JP2010263477A - Radio communication terminal and radio communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication terminal and a radio communication control method for reducing influence of a harmonic wave of a clock signal on a receiving performance without significantly changing a frequency of the clock signal. <P>SOLUTION: A harmonic wave receiving part 304 receives harmonic wave of the clock signal. A frequency information storing part 305 causes a storing means to store the frequency information indicating the frequency of the harmonic wave within a received carrier wave frequency band. A clock signal generation part 303 compares a phase of a clock signal frequency-divided by an arbitrary frequency division ratio to generate a clock signal having the frequency according to the comparison result. A control part 306 controls the frequency of the clock signal by controlling the frequency division ratio. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication terminal and a wireless communication control method for reducing the influence on reception performance due to harmonics of a clock signal.

  In addition to basic wireless communication functions, wireless communication terminals such as mobile phone terminals are equipped with additional parts for realizing various additional functions such as a photographing function and a terrestrial digital television broadcast receiving function. Since these additional parts operate using clock signals of individual frequencies, the reception sensitivity decreases when the harmonics of these clock signals are included in the desired wave frequency band of the received signal used in wireless communication. As a result, the reception characteristics deteriorate.

  As a technique for suppressing the influence of the harmonics of the clock signal on the reception characteristics, when the harmonics of these clock signals match the reception carrier frequency of the reception signal used in wireless communication, the frequency of the harmonics is Techniques have been proposed for adjusting the frequency of a clock signal using a PLL circuit so as not to match the received carrier frequency (see, for example, Patent Documents 1 and 2).

JP 2004-179861 A JP 2006-246301 A

  When the digital modulation method is used in wireless communication, the frequency of the received signal is included in the desired wave frequency band centered on the received carrier frequency. Therefore, in order to suppress the influence of the harmonics of the clock signal on the reception characteristics using the related technique described above, it is necessary to prevent the harmonics of the clock signal from being included in the desired wave frequency band of the received signal. There is.

  In this case, according to the related art described above, the harmonic frequency is changed from the desired wave frequency band of the received signal by changing the frequency of the clock signal by switching the frequency division ratio of the PLL circuit to a preset fixed value. Excluded. For this reason, when the desired wave frequency band of the received signal is wide, it is necessary to set the frequency division ratio with a margin and widen the frequency adjustment range of the clock signal.

  However, when the frequency adjustment range of the clock signal is wide, the lock time required for the clock signal to change to the desired frequency after changing the frequency division ratio of the PLL circuit becomes long. It takes a long time to eliminate the higher harmonics, during which time the received signal is affected, and the received signal may become unstable at the start of communication.

  Further, in order to shorten the lock time, it is necessary to increase the cutoff frequency of the loop filter used in the PLL circuit, and as a result, the influence of the phase comparison frequency component used in the PLL circuit on the received signal due to spurious is large. Become.

  The present invention is intended to solve such a problem, and a radio communication terminal and a radio communication control method for reducing the influence on the reception performance due to the harmonics of the clock signal without greatly changing the frequency of the clock signal The purpose is to provide.

  A wireless communication terminal according to the present invention includes a wireless processing unit that outputs a reception baseband signal based on a reception signal received by an antenna during wireless communication and a local oscillation signal of a reception carrier frequency, and a reference signal that generates a reference signal of a reference frequency A generator, a clock signal generator for generating a clock signal, a harmonic detector for detecting harmonics of the clock signal, and frequency information indicating the frequency of the harmonics in the received carrier frequency band are generated and stored in the storage means. A frequency information storage unit to store, a control unit that controls the clock signal generation unit to match the harmonic frequency with the received carrier frequency based on the frequency indicated by the frequency information stored in the storage unit; Transitions between an open state where the received signal received by the antenna is not input to the harmonic detector and a closed state where the received signal is input to the harmonic detector The harmonic detection unit detects the harmonics of the clock signal when the antenna switch is open, and the clock signal generation unit divides the phase of the reference signal and the clock signal by any frequency. A PLL circuit that compares the phase divided by the ratio and generates a clock signal having a clock frequency according to the comparison result, and the control unit controls the frequency division ratio to adjust the frequency of the clock signal. Features.

  A wireless communication terminal according to another aspect of the present invention includes a wireless processing unit that outputs a received baseband signal based on a received signal received by an antenna during wireless communication and a local oscillation signal of a received carrier frequency, and a reference frequency reference A reference signal generator for generating a signal, a clock signal generator for generating a clock signal, a harmonic detector for detecting harmonics of the clock signal, and frequency information indicating the frequency of the harmonics within the received carrier frequency band. A frequency information storage unit that generates and stores the frequency in the storage unit, and a clock signal generation unit that matches the harmonic frequency with the received carrier frequency based on the frequency indicated by the frequency information stored in the storage unit. A control unit for controlling, and the harmonic detection unit is provided with a detection end for detecting harmonics of the clock signal. The generation unit includes a PLL circuit that compares the phase of the reference signal with the phase obtained by dividing the clock signal by an arbitrary division ratio, and generates a clock signal having a clock frequency according to the comparison result. The frequency division ratio is controlled to adjust the frequency of the clock signal.

  The wireless communication control method according to the present invention includes a clock signal generation step for generating a clock signal, a harmonic detection step for detecting a harmonic of the clock signal, and frequency information indicating the frequency of the harmonic within the reception carrier frequency band. The frequency information storage step to be stored in the storage means, and based on the frequency indicated by the frequency information stored in the storage means, the generation of the clock signal is controlled so that the harmonic frequency matches the received carrier frequency. A control step, a radio processing step for outputting a received baseband signal based on a received signal received by an antenna during wireless communication and a local oscillation signal of a received carrier frequency, and a reference signal generating step for generating a reference signal of a reference frequency The received signal received by the antenna is not input in the harmonic detection step. In the clock signal generation step, the phase of the reference signal is compared with the phase obtained by dividing the clock signal by an arbitrary division ratio, and the clock with the clock frequency corresponding to the comparison result is detected. A signal is generated, and the frequency of the clock signal is adjusted by controlling the frequency division ratio in the control step.

  According to another aspect of the wireless communication control method of the present invention, a clock signal generation step for generating a clock signal, a harmonic detection step for detecting a harmonic of the clock signal, and a frequency of the harmonic within the reception carrier frequency band are shown. Based on the frequency information storage step of generating frequency information and storing it in the storage means, and the frequency indicated by the frequency information stored in the storage means, the clock signal is made to match the frequency of the harmonic with the received carrier frequency. A control step for controlling generation, a radio processing step for outputting a received baseband signal based on a received signal received by an antenna during wireless communication and a local oscillation signal of a received carrier frequency, and a reference for generating a reference signal of a reference frequency A signal generation step, and a harmonic detection step for detecting harmonics of the clock signal. In the clock signal generation step, the phase of the reference signal is compared with the phase obtained by dividing the clock signal by an arbitrary division ratio, and the result of the comparison is detected. A clock signal having the clock frequency is generated, and the frequency of the clock signal is adjusted by controlling the frequency division ratio in the control step.

  According to the present invention, the adjustment range of the clock frequency can be reduced by switching the frequency division ratio to a predetermined fixed value, compared with the case where the harmonics are excluded from the desired wave frequency band. Then, the lock time required to adjust the clock signal can be shortened, and the influence on the received baseband signal at the start of communication can be suppressed. In addition, the influence on the received baseband signal due to spurious phase comparison frequency components used in the PLL circuit can be suppressed.

  In addition, since it is configured to actually measure the reception level of the harmonics of the clock signal, it identifies the harmonics that affect the received baseband signal in the actual mounting state and usage environment, and affects the reception performance. Reduction processing can be performed.

  And compared with the case where the harmonic frequency of a clock signal is previously memorize | stored in a memory | storage means, the memory capacity to be used can be reduced. In addition, it is possible to prevent the clock frequency from being adjusted for harmonics that do not actually affect the reception performance.

It is a block diagram which shows the structural example of the radio | wireless communication terminal of 1st Embodiment. It is a block diagram which shows the structural example of a radio | wireless process part. It is a block diagram which shows the structural example of a clock signal generation part. It is a flowchart which shows the frequency information storage process of the radio | wireless communication terminal of the 1st Embodiment of this invention. It is explanatory drawing which shows the reception level which the reception level measurement part measured. It is a flowchart which shows the clock frequency adjustment process of the radio | wireless communication terminal of the 1st Embodiment of this invention. It is explanatory drawing which shows the relationship between the received signal before a clock frequency adjustment, and the harmonics of a clock signal. It is explanatory drawing which shows the relationship between the received signal after clock frequency adjustment, and the harmonics of a clock signal. It is a block diagram which shows the structural example of the radio | wireless process part of the radio | wireless communication terminal of 2nd Embodiment. It is a flowchart which shows the frequency information storage process of the radio | wireless communication terminal of the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication terminal of the 3rd Embodiment of this invention. It is a block diagram which shows the outline | summary of this invention.

Embodiment 1. FIG.
A wireless communication terminal according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of a wireless communication terminal 10 according to the first embodiment.

  The wireless communication terminal 10 is a terminal device having a wireless communication function such as a mobile phone or a PDA (Personal Digital Assistant), for example, and in addition to the wireless communication function, an imaging function, a terrestrial digital television broadcast reception function, and the like are added. It is a terminal device equipped with additional parts that realize the function.

  The wireless communication device 10 includes an antenna 11, a wireless processing unit 12, a control unit 13, a storage unit 14, a reference signal generation unit 15, a clock signal generation unit 16, and a function unit 17.

  The wireless processing unit 12 has a function of performing wireless communication by transmitting and receiving radio waves according to the control of the control unit 13, and in particular, as a reception processing function, local oscillation of a received signal received at the time of wireless communication and a received carrier frequency Frx It has a function of outputting a received baseband signal based on the signal.

  FIG. 2 is a block diagram illustrating a configuration example of the wireless processing unit 12. As illustrated in FIG. 2, the wireless processing unit 12 includes a reception unit 121, a transmission unit 122, an antenna switch 123, a reception level measurement unit 124, a determination unit 125, and a frequency measurement unit 126. The harmonic detection unit is realized by the reception level measurement unit 124. Further, the frequency information storage unit is realized by the determination unit 125 and the frequency measurement unit 126.

  The receiving unit 121 realizes a reception processing function. The transmission unit 122 realizes a transmission processing function for transmitting radio waves via the antenna 11. The antenna switch 123 is in a closed state (the state shown in FIG. 2) in which the radio wave received by the antenna 11 is input to the receiving unit 121 and an open state in which the radio wave is not input to the receiving unit 121 according to the control of the control unit 13. Transition to each other. The reception level measurement unit 124 measures the intensity (reception level) of the radio wave input in the open state. The determination unit 125 determines whether or not the reception level measured by the reception level measurement unit 124 is equal to or higher than a predetermined level (for example, −100 dBm). When the determination unit 125 determines that the frequency is equal to or higher than a predetermined level, the frequency measurement unit 126 measures the frequency of the radio wave equal to or higher than the predetermined level, and generates frequency information indicating the measured frequency.

  The receiver 121 shown in FIG. 2 exemplifies the reception processing function of the phase modulation scheme (PSK: Phase-shift keying) used in the mobile phone terminal, but the radio processing unit 12 of the present invention uses the phase modulation scheme. It is not limited and other phase modulation methods may be used.

The operation of the receiving unit 121 will be described. A reception signal 11R received by the antenna 11 is input to the multipliers 12A and 12B. One of the received signals 11R input to the multiplier 12A is multiplied by the local oscillation signal (cosω _rx t) 12S of the carrier frequency Frx of the received signal 11R output from the local oscillation circuit 12C in the multiplier 12A. It is detected and becomes an in-phase I component signal 12I through a low-pass filter (LPF) 12E.

The other received signal 11R input to the multiplier 12B is a local oscillation signal obtained by shifting the local oscillation signal (cosω _rx t) 12S of the local oscillation circuit 12C by π / 2 by the phase shifter 12D in the multiplier 12B. (−sinω _rx t) is multiplied and detected, and becomes an orthogonal Q component signal 12Q via a low-pass filter (LPF) 12F. The reception signal generation unit 12G generates a reception baseband signal 12R from the I component signal 12I and the Q component signal 12Q and inputs the reception baseband signal 12R to the control unit 13.

  The reception level measurement unit 124 is, for example, a RSSI (Receive Signal Strength Indicator). The frequency measurement unit 126 is realized by, for example, a frequency counter and an IC (Integrated Circuit) that generates and outputs frequency information indicating the frequency measured by the frequency counter, and the generated frequency information is stored in the storage unit 14. Remember.

  In FIG. 1, the control unit 13 includes a CPU and its peripheral circuits. The control unit 13 controls the wireless processing unit 12 to perform wireless communication, and controls the clock signal generation unit 16 by using the division ratio signal 13S. The function of setting the clock frequency Fclk so that the frequency of the high frequency 17S of the signal 16S, that is, the harmonic frequency that is an integral multiple of the clock frequency Fclk, matches the received carrier frequency Frx, and the antenna switch 123 between the open state and the closed state. And has a function of transition.

  The storage unit 14 includes a memory circuit, and has a function of storing various processing information and programs used for processing in the control unit 13. And the memory | storage part 14 has memorize | stored the information which shows the receiving carrier frequency of the received signal for every receiving channel used by radio | wireless communication, and the information which shows the desired wave frequency band BW.

  The storage unit 14 stores frequency information generated by the frequency measurement unit 126.

  The reference signal generation unit 15 includes an oscillation circuit and has a function of generating a reference signal 15S at a constant reference frequency Fs.

  The clock signal generation unit 16 includes a PLL circuit and a frequency dividing circuit, and has a function of generating a clock signal 16S having an arbitrary clock frequency Fclk based on the inputted reference signal 15S.

  FIG. 3 is a block diagram illustrating a configuration example of the clock signal generation unit 16. In the example shown in FIG. 3, the clock signal generation unit 16 includes a PLL circuit 16A and a frequency dividing circuit 16E. The PLL circuit 16A compares the phase of the inputted reference signal 15S with the phase obtained by dividing the clock signal 16S by the frequency dividing circuit 16E by a predetermined frequency dividing ratio by the phase comparator 16B, and the comparison result The signal is stabilized by a loop filter 16C, and a clock signal 16S having a clock frequency Fclk corresponding to the obtained voltage ratio is generated by a voltage controlled oscillator (VCO) 16D. The frequency dividing circuit 16E divides the clock signal 16S by a frequency dividing ratio corresponding to the frequency dividing ratio signal 13S from the control unit 13 and feeds back to the phase comparator 16B.

  In FIG. 1, a function unit 17 is a circuit unit that implements various additional functions such as a shooting function and a digital terrestrial television broadcast reception function. Each additional component that constitutes the function unit 17 includes a clock signal generation unit 16. It operates based on the generated clock signal 16S. Note that an IC that implements the control unit 13 and the like may be configured to operate based on the clock signal 16S.

  Next, the operation of the wireless communication terminal 10 according to the first embodiment of this invention will be described with reference to the drawings. FIG. 4 is a flowchart illustrating frequency information storage processing of the wireless communication terminal 10 according to the first embodiment of this invention.

  When the user performs a power-on operation, the control unit 13 causes the antenna switch 123 to transition to the open state (step S10).

  The reception level measurement unit 124 detects a reception signal in a state in which all reception frequencies used in wireless communication are not input (that is, the antenna switch 123 is open), and a reception signal level (detection signal) of the detected reception signal (detection signal) (Detection level) is measured (step S11). The total reception frequency used in the wireless communication is, for example, a desired wave frequency band BW (800 MHz band or 1.7 GHz band) used in wireless communication of a W-CDMA (Wideband Code Division Multiple Access) method by a wireless communication terminal. 2 GHz band).

  The reception level measurement unit 124 reads information indicating the desired wave frequency band BW stored in the storage unit 14 and measures the reception signal level for each frequency in the desired wave frequency band BW indicated by the information. To do.

  The determination unit 125 determines whether or not the reception level measured by the reception level measurement unit 124 is equal to or higher than a predetermined level (step S12).

  FIG. 5 is an explanatory diagram showing the reception level measured by the reception level measurement unit 124. In the example shown in FIG. 5, a plurality of harmonics (N × Fclk, (N + 1) × Fclk, (N + 2) × Fclk) are included in a desired wave frequency band BW. The harmonic reception level of the frequency N × Fclk and the harmonic reception level of the frequency (N + 2) × Fclk are equal to or higher than a predetermined level (Lvl_no), and the reception level of the frequency (N + 1) × Fclk is predetermined. Is less than the level.

  When the determination unit 125 determines that the frequency is equal to or higher than the predetermined level (Y in step S12), the frequency measurement unit 126 measures the frequency of the radio wave equal to or higher than the predetermined level (step S13), and the frequency indicating the frequency Information is generated and stored in the storage unit 14 (step S14).

  When the reception signal level measurement by the reception level measurement unit 124 is completed for all reception frequencies used in wireless communication (Y in step S15), the control unit 13 closes the antenna switch 123 to be used. (Step S16), and the process ends. When there is an unmeasured frequency (N in Step S15), the process proceeds to Step S11, and the received signal level of the unmeasured frequency is measured (Step S11).

  The reception level measurement unit 124 changes (sweeps) the frequency at which the reception level is measured in a frequency band that affects reception performance (for example, the desired wave frequency band BW), and the reception level is equal to or higher than a predetermined level. In this case, the storage unit 14 may be configured to store frequency information indicating the measurement frequency at that time.

  FIG. 6 is a flowchart showing a clock frequency adjustment process of the wireless communication terminal according to the first embodiment of this invention.

  The control unit 13 of the wireless communication terminal 10 executes the clock frequency adjustment process shown in FIG. 6 when performing new wireless communication.

  First, the control unit 13 reads the received carrier frequency Frx and the desired wave frequency band BW used in the reception channel of the wireless communication from the storage unit 14 (step S100), and reads the frequency information from the storage unit 14 (step S101). The frequency indicated by the frequency information is compared with the desired wave frequency band BW (step S102).

  Here, when none of the frequencies indicated by the frequency information exists in the desired wave frequency band BW (N in step S103), the frequency indicated by the frequency information for the received signal (for example, harmonic frequency N × Fclk) ), The clock frequency adjustment is not necessary, and the series of clock frequency adjustment processing is terminated. Since the reception level is measured only in the desired wave frequency band BW in the process of step S11 described above, the processes of steps S102 and S103 need not be executed.

  When one of the frequencies indicated by the frequency information (for example, harmonic frequency N × Fclk) exists in the desired wave frequency band BW (Y in step S103), the control unit 13 exists in the desired wave frequency band BW. The harmonic frequency N × Fclk to be compared is compared with the received carrier frequency Frx (step S104).

  If the harmonic frequency N × Fclk matches the received carrier frequency Frx (N in step S105), there is no influence of the harmonic frequency N × Fclk on the received baseband signal, and no clock frequency adjustment is required. Thus, a series of clock frequency adjustment processing is completed.

  On the other hand, when the harmonic frequency N × Fclk does not match the received carrier frequency Frx (Y in step S105), the control unit 13 matches the harmonic frequency of the high frequency 17S of the clock signal 16S with the received carrier frequency Frx. Is calculated (step S106). In this case, since Fclk = M × Fs and Frx = N × Fclk, M = Frx / (N × Fs).

  The storage unit 14 stores in advance information indicating the clock frequency of each additional component to be mounted, for example, and based on the information indicating the clock frequency and the frequency indicated by the frequency information, The order N is specified.

  The control unit 13 obtains the frequency division ratio M in this way, outputs the frequency division ratio signal 13S indicating the frequency division ratio M to the clock signal generation unit 16 (step S107), and ends the series of clock frequency adjustment processing. To do.

  As a result, the clock signal generator 16 outputs a clock signal 16S having a frequency M × Fs obtained by multiplying the input reference signal 15S. For this reason, the harmonic frequency of the clock signal 16S matches the reception carrier frequency Frx.

  Therefore, when the radio processing unit 12 removes the signal component of the reception carrier frequency Frx, harmonics of the clock signal 16S are removed by the radio processing unit 12, so that the reception baseband due to the harmonics of the clock signal 16S is removed. The influence on the signal can be suppressed.

  7A and 7B are explanatory diagrams showing the relationship between the received signal and the harmonics of the clock signal before the clock frequency adjustment, FIG. 7A is a frequency band diagram, and FIG. 7B is a frequency spectrum diagram.

  8A and 8B are explanatory diagrams showing the relationship between the received signal and the harmonics of the clock signal after the clock frequency adjustment, FIG. 8A is a frequency band diagram, and FIG. 8B is a frequency spectrum diagram.

  As shown in FIG. 7, before the clock frequency adjustment, the harmonics SP1 and SP2 of the clock signal appear as the harmonics of the clock signal 16S. Of these, the harmonic SP1 having the frequency Fsp1 = N × Fclk is received and transmitted. The desired reception wave frequency band BW centered on the frequency Frx exists, and the harmonic SP2 of the frequency Fsp2 exists outside the reception desired wave frequency band BW.

  In such a situation, a spectrum SP1b having the frequency Fbsp1 is generated as a spectrum caused by the harmonic SPq near the frequency Fb of the reception baseband signal obtained from the reception signal. Therefore, this spectrum SP1b causes an error in the received baseband signal.

  On the other hand, as shown in FIG. 8, after the clock frequency adjustment, since the frequency of the harmonic SP1 of the clock signal matches the received carrier frequency Frx, the harmonic SP1 is removed in the same manner as the received carrier component. The spectrum SP1b having the frequency Fbsp1 is not generated near the frequency Fb of the received baseband signal. Therefore, the influence on the received baseband signal by the harmonic SP1 is suppressed.

  As described above, according to this embodiment, the frequency division ratio of the PLL circuit is adjusted by the control unit so that the harmonic frequency of the clock signal that affects the received baseband signal matches the received carrier frequency. Since the clock frequency is adjusted by controlling the frequency division ratio, the adjustment range of the clock frequency can be reduced by switching the frequency division ratio to a predetermined fixed value as compared with the case where the harmonics are excluded from the desired wave frequency band.

  For this reason, the lock time required to adjust the frequency of the clock signal to the reception carrier frequency by the PLL circuit for adjusting the clock frequency is short, and the influence on the reception baseband signal at the start of communication can be suppressed. In addition, in order to shorten the lock time of the PLL circuit, it is not necessary to increase the cutoff frequency of the loop filter used in the PLL circuit, and as a result, the phase comparison frequency component used in the PLL circuit is reduced to the received baseband signal due to spurious. The influence can be suppressed.

  In the present embodiment, the control unit sets the value obtained by dividing the received carrier frequency by the reference frequency and the harmonic order N (N is an integer of 2 or more) as the division ratio. The harmonic frequency of the clock signal can be easily matched with the received carrier frequency without requiring computation or control.

  Further, in the present embodiment, since it is configured to actually measure the reception level of the harmonics of the clock signal when the power is turned on, the reception baseband signal is affected in the actual mounting state and usage environment. Therefore, it is possible to reduce the influence on reception performance.

  Further, the storage capacity to be used can be reduced as compared with the case where the harmonic frequency of the clock signal is stored in the storage unit 14 in advance. In addition, it is possible to prevent the clock frequency from being adjusted for harmonics that do not actually affect the reception performance.

Embodiment 2. FIG.
Next, a second embodiment of the wireless communication terminal of the present invention will be described with reference to the drawings. The wireless communication terminal 20 of the second embodiment includes a wireless processing unit 21 instead of the wireless processing unit 12 of the wireless communication terminal 10 of the first embodiment. FIG. 9 is a block diagram illustrating a configuration example of the wireless processing unit 21 of the wireless communication terminal 20 according to the second embodiment.

  As shown in FIG. 9, in the wireless communication terminal 20 of the second embodiment, the wireless processing unit 21 is not connected to the antenna 11 instead of the antenna switch 123 in the wireless processing unit 12 of the first embodiment. A receiving end (detection end) 201 is included. The receiving end 201 is, for example, an end of a signal line provided for receiving harmonics emitted from the function unit 17 (for example, a protrusion), and is not connected to the antenna 11. .

  Then, the level measuring unit 124 can detect the radio wave received by the receiving end 201 even when the reception signal received by the antenna 11 is input to the receiving unit 121 (corresponding to the closed state of the first embodiment). Measure the reception level.

  Next, the operation of the wireless communication terminal 20 according to the second embodiment of this invention will be described with reference to the drawings. FIG. 10 is a flowchart illustrating frequency information storage processing of the wireless communication terminal 20 according to the second embodiment of this invention.

  When the control unit 13 selects a desired wave frequency band BW used in wireless communication, the reception level measuring unit 124 measures the reception level of the radio wave received by the receiving end 201 within the band (step S20). The desired wave frequency band BW selected by the control unit 13 is a frequency band used in the current wireless communication by the wireless communication terminal 20 among a plurality of frequency bands used in the W-CDMA wireless communication. is there.

  The determination unit 125 determines whether or not the reception level measured by the reception level measurement unit 124 is equal to or higher than a predetermined level (step S21).

  When the determination unit 125 determines that the frequency is equal to or higher than the predetermined level (Y in step S21), the frequency measurement unit 126 measures the frequency of the radio wave equal to or higher than the predetermined level (step S22), and the frequency indicating the frequency Information is generated and stored in the storage unit 14 (step S23).

  When the reception signal level measurement by the reception level measurement unit 124 is completed for all reception frequencies used in wireless communication (Y in step S24), the control unit 13 ends the process. When there is an unmeasured frequency (N in Step S24), the process proceeds to Step S20, and the received signal level of the unmeasured frequency is measured (Step S20).

  The reception level measurement unit 124 changes (sweeps) the frequency at which the reception level is measured in a frequency band that affects reception performance, for example, at a timing when radio waves are not transmitted by the transmission unit 122, and the reception level is predetermined. The frequency information indicating the measurement frequency at that time may be stored in the storage unit 14 when the level is equal to or higher than the level. In addition, the receiving end 201 is connected to the receiving unit 121, and the receiving unit 121 has a function of measuring the receiving level. The receiving end 201 is used to measure the receiving level and receive radio waves via the antenna 11. The processing to be performed may be configured to be switched at a predetermined time interval and executed.

  The clock frequency adjustment process in the second embodiment is the same as the clock frequency adjustment process shown in FIG. 6 illustrated in the first embodiment, and thus description thereof is omitted.

  As described above, according to the present embodiment, it is possible to measure harmonic frequencies even in a state where wireless communication is performed. The harmonics of the original clock signal can be specified and the clock frequency can be adjusted.

Embodiment 3. FIG.
Next, a wireless communication terminal according to the third embodiment of the present invention will be described with reference to FIG. FIG. 11 is a block diagram illustrating a configuration of the wireless communication terminal 30 according to the third embodiment of this invention.

  In the present embodiment, a clock frequency adjustment method when a clock signal is generated by a PLL circuit based on the reference signal 15S will be described.

  In this embodiment, the local oscillation signal generation method in the wireless processing unit 12 and the clock frequency adjustment method in the control unit 13 are different, but the other configurations are the same as those in the first embodiment or the second embodiment. The configuration is the same as that of the embodiment, and detailed description thereof is omitted.

  The wireless processing unit 12 according to the present embodiment includes the PLL circuit 16A and the frequency dividing circuit 16E as shown in FIG. 3 as the local oscillation circuit 12C of FIG. 2 described above, and receives the reference signal 15S. The local oscillation signal 12S shown in FIG.

  When performing a new wireless communication, the control unit 13 of the wireless communication terminal 30 executes the above-described clock frequency adjustment process shown in FIG. In step S106 of the clock frequency adjustment process, when calculating the frequency division ratio M in the clock signal generation unit 16, the control unit 13 calculates the frequency division ratio M as follows.

  When the reception carrier frequency used in wireless communication is Frx, the reference frequency of the reference signal 15S is Fs, and the frequency division ratio used when the local oscillation signal 12 equal to the reception carrier frequency Frx is generated by the PLL circuit is P Frx = P × Fs is established.

  On the other hand, when the frequency of the harmonic of the clock signal 16S existing in the desired wave frequency band BW is Fsp = N × Fclk, and the frequency division ratio used when the clock signal 16S is generated by the PLL circuit is Q, FSP = N × Q × Fs is established.

  For this reason, Q = P / N is derived as the frequency division ratio Q for making the harmonic frequency Fsp equal to the reception carrier frequency Frx.

  Accordingly, in step S106, the control unit 13 can easily obtain the frequency division ratio Q from the frequency division ratio P stored in the storage unit 14 and the integer N obtained in step S102.

  As described above, according to the present embodiment, in the control unit, the multiplication number P (P is an integer equal to or larger than 2) when generating the local oscillation signal from the reference signal is changed to the harmonic order N (N is an integer). Since the value divided by (integer of 2 or more) is set as the frequency division ratio of the PLL circuit, even when the local oscillation signal is generated by multiplying the reference frequency of the reference signal by P in the wireless processing unit. Thus, the frequency division ratio Q for easily matching the harmonic frequency to the received carrier frequency can be obtained without requiring a complicated calculation.

  Next, the outline of the present invention will be described. FIG. 12 is a block diagram showing an outline of the present invention. The wireless communication terminal of the present invention includes a wireless processing unit 301, a reference signal generation unit 302, a clock signal generation unit 303, a harmonic detection unit 304, a frequency information storage unit 305, a control unit 306, and an antenna switch 307. With.

  The wireless processing unit 301 outputs a reception baseband signal based on a reception signal received by the antenna during wireless communication and a local oscillation signal having a reception carrier frequency.

  The reference signal generator 302 generates a reference signal having a reference frequency. The clock signal generation unit 303 generates a clock signal. The harmonic detection unit 304 receives the harmonics of the clock signal. The frequency information storage unit 305 generates frequency information indicating the harmonic frequency in the received carrier frequency band (for example, the desired wave frequency band BW) and stores the frequency information in the storage unit.

  The control unit 306 controls the clock signal generation unit 303 so that the harmonic frequency matches the reception carrier frequency based on the frequency indicated by the frequency information stored in the storage unit.

  The antenna switch 307 transits between an open state in which a reception signal received by the antenna is not input to the harmonic detection unit 304 and a closed state in which a reception signal is input to the harmonic detection unit 304. The harmonic detection unit 304 is connected to the antenna switch 307 and receives the harmonics of the clock signal in the open state.

  The clock signal generation unit 303 includes a PLL circuit 308 that compares the phase of the reference signal with the phase obtained by dividing the clock signal by an arbitrary division ratio and generates a clock signal having a clock frequency corresponding to the comparison result. .

  The control unit 306 controls the frequency division ratio to adjust the frequency of the clock signal.

  According to such a configuration, the adjustment range of the clock frequency can be reduced by switching the frequency division ratio to a predetermined fixed value as compared with the case where the harmonics are excluded from the desired wave frequency band. Then, the lock time required to adjust the clock signal can be shortened, and the influence on the received baseband signal at the start of communication can be suppressed. In addition, the influence on the received baseband signal due to spurious phase comparison frequency components used in the PLL circuit can be suppressed.

  In addition, since it is configured to actually measure the reception level of the harmonics of the clock signal, it identifies the harmonics that affect the received baseband signal in the actual mounting state and usage environment, and affects the reception performance. Can be reduced.

  And compared with the case where the harmonic frequency of a clock signal is previously memorize | stored in the memory | storage part 14, the memory capacity to be used can be reduced. In addition, it is possible to prevent the clock frequency from being adjusted for harmonics that do not actually affect the reception performance.

  Further, in the above embodiment, assuming that a part of the configuration of the wireless communication terminal illustrated in FIG. 12 is converted, the harmonic detection unit 304 has a detection end for detecting the harmonic of the clock signal. The provided configuration is disclosed.

  According to such a configuration, the harmonic frequency can be measured even when wireless communication is being performed, so the harmonics of the clock signal based on a function that is not always operating, such as an imaging function. And the clock frequency can be adjusted.

  In the above embodiment, the harmonic detection unit 304 measures the detection level of the detection signal, and the frequency information storage unit 305 detects the detection level measured by the harmonic detection unit 304 is equal to or higher than a predetermined level. Includes a frequency measurement unit that measures the frequency of the detection signal, and stores frequency information indicating the frequency measured by the frequency measurement unit in a storage unit.

  According to such a configuration, frequency information indicating the frequency of harmonics of a predetermined level or higher (specifically, for example, harmonics (detection signals) that affect the reception performance of the wireless communication terminal) is stored in the storage unit. Since it is stored, the clock frequency is adjusted when such a harmonic exists, and the influence on the reception performance can be prevented.

  In the above embodiment, it is disclosed that the control unit 306 sets a value obtained by dividing the received carrier frequency by the reference frequency and the harmonic order N (N is an integer of 2 or more) as the frequency division ratio. ing. According to such a configuration, the harmonic frequency of the clock signal can be easily matched with the reception carrier frequency without requiring complicated calculation and control.

  In the above embodiment, the wireless processing unit 301 includes a local oscillation circuit that generates a local oscillation signal by multiplying the reference frequency of the reference signal by P (P is an integer of 2 or more). However, it is disclosed that a value obtained by dividing P by a harmonic order N (N is an integer of 2 or more) is set as a frequency division ratio. According to such a configuration, even when a local oscillation signal is generated, it is possible to easily obtain a frequency division ratio for making the harmonic frequency coincide with the reception carrier frequency without requiring complicated calculation. Become.

  The present invention can be applied to a wireless communication terminal using a clock signal.

10, 20, 30 Wireless communication terminal 11 Antenna 12 Wireless processing unit 12A, 12B Multiplier 12C Local oscillation circuit 12D Phase shifter 12E, 12F Low-pass filter 12G Received signal generation unit 13 Control unit 14 Storage unit 15 Reference signal generation unit 16 Clock Signal generator 16A PLL circuit 16B Phase comparator 16C Loop filter 16D VCO
16E Frequency Divider 17 Functional Unit 121 Receiving Unit 122 Transmitting Unit 123 Antenna Switch 124 Reception Level Measuring Unit 125 Judging Unit 126 Frequency Measuring Unit 201 Receiving End

Claims (8)

A radio processing unit that outputs a reception baseband signal based on a reception signal received by an antenna during wireless communication and a local oscillation signal of a reception carrier frequency;
A reference signal generator for generating a reference signal of a reference frequency;
A clock signal generator for generating a clock signal;
A harmonic detection unit for detecting harmonics of the clock signal;
A frequency information storage unit for generating frequency information indicating the frequency of the harmonics in the received carrier frequency band and storing the frequency information in the storage unit;
Based on the frequency indicated by the frequency information stored in the storage means, a control unit that controls the clock signal generation unit so that the harmonic frequency matches the reception carrier frequency;
An antenna switch that transitions between an open state in which a reception signal received by the antenna is not input to the harmonic detection unit and a closed state in which the reception signal is input to the harmonic detection unit;
The harmonic detection unit detects harmonics of the clock signal when the antenna switch is in the open state,
The clock signal generation unit compares a phase of the reference signal with a phase obtained by dividing the clock signal by an arbitrary division ratio, and generates a PLL circuit that generates a clock signal having a clock frequency according to the comparison result. Including
The wireless communication terminal, wherein the control unit controls the frequency division ratio to adjust a frequency of the clock signal. A radio processing unit that outputs a reception baseband signal based on a reception signal received by an antenna during wireless communication and a local oscillation signal of a reception carrier frequency;
A reference signal generator for generating a reference signal of a reference frequency;
A clock signal generator for generating a clock signal;
A harmonic detection unit for detecting harmonics of the clock signal;
A frequency information storage unit for generating frequency information indicating the frequency of the harmonics in the received carrier frequency band and storing the frequency information in the storage unit;
A control unit that controls the clock signal generation unit so as to match the frequency of the harmonic with the reception carrier frequency based on the frequency indicated by the frequency information stored in the storage unit;
The harmonic detection unit is provided with a detection end for detecting harmonics of the clock signal,
The clock signal generation unit compares a phase of the reference signal with a phase obtained by dividing the clock signal by an arbitrary division ratio, and generates a PLL circuit that generates a clock signal having a clock frequency according to the comparison result. Including
The wireless communication terminal, wherein the control unit controls the frequency division ratio to adjust a frequency of the clock signal. The harmonic detection unit measures the detection level of the detection signal,
The frequency information storage unit
A frequency measurement unit that measures the frequency of the detection signal when the detection level measured by the harmonic detection unit is equal to or higher than a predetermined level;
The wireless communication terminal according to claim 1, wherein frequency information indicating the frequency measured by the frequency measurement unit is stored in a storage unit. The control unit sets a value obtained by dividing the received carrier frequency by a reference frequency and a harmonic order N (N is an integer of 2 or more) as a frequency division ratio. Wireless communication terminal. The wireless processing unit includes a local oscillation circuit that generates a local oscillation signal by multiplying the reference frequency of the reference signal by P (P is an integer of 2 or more),
The wireless communication terminal according to any one of claims 1 to 3, wherein the control unit sets a value obtained by dividing the P by a harmonic order N (N is an integer of 2 or more) as a division ratio. A clock signal generating step for generating a clock signal;
A harmonic detection step of detecting harmonics of the clock signal;
A frequency information storage step of generating frequency information indicating the frequency of the harmonics in the received carrier frequency band and storing the frequency information in the storage means;
A control step for controlling the generation of the clock signal so as to match the frequency of the harmonic with the received carrier frequency based on the frequency indicated by the frequency information stored in the storage means;
A radio processing step of outputting a received baseband signal based on a received signal received by an antenna during wireless communication and a local oscillation signal of a received carrier frequency;
Generating a reference signal having a reference frequency, and generating a reference signal
In the harmonic detection step, the harmonics of the clock signal are detected in a state where the reception signal received by the antenna is not input,
In the clock signal generation step, the phase of the reference signal and the phase obtained by dividing the clock signal by an arbitrary division ratio are compared, and a clock signal having a clock frequency according to the comparison result is generated.
In the control step, the frequency ratio of the clock signal is adjusted by controlling the frequency division ratio. A clock signal generating step for generating a clock signal;
A harmonic detection step of detecting harmonics of the clock signal;
A frequency information storage step of generating frequency information indicating the frequency of the harmonics in the received carrier frequency band and storing the frequency information in the storage means;
A control step for controlling the generation of the clock signal so as to match the frequency of the harmonic with the received carrier frequency based on the frequency indicated by the frequency information stored in the storage means;
A radio processing step of outputting a received baseband signal based on a received signal received by an antenna during wireless communication and a local oscillation signal of a received carrier frequency;
Generating a reference signal having a reference frequency, and generating a reference signal
Detecting harmonics of the clock signal at the detection end for detecting harmonics of the clock signal in the harmonic detection step;
In the clock signal generation step, the phase of the reference signal and the phase obtained by dividing the clock signal by an arbitrary division ratio are compared, and a clock signal having a clock frequency according to the comparison result is generated.
In the control step, the frequency ratio of the clock signal is adjusted by controlling the frequency division ratio. In the harmonic detection step, measure the detection level of the detection signal,
5. In the frequency information storage step, when the detection level measured in the harmonic detection step is equal to or higher than a predetermined level, the frequency of the detection signal is measured, and the frequency information indicating the measured frequency is stored in the storage unit. The wireless communication control method according to claim 6 or 7.

Images