JP6985592B2 - Frequency regulators, frequency regulators, and wireless devices - Google Patents

Description

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

In the superheterodyne receiver, the input signal received via the antenna is amplified by a high-frequency circuit, and the amplified signal is mixed with a signal of a predetermined frequency generated by a local oscillator by a frequency mixer to form 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 the speaker or the like.

In addition to the amplifier circuit, the intermediate frequency circuit is provided with an IF filter or the like for passing a desired intermediate frequency signal. The characteristics (for example, center frequency) of an IF filter fluctuate due to individual differences as individual components 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 properly, it is necessary to understand the characteristics of the IF filter, especially the center frequency.

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

Further, Patent Document 2 describes a method of specifying a center frequency of a filter by passing a measurement signal having a different measurement frequency through a filter, measuring the intensity of the passed measurement signal, and obtaining a peak value. There is.

Japanese Unexamined Patent Publication No. 9-247030 (published on September 19, 1997) Japanese Unexamined Patent Publication No. 2016-12293 (published on July 7, 2016)

Certainly, even with the above-mentioned conventional technique, it is possible to adjust the deviation of the center frequency of the filter with respect to the desired center frequency. However, the above-mentioned conventional technique has room for improvement in terms of processing time and processing process.

For example, in the technique described in Patent Document 1, when the center frequency of the filter is obtained, 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 the demodulated signal is detected through a filter. Next, a signal having a level 3 dB higher than the reference level is swept out at a frequency of ± 4 kHz, and the levels at each sweep frequency passed through the filter are compared. Then, a frequency equal to the detection level of the reference level 0 dBm is obtained, and the intermediate value of these frequencies is set as the center frequency of the filter. As described above, in the technique described in Patent Document 1, a large number of processing steps are required.

Further, when a digital filter having no individual difference as an individual component 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 the filter in response to a deviation in the center frequency of the filter with a simple configuration without making a major circuit change from the prior art. The purpose is to realize a frequency adjustment device or the like that can appropriately adjust the frequency of a signal.

In order to solve the above problems, the frequency adjusting device according to one aspect of the present invention is a frequency adjusting device that adjusts the frequency of the signal input to the filter in accordance with the deviation of the center frequency of the filter. The process of sequentially inputting the signal of the first frequency higher than the reference frequency and the signal of the second frequency lower than the reference frequency to the filter, the signal strength after the signal of the first frequency has passed through the filter, and the above. Each time the adjustment value for changing the frequency of the signal input to the filter is changed by a predetermined value, the process of calculating the difference from the signal strength after the signal of the second frequency has passed through the filter is used as the processing unit. It is characterized by including 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 below the reference value is calculated.

According to the above configuration, the frequency of the signal input to the filter corresponding to the deviation of the center frequency of the filter by using the difference in the intensity of the signal after passing through the filter when the frequencies before and after the reference frequency are input. To 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 appropriately adjusted in response to the deviation of the center frequency of the filter. Therefore, even a filter having a large deviation in the center frequency can appropriately exhibit its performance. In addition, since it only calculates the difference in signal strength between the signal with a frequency higher than the reference frequency and the signal with a frequency lower than the reference frequency, it can be realized with a simple configuration without major circuit changes from the conventional technology, and it can be centered in a short time. The frequency of the signal input to the filter can be adjusted according to the frequency deviation.

In the frequency adjusting device according to one aspect of the present invention, when there are a plurality of the adjusting values when the difference below the reference value is calculated, the frequency adjusting unit sets the median value among the plurality of adjusted values. It may be used to make the above adjustment.

According to the above configuration, the frequency of the signal input to the filter is adjusted in response to the deviation of the center frequency by using the median value among the adjustment values having a difference equal to or less than the 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. By adjusting the frequency of the signal input to the filter correspondingly, the deviation of the center frequency can be adjusted appropriately.

In the frequency adjustment device according to one aspect of the present invention, the adjustment execution unit converts the adjustment signal on which the reference frequency is the basis of the signal input to the filter into the frequency channel of the adjustment signal. When the frequency is frequency-converted at the frequency of, the adjusted signal is defined as the first frequency, and the frequency converted at the frequency for frequency-converting the channel one channel after the adjusted signal is used as the first frequency. The second frequency may be the frequency converted by the frequency for frequency conversion of the channel immediately before the frequency of the adjustment signal.

According to the above configuration, the first frequency and the second frequency can be easily set.

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

According to the above configuration, when the increase / decrease direction of the adjustment value is not appropriate, the increase / decrease direction can be corrected to an appropriate one. This makes it possible to appropriately adjust the deviation of the center frequency of the filter.

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

According to the above configuration, the increase / decrease direction of the adjustment value can be uniquely determined. As a result, the deviation of the center frequency of the filter can be quickly adjusted.

In order to solve the above problems, the wireless device according to one aspect of the present invention has a configuration including the above frequency adjusting device. As a result, the same effect as the above-mentioned effect is obtained.

In order to solve the above problems, the frequency adjustment method according to one aspect of the present invention is a frequency adjustment method that adjusts the frequency of the signal input to the filter in accordance with the deviation of the center frequency of the filter. The process of sequentially inputting the signal of the first frequency higher than the reference frequency and the signal of the second frequency lower than the reference frequency, the signal strength after the signal of the first frequency has passed through the filter, and the first. Each time the adjustment value for changing the frequency of the signal input to the filter is changed by a predetermined value, the process of calculating the difference from the signal strength after the signal of two frequencies has passed through the filter is used as the processing unit. It is characterized by including an adjustment execution step in which a processing unit is repeatedly executed, and a frequency adjustment step in which the adjustment is performed using the adjustment value when the difference below the reference value is calculated.

According to the above method, the above-mentioned effect has the same effect.

The frequency adjusting device according to each aspect of the present invention may be realized by a computer, and in this case, the frequency adjusting device is made into a computer by operating the computer as each part (software element) provided in the frequency adjusting device. The control program of the frequency adjusting device and the computer-readable recording medium on which the control program is recorded are also included in the scope of the present invention.

According to one aspect of the present invention, it is possible to appropriately adjust the frequency of the signal input to the filter in response to the deviation of the center frequency of the filter by using the difference in the intensity of the RSSI voltage. Therefore, even a filter having a large deviation in the center frequency can appropriately exhibit its performance.

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 major circuit changes from the conventional technology, and it can respond to the deviation of the center frequency in a short time. The effect is that the frequency of the signal input to the filter can be adjusted.

It is a block diagram which shows the main part structure of the wireless device which concerns on embodiment of this invention. It is a block diagram which shows the main part structure of the adjustment device provided in the said wireless device. It is a figure for demonstrating the reason why the deviation of the center frequency of an IF filter can be absorbed by adjusting a 2nd local signal oscillated by a 2nd local oscillator. It is a figure for demonstrating the reason why the deviation of the center frequency of an IF filter can be absorbed by adjusting a 2nd local signal oscillated by a 2nd local oscillator. It is a flowchart which shows the flow of processing in the said adjustment apparatus. It is a figure for demonstrating how to increase or decrease the adjustment value used by the said adjustment apparatus.

[Embodiment]
〔Overview〕
Hereinafter, an embodiment of the present invention will be described. In the present embodiment, a double superheterodyne type wireless device will be described as an example, but the present embodiment is not limited thereto. First, an outline 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 configuration of a main part 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 adjusting device (frequency adjusting 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.

Then, as shown in FIG. 1, in the wireless device 1, in the frequency adjustment process described in detail below, the adjustment signal is input to the mixer 51 as an input signal from the signal generator (not shown). 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 the frequency to the IF filter 52. The first local oscillator 20 and the second local oscillator 30 generate a local signal having a frequency corresponding to the control voltage output from the adjusting device 10 and oscillate. For example, the first local oscillator 20 oscillates a signal having a reception frequency of +46.35 MHz. Further, the second local oscillator 30 oscillates a signal having a frequency based on the "adjustment value" described later. As described above, in the present embodiment, the signal input to the wireless device 1 when the frequency adjustment process is executed is referred to as an adjustment signal. Further, 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 with 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 the ideal center frequency of the IF filter 55 is 0.450 MHz. Since the ceramic filter has a large variation in the center frequency (characteristics), the reception selectivity of the wireless device 1 is lowered. By adjusting and absorbing the second local signal oscillated by the second local oscillator 30 to absorb the deviation of the center frequency by the configuration of this embodiment, it is possible to prevent the reception selectivity of the wireless device 1 from deteriorating.

The signal that has passed through the IF filter 55 is input to the amplifier 56 and the amplifier 57, respectively, amplified to a demodable level, 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 the input signals, respectively.

Further, RSSI (Received Signal Strength Indication) of the signal that has passed through the amplifier 57 is input to the adjusting 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, it is possible to change the frequency to receive a frequency (channel) different from the frequency when the adjusted signal is input.

Further, the adjusting device 10 determines an adjustment value (control voltage) for adjusting the frequency of the second local signal oscillated by the second local oscillator 30 using the acquired RSSI, and the control voltage (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 adjusting device 10 adjusts and absorbs the deviation of the center frequency of the IF filter 55 by adjusting the second local signal oscillated by the second local oscillator 30. The details of the frequency adjustment process will be described later.

[Structure of adjusting device 10]
Next, the adjusting device 10 will be described with reference to FIG. FIG. 2 is a block diagram showing a main configuration of the adjusting device 10. As shown in FIG. 2, the adjusting 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, and 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 has a predetermined number of times (for example, several to several tens of times) after a predetermined time (for example, several tens of ms) has elapsed since the control voltage was output by the first local oscillator adjustment unit 152 described later, and the RSSI voltage. Is acquired, and the average value thereof is output to the voltage difference determination unit 12.

In the voltage difference determination unit 12, the first frequency signal and the second frequency signal, which will be described later, pass through the IF filter 55, and the voltage difference of the RSSI voltage amplified by the amplifier 57 is equal to or less than the reference value (for example, several hundred mV). Determine if it exists. Then, if it is equal to or less than the reference value, the adjustment value storage unit 13 is notified to that effect.

When the voltage difference determination unit 12 notifies that the voltage difference described above 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 center value of the adjustment values stored in the storage unit 16 as the final adjustment value, and notifies the adjustment unit 15.

In the frequency adjustment process, the adjustment unit 15 outputs a control signal for switching the frequency of the first local signal to the first local oscillator 20, and outputs a control voltage corresponding to the adjustment value for adjusting the second local signal. 2 Output to the local oscillator 30. Further, 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. The adjusting unit 15 includes a second local oscillator adjusting unit 151 and a first local oscillator adjusting 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 deviation of the center frequency of the IF filter 55, the second local oscillator adjusting unit 151 determines the initial value of the adjusted value and sets it 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 (for example, by 10 in decimal) from the initial value, and outputs the control voltage corresponding to the changed adjustment value.

When performing frequency adjustment processing, the first local oscillator adjustment unit 152 has a channel one after which the frequency is higher than the frequency of the adjustment signal input to the radio device 1, and one before which the frequency is lower than the frequency. When receiving the channel of, the first local oscillator 20 outputs a control voltage which is the frequency of the first local signal oscillated. The first frequency is the IF filter 55 when the first local signal oscillated by the first local oscillator and the adjustment signal are mixed by the mixer 51 when the channel one after the frequency of the adjustment signal is received. It 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 one channel after the frequency of the adjustment signal.

The second frequency is the IF filter 55 when the first local signal oscillated by the first local oscillator and the adjustment signal are mixed by the mixer 51 when the channel immediately before the frequency of the adjustment signal is received. It 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 the frequency of the signal in this embodiment will be described. For example, an unmodulated adjustment signal with 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 part is as follows.

Since the frequency of the signal oscillated from the first local oscillator 20 is the reception frequency + 46.35 MHz, when a signal with the reception frequency 127.510 MHz is received, 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 in the case of the previous channel, and 173.865-127.510 = 46.355 MHz in the case of the next channel. Since these signals are within the pass band of the IF filter 52, a signal having this frequency is input to the mixer 54.

When the frequency of the signal oscillated from the second local oscillator 30 when the adjustment value is 0x82 is 15.3 MHz, it is tripled by the frequency multiplier 40, and 15.3 × 3 = 45 in the mixer 54. A 9.9 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.

The above-mentioned numerical values are examples, and are not limited to these.

As described above, when the adjusting device 10 performs the frequency adjusting process, the difference (voltage difference) of the RSSI voltage of the signal after the first frequency signal and the second frequency signal have passed through the IF filter 55 is used as a reference. Based on the adjustment value that is equal to or less than the value, the deviation of the center frequency of the IF filter 55 is adjusted and absorbed by the second local signal oscillated by the second local oscillator 30. As a result, the frequency of the signal input to the filter can be appropriately adjusted in response to the deviation of the center frequency of the filter.

The adjusting 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 is a frequency higher than the reference frequency (first frequency) of the IF filter 55. The process of sequentially inputting a signal and a signal having a frequency lower than the reference frequency (second frequency), the RSSI voltage (signal strength) after the signal of the first frequency has passed through the IF filter 55, and the second The adjustment value for changing the frequency of the signal input to the IF filter 55 is set as a predetermined value, with the process of calculating the difference from the RSSI voltage (signal strength) after the frequency signal has passed through the IF filter 55 as the processing unit. For example, the adjustment is performed using the adjustment execution unit (adjustment unit 15) that repeatedly executes the processing unit every time the change is made by 10) in decimal, and the adjustment value when the difference below the reference value is calculated. It is provided with a frequency adjusting unit (final adjustment value determining unit 14) for performing.

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

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

3 and 4 show the filter characteristics of the IF filter 55 and the signal intensities of the first frequency signal and the second frequency signal after passing through the IF filter 55, and the horizontal axis is frequency and the vertical axis is vertical. The axis shows 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 signal of the first frequency and the signal of the second frequency after passing through the IF filter 55. FIG. 3B shows a case where the center frequency of the IF filter 55 is deviated, the filter characteristic when the center frequency is not deviated is shown by a broken line, and the filter characteristic when the center frequency is deviated is shown. Shown by the solid line. As shown in FIG. 3B, when there is a deviation in the center frequency, it can be seen that there is a difference in the signal strength between the signal of the first frequency and the signal of the second frequency after passing through the IF filter 55. .. If the difference in signal strength is greater than or equal to 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 so much. This causes the reception selectivity to decrease.

FIGS. 4A to 4C show the adjustment when the center frequency of the IF filter 55 is deviated. 4 (a) shows the case where the adjustment value is the initial value “0x82”, FIG. 4 (b) shows the case where the adjustment value is “0x78”, and FIG. 4 (c) shows the case where the adjustment value is “0x6E”. Shown. In the present embodiment, the difference in signal strength between the signal of the first frequency and the signal of the second frequency after passing through the IF filter 55 is set to Dn (n = 1, 2, 3 ... n), and the adjusted value is set. By increasing or decreasing, the difference in signal strength Dn is adjusted to be equal to or less than the reference value.

For example, as shown in FIG. 4A, D1 is the difference in signal strength between the signal of the first frequency and the signal of the second frequency 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, it is reduced from "0x82" to "0x78". FIG. 4B shows a state when the adjustment value is reduced to "0x78". In FIG. 4B, the signal of the first frequency and the signal of the second frequency when the adjustment value is “0x82” are shown by a broken line, and the signal when the adjustment value is “0x78” is shown by a solid line. It can be seen that the first frequency signal and the second frequency signal input to the IF filter 55 are shifted higher than those in FIG. 4A. The difference in signal strength at this time is D2. It can be seen from (a) and (b) of FIG. 4 that D1> D2. Here, if D2 is not equal to or less than the reference value, the adjustment value is further reduced to "0x6E". FIG. 4 (c) shows the case where the adjustment value is “0x6E”. From (a) to (c) of FIG. 4, it can be seen that D1> D2> D3.

As described above, when the center frequency of the IF filter 55 deviates 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 through. By bringing the frequency of the signal closer to the center frequency of the IF filter 55 whose center frequency is deviated, the deviation of the center frequency of the IF filter 55 can be absorbed.

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

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

Next, the first local oscillator adjustment unit 152 outputs a control voltage so that the first local signal becomes the 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 becomes the frequency at which the channel one after the frequency of the adjustment signal is received (S104). Then, the RSSI acquisition unit 11 acquires the RSSI voltage of the signal that has passed through the amplifier 57 (S105).

Then, the voltage difference determination unit 12 obtains the difference between the RSSI voltage acquired in step S103 and the RSSI voltage acquired in 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), and the adjustment value has been changed a predetermined number of times. If it has not been changed, or if the difference has 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 less 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 number 10) (S121), and the process proceeds to step S102. After that, if the difference in RSSI voltage becomes large as a result of changing the adjustment value a predetermined number of times (for example, several times) by proceeding to step S106 (YES in S107), the process proceeds to step S131 to proceed to 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 it is increased or decreased), 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 difference of the RSSI voltage 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 number 10). The same process as the process from step S102 to S106 is performed to obtain the difference in RSSI voltage (S110). Then, the voltage difference determination unit 12 determines whether or not the difference in RSSI voltage is equal to or less than the reference value (S111), and if it is equal to or less than the reference value (YES in S111), returns to step S109 and returns to the adjustment value storage unit. 13 stores the adjustment value at that time in the storage unit 16. Then, the adjusting device 10 repeats the processes from steps S109 to S111 until the difference in RSSI voltage becomes larger than the reference value. (The processes from steps S101 to S111 correspond to the adjustment execution step.)
After that, when the voltage difference determination unit 12 determines that the difference in RSSI voltage is larger than the reference value (NO in S111), the final adjustment value determination unit 14 is the center of the adjustment values stored in the storage unit 16. Is determined as the final adjustment value (S112, frequency adjustment step).

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

Next, a state of increasing or decreasing the adjustment value 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, which corresponds to step S101 in FIG. 5). Then, the second local oscillator adjustment unit 151 reduces the adjustment value by 10 in decimal so that the adjustment value becomes smaller (0x78 → 0x6E → 0x64 → ...) (“2” in FIG. 6). In this process, when the difference in 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 difference in RSSI voltage gradually increases as a result of gradually reducing the adjustment value (“3” in FIG. 6), the second local oscillator adjustment unit 151 once returns the adjustment value to the initial value. Above (“4” in FIG. 6), the adjustment value is incremented by 10 in decimal (0x8c → 0x96 → 0xA0 → ...) (“5” in FIG. 6).

Then, the adjustment value storage unit 13 stores the adjustment value (for example, 0x96, 0xA0, 0xAA) whose RSSI voltage difference is equal to or less than the reference value in the storage unit 16 (“6” in FIG. 6). Then, the final adjustment value determination unit 14 determines the median value (0xA0) of 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 so as to decrease first, and when the difference in RSSI voltage gradually increases as a result, the adjustment value is gradually changed to increase. The present invention is not limited to this configuration, and conversely, if the adjustment value is gradually changed to increase the adjustment value first, and as a result, the difference in RSSI voltage gradually increases, the adjustment value is gradually reduced. The configuration may be changed.

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

As a result, the adjustment time of the center frequency of the IF filter 55 can be shortened.

[Example of implementation by software]
The control block of the 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 adjusting device 10 includes a computer that executes instructions of a program that is software that realizes each function. The computer includes, for example, one or more processors and a computer-readable recording medium that stores the program. Then, 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 the processor, for example, a DSP (digital signal processor) or a CPU (Central Processing Unit) can be used. As the recording medium, a "non-temporary tangible medium", for example, a ROM (Read Only Memory) or the like, 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 above program may be further provided. Further, the program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. It should be noted that one aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the above program is embodied by electronic transmission.

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

1 Wireless device 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 section (adjustment execution section)
55 IF filter (filter)

Claims (7)

It is a frequency adjusting device that adjusts the frequency of the signal input to the filter according to the deviation from the ideal center frequency of the filter.
The process of sequentially inputting the signal of the first frequency higher than the reference frequency and the signal of the second frequency lower than the reference frequency to the filter, and the signal strength after the signal of the first frequency has passed through the filter. Each time the adjustment value for changing the frequency of the signal input to the filter is changed by a predetermined value, the process of calculating the difference from the signal strength after the signal of the second frequency has passed through the filter is used as the processing unit. The adjustment execution unit that repeatedly executes the above processing unit,
Using the adjustment value when the difference below the reference value is calculated, the adjustment is made so that the frequency of the signal input to the filter approaches the center frequency deviated from the ideal center frequency of the filter. A frequency adjusting device including a frequency adjusting unit. A claim characterized in that, when a plurality of the above adjustment values exist when the difference below the reference value is calculated, the frequency adjustment unit makes the above adjustment using the median value among the plurality of adjustment values. Item 1. The frequency adjusting device according to Item 1. When the reference frequency is a frequency obtained by frequency-converting the adjustment signal, which is the basis of the signal input to the filter, with a frequency for frequency-converting the channel of the frequency of the adjustment signal, the adjustment execution unit may perform the adjustment.
The frequency obtained by frequency-converting the adjusted signal with a frequency for frequency-converting the channel one channel after the frequency of the adjusted signal is defined as the first frequency.
The frequency according to claim 1 or 2, wherein the frequency obtained by frequency-converting the adjustment signal with a frequency for frequency-converting the channel immediately preceding the frequency of the adjustment signal is defined as the second frequency. Adjustment device. The above 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 by the predetermined value from the initial value, or the adjustment value is decreased by the predetermined value.
(2) Claims 1 to 3 characterized in that, when the difference increases each time the adjustment value is decreased from the initial value by the predetermined value, the adjustment value is increased by the predetermined value from the initial value. The frequency adjusting device according to any one of the following items. The adjustment execution unit is the frequency of the signal having the higher intensity, that is, the signal after the signal of the first frequency has passed through the filter and the signal after the signal of the second frequency has passed through the filter. The frequency adjusting device according to any one of claims 1 to 3, wherein the adjusting value is changed by a predetermined value so that the frequency of the signal input to the filter is shifted to the side. A wireless device including the frequency adjusting device according to any one of claims 1 to 5. It is a frequency adjustment method that adjusts the frequency of the signal input to the filter according to the deviation from the ideal center frequency of the filter.
The process of sequentially inputting the signal of the first frequency higher than the reference frequency and the signal of the second frequency lower than the reference frequency to the filter, and the signal strength after the signal of the first frequency has passed through the filter. Each time the adjustment value for changing the frequency of the signal input to the filter is changed by a predetermined value, the process of calculating the difference from the signal strength after the signal of the second frequency has passed through the filter is used as the processing unit. The adjustment execution step that repeatedly executes the above processing unit, and
Using the adjustment value when the difference below the reference value is calculated, the adjustment is made so that the frequency of the signal input to the filter approaches the center frequency deviated from the ideal center frequency of the filter. A frequency adjustment method comprising: a frequency adjustment step.

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