JP2002026769A - Automatic frequency controller and automatic frequency control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably control oscillated frequency by decreasing the frequency errors of an original oscillation oscillating frequency generating VCTCXO (oscillator) between a transmitter and a receiver, even when frequency shift due to fading occurs. SOLUTION: A frequency error calculation section 102 uses an inverse spread value of a reception pilot symbol to calculate a frequency error, a hard discrimination section 103 discriminates the sign of the calculated result to obtain a frequency control variable per control, an AFC control variable update section 104 subtracts the frequency control variable from a preceding automatic frequency control variable to update the automatic frequency control variable. When a VCTCXO control section 105 controls an oscillated frequency of the VCTCXO by using a control voltage, in response to the automatic frequency control variable before or after the update, a mean speed calculation section 109 calculates the mean mobile speed of a mobile means for mounting the automatic frequency controller and an AFC control ON/OFF control means 110 will not conduct the updating, when the mean mobile speed is a prescribed speed or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a mobile station device such as a mobile phone in a mobile communication system or an information terminal device having a mobile phone function and a computer function. The present invention relates to an automatic frequency control device and an automatic frequency control method for controlling an oscillation frequency of a VCTCXO (oscillator) for generating an original oscillation frequency between a transceiver and a transceiver.

[0002]

2. Description of the Related Art Conventionally, as this type of automatic frequency control device and automatic frequency control method, there is one disclosed in Japanese Patent Application Laid-Open No. 9-8699.

Automatic frequency control AFC (Auto Frequency Control)
Control)｝ is known as a technique for guaranteeing a frequency error caused by a variation in a product or a temperature change between a transmission carrier frequency and a reception reference frequency in wireless communication.

FIG. 9 is a block diagram showing a configuration of a conventional AFC device.

The AFC apparatus shown in FIG. 9 comprises a pilot channel despreading section 901, a frequency error calculating section 902, a hard decision section 903, an AFC control value updating section 904, a VCT
A CXO control unit 905 and an AFC control ON / OFF control unit 906 are provided.

In such a configuration, the received pilot signal is despread by despreading section 901, and a frequency error is calculated by frequency error calculating section 902. Here, a schematic configuration diagram of the frequency error calculation unit 902 is shown in FIG.

[0007] As shown in FIG.
02 denotes delay elements 1001 and 1002 and a multiplier 100
3, 1004, a subtractor 1005, and an adder 1006.

A delay element 1001 delays the pilot symbol of the I-phase component by a plurality of symbols,
Is to delay the pilot symbol of the Q-phase component by a plurality of symbols.

A multiplier 1003 multiplies the delayed I-phase component pilot symbol by the delayed Q-phase component pilot symbol, and a multiplier 1004 generates a delayed Q-phase component pilot symbol by the delayed symbol. This is to multiply by the previous I-phase component pilot symbol.

The subtractor 1005 subtracts the result of the multiplier 1003 from the result of the multiplier 1004,
Takes an average of a predetermined number of the subtraction results.

That is, in order to detect a phase difference from a pilot symbol before a plurality of symbols, for example, when detecting a frequency error at intervals of 5 symbols, if an error amount per symbol is Δθ, the frequency error calculation result is as follows. R (t-Δt) × R
It is calculated as (t) × Sin (Δθ × 5). Where R (t-Δt) and
R (t) means the amplitude of the despread symbol.

Further, an addition for averaging and canceling out the influence of noise included in the calculated frequency error is performed.
Therefore, for example, if the frequency error is detected at intervals of 5 symbols and the number of times of averaging is set to 100, the control interval of the AFC device is 5 × 100 = 500 symbols.

The frequency error value calculated by the frequency error calculator 902 is sign-determined by the hard decision unit 903, and the frequency control update value per control corresponding to the sign is represented by A
Output to the FC control value update unit 904.

On the other hand, the AFC control ON / OFF control unit 90
In 6, when the magnitude of the frequency error value does not exceed a certain value, it is considered that the frequency error value is not the frequency error value to be controlled, and the AFC
A signal (OFF) for instructing the control value updating unit 904 to stop updating the control value at that time is output.

The AFC control value update unit 904 updates the frequency control per control output from the hard decision unit 903 only when the signal from the AFC control ON / OFF control unit 906 is ON. At this time, the VCTCXO control unit 9
In step 05, the updated frequency control is performed on the VCTCXO connected to the subsequent stage (not shown).

By adopting the above configuration, it is possible to reduce the frequency error between the transmitter and the receiver by reducing the control frequency per step.

[0017]

However, in the conventional device, the following problem arises because the magnitude of the fluctuation of the frequency component due to fading is not considered.

For example, in a wireless line such as mobile communication,
As the mobile station apparatus moves, a frequency shift due to fading occurs in addition to the oscillation frequency error of the original oscillation frequency generation VCTCXO of the receiving apparatus.

However, the prior art does not consider the magnitude of frequency component fluctuation due to fading. For this reason, when the oscillation frequency error amount of the VCTCXO between the transmitter and the receiver is smaller than the frequency shift amount due to fading, the probability that an accurate frequency error amount cannot be detected increases.

As a result, there is a problem that the probability of erroneous control increases, and the frequency shift due to fading follows even after the frequency is once pulled into a stable frequency, so that stable oscillation frequency control cannot be performed.

The present invention has been made in view of the above point, and even when a frequency shift due to fading occurs, a stable oscillation frequency can be obtained by reducing the frequency error of the original oscillation frequency generation VCTCXO between the transmitter and the receiver. An object is to provide an automatic frequency control device and an automatic frequency control method capable of performing control.

[0022]

An automatic frequency control apparatus according to the present invention is an automatic frequency control apparatus mounted on a mobile terminal. The automatic frequency control apparatus according to the present invention uses a frequency for periodically calculating a frequency error using a despread value of a received pilot symbol. An error calculating means, a hard decision means for outputting a frequency control value according to the positive / negative judgment of the calculation result, and an automatic frequency control value obtained by subtracting the frequency control value output from this means from the previous automatic frequency control value Updating means for updating the frequency, an oscillating frequency control means for controlling the oscillating frequency of the oscillating means according to the automatic frequency control value output from the means, and when the mobile terminal moves, the movement of the mobile terminal A speed calculating means for calculating a speed, and an updating control means for controlling the updating so as not to be performed when the moving speed calculated by the means is equal to or higher than a predetermined speed. The take.

According to this configuration, when the moving speed is equal to or higher than the predetermined speed, the frequency error value calculated at this time is considered to be mostly influenced by the frequency shift due to fading, and the frequency error value is controlled so as not to be reflected in the automatic frequency control. This can reduce the probability of erroneous control due to fading fluctuations after the frequency is once pulled into the transmission carrier frequency.

The automatic frequency controller according to the present invention, in the above configuration, further comprises a Doppler shift detecting means for detecting a Doppler shift amount of a multiplex wave using a despread value of a received pilot symbol instead of the speed calculating means. The control means performs control so that the update is not performed when the moving speed calculated by the speed calculation means is equal to or higher than a predetermined speed, but performs the update when the Doppler shift amount is equal to or more than the predetermined amount. A configuration is adopted in which control is performed so as not to be performed.

According to this configuration, the Doppler shift amount of the multiplex wave is detected from the despread value of the received pilot channel, and if the detected shift amount is equal to or larger than a certain threshold, the shift amount is included in the calculated frequency error value. The frequency shift due to fading is considered to be dominant, and control is performed so as not to update the automatic frequency control value, which reduces the probability of erroneous control due to fading fluctuation after being pulled into the transmission carrier frequency once be able to.

The automatic frequency control apparatus according to the present invention, in the above configuration, comprises a level detecting means for detecting a pilot signal level from a despread value of a received pilot symbol, a moving speed calculated by a speed calculating means, and the pilot signal level. Threshold calculation means for determining a threshold value of a frequency error used for performing automatic frequency control in accordance with the update control means, wherein the update control means performs the update when the moving speed calculated by the speed calculation means is equal to or higher than a predetermined speed. Instead of performing control so that the update is not performed, a configuration is employed in which the update is performed when the frequency error exceeds the threshold.

According to this configuration, the level of the pilot signal is detected from the signal after despreading the received pilot channel, and if the moving speed is low, the reliability is low if the pilot signal level is low. The control is performed so that the automatic frequency control value is not updated, and erroneous control can be prevented by changing the magnitude of the frequency error value required to reflect the automatic frequency control value update.

The automatic frequency controller according to the present invention, in the above configuration, comprises a level detecting means for detecting a pilot signal level from a despread value of a received pilot symbol, a Doppler shift amount detected by the Doppler shift detecting means and the pilot signal. Threshold value calculating means for determining a threshold value of a frequency error used for performing automatic frequency control according to the level, wherein the update control means does not perform the update when the Doppler shift amount is equal to or more than a predetermined amount. , The control is performed such that the update is performed when the frequency error exceeds the threshold.

According to this configuration, the pilot signal level and the Doppler shift amount of the multiplex wave are detected from the despread signal of the received pilot channel, and even if it is detected that the Doppler shift amount is small, the pilot signal level is reduced. If the signal level is low, it is considered that the reliability is low and the automatic frequency control value is not updated, and the magnitude of the frequency error value required to reflect the automatic frequency control value update varies. By doing so, erroneous control can be prevented.

In the automatic frequency control apparatus according to the present invention, the frequency error calculating means controls the frequency error averaging frequency in the frequency error calculating process according to the moving speed calculated by the speed calculating means. Control means, the threshold value calculating means, instead of determining the threshold value according to the moving speed and the pilot signal level, the threshold value based on the pilot signal level, the moving speed and the frequency error averaging count Is adopted.

According to this configuration, by changing the cycle for calculating the frequency error in accordance with the moving speed, when the moving speed is high and the reliability of the calculated frequency error is detected to be low, a constant value is obtained. By increasing the number of calculations per time, the number of controls per time is increased, and stable automatic frequency control can be performed even when moving at a high speed for a long time.

In the automatic frequency control apparatus according to the present invention, the average for controlling the frequency error averaging frequency in the frequency error calculating process of the frequency error calculating means according to the Doppler shift amount detected by the Doppler shift detecting means. A threshold value calculating means, instead of determining a threshold value according to the Doppler shift amount and a pilot signal level, the pilot signal level;
A configuration is adopted in which the threshold is determined based on the Doppler shift amount and the frequency error averaging count.

According to this configuration, the Doppler shift amount of the multiplex wave is detected from the despread signal of the received pilot channel, and it is detected that the Doppler shift amount is large and the reliability of the calculated frequency error value is low. In this case, by increasing the number of calculations per fixed time, the number of controls per time is increased, and stable automatic frequency control can be performed even when the vehicle is moving at a high speed for a long time.

In the automatic frequency control device according to the present invention, the timing of calculating the frequency error in the frequency error calculating means is determined in accordance with the pilot signal level detected by the level detecting means and the moving speed calculated by the speed calculating means. It comprises calculation timing control means for controlling, and the threshold value calculation means, instead of determining a threshold value according to the moving speed and the pilot signal level, according to the moving speed and the pilot signal level and the calculation timing A configuration for determining a threshold is employed.

According to this configuration, when it is estimated that the moving speed is low, the pilot signal level is high, and the signal-to-noise power ratio is high, the frequency error calculation timing is reduced and the erroneous control probability is not increased. The retraction speed can be increased.

In the automatic frequency controller according to the present invention, the frequency error is calculated by the frequency error calculator in accordance with the pilot signal level detected by the level detector and the Doppler shift amount detected by the Doppler shift detector. Calculating timing control means for controlling a timing, wherein the threshold value calculating means determines the threshold value according to the Doppler shift amount and the pilot signal level, and replaces the Doppler shift amount and the pilot signal level with the calculation timing. A configuration is adopted in which the threshold value is determined according to.

According to this configuration, when it is estimated that the detected value of the Doppler shift amount of the multiplex wave is small, the level of the detected pilot signal is high, and the signal-to-noise power ratio is large, the frequency error calculation timing Can be reduced, and the pull-in speed can be increased without increasing the erroneous control probability.

In the automatic frequency control apparatus according to the present invention, in the above configuration, when the mobile means is a mobile station apparatus in a mobile communication system, the speed calculating means transmits the position information of the mobile station apparatus transmitted from the base station apparatus. Is used to calculate the average moving speed based on

According to this configuration, since the moving speed can be more accurately obtained, more accurate automatic frequency control can be performed.

The mobile station apparatus of the present invention employs a configuration including an automatic frequency control device having the same configuration as any of the above.

According to this configuration, in the mobile station device,
The same operation and effect as any of the above can be obtained.

According to the automatic frequency control method of the present invention, a frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained in accordance with the positive / negative judgment of the calculation result, and this frequency control value is calculated in the previous The automatic frequency control value is subtracted from the automatic frequency control value to update the automatic frequency control value, and when controlling the oscillation frequency of the oscillating means in accordance with the automatic frequency control value before or after the update, the automatic frequency control function mounted moving means The moving speed is calculated, and whether or not the update is possible is determined according to the calculated moving speed.

According to this method, when the moving speed is equal to or higher than the predetermined speed, the frequency error value calculated at that time is considered to be mostly affected by the frequency shift due to fading, and the frequency error value is controlled so as not to be reflected in the automatic frequency control. This can reduce the probability of erroneous control due to fading fluctuations after the frequency is once pulled into the transmission carrier frequency.

According to the automatic frequency control method of the present invention, a frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to the positive / negative judgment of the calculation result, and this frequency control value is calculated in the previous Update the automatic frequency control value by subtracting from the automatic frequency control value of the above, when controlling the oscillation frequency of the oscillating means according to the automatic frequency control value before or after this update, the multiplexed wave using the despread value The amount of Doppler shift is detected, and whether or not the update is possible is determined according to the detected amount of Doppler shift.

According to this method, the amount of Doppler shift of the multiplex wave is detected from the despread value of the received pilot channel, and if the detected value of the amount of shift is equal to or greater than a certain threshold value, it is included in the calculated frequency error value. The frequency shift due to fading is considered to be dominant, and control is performed so as not to update the automatic frequency control value, which reduces the probability of erroneous control due to fading fluctuation after being pulled into the transmission carrier frequency once be able to.

According to the automatic frequency control method of the present invention, a frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is determined according to the positive / negative determination of the calculation result, and the frequency control value is calculated in the previous The automatic frequency control value is subtracted from the automatic frequency control value to update the automatic frequency control value, and when controlling the oscillation frequency of the oscillating means in accordance with the automatic frequency control value before or after the update, the automatic frequency control function mounted moving means Calculate a moving speed, detect a pilot signal level from the despread value, determine a threshold value according to the moving speed and the pilot signal level, and determine whether the update is possible according to a relationship between the frequency error and the threshold value. Was decided.

According to this method, the level of the pilot signal is detected from the despread signal of the received pilot channel, and if the moving speed is low, the reliability is low if the pilot signal level is low. The control is performed so that the automatic frequency control value is not updated, and erroneous control can be prevented by changing the magnitude of the frequency error value required to reflect the automatic frequency control value update.

According to the automatic frequency control method of the present invention, a frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is determined in accordance with the positive / negative judgment of the calculation result, and the frequency control value is calculated in the previous Update the automatic frequency control value by subtracting from the automatic frequency control value of the above, when controlling the oscillation frequency of the oscillating means according to the automatic frequency control value before or after this update, the multiplexed wave using the despread value The Doppler shift amount is detected, a pilot signal level is detected from the despread value, a threshold is determined according to the Doppler shift amount and the pilot signal level, and the threshold is determined according to a relationship between the frequency error and the threshold. Decide whether to update.

According to this method, the pilot signal level and the Doppler shift amount of the multiplex wave are detected from the despread signal of the received pilot channel, and even if the Doppler shift amount is detected to be small, the pilot signal level is detected. If the signal level is low, it is considered that the reliability is low and the automatic frequency control value is not updated, and the magnitude of the frequency error value required to reflect the automatic frequency control value update varies. By doing so, erroneous control can be prevented.

According to the automatic frequency control method of the present invention, a frequency error is calculated using a despread value of a received pilot symbol, and a frequency control value is obtained in accordance with a positive or negative judgment of the calculation result. The automatic frequency control value is subtracted from the automatic frequency control value to update the automatic frequency control value, and when controlling the oscillation frequency of the oscillating means in accordance with the automatic frequency control value before or after the update, the automatic frequency control function mounted moving means Calculate the moving speed, detect the pilot signal level from the despread value, control the frequency error averaging frequency in the process of calculating the frequency error according to the moving speed, the pilot signal level, the moving speed and the A threshold is determined based on the frequency error averaging count, and whether or not the update is possible is determined according to a relationship between the frequency error and the threshold.

According to this method, by changing the cycle for calculating the frequency error according to the moving speed, when the moving speed is high and the reliability of the calculated frequency error is detected to be low, the constant is obtained. By increasing the number of calculations per time, the number of controls per time is increased, and stable automatic frequency control can be performed even when moving at a high speed for a long time.

According to the automatic frequency control method of the present invention, a frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained in accordance with the positive / negative judgment of the calculation result, and this frequency control value is calculated in the previous time. Update the automatic frequency control value by subtracting from the automatic frequency control value of the above, when controlling the oscillation frequency of the oscillating means according to the automatic frequency control value before or after this update, the multiplexed wave using the despread value , The pilot signal level is detected from the despread value, the number of frequency error averaging in the frequency error calculation process is controlled in accordance with the Doppler shift amount, the pilot signal level, the Doppler shift Determining the threshold based on the amount and the frequency error averaging count, and determining whether or not the update is possible according to the relationship between the frequency error and the threshold. It was so.

According to this method, the Doppler shift amount of the multiplex wave is detected from the despread signal of the received pilot channel, and it is detected that the Doppler shift amount is large and the reliability of the calculated frequency error value is low. In this case, by increasing the number of calculations per fixed time, the number of controls per time is increased, and stable automatic frequency control can be performed even when the vehicle is moving at a high speed for a long time.

According to the automatic frequency control method of the present invention, a frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained in accordance with the positive / negative judgment of the calculation result, and this frequency control value is calculated by The automatic frequency control value is subtracted from the automatic frequency control value to update the automatic frequency control value, and when controlling the oscillation frequency of the oscillating means in accordance with the automatic frequency control value before or after the update, the automatic frequency control function mounted moving means Calculate the moving speed, detect the pilot signal level from the despread value, control the calculation timing of the frequency error according to the pilot signal level and the moving speed,
A threshold value is determined according to the moving speed, the pilot signal, and the calculation timing, and whether or not the update is possible is determined according to a relationship between the frequency error and the threshold value.

According to this method, when it is estimated that the moving speed is slow, the pilot signal level is high, and the signal-to-noise power ratio is large, the frequency error calculation timing is reduced and the error control probability is not increased. The retraction speed can be increased.

According to the automatic frequency control method of the present invention, a frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to the positive / negative judgment of the calculation result, and this frequency control value is calculated in the previous Update the automatic frequency control value by subtracting from the automatic frequency control value of the above, when controlling the oscillation frequency of the oscillating means according to the automatic frequency control value before or after this update, the multiplexed wave using the despread value The Doppler shift amount is detected, the pilot signal level is detected from the despread value, the timing of calculating the frequency error is controlled according to the pilot signal level and the Doppler shift amount, and the Doppler shift amount and the pilot signal are A threshold value is determined according to the calculation timing, and whether or not the update is permitted is determined according to a relationship between the frequency error and the threshold value. It was.

According to this method, when it is estimated that the detected value of the Doppler shift amount of the multiplex wave is small, the level of the detected pilot signal is high, and the signal-to-noise power ratio is large, the frequency error calculation timing Can be reduced, and the pull-in speed can be increased without increasing the erroneous control probability.

[0058]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of an AFC apparatus according to Embodiment 1 of the present invention.

The AFC device according to the first embodiment shown in FIG. 1 is applied to a mobile station device such as a mobile phone in a mobile communication system. The feature is that the moving speed is detected from the position information transmitted from the base station device, and if it is detected that the mobile station device is moving at high speed, it is detected that the calculated frequency error value has low reliability. However, control is performed so as not to be reflected in the update of the AFC control value.

As shown in FIG. 1, the AFC apparatus includes a pilot channel despreading unit 101, a frequency error calculating unit 102, a hard decision unit 103, and an AFC control value updating unit 10.
4, a VCTCXO control unit 105, a data channel despreading unit 106, a synchronous detection unit 107, a position information extraction unit 108, an average speed calculation unit 109, an AFC control ON / OFF
An OFF control unit 110 is provided.

[0062] Pilot channel despreading section 101 despreads a pilot signal using a pilot channel spreading code. The frequency error calculation unit 102
The frequency error is calculated using the despread pilot signal. The configuration of the frequency error calculator 102 is the same as the configuration shown in FIG. 10 described in the conventional example.

The hard decision section 103 decides whether the calculated frequency error value is positive or negative and outputs a frequency control value per control. The AFC control value updating unit 104 subtracts the frequency control value output from the hard decision unit 103 from the previous AFC control value and outputs a new AFC control value.

The VCTCXO control unit 105 controls the oscillation frequency of the original oscillation frequency generation VCTCXO (not shown) by changing the control voltage according to the AFC control value.

The data channel despreading unit 106 despreads the data signal using the data channel spreading code. The synchronous detection unit 107 generates demodulated data by correcting phase rotation using pilot symbols and data symbols.

The position information extracting section 108 extracts position information from the demodulated data. Average speed calculation unit 1
09 is for calculating the speed from the position information.
The AFC control ON / OFF control unit 110 determines whether or not to update the AFC control value.

The operation of such a configuration will be described. Pilot symbols of the received signal are despread in pilot channel despreading section 101 and frequency error calculation section 102
Is output to

The frequency error calculator 102 calculates a frequency offset at a fixed symbol interval for the despread pilot symbols. In order to average the calculated frequency error results, the results are added a plurality of times.

In the hard decision section 103, the frequency error calculation section 1
02 is determined, and the frequency control value per control is output to the AFC control value updating unit 104.

On the other hand, the data symbols are despread by data channel despreading section 106 and then by synchronous detection section 107.
After the correction of the phase rotation in, the position information is extracted by the position information extraction unit 108, and the position information is extracted from the decoded data.

Based on this position information, the average speed calculation unit 1
At 09, the average speed in the AFC control interval is obtained,
It is output to the AFC control ON / OFF control unit 110.

When the AFC control ON / OFF control section 110 detects a speed higher than a certain average speed, the frequency fluctuation due to fading fluctuation has a large effect, and it is difficult to detect a frequency error value between the transmitter and the receiver. .

In this case, the frequency error value calculated by the frequency error calculation section 102 is regarded as having low reliability, and the frequency error value is not reflected in the AFC control. That is, the control unit 110 performs the OFF control so that the control value is not updated by the AFC control value updating unit 104.

As described above, according to the AFC device of the first embodiment, the moving speed is detected based on the position information transmitted from the base station device, and if the speed is high, the reliability of the calculated frequency error value is determined. Because the degree is low, it is not reflected in AFC control. When the speed is slow and the frequency fluctuation due to fading is small, the frequency error calculation result of the AFC control is reflected.

As a result, it is possible to reduce the probability of erroneous control due to fading fluctuations after the frequency is once pulled into the transmission carrier frequency. Therefore, even if a frequency shift due to fading occurs, the original oscillation frequency between the transmitter and the receiver can be reduced. By reducing the frequency error of the VCTCXO, stable oscillation frequency control can be performed.

(Embodiment 2) FIG. 2 is a block diagram showing a configuration of an AFC device according to Embodiment 2 of the present invention. However, in the second embodiment shown in FIG. 2, portions corresponding to the respective portions of the first embodiment in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The feature of the AFC device according to the second embodiment shown in FIG. 2 is that the amount of Doppler shift of the despread pilot symbol is detected, and when it is detected that the amount of frequency shift due to fading is large, the calculated frequency is used. It is to detect that the reliability of the error value is low, and to control the error value so that the error value is not reflected in the update.

As shown in FIG. 2, the AFC apparatus includes a pilot channel despreading unit 101, a frequency error calculating unit 102, a hard decision unit 103, and an AFC control value updating unit 10.
4, a VCTCXO control unit 105, a multiplex wave Doppler shift detection unit 201, and an AFC control ON / OFF control unit 202.

The AFC device shown in FIG. 2 does not use the decoding result of the data symbol like the AFC device shown in FIG. 1 and uses the amount of Doppler shift detected by the multiplex Doppler shift detection unit 201 to control the AFC ON / OFF control unit 202. The control is performed.

The operation of such a configuration will be described. The received signal fluctuates in amplitude and phase due to a frequency error of the receiver and a frequency shift due to fading.

The multi-wave Doppler shift detector 201
By detecting the spectrum of the pilot symbol from pilot channel despreading section 101, the Doppler shift amount corresponding to each multiplex wave is obtained.

As a spectrum detecting means, a band-pass filter (BP) that passes only a specific frequency band is used.
F) are arranged, and the frequency band of each multiplex wave is obtained by observing the output signal levels of these. Or,
A method of performing a Fourier transform on the despread pilot symbols to obtain a spectrum is conceivable.

The Doppler shift amount of the multiplex wave thus obtained is output to the AFC control ON / OFF control unit 202. In the AFC control ON / OFF control unit 202,
A control signal of AFC control value updating section 104 is transmitted based on the Doppler shift amount of each multiplex wave.

When the Doppler shift amount of the multiplex wave is large, the frequency error due to fading, which is included in the frequency error value calculated by the frequency error calculation unit 102, occupies a large part. Is not updated.

On the other hand, when the Doppler shift amount is small, it is considered that the influence of fading is small, so that the AFC control value updating unit 104 updates the control value.

As described above, according to the AFC apparatus of the second embodiment, the multiplexed wave Doppler shift amount of the despread pilot symbol is detected, and when the detected Doppler shift amount is large, the calculated frequency error value is Since the amount of frequency shift due to the included fading is considered to be dominant, the AFC control value is not updated. Conversely, when the detected Doppler shift amount is small, the AFC control value is updated.

As a result, it is possible to reduce the probability of erroneous control due to fading fluctuations after the frequency is once pulled into the transmission carrier frequency. Therefore, even if a frequency shift due to fading occurs, it is possible to generate an original oscillation frequency between the transmitter and the receiver. By reducing the frequency error of the VCTCXO, stable oscillation frequency control can be performed.

(Embodiment 3) FIG. 3 is a block diagram showing a configuration of an AFC device according to Embodiment 3 of the present invention. However, in the third embodiment shown in FIG. 3, portions corresponding to the respective portions of the first embodiment in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The feature of the AFC device according to the third embodiment shown in FIG. 3 is that AFC is performed based on a pilot signal level detected from a despread pilot symbol and a moving speed detected from position information transmitted from a base station. By varying the magnitude of the frequency error value required to be reflected in the control value update, the frequency error value obtained in a highly reliable time zone has a higher probability of being reflected in the AFC control value update. That is to control.

The AFC apparatus shown in FIG. 3 varies the magnitude of the frequency error value required for updating the AFC control value in accordance with the pilot signal level in addition to the average moving speed calculated in the AFC apparatus shown in FIG. Is taken.

Pilot signal level detecting section 301 detects the average strength of despread pilot symbols,
It outputs to FC control threshold value calculation section 302. The average intensity is an average for the symbol interval used when the frequency error calculator 102 calculates the frequency error value.

The AFC control threshold value calculating section 302 calculates the AFC control value updating section 10 based on the detected pilot signal level and the average speed calculated by the average speed calculating section 109.
Then, a threshold value of the frequency error value reflected in the AFC control in step 4 is calculated.

When the pilot signal level is high, the reliability of the frequency error value calculated from the high signal-to-noise power ratio (S / N ratio) is high. In addition, the lower the speed, the smaller the amount of frequency shift due to fading. Therefore, the frequency error value required to be reflected on the AFC control value updating unit 104 is reduced, that is, the threshold value is reduced.

Conversely, when the pilot signal level is small and the speed is high, the threshold value is set higher because the reliability is low. The set threshold is output to the AFC control ON / OFF control unit 303.

The AFC control ON / OFF control unit 303 calculates the threshold value calculated by the AFC control threshold value calculation unit 302,
The frequency error values calculated by the frequency error calculation unit 102 are compared, and if the absolute value of the frequency error value exceeds the threshold, the update of the AFC control value update unit 104 is permitted.

As described above, according to the AFC apparatus of the third embodiment, AFC is performed based on the pilot signal level detected from the despread pilot symbols and the moving speed detected from the position information transmitted from the base station. The threshold value of the frequency error value required for updating the control value is changed.

As a result, even if the speed is low, the erroneous control probability can be reduced when the pilot signal level is low and the reliability of the frequency error value is low, so that the VCTCXO for generating the original oscillation frequency between the transmitter and the receiver can be reduced. Thus, stable oscillation frequency control can be performed by reducing the frequency error of.

(Embodiment 4) FIG. 4 is a block diagram showing a configuration of an AFC device according to Embodiment 4 of the present invention. However, in the fourth embodiment shown in FIG. 4, portions corresponding to the respective portions of the second embodiment in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

The feature of the AFC apparatus according to the fourth embodiment shown in FIG. 4 is that the pilot signal level and the Doppler shift amount are detected from the despread pilot symbols, and the pilot signal level is small even when the frequency shift amount due to fading is small. Is detected, the reliability of the calculated frequency error value is estimated to be low, and the control is performed so that the calculated frequency error value is not reflected in the update of the AFC control value.

The AFC apparatus shown in FIG. 4 performs an AF operation in accordance with the pilot signal level in addition to the detected Doppler shift amount.
A configuration is employed in which the magnitude of the frequency error value required for updating the C control value is changed.

The operation of such a configuration will be described. AFC
The control threshold value calculation unit 401 performs the AFC control in the AFC control value update unit 104 according to the pilot signal level detected by the pilot signal level detection unit 301 and the Doppler shift amount detected by the multiplexed wave Doppler shift detection unit 201.
A threshold value of the frequency error value reflected in the control is calculated.

Even when the Doppler shift amount is small, when the pilot signal level is small, it is estimated that the signal-to-noise power ratio is small. Therefore, the reliability of the frequency error value calculated at that time is low. And the threshold is set higher. The set threshold value is AFC control ON / O
Output to the FF control unit 403.

The AFC control ON / OFF control unit 403 calculates the threshold calculated by the AFC control threshold calculation unit 401,
The frequency error values calculated by the frequency error calculation unit 102 are compared, and if the absolute value of the frequency error value exceeds the threshold, the update of the AFC control value update unit 104 is permitted.

As described above, according to the AFC apparatus of the fourth embodiment, the AFC control value is obtained by detecting the pilot signal level detected by the despread pilot symbol and the amount of multiplex Doppler shift of the despread pilot symbol. The threshold value of the frequency error value required for updating is changed.

As a result, even if the Doppler shift amount is small, the probability of erroneous control when the pilot signal level is low and the reliability of the frequency error value is low can be reduced. VCTC for
By reducing the XO frequency error, stable control of the oscillation frequency can be performed.

(Embodiment 5) FIG. 5 is a block diagram showing a configuration of an AFC device according to Embodiment 5 of the present invention. However, in the fifth embodiment shown in FIG. 5, portions corresponding to those in the third embodiment shown in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

The feature of the AFC device according to the fifth embodiment shown in FIG. 5 is that the number of additions for averaging the frequency error value in the frequency error calculation is based on the moving speed detected by the position information transmitted from the base station. Is controlled to increase the number of frequency error calculations in a time zone with low reliability due to fading fluctuations, and to increase the number of times of reflection in updating the AFC control value.

The AFC device in FIG. 5 is different from the AFC device in FIG. 3 in that an averaging number control unit 501 is provided.
AFC control threshold value calculation unit 5 instead of control threshold value calculation unit 302
02.

The averaging number control section 501 controls the number of additions for averaging the frequency error value in the frequency error calculation section 102 based on the average moving speed calculated by the average speed calculation section 109, and This is reflected on the calculation unit 502.

The frequency error value calculated by the frequency error calculation section 102 includes a large amount of frequency shift due to fading. Particularly, when the moving speed is high, the phase rotation is fast, so that the phase error is necessary for averaging. Even if the number of additions is reduced, the error control probability does not change.

From this, when it is determined that the moving speed is fast, the number of times of averaging is reduced, and the output cycle of the frequency error calculator is controlled to be short.

On the other hand, the AFC control threshold value calculation section 502
Based on the controlled number of times of averaging, the pilot signal level detected by pilot signal level detecting section 301, and the average moving speed, a threshold value of a frequency error value reflected in AFC control in AFC control value updating section 104 Is calculated.

The AFC control ON / OFF control unit 303 compares the threshold value calculated by the AFC control threshold value calculation unit 502 with the frequency error value calculated by the frequency error calculation unit 102, and determines the absolute value of the frequency error value. If the threshold value is exceeded, the update of the AFC control value update unit 104 is permitted.

As described above, according to the AFC apparatus of the fifth embodiment, when the moving speed calculated from the position information transmitted from the base station is high, the frequency error calculating section 102 averages the frequency errors. The number of times that the automatic frequency control is performed within a certain time is increased by outputting to the AFC control ON / OFF control unit 303 in a cycle shorter than the control cycle when the moving speed is low, Even when moving at a high speed for a long time, stable automatic frequency control becomes possible.

(Embodiment 6) FIG. 6 is a block diagram showing a configuration of an AFC device according to Embodiment 6 of the present invention. However, in the sixth embodiment shown in FIG. 6, portions corresponding to the respective portions of the fourth embodiment in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

A feature of the AFC apparatus according to the sixth embodiment shown in FIG. 6 is that the amount of Doppler shift of a despread pilot symbol is detected, and when the amount of frequency shift due to fading is detected to be large, the frequency error calculation is performed. By controlling the number of additions for averaging the frequency error value in the above, the frequency error calculation number is increased in a time zone in which the influence of the fading fluctuation on the frequency error calculation value is large, and the number of times of reflection in the AFC control value update unit is increased. Is controlled so as to be increased.

The difference between the AFC device in FIG. 6 and the AFC device in FIG. 4 is that an averaging number control unit 601 is provided.
AFC control threshold calculation section 6 instead of control threshold calculation section 401
02.

The averaging number control section 601 controls the number of additions for averaging the frequency error value in the frequency error calculation section 102 based on the amount of Doppler shift detected by the multiplex wave Doppler shift detection section 201, and 1
02 is reflected.

When the detected amount of Doppler shift is large, the amount of frequency shift due to fading included in the calculated frequency error value is dominant. However, since the phase rotation is fast, the number of additions required in calculating the frequency error is reduced. In this case, the output cycle of the frequency error calculator 102 is controlled to be shorter. Thus, since the reliability of the frequency error value is low, the number of times of control is increased by the number of times of calculation and stable control is performed.

The AFC control threshold value calculating section 602 controls the number of controlled averaging and the pilot signal level detecting section 301
The threshold value of the frequency error value that is reflected in the AFC control in the AFC control value updating unit 104 is calculated based on the pilot signal level detected in step (1) and the Doppler shift amount.

As described above, according to the AFC apparatus of the sixth embodiment, when the multiplexed wave Doppler shift amount of the despread pilot symbol is large, frequency error calculating section 10
2, the number of additions used for averaging the frequency error is reduced,
By outputting to the AFC control ON / OFF control unit 403 in a cycle shorter than the control cycle when the Doppler shift amount is small, the number of times the control is performed within a certain time is increased, and the vehicle moves at a high speed for a long time. In this case, stable automatic frequency control is possible.

(Embodiment 7) FIG. 7 is a block diagram showing a configuration of an AFC device according to Embodiment 7 of the present invention. However, in the seventh embodiment shown in FIG. 7, parts corresponding to the respective parts of the third embodiment in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

The feature of the AFC apparatus according to the seventh embodiment shown in FIG. 7 is that the frequency is determined by the pilot signal level detected from the despread pilot symbols and the moving speed estimated from the position information transmitted from the base station. By controlling the frequency error value calculation timing in the error calculation,
This is to control so as to increase the number of times of reflection in the AFC control value update without increasing the erroneous control probability.

In the AFC apparatus shown in FIG. 7, a frequency error timing control section 702 calculates a frequency error based on the signal level detected by the pilot signal level detection section 301 and the speed calculated by the average speed calculation section 701. Part 70
The timing for calculating the frequency error value calculated in step 4 is controlled.

When the signal level is large, the signal-to-noise power ratio is considered to be high, so that the moving speed is calculated to be slow. If the reliability of the frequency error value is estimated to be high, the calculation timing interval is shortened.

The frequency error calculator 704 calculates a frequency error value according to the calculation timing specified by the frequency error timing controller 702. The AFC control threshold value calculation unit 703 uses the calculation timing, the pilot signal level detected by the detection unit 302, and the average moving speed to calculate the frequency error reflected in the AFC control by the AFC control value update unit 104. Calculate the threshold value.

As described above, according to the AFC apparatus of the seventh embodiment, the level detection value of the despread pilot symbol is large, the signal-to-noise power ratio is estimated to be large, and it is determined that the moving speed is slow. In this case, the AFC control ON / OFF control unit 303 can be shortened in a short cycle by reducing the frequency error calculation timing of the frequency error calculation unit 102.
, The number of times control is performed within a certain time can be increased, and the pull-in time can be reduced without increasing the probability of erroneous control.

(Eighth Embodiment) FIG. 8 is a block diagram showing a configuration of an AFC device according to an eighth embodiment of the present invention. However, in the eighth embodiment shown in FIG. 8, portions corresponding to the respective portions of the fourth embodiment in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

The feature of the AFC apparatus according to the eighth embodiment shown in FIG. 8 is that the frequency is controlled in accordance with the pilot signal level detected from the despread pilot symbol and the Doppler shift amount detected from the despread pilot symbol. By controlling the frequency error value calculation timing in error calculation, control is performed so as to increase the number of times of reflection in the AFC control value update without increasing the erroneous control probability.

In the AFC apparatus shown in FIG. 8, frequency error timing control section 802 determines the frequency level based on the signal level detected by pilot signal level detection section 301 and the frequency shift amount calculated by multiplex Doppler shift detection section 801. And the timing of calculating the frequency error value calculated by the frequency error calculation unit 102.

When the signal level is detected to be high,
It is considered that the signal-to-noise power ratio is high. From this,
If the amount of frequency shift is small and the reliability of the calculated frequency error value is estimated to be high, A
Control is performed to increase the number of times of reflection on the FC control value updating unit 104.

The AFC control threshold value calculation unit 803 determines the controlled calculation timing and the pilot signal level detection unit 3
Based on the pilot signal level detected in 02 and the amount of frequency shift, a threshold value of a frequency error value reflected in AFC control in AFC control value updating section 104 is calculated.

As described above, according to the AFC apparatus of the eighth embodiment, the level detection value of the despread pilot symbol is large, it is estimated that the signal-to-noise power ratio is large, and it is determined that the amount of frequency shift is small. In such a case, the frequency of the frequency error calculation by the frequency error calculation unit is reduced to output to the AFC control ON / OFF control unit in a short cycle, thereby increasing the number of times that the control is performed within a certain period of time. The pull-in time can be reduced without increasing the control probability.

[0134]

As described above, according to the present invention,
Even if a frequency shift occurs due to fading,
By reducing the frequency error of the original oscillation frequency generation VCTCXO between the transmitter and the receiver, stable oscillation frequency control can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an AFC device according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of an AFC device according to Embodiment 2 of the present invention.

FIG. 3 is a block diagram showing a configuration of an AFC device according to Embodiment 3 of the present invention.

FIG. 4 is a block diagram showing a configuration of an AFC device according to Embodiment 4 of the present invention.

FIG. 5 is a block diagram showing a configuration of an AFC device according to Embodiment 5 of the present invention.

FIG. 6 is a block diagram showing a configuration of an AFC device according to Embodiment 6 of the present invention.

FIG. 7 is a block diagram showing a configuration of an AFC device according to Embodiment 7 of the present invention.

FIG. 8 is a block diagram showing a configuration of an AFC device according to Embodiment 8 of the present invention.

FIG. 9 is a block diagram showing a configuration of a conventional AFC device.

FIG. 10 is a block diagram showing a configuration of a frequency error calculator in the AFC device.

[Explanation of symbols]

101,901 Pilot channel despreading unit 102,902 Frequency error calculating unit 103,903 Hard decision unit 104,904 AFC control value updating unit 105,905 VCTCXO control unit 106 Data channel despreading unit 107 Synchronous detection unit 108 Position information extraction unit 109, 701 Average speed calculation unit 110, 202, 303, 906 AFC control ON / O
FF control section 201 Multiplex Doppler shift detection section 301 Pilot signal level detection section 302, 401, 502, 602, 703, 803 A
FC control threshold value calculation unit 501, 601 Averaging number control unit 702, 802 Frequency error timing control unit

Claims (18)

[Claims] 1. An automatic frequency control device mounted on a mobile terminal, wherein a frequency error calculating means for periodically calculating a frequency error using a despread value of a received pilot symbol, and for determining whether the calculation result is positive or negative. A hard decision means for outputting a frequency control value in response thereto, an updating means for subtracting the frequency control value output from this means from the previous automatic frequency control value to update the automatic frequency control value, and an output from this means Oscillation frequency control means for controlling the oscillation frequency of the oscillation means according to the automatic frequency control value; speed calculation means for calculating the moving speed of the mobile terminal when the mobile terminal moves; Update control means for controlling the updating so as not to be performed when the moved speed is equal to or higher than a predetermined speed. 2. The apparatus according to claim 1, further comprising: a Doppler shift detecting means for detecting a Doppler shift amount of the multiplexed wave using a despread value of the received pilot symbol instead of the speed calculating means. The control is performed such that the update is not performed when the moving speed is equal to or higher than a predetermined speed, and the update is not performed when the Doppler shift amount is equal to or more than a predetermined amount. The automatic frequency control device according to claim 1. 3. A level detecting means for detecting a pilot signal level from a despread value of a received pilot symbol, and a frequency used for performing automatic frequency control according to the moving speed calculated by the speed calculating means and the pilot signal level. Threshold update means for determining a threshold value of the error, the update control means, instead of controlling so that the update is not performed when the moving speed calculated by the speed calculation means is a predetermined speed or more, 2. The automatic frequency control device according to claim 1, wherein the control is performed so that the update is performed when the frequency error exceeds the threshold. 4. A level detecting means for detecting a pilot signal level from a despread value of a received pilot symbol, and used for performing automatic frequency control according to the Doppler shift amount detected by the Doppler shift detecting means and the pilot signal level. Threshold calculation means for determining a threshold value of the frequency error to be obtained, the update control means instead of controlling so that the update is not performed when the Doppler shift amount is a predetermined amount or more, the frequency error is 3. The automatic frequency control device according to claim 2, wherein the control is performed such that the update is performed when the threshold value is exceeded. 5. An averaging frequency control means for controlling a frequency error averaging frequency in a frequency error calculation process of the frequency error calculation means in accordance with the moving speed calculated by the speed calculation means, wherein the threshold value calculation means comprises: 4. The method according to claim 3, wherein the threshold is determined based on the pilot signal level, the moving speed, and the frequency error averaging count, instead of determining the threshold according to the moving speed and the pilot signal level. Automatic frequency control device as described. 6. An average number control means for controlling the frequency error averaging number in the frequency error calculation process of the frequency error calculation means in accordance with the Doppler shift amount detected by the Doppler shift detection means, wherein the threshold calculation means is provided. Instead of determining a threshold value according to the Doppler shift amount and the pilot signal level, the threshold value is determined based on the pilot signal level, the Doppler shift amount and the frequency error averaging count. The automatic frequency control device according to claim 4, wherein 7. A calculation timing control means for controlling a calculation timing of a frequency error in the frequency error calculation means according to a pilot signal level detected by the level detection means and a moving speed calculated by the speed calculation means, The calculation means, instead of determining a threshold value according to the moving speed and the pilot signal level, determines a threshold value according to the moving speed and the pilot signal level and the calculation timing. 3. The automatic frequency controller according to 3. 8. A calculation timing control means for controlling the calculation timing of the frequency error in the frequency error calculation means according to the pilot signal level detected by the level detection means and the Doppler shift amount detected by the Doppler shift detection means. Wherein the threshold calculating means determines a threshold in accordance with the Doppler shift amount and the pilot signal level and the calculation timing, instead of determining the threshold value in accordance with the Doppler shift amount and the pilot signal level. The automatic frequency control device according to claim 4, wherein 9. When the moving means is a mobile station device in a mobile communication system, the speed calculating means calculates an average moving speed based on the position information of the mobile station device transmitted from the base station device. Claims 1, 3, 5,
7. The automatic frequency control device according to any one of 7. 10. A mobile station device comprising the automatic frequency control device according to claim 2. 11. A frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to a positive / negative determination of the calculation result, and the frequency control value is subtracted from a previous automatic frequency control value. When updating the automatic frequency control value and controlling the oscillation frequency of the oscillating means in accordance with the automatic frequency control value before or after the update, the moving speed of the moving means equipped with the automatic frequency control function is calculated. An automatic frequency control method, wherein whether or not the update is possible is determined according to a calculated moving speed. 12. A frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is determined according to a positive or negative determination of the calculation result, and the frequency control value is subtracted from a previous automatic frequency control value. When updating the automatic frequency control value, when controlling the oscillation frequency of the oscillation means according to the automatic frequency control value before or after this update, the Doppler shift amount of the multiplex wave is detected using the despread value. And determining whether or not the update is possible in accordance with the detected Doppler shift amount. 13. A frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to a positive or negative determination of the calculation result, and the frequency control value is subtracted from a previous automatic frequency control value. When updating the automatic frequency control value, when controlling the oscillation frequency of the oscillation means according to the automatic frequency control value before or after this update, calculate the moving speed of the automatic frequency control function equipped moving means, Detecting a pilot signal level from a despread value, determining a threshold value in accordance with the moving speed and the pilot signal level, and determining whether or not the update is possible according to a relationship between the frequency error and the threshold value. Automatic frequency control method. 14. A frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to a positive or negative determination of the calculation result, and the frequency control value is subtracted from a previous automatic frequency control value. When updating the automatic frequency control value, when controlling the oscillation frequency of the oscillation means according to the automatic frequency control value before or after this update, the Doppler shift amount of the multiplex wave is detected using the despread value. Detecting a pilot signal level from the despread value, determining a threshold according to the Doppler shift amount and the pilot signal level, and determining whether or not to update according to a relationship between the frequency error and the threshold. An automatic frequency control method characterized by the following. 15. A frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to a positive / negative determination of the calculation result, and the frequency control value is subtracted from a previous automatic frequency control value. When updating the automatic frequency control value, when controlling the oscillation frequency of the oscillation means according to the automatic frequency control value before or after this update, calculate the moving speed of the automatic frequency control function equipped moving means, Detecting the pilot signal level from the despread value, controlling the frequency error averaging count in the process of calculating the frequency error according to the moving speed, and also controlling the pilot signal level, the moving speed and the frequency error averaging count. Automatically determining whether or not the update can be performed according to a relationship between the frequency error and the threshold. 16. A frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to a positive / negative determination of the calculation result, and the frequency control value is subtracted from a previous automatic frequency control value. When updating the automatic frequency control value, when controlling the oscillation frequency of the oscillation means according to the automatic frequency control value before or after this update, the Doppler shift amount of the multiplex wave is detected using the despread value. Detecting the pilot signal level from the despread value, controlling the frequency error averaging frequency in the process of calculating the frequency error according to the Doppler shift amount, and controlling the pilot signal level, the Doppler shift amount and the frequency error averaging. Determining the threshold value based on the number of times, and determining whether or not the update is possible according to a relationship between the frequency error and the threshold value. Control method. 17. A frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to a positive or negative determination of the calculation result, and the frequency control value is subtracted from a previous automatic frequency control value. When updating the automatic frequency control value, when controlling the oscillation frequency of the oscillation means according to the automatic frequency control value before or after this update, calculate the moving speed of the automatic frequency control function equipped moving means, Detecting a pilot signal level from a despread value, controlling a calculation timing of the frequency error according to the pilot signal level and the moving speed, and determining a threshold value according to the moving speed and the pilot signal and the calculation timing. And
An automatic frequency control method, wherein whether or not the update is possible is determined according to a relationship between the frequency error and the threshold. 18. A frequency error is calculated using a despread value of a received pilot symbol, a frequency control value is obtained according to a positive or negative determination of the calculation result, and the frequency control value is subtracted from a previous automatic frequency control value. When updating the automatic frequency control value, when controlling the oscillation frequency of the oscillation means according to the automatic frequency control value before or after this update, the Doppler shift amount of the multiplex wave is detected using the despread value. Detecting the pilot signal level from the despread value, controlling the timing of calculating the frequency error according to the pilot signal level and the Doppler shift amount, and controlling the Doppler shift amount and the pilot signal and the calculation timing. Determining a threshold, and determining whether or not the update is possible according to a relationship between the frequency error and the threshold. .