is a figure which shows the characteristic of a noise level. It is a figure which shows an inversion noise level. It is a figure which shows a synthetic | combination reception level. It is a figure which shows the structure of a radio | wireless communication apparatus. It is a figure which shows the structure of a radio | wireless communication apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 10 Frequency conversion part 20a, 20b Composite reception level production | generation part 21a, 21b Intermediate frequency amplification part 22a, 22b Noise level detection part 23a, 23b Inverted noise level production | generation part 24a, 24b Level synthesis part 30 Comparison part 40 Antenna switching Part RF1, RF2 Radio signal IF1, IF2 Intermediate frequency signal L1, L2 Reception level N1, N2 Inverted noise level C1, C2 Combined reception level MN First antenna SD Second antenna

Claims (5)

In a wireless communication device that performs wireless communication,
A first antenna;
A second antenna;
A frequency converter that converts a first radio signal received from the first antenna into a first intermediate frequency signal and converts a second radio signal received from the second antenna into a second intermediate frequency signal. When,
After amplifying the first intermediate frequency signal, a first intermediate frequency amplifier for detecting a first reception level for the first radio signal, and a first for detecting a noise level for the first radio signal. A noise level detector, an inverted noise level generator for generating an inverted noise level by inverting the polarity of the detected noise level, and a first inversion in a weak electric field level region of the first radio signal A first combined reception level generation unit configured to combine a noise level with a weak electric field level portion of the first reception level to generate a first combined reception level; When,
After amplifying the second intermediate frequency signal, a second intermediate frequency amplifier for detecting a second reception level for the second radio signal, and a second for detecting a noise level for the second radio signal A noise level detection unit, an inversion noise level generation unit for generating an inversion noise level by inverting the polarity of the detected noise level, and a second inversion in a weak electric field level region of the second radio signal A second combined reception level generation unit configured to combine a noise level with a weak electric field level portion of the second reception level to generate a second combined reception level; When,
A comparison unit that compares the first combined reception level with the second combined reception level and outputs a comparison signal indicating a comparison result;
Based on the comparison signal, as a receiving antenna, an antenna that selects and switches between the first antenna and the second antenna having the higher one of the first combined reception level and the second combined reception level. A switching unit;
A wireless communication apparatus comprising:   The first combined reception level generation unit performs direct current conversion on the first inverted noise level and then combines the first inverted reception level with the first reception level so that a straight line is added to the weak electric field level portion of the first reception level. The second combined reception level generation unit performs DC conversion on the second inverted noise level, and then combines the second reception level with the second reception level, thereby generating a weak electric field of the second reception level. 2. The wireless communication apparatus according to claim 1, wherein the level portion is linear.   The first combined reception level generation unit combines the first inversion noise level in a region of -100 dBm or less as a weak electric field level with a weak electric field level of -100 dBm or less of the first reception level. Then, the first composite reception level is generated by expanding the dynamic range to a range of -100 dBm or less, and the second composite reception level generation unit is -100 dBm or less as a weak electric field level. Combining the second inverted noise level in the region with a weak electric field level portion of −100 dBm or less of the second reception level, the dynamic range is expanded to a range of −100 dBm or less of the second reception level. The wireless communication apparatus according to claim 1, wherein the second combined reception level is generated.   The wireless communication apparatus according to claim 1, further comprising a display unit configured to display at least one of a level numerical value display related to the first combined reception level and the second combined reception level and an antenna switching display. A pilot signal detector that detects a pilot signal transmitted from a base station; and the comparator performs a comparison process only when the pilot signal is detected, and the antenna switching unit includes the pilot signal 2. The wireless communication apparatus according to claim 1, wherein the antenna switching control is performed only when the signal is detected.

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