JP2019054462A - Frequency adjustment apparatus, frequency adjustment method, and wireless device - Google Patents

Abstract

To provide a frequency adjustment device capable of appropriately adjusting a frequency of a signal input to a filter according to a shift in a center frequency of a filter with a simple configuration.SOLUTION: An adjustment device (10) includes: an adjustment unit (15) which sets a process of sequentially input in a filter a signal of a first frequency higher than a reference frequency and a signal of a second frequency lower than the reference frequency and a process of calculating a difference of signal intensity of respective signals after passing the filter to be a process unit and repeats the process unit every time when an adjustment value with which a frequency of a signal input to the filter is changed is changed by a predetermined value; and a final adjustment value determination unit (14) that performs an adjustment using an adjustment value that is a difference equal to or less than a reference value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a frequency adjusting device, a frequency adjusting method, and a wireless device including the frequency adjusting device that adjust the frequency of a signal input to the filter in response to a shift in the center frequency of the filter.

  In a superheterodyne receiver, an input signal received via an antenna is amplified by a high frequency circuit, and a signal of a predetermined frequency generated by a local oscillator is mixed with the amplified signal by a frequency mixer to obtain an intermediate frequency signal. Convert. Then, after the intermediate frequency signal is amplified by the intermediate frequency circuit, it is demodulated by the demodulation circuit, and the sound is output from a speaker or the like.

  In addition to the amplifier circuit, the intermediate frequency circuit is provided with an IF filter for allowing a desired intermediate frequency signal to pass therethrough. The characteristics (for example, center frequency) of the IF filter vary due to individual differences as individual parts and the influence of temperature characteristics. Therefore, it is necessary to adjust (calibrate) the oscillation frequency of the local oscillator so that the intermediate frequency signal generated by the frequency mixer passes through the center of the IF filter. In order to perform calibration appropriately, it is necessary to grasp the characteristics of the IF filter, particularly the center frequency.

  Therefore, for example, Patent Document 1 discloses a wireless receiver that corrects a frequency shift of the filter by measuring a frequency shift from the center frequency of the filter and giving a deviation corresponding to the frequency shift to the frequency of the local signal generator. Is described.

  Patent Document 2 describes a method of specifying a center frequency of a filter by passing a measurement signal with different measurement frequencies through a filter, measuring the intensity of the passed measurement signal, and obtaining a peak value. Yes.

Japanese Patent Laid-Open No. 9-247030 (published on September 19, 1997) JP, 2006-122903, A (July 7, 2016 release)

  Certainly, even with the above-described prior art, it is possible to adjust the deviation of the center frequency of the filter with respect to the desired center frequency. However, the above-described conventional technology has room for improvement in terms of processing time and processing steps.

  For example, in the technique described in Patent Document 1, when obtaining the center frequency of the filter, it is necessary to perform the following processing. First, the input is switched to a frequency synthesizer, a continuous wave of a reference level at a predetermined frequency is frequency-converted by a mixer, and the level of a signal demodulated through a filter is detected. Next, a signal having a level 3 dB higher than the reference level is swept out at a frequency of ± 4 kHz, and the level at each frequency swept via the filter is compared. Then, a frequency equal to the detection level of the reference level 0 dBm is obtained, and an intermediate value of these frequencies is set as the center frequency of the filter. As described above, the technique described in Patent Document 1 requires many processing steps.

  Further, when a digital filter without individual differences as individual components is used, there arises a problem that power consumption is significantly increased.

  One aspect of the present invention has been made in view of the above problems, and is input to a filter in accordance with a shift in the center frequency of the filter with a simple configuration without performing a significant circuit change from the related art. An object of the present invention is to realize a frequency adjusting device or the like that can appropriately adjust the frequency of a signal.

  In order to solve the above problem, a frequency adjustment device according to an aspect of the present invention is a frequency adjustment device that adjusts the frequency of a signal input to a filter in accordance with a shift in the center frequency of the filter, A process for sequentially inputting a signal having a first frequency higher than a reference frequency and a signal having a second frequency lower than the reference frequency to the filter; a signal strength after the signal having the first frequency passes through the filter; and Every time the adjustment value for changing the frequency of the signal input to the filter is changed by a predetermined value, the processing unit of calculating the difference from the signal intensity after the signal of the second frequency passes through the filter is a processing unit. An adjustment execution unit that repeatedly executes the processing unit; and a frequency adjustment unit that performs the adjustment using the adjustment value when the difference equal to or less than a reference value is calculated. It is set to.

  According to said structure, the frequency of the signal input into a filter corresponding to the shift | offset | difference of the center frequency of a filter using the difference of the intensity | strength of the signal after a filter when the frequency before and behind the reference frequency is input is input. Adjust. The difference in intensity after passing through the filter becomes smaller as the difference between the frequency of each signal input to the filter and the center frequency of the filter becomes smaller. Therefore, by using the difference in signal strength, the frequency of the signal input to the filter can be adjusted appropriately in accordance with the shift of the center frequency of the filter. Therefore, even if the filter has a large deviation of the center frequency, the performance can be appropriately exhibited. In addition, since it only calculates the difference in signal strength between a signal with a frequency higher than the reference frequency and a signal with a lower frequency, it can be realized with a simple configuration without significant circuit changes from the prior art, and can be centered in a short time. The frequency of the signal input to the filter can be adjusted corresponding to the frequency shift.

  In the frequency adjustment device according to one aspect of the present invention, when there are a plurality of the adjustment values when the difference equal to or less than the reference value is calculated, the frequency adjustment unit calculates a median value among the plurality of adjustment values. May be used to make the above adjustment.

  According to said structure, the frequency of the signal input into a filter is adjusted corresponding to the shift | offset | difference of a center frequency using the median value of the adjustment values used as the difference below a reference value. As described above, the difference in signal strength after passing through the filter becomes smaller as the difference between the frequency of each signal input to the filter and the center frequency of the filter becomes smaller. Correspondingly, the deviation of the center frequency can be appropriately adjusted by adjusting the frequency of the signal input to the filter.

  In the frequency adjustment device according to one aspect of the present invention, the adjustment execution unit performs frequency conversion on an adjustment signal whose reference frequency is a basis of a signal input to the filter, and a frequency channel of the adjustment signal. The frequency obtained by frequency conversion of the adjustment signal with the frequency for frequency conversion of the channel immediately after the frequency of the adjustment signal is the first frequency, and the adjustment signal is The frequency converted by the frequency for frequency conversion of the channel immediately before the frequency of the adjustment signal may be the second frequency.

  According to said structure, a 1st frequency and a 2nd frequency can be set easily.

  In the frequency adjustment device according to one aspect of the present invention, the adjustment execution unit (1) sets the adjustment value to an initial value when the difference increases each time the adjustment value is increased from the initial value by the predetermined value. (2) When the difference increases each time the adjustment value is decreased from the initial value by the predetermined value, the adjustment value is increased from the initial value by the predetermined value. It may be.

  According to the above configuration, when the adjustment value increase / decrease direction is not appropriate, the increase / decrease direction can be corrected to an appropriate one. Thereby, the shift | offset | difference of the center frequency of a filter can be adjusted appropriately.

  In the frequency adjustment device according to one aspect of the present invention, the adjustment execution unit includes a signal after the first frequency signal has passed through the filter and a signal after the second frequency signal has passed through the filter. The reference frequency may be changed by a predetermined value so that the frequency of the signal input to the filter is shifted to the frequency side of the signal having the higher intensity.

  According to said structure, the increase / decrease direction of an adjustment value can be determined uniquely. Thereby, the shift | offset | difference of the center frequency of a filter can be adjusted rapidly.

  In order to solve the above problem, a wireless device according to one embodiment of the present invention includes the frequency adjustment device. Thereby, there exists an effect similar to the effect mentioned above.

  In order to solve the above problem, a frequency adjustment method according to an aspect of the present invention is a frequency adjustment method for adjusting a frequency of a signal input to a filter in accordance with a shift of a center frequency of the filter, the filter The first frequency signal higher than the reference frequency and the second frequency signal lower than the reference frequency are sequentially input, the signal strength after the first frequency signal passes through the filter, and the first frequency Each time the adjustment value for changing the frequency of the signal input to the filter is changed by a predetermined value, the processing for calculating the difference from the signal intensity after the signal of two frequencies passes through the filter is the processing unit. An adjustment execution step for repeatedly executing a processing unit; and a frequency adjustment step for performing the adjustment using the adjustment value when the difference equal to or less than a reference value is calculated. It is characterized by a door.

  According to said method, there exists an effect similar to the effect mentioned above.

  The frequency adjustment apparatus according to each aspect of the present invention may be realized by a computer. In this case, the frequency adjustment apparatus is operated on each computer by causing the computer to operate as each unit (software element) included in the frequency adjustment apparatus. The control program for the frequency adjusting device to be realized in this way and a computer-readable recording medium on which the control program is recorded also fall within the scope of the present invention.

  According to one aspect of the present invention, there is an effect that the frequency of a signal input to the filter can be appropriately adjusted in accordance with the shift of the center frequency of the filter by using the difference in RSSI voltage intensity. Therefore, even if the filter has a large deviation of the center frequency, there is an effect that the performance can be appropriately exhibited.

  In addition, since it only calculates the difference in signal strength between the channels before and after the reference frequency, it can be realized with a simple configuration without any significant circuit changes from the prior art, and it can handle a shift in the center frequency in a short time. As a result, the frequency of the signal input to the filter can be adjusted.

It is a block diagram which shows the principal part structure of the radio | wireless apparatus which concerns on embodiment of this invention. It is a block diagram which shows the principal part structure of the adjustment apparatus with which the said radio | wireless apparatus is provided. It is a figure for demonstrating the reason which can adjust the 2nd local signal which a 2nd local oscillator oscillates, and can absorb the gap of the center frequency of IF filter. It is a figure for demonstrating the reason which can adjust the 2nd local signal which a 2nd local oscillator oscillates, and can absorb the gap of the center frequency of IF filter. It is a flowchart which shows the flow of the process in the said adjustment apparatus. It is a figure for demonstrating a mode that the adjustment value which the said adjustment apparatus uses is increased / decreased.

Embodiment
〔Overview〕
Hereinafter, an embodiment of the present invention will be described. In the present embodiment, a double superheterodyne wireless device will be described as an example, but the present invention is not limited to this. First, an overview of the wireless device 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing a main configuration of the wireless device 1. In the functional block diagram shown in FIG. 1, among the functions of the wireless device 1, blocks showing functions not related to the present invention are omitted.

  As shown in FIG. 1, the wireless device 1 includes an adjustment device (frequency adjustment device) 10, a first local oscillator 20, a second local oscillator 30, a frequency multiplier 40, a mixer 51, and an IF filter 52 (1st IF filter). , Amplifier 53, mixer 54, IF filter 55 (2nd IF filter), amplifier 56, amplifier 57, AM detection circuit 58, and FM detection circuit 59.

  As shown in FIG. 1, in the wireless device 1, an adjustment signal is input to the mixer 51 as an input signal from a signal generator (not shown) in a frequency adjustment process described in detail below. The mixer 51 mixes the adjustment signal with the first local signal generated by the first local oscillator 20, converts the frequency of the adjustment signal, and outputs it to the IF filter 52. The first local oscillator 20 and the second local oscillator 30 generate and oscillate a local signal having a frequency corresponding to the control voltage output from the adjustment device 10. For example, the first local oscillator 20 oscillates a signal having a frequency of reception frequency +46.35 MHz. The second local oscillator 30 oscillates a signal having a frequency based on an “adjustment value” to be described later. As described above, in the present embodiment, a signal input to the wireless device 1 when executing the frequency adjustment process is referred to as an adjustment signal. The local signal generated by the first local oscillator 20 is referred to as a “first local signal”, and the local signal generated by the second local oscillator 30 is referred to as a “second local signal”.

  The IF filter 52 is a band limiting filter. An example of the IF filter 52 is a crystal filter (XTAL filter). An example of the center frequency of the IF filter 52 is 46.35 MHz.

  The signal that has passed through the IF filter 52 is amplified by the amplifier 53 and input to the mixer 54. The mixer 54 mixes the signal that has passed through the amplifier 53 and the signal obtained by multiplying the second local signal generated by the second local oscillator 30 by the frequency multiplier 40, and frequency-converts the input signal. Output to the IF filter 55. The IF filter 55 is a band limiting filter. An example of the IF filter 55 is a ceramic filter. An example of an ideal center frequency of the IF filter 55 is 0.450 MHz. Since the ceramic filter has a large variation in the center frequency (characteristic), the reception selectivity of the wireless device 1 is lowered. By adjusting the second local signal oscillated by the second local oscillator 30 and absorbing the deviation of the center frequency by the configuration of the present embodiment, it is possible to prevent the reception selectivity of the wireless device 1 from being lowered.

  The signal that has passed through the IF filter 55 is input to the amplifier 56 and the amplifier 57, amplified to a level that can be demodulated, and then input to the AM detection circuit 58 or the FM detection circuit 59. The AM detection circuit 58 and the FM detection circuit 59 demodulate each input signal.

  Also, the RSSI (Received Signal Strength Indication) of the signal that has passed through the amplifier 57 is input to the adjustment device 10.

  The adjusting device 10 outputs a control voltage for adjusting the frequency of the first local signal oscillated by the first local oscillator 20 to the first local oscillator 20. By adjusting the frequency of the first local signal, the frequency can be changed to a frequency for receiving a frequency (channel) different from the frequency when the adjustment signal is input.

  Moreover, the adjustment apparatus 10 determines the adjustment value (control voltage) which adjusts the frequency of the 2nd local signal which the 2nd local oscillator 30 oscillates using acquired RSSI, and the control voltage (corresponding to the determined adjustment value ( 2nd Lo Control (2LOC)) is output to the second local oscillator 30. By adjusting the frequency of the second local signal, the frequency of the signal output from the mixer 54 (that is, the signal input to the IF filter 55) is changed. Therefore, the adjustment value changes the frequency of the signal input to the IF filter 55. As a result, the adjustment device 10 performs frequency adjustment processing for adjusting and absorbing the second local signal generated by the second local oscillator 30 by shifting the center frequency of the IF filter 55. Details of the frequency adjustment processing will be described later.

[Configuration of Adjustment Device 10]
Next, the adjustment device 10 will be described with reference to FIG. FIG. 2 is a block diagram illustrating a main configuration of the adjustment device 10. As shown in FIG. 2, the adjustment device 10 includes an RSSI acquisition unit 11, a voltage difference determination unit 12, an adjustment value storage unit 13, a final adjustment value determination unit (frequency adjustment unit) 14, an adjustment unit (adjustment execution unit) 15, And a storage unit 16.

  The RSSI acquisition unit 11 acquires the RSSI voltage of the signal output from the amplifier 57. Then, the acquired RSSI voltage is output to the voltage difference determination unit 12. The RSSI acquisition unit 11 receives the RSSI voltage a predetermined number of times (for example, several times to several tens of times) after a predetermined time (for example, several tens of ms) has passed since the control voltage is output by the first local oscillator adjustment unit 152 described later. And the average value thereof is output to the voltage difference determination unit 12.

  The voltage difference determination unit 12 passes a first frequency signal and a second frequency signal, which will be described later, through the IF filter 55, and the voltage difference of the RSSI voltage amplified by the amplifier 57 is less than a reference value (for example, several hundred mV). It is determined whether or not there is. If the value is equal to or less than the reference value, the adjustment value storage unit 13 is notified of that.

  When the adjustment value storage unit 13 is notified from the voltage difference determination unit 12 that the voltage difference is equal to or less than the reference value, the adjustment value storage unit 13 stores the adjustment value at that time in the storage unit 16.

  The final adjustment value determination unit 14 determines the central value of the adjustment values stored in the storage unit 16 as the final adjustment value, and notifies the adjustment unit 15 of it.

  The adjustment unit 15 outputs a control signal for switching the frequency of the first local signal to the first local oscillator 20 in the frequency adjustment process, and outputs a control voltage corresponding to the adjustment value for adjusting the second local signal. Output to the two local oscillator 30. The adjustment unit 15 adjusts the second local signal oscillated by the second local oscillator 30 based on the adjustment value determined by the final adjustment value determination unit 14. Adjustment unit 15 includes a second local oscillator adjustment unit 151 and a first local oscillator adjustment unit 152.

  The second local oscillator adjustment unit 151 outputs a control voltage for determining the frequency of the second local signal oscillated by the second local oscillator 30 to the second local oscillator 30. Further, when performing the process of adjusting the second local signal for absorbing the shift of the center frequency of the IF filter 55, the second local oscillator adjustment unit 151 determines the initial value of the adjustment value, and sets the initial value to the determined initial value. The corresponding control voltage is output to the second local oscillator 30.

  Then, the second local oscillator adjustment unit 151 changes the adjustment value by a predetermined value from the initial value (for example, every 10 decimal numbers), and outputs a control voltage corresponding to the changed adjustment value.

  When performing the frequency adjustment process, the first local oscillator adjustment unit 152 performs the next channel that is higher than the frequency of the adjustment signal input to the wireless device 1 and the previous one that is lower than the frequency. When the first channel is received, a control voltage that is the frequency of the first local signal oscillated by the first local oscillator 20 is output. The first frequency refers to the IF filter 55 when the mixer 51 mixes the first local signal oscillated by the first local oscillator when receiving a channel one frequency after the frequency of the adjustment signal. This is the frequency of the signal input to. That is, the first frequency is a frequency obtained by frequency-converting the adjustment signal with a frequency for frequency-converting the channel immediately after the frequency of the adjustment signal.

  The second frequency is the IF filter 55 when the mixer 51 mixes the first local signal oscillated by the first local oscillator when receiving the channel one frequency before the frequency of the adjustment signal. This is the frequency of the signal input to. That is, the second frequency is a frequency obtained by frequency-converting the adjustment signal with a frequency for frequency-converting the channel immediately before the frequency of the adjustment signal.

  Next, an example of signal frequencies in the present embodiment will be described. For example, an unmodulated adjustment signal having a frequency of 127.510 MHz and an intensity of +60 dBμ or more is input from the signal generator, and the frequency of the previous channel is 127.505 MHz, and the frequency of the next channel is 127.515 MHz. In this case, the frequency of the signal oscillated or output from each unit is as follows.

  Since the frequency of the signal oscillated from the first local oscillator 20 is the reception frequency +46.35 MHz, when receiving a signal with the reception frequency 127.510 MHz, it becomes 127.510 + 46.35 = 176.860 MHz. In the case of the previous channel, 127.505 + 46.35 = 173.855 MHz, and in the case of the next channel, 127.515 + 46.35 = 173.865 MHz.

  The output of the mixer 51 is 173.855-127.510 = 46.345 MHz for the previous channel, and 173.865-127.510 = 46.355 MHz for the next channel. Since these signals are within the pass band of the IF filter 52, signals of this frequency are input to the mixer 54.

  If the frequency of the signal oscillated from the second local oscillator 30 when the adjustment value is 0x82 is 15.3 MHz, it is multiplied by 3 by the frequency multiplier 40, and the mixer 54 has 15.3 × 3 = 45. A 9 MHz signal is input.

  Therefore, the output of the mixer 54 is 46.345-45.9 = 0.445 MHz in the case of the previous channel, and 46.355-45.9 = 0.455 MHz in the case of the next channel. Become.

  In addition, the numerical value mentioned above is an example, and is not restricted to this.

  As described above, when the adjustment device 10 performs the frequency adjustment process, the difference (voltage difference) between the RSSI voltages of the signals after the first frequency signal and the second frequency signal have passed through the IF filter 55 is a reference. The second local signal generated by the second local oscillator 30 is adjusted to absorb the deviation of the center frequency of the IF filter 55 based on the adjustment value that is less than or equal to the value. Thereby, it is possible to appropriately adjust the frequency of the signal input to the filter corresponding to the shift of the center frequency of the filter.

  The adjustment device 10 is a device that adjusts the frequency of the signal input to the IF filter 55 in accordance with the deviation of the center frequency of the IF filter 55, and has a higher frequency (first frequency) than the reference frequency in the IF filter 55. A process of sequentially inputting a signal and a signal having a frequency lower than the reference frequency (second frequency), an RSSI voltage (signal strength) after the signal of the first frequency passes through the IF filter 55, and the second An adjustment value for changing the frequency of a signal input to the IF filter 55 is set to a predetermined value (processing for calculating a difference from the RSSI voltage (signal strength) after the frequency signal passes through the IF filter 55 as a processing unit. For example, an adjustment execution unit (adjustment unit 15) that repeatedly executes the above processing unit every time it is changed by 10), and when the above difference below a reference value is calculated Frequency adjusting unit that performs the adjustment by using the adjustment value (final adjustment value determination section 14), and a.

  The reference frequency is a frequency of a signal input to the IF filter 55 when the wireless device 1 receives a frequency channel of the adjustment signal.

  The reason why the above configuration can absorb the deviation of the center frequency of the IF filter 55 by adjusting the second local signal oscillated by the second local oscillator 30 will be described with reference to FIGS. FIG. 3 and FIG. 4 are diagrams for explaining the reason why the shift of the center frequency of the IF filter 55 can be adjusted and absorbed by the second local oscillator 30 oscillating by the configuration of the present embodiment. .

  3 and 4 show the filter characteristics of the IF filter 55 and the signal strengths of the first frequency signal and the second frequency signal after passing through the IF filter 55. The horizontal axis represents the frequency, and the vertical axis represents the frequency. The axis indicates the signal strength. FIG. 3A shows a case where there is no deviation in the center frequency of the IF filter 55 when the adjustment value is the initial value “0x82”. At this time, the center frequency of the IF filter 55 is 0.450 MHz, and there is no difference in signal strength between the first frequency signal and the second frequency signal after passing through the IF filter 55. FIG. 3B shows a case where the center frequency of the IF filter 55 has a deviation, the filter characteristics when there is no deviation in the center frequency is indicated by a broken line, and the filter characteristics when there is a deviation in the center frequency. Shown in solid line. As shown in FIG. 3B, when the center frequency is shifted, it can be seen that there is a difference in signal strength between the first frequency signal and the second frequency signal after passing through the IF filter 55. . When the difference in signal strength is equal to or greater than the reference value, the adjustment value is increased or decreased so that the difference in signal strength is equal to or less than the reference value. Incidentally, in FIG. 3B, the signal of the second frequency is sufficiently attenuated by the IF filter 55, but the signal of the first frequency is not attenuated much. This causes a decrease in reception selectivity.

  4A to 4C show how adjustment is performed when the center frequency of the IF filter 55 is shifted. 4A shows the case where the adjustment value is “0x82”, which is the initial value, FIG. 4B shows the case where the adjustment value is “0x78”, and FIG. 4C shows the case where the adjustment value is “0x6E”. Show. In the present embodiment, the difference in signal strength between the first frequency signal and the second frequency signal after passing through the IF filter 55 is Dn (n = 1, 2, 3... N), and the adjustment value is The signal intensity difference Dn is adjusted to be equal to or less than the reference value by increasing or decreasing.

  For example, as shown in FIG. 4A, D1 is the difference in signal strength between the first frequency signal and the second frequency signal after passing through the IF filter 55 when the adjustment value is “0x82”. If is greater than or equal to the reference value, the adjustment value is increased or decreased. Here, the number is reduced from “0x82” to “0x78”. FIG. 4B shows a state when the adjustment value is reduced to “0x78”. In FIG. 4B, the first frequency signal and the second frequency signal when the adjustment value is “0x82” are indicated by broken lines, and the adjustment frequency “0x78” is indicated by a solid line. It can be seen that the signal of the first frequency and the signal of the second frequency input to the IF filter 55 are shifted higher than those in FIG. The difference in signal strength at this time is represented as D2. It can be seen from FIGS. 4A and 4B that D1> D2. If D2 is not less than or equal to the reference value, the adjustment value is further reduced to “0x6E”. FIG. 4C illustrates a case where the adjustment value is “0x6E”. 4A to 4C that D1> D2> D3.

  As described above, when the center frequency of the IF filter 55 is deviated from the ideal center frequency, the frequency of the second local signal is adjusted by adjusting the adjustment value as described above, and the IF filter 55 is passed. By making the frequency of the signal approach the center frequency of the IF filter 55 whose center frequency is shifted, the shift of the center frequency of the IF filter 55 can be absorbed.

[Process flow]
Next, the flow of processing in the wireless device 1 will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of processing in the wireless device 1.

  As shown in FIG. 5, first, an adjustment signal having a predetermined frequency (for example, 127.510 MHz) is input to the wireless device 1, and the second local oscillator adjustment unit 151 sets the adjustment value to an initial value (S101). The initial value of the adjustment value is, for example, “0x82” that is a median value from “0x00” to “0xFF” in hexadecimal. The frequency of the adjustment signal input to the wireless device 1 is, for example, 127.510 MHz, and the signal intensity is +60 dBμ or more. Note that the adjustment signal is preferably an unmodulated signal, and therefore, a signal generated by a signal generator may be input.

  Next, the first local oscillator adjustment unit 152 outputs a control voltage so that the first local signal has a frequency at which the channel immediately before the frequency of the adjustment signal is received (S102). Then, the RSSI acquisition unit 11 acquires the RSSI voltage of the signal that has passed through the amplifier 57 (S103).

  Next, the first local oscillator adjustment unit 152 outputs a control voltage so that the first local signal has a frequency when receiving the channel immediately after the frequency of the adjustment signal (S104). Then, the RSSI acquisition unit 11 acquires the RSSI voltage of the signal that has passed through the amplifier 57 (S105).

  And the voltage difference determination part 12 calculates | requires the difference of the RSSI voltage acquired by step S103, and the RSSI voltage acquired by step S105 (S106). Next, the second local oscillator adjustment unit 151 determines whether the adjustment value has been changed a predetermined number of times, or whether the difference has increased as a result of changing the adjustment value a predetermined number of times (S107). If not changed, or if the difference is not increased as a result of changing the adjustment value a predetermined number of times (NO in S107), the process proceeds to step S108. If the difference is equal to or smaller than the reference value (YES in S108), the adjustment value storage unit 13 stores the adjustment value at that time in the storage unit 16 (S109). On the other hand, if the difference is larger than the reference value (NO in S108), the adjustment value is reduced by a predetermined value (decimal 10) (S121), and the process proceeds to step S102. After that, the process proceeds to step S106, and if the RSSI voltage difference increases as a result of changing the adjustment value a predetermined number of times (for example, several times) (YES in S107), the process proceeds to step S131 and the second local oscillator adjustment unit 151 returns the adjustment value to the initial value (here, 0x82). Then, the second local oscillator adjustment unit 151 changes the direction in which the adjustment value is changed (that is, whether to increase or decrease), and proceeds to step S121. In step S121, the second local oscillator adjustment unit 151 increases the adjustment value by a predetermined value (decimal number 10), and proceeds to step S102.

In step S109, after the adjustment value when the RSSI voltage difference is equal to or less than the reference value is stored in the storage unit 16, the second local oscillator adjustment unit 151 changes the adjustment value by a predetermined value (decimal 10). Then, processing similar to the processing from step S102 to S106 is performed, and the difference between the RSSI voltages is obtained (S110). And the voltage difference determination part 12 determines whether the difference of RSSI voltage is below a reference value (S111), and if it is below a reference value (it is YES at S111), it will return to step S109 and an adjustment value storage part 13 stores the adjustment value at that time in the storage unit 16. And the adjustment apparatus 10 repeats the process from step S109 to S111 until the difference of RSSI voltage becomes larger than a reference value. (The processing from step S101 to S111 corresponds to the adjustment execution step.)
Thereafter, when the voltage difference determination unit 12 determines that the RSSI voltage difference is larger than the reference value (NO in S111), the final adjustment value determination unit 14 determines the center of the adjustment values stored in the storage unit 16. Is determined as the final adjustment value (S112, frequency adjustment step).

  Thereafter, the wireless device 1 performs input signal reception processing using the second local signal based on the determined final adjustment value.

  Next, how the adjustment value is increased or decreased will be described with reference to FIG. FIG. 6 is a diagram for explaining how the adjustment value is increased or decreased.

  As shown in FIG. 6, the second local oscillator adjustment unit 151 sets the initial value of the adjustment value to “0x82” (“1” in FIG. 6, corresponding to step S101 in FIG. 5). Then, the second local oscillator adjustment unit 151 decreases the adjustment value by 10 in decimal numbers (0x78 → 0x6E → 0x64 →...) (“2” in FIG. 6). In this process, when the difference of the RSSI voltage becomes equal to or less than the reference value, the adjustment value storage unit 13 stores the adjustment value at that time in the storage unit 16.

  On the other hand, when the RSSI voltage difference gradually increases as a result of gradually reducing the adjustment value (“3” in FIG. 6), the second local oscillator adjustment unit 151 once returned the adjustment value to the initial value. Above (“4” in FIG. 6), the decimal value is increased by 10 (0x8c → 0x96 → 0xA0 →...) (“5” in FIG. 6) so that the adjustment value increases.

  Then, the adjustment value storage unit 13 causes the storage unit 16 to store adjustment values (for example, 0x96, 0xA0, 0xAA) whose RSSI voltage difference is equal to or less than the reference value ("6" in FIG. 6). Then, the final adjustment value determination unit 14 determines the median value (0xA0) among the adjustment values stored in the storage unit 16 as the final adjustment value.

  In the above-described embodiment, the adjustment value is gradually changed to decrease first, and when the difference between the RSSI voltages gradually increases as a result, the adjustment value is gradually changed to increase. The present invention is not limited to this configuration. Conversely, when the RSSI voltage difference gradually increases as a result of gradually changing the adjustment value at first, the adjustment value is gradually decreased. The structure to change may be sufficient.

[Modification]
The method of increasing / decreasing the adjustment value is not limited to the above-described embodiment. For example, the adjustment value may be increased / decreased based on the magnitude of the RSSI voltage. Specifically, the second local oscillator adjustment unit 151 acquires the RSSI voltage values of the previous channel and the next channel acquired by the RSSI acquisition unit 11 from the RSSI acquisition unit 11, and among these RSSI voltages, The configuration may be such that the adjustment value is reduced if the RSSI voltage of the next channel is large, and the adjustment value is changed if the RSSI voltage of the previous channel is large. That is, the adjustment value may be changed so that the frequency of the signal input to the IF filter 55 is shifted to the frequency side of the signal having the larger RSSI voltage.

  Thereby, the adjustment time of the center frequency of the IF filter 55 can be shortened.

[Example of software implementation]
Control block of adjustment device 10 (particularly RSSI acquisition unit 11, voltage difference determination unit 12, adjustment value storage unit 13, final adjustment value determination unit 14, adjustment unit 15 (second local oscillator adjustment unit 151, first local oscillator adjustment unit) 152)) may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.

  In the latter case, the adjustment apparatus 10 includes a computer that executes instructions of a program that is software for realizing each function. The computer includes, for example, one or more processors and a computer-readable recording medium storing the program. In the computer, the processor reads the program from the recording medium and executes the program, thereby achieving the object of the present invention. As said processor, DSP (digital signal processor) and CPU (Central Processing Unit) can be used, for example. As the recording medium, a “non-temporary tangible medium” such as a ROM (Read Only Memory), a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, a RAM (Random Access Memory) for expanding the program may be further provided. The program may be supplied to the computer via an arbitrary transmission medium (such as a communication network or a broadcast wave) that can transmit the program. Note that one embodiment of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

1 Radio equipment 10 Adjustment device (frequency adjustment device)
11 RSSI acquisition unit 12 Voltage difference determination unit 13 Adjustment value storage unit 14 Final adjustment value determination unit (frequency adjustment unit)
15 Adjustment unit (Adjustment execution unit)
55 IF filter (filter)

Claims (7)

A frequency adjustment device that adjusts the frequency of a signal input to a filter in accordance with a shift in the center frequency of the filter,
A process of sequentially inputting a signal having a first frequency higher than a reference frequency and a signal having a second frequency lower than the reference frequency to the filter, signal strength after the signal having the first frequency passes through the filter, and Every time the adjustment value for changing the frequency of the signal input to the filter is changed by a predetermined value, the processing unit of calculating the difference from the signal intensity after the signal of the second frequency passes through the filter is a processing unit. An adjustment execution unit that repeatedly executes the above processing unit;
And a frequency adjusting unit that performs the adjustment using the adjustment value when the difference equal to or less than a reference value is calculated.   The frequency adjustment unit performs the adjustment using a median value of the plurality of adjustment values when there are a plurality of the adjustment values when the difference equal to or less than a reference value is calculated. Item 2. The frequency adjustment device according to Item 1. The adjustment execution unit, when the reference frequency is a frequency obtained by frequency-converting an adjustment signal that is a basis of a signal input to the filter with a frequency for frequency conversion of the frequency channel of the adjustment signal,
A frequency obtained by frequency-converting the adjustment signal with a frequency for frequency-converting a channel immediately after the frequency of the adjustment signal is defined as the first frequency,
The frequency according to claim 1 or 2, wherein a frequency obtained by frequency-converting the adjustment signal with a frequency for frequency-converting a channel immediately before the frequency of the adjustment signal is the second frequency. Adjustment device. The adjustment execution unit
(1) When the difference increases each time the adjustment value is increased from the initial value by the predetermined value, the adjustment value is decreased from the initial value by the predetermined value, or
(2) The adjustment value is increased from the initial value by the predetermined value when the difference increases each time the adjustment value is decreased from the initial value by the predetermined value. The frequency adjustment apparatus of any one of Claims.   The adjustment execution unit is configured to select a frequency of a signal having a higher intensity among a signal after the signal of the first frequency passes through the filter and a signal after the signal of the second frequency passes through the filter. The frequency adjustment device according to any one of claims 1 to 3, wherein the adjustment value is changed by a predetermined value so that a frequency of a signal input to the filter is shifted to the side.   A wireless device including the frequency adjustment device according to claim 1. A frequency adjustment method for adjusting a frequency of a signal input to a filter in accordance with a shift of a center frequency of the filter,
A process of sequentially inputting a signal having a first frequency higher than a reference frequency and a signal having a second frequency lower than the reference frequency to the filter, signal strength after the signal having the first frequency passes through the filter, and Every time the adjustment value for changing the frequency of the signal input to the filter is changed by a predetermined value, the processing unit of calculating the difference from the signal intensity after the signal of the second frequency passes through the filter is a processing unit. An adjustment execution step for repeatedly executing the above processing unit;
A frequency adjustment step of performing the adjustment using the adjustment value when the difference equal to or less than a reference value is calculated.

Images