JP2001069039A - Spread spectrum signal receiver and spread spectrum signal reception method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spread spectrum signal receiver where a reception level is made stable, a noise included in the received signal can be reduced, and a processing amount of tracking processing can be reduced. SOLUTION: The spread spectrum signal receiver is provided with an inverse spread section 1 that applies inverse spread processing to a spread spectrum signal to output a received signal, a reception signal level detection section 2 that detects a level of the received signal to output a received level signal, an inverse spread signal generating section 5 that generates the inverse spread signal, a phase control section 3 that generates a phase control signal to control a phase of the inverse spread signal outputted from the inverse spread signal generating section 5 on the basis of the received level signal, a reference clock generating section 6 that generates a reference clock signal received by the inverse spread signal generating section 5, and a reference frequency control section 4 that controls the frequency of the reference clock signal generated by the reference clock generating section 6 on the basis of the phase control signal outputted from the phase control section 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a spread spectrum signal receiving apparatus and a spread spectrum signal receiving method for performing spread spectrum communication.

[0002]

2. Description of the Related Art Conventionally, spread spectrum signal receiving apparatuses have been used for cordless telephones, portable telephones, wireless LAN systems, and the like.

Hereinafter, a conventional spread spectrum signal receiving apparatus will be described.

FIG. 15 is a block diagram showing a conventional spread spectrum signal receiving apparatus.

In FIG. 15, reference numeral 71 denotes a despreading unit which receives a spread spectrum signal S (t) and outputs a received signal R (t), and 72 detects the level of the despread received signal R (t). A reception signal level detecting section 73 for outputting a reception level signal indicating the level thereof;
A phase control unit 74 for outputting a phase control signal for controlling the phase of the despread signal based on the reception level signal output from the phase control unit 73 generates a despread signal based on the phase control signal from the phase control unit 73. A spread signal generator 75 is a reference clock generator that supplies a reference clock signal to the despread signal generator 74. The reference clock generator 75 is formed of a crystal oscillation circuit, and has a fixed oscillation frequency.

The operation of the conventional spread spectrum signal receiving apparatus configured as described above will be described with reference to FIG. FIG. 8 is a graph showing an autocorrelation characteristic of a spread code sequence used for spread spectrum communication, in which the horizontal axis indicates a phase difference and the vertical axis indicates an autocorrelation value. In FIG. 8, 4
Reference numeral 6 denotes an autocorrelation characteristic in the case where the sequence of the spread signal and the despread signal is the same pseudo random signal (hereinafter, referred to as “PN signal”).

First, in spread spectrum communication,
The same signal as the spread signal on the transmission side is generated as a despread signal on the reception side by the despread signal generation unit 74, and further between the spread signal on the transmission side included in the received signal and the despread signal generated on the reception side. By multiplying in a state where there is no phase difference, a received signal R (t) is obtained. Immediately after the start of the reception, an acquisition process for pulling in the phase is performed, and thereafter, during the reception, a tracking process for always following the phase of the spread signal included in the received signal so that the phase is not shifted is performed on the receiving side. In the tracking processing, a signal used to detect a phase difference is a reception level signal indicating the strength of the reception signal level after despreading. As the spread signal and the despread signal, a PN signal is used. As shown in FIG. 8, the autocorrelation characteristic 46 of the PN signal shows the maximum when the phase difference is zero, and decreases as the phase difference occurs. Become. That is, the smaller the phase difference between the spread signal included in the received signal R (t) and the despread signal generated by the despread signal generator 74 on the receiving side, the higher the reception level after despreading, and conversely. As the phase difference increases, the reception level decreases. Based on such a principle, in the tracking process in receiving the spread spectrum signal S (t), the despread signal generation unit 74 of the spread spectrum signal receiving apparatus generates the correlation value so that the reception level becomes maximum. The phase of the despread signal is always controlled.

FIG. 16 is a flowchart showing a tracking process in the conventional spread spectrum signal receiving method. A conventional technique will be described with reference to a flowchart of FIG.

In the tracking processing, initialization is first performed in the phase control section 73 (S1). Next, in the reception signal level detection section 72, the reception signal indicating the level of the reception signal R (t) is taken every T seconds of the tracking processing cycle. Level signal RL
(N) is sampled (S2, S3). Next, the phase control unit 73 determines whether the reception level indicated by the reception level signal RL (n) is higher or lower than the threshold level RLThre (S4). The phase control unit 73 sets the reception level error counter RLLow to zero when the reception level is higher than the reception signal threshold level RLThre (S5), and sets the reception level when the reception signal level is lower than the reception signal threshold level RLThre. The error counter RLLow is incremented by one (S
6). If the value of the reception level error counter RLLow is smaller than the tracking processing end count number MaxK, the phase control unit 73 continues the tracking processing, and if the value of the reception level error counter RLLow is larger than the tracking processing end count number MaxK. , It is determined that the received signal level is low, and the tracking process ends (S7).

[0010] Next, the phase control unit 73 generates a current reception level signal RL (n) and a previous reception signal level RL (n-n).
1) to determine whether the reception level difference between the current and previous times is within the tracking execution threshold level ± ε and the reception level fluctuation is small, or whether the reception level difference is larger than ± ε and the reception level fluctuation is large. (S8), when it is determined that the fluctuation of the reception level is small, the phase control signal ΔPhase is set to zero and the phase control is not performed (S8).
9). If there is a level difference between the current reception level signal RL (n) and the previous reception level signal RL (n−1), the reception level signal RL sampled last time
It is determined whether the reception level signal RL (n) sampled this time is larger or smaller than (n-1) (S1).
0). Here, the level difference ΔRL (n) is calculated by (Equation 1),

[0011]

(Equation 1)

If ΔRL (n) is greater than + ε, the phase control section 73 sets the phase control signal ΔPhase to be the same as the previous phase control signal (S11). Conversely, if the level difference ΔRL (n) is smaller than −ε, the phase control signal ΔPh
"ase" has the opposite phase to the previous phase control signal (S1
2). The (n) -th phase control signal set in steps S11 and S12 is held for the next tracking processing (S13).

The despread signal generator 74 in FIG. 15 shifts the phase of the despread signal according to the phase control signal output from the phase controller 73 (S14). By repeatedly performing such phase control, the received electric field strength of the phase difference between the spread signal included in the received signal R (t) and the despread signal output from the despread signal generator 74 is stable. Case is always within a certain range.

[0014]

However, in the above-mentioned conventional spread spectrum signal receiving apparatus and the conventional spread spectrum signal receiving method, the received electric field strength greatly changes or the received electric field strength is affected by multipath fading. In a reception environment where the received signal contains a lot of noise, the tracking processing becomes unstable because the received signal level contains a lot of noise, so the reception level decreases, the noise of the received signal increases, In such a case, there is a problem that reception becomes impossible.

Further, in the above-mentioned conventional spread spectrum signal receiving apparatus and the conventional spread spectrum signal receiving method, it is necessary to stabilize the tracking processing by shortening the tracking processing cycle. There was a problem that it increased.

Further, in a spectrum communication system for performing two-way communication, a crystal oscillator or the like is used for a reference frequency signal generation unit when performing transmission and reception, and the signal is multiplied and transmitted.
In general, a carrier is generated by dividing the frequency. However, when controlling communication, it is dependent on controlling communication with a wireless station (hereinafter, referred to as "master station") as a control station. A frequency difference occurs between a signal output from a reference frequency signal generation unit and a radio station (hereinafter, referred to as a “substation”) serving as a station. For this reason, there is a shift in the frequency relationship between the carrier output from the carrier generation unit of the master station and the slave station,
An intermediate frequency signal (hereinafter, referred to as an “IF signal”) of the received signal is a signal including a frequency shift from a center frequency of the intermediate frequency designed by the frequency difference of the carrier. In particular, in a cordless telephone, since a crystal oscillator or the like having low frequency accuracy and low frequency stability is used for the reference frequency signal generator, the frequency deviation of the IF signal becomes large. This I
An intermediate frequency filter (hereinafter, referred to as “IF-BPF”) having a band wider than the occupied frequency band of the received signal is used to reduce deterioration of the received signal due to the shift of the F signal. For this reason, there has been a problem that the received signal is apt to be affected by adjacent channels and the noise band is wide, so that much noise appears in the received signal.

According to the spread spectrum signal receiving apparatus and the spread spectrum signal receiving method, it is possible to stabilize the received signal level by performing a stable tracking process with respect to the fluctuation of the received level, and to reduce noise included in the received signal. Is required, and by controlling the frequency difference between the frequency of the reference clock signal for driving the despread signal generator and the frequency of the reference clock signal of the spread signal generator on the transmission side to be as close to zero as possible, It is required to reduce the processing amount of the tracking process, and furthermore, it is required that the noise of the received signal can be reduced by minimizing adjacent channel interference and transmission path noise.

According to the present invention, it is possible to stabilize a received signal level by performing a stable tracking process with respect to a change in the received level, to reduce noise included in the received signal, and to perform a reference for driving a despread signal generator. By controlling the frequency difference between the frequency of the clock signal and the frequency of the reference clock signal of the spread signal generator on the transmission side to be as close to zero as possible, it is possible to reduce the processing amount of the tracking process,
Spread-spectrum signal receiver that can reduce the noise of the received signal by minimizing adjacent channel interference and transmission line noise, and stabilizes the received signal level by performing stable tracking processing against fluctuations in the received level The frequency difference between the frequency of the reference clock signal for driving the despread signal generator and the frequency of the reference clock signal of the spread signal generator on the transmitting side is reduced to zero as much as possible. Therefore, it is an object of the present invention to provide a spread spectrum signal receiving method for reducing the amount of tracking processing by controlling the number of adjacent channels and minimizing adjacent channel interference and transmission path noise to reduce noise of a received signal.

[0019]

SUMMARY OF THE INVENTION In order to solve the above problems, a spread spectrum signal receiving apparatus according to the present invention despreads a spread spectrum signal and outputs a received signal, and an output signal from the despreading section. A received signal level detector for detecting a level of the received signal and outputting a received level signal indicating the received signal level; a despread signal generator for generating a despread signal based on the reference clock signal; A phase control unit for generating a phase control signal for controlling the phase of the despread signal output from the despread signal generation unit based on the reception level signal output from the unit, and a reference input to the despread signal generation unit A reference clock generator for generating a clock signal, and a frequency of the reference clock signal generated by the reference clock generator is controlled based on a phase control signal output from the phase controller. And a structure having a quasi-frequency control unit.

Thus, by performing a stable tracking process with respect to the fluctuation of the reception level, the reception signal level can be stabilized, and the noise included in the reception signal can be reduced.
Reduces the amount of tracking processing by controlling the frequency difference between the frequency of the reference clock signal that drives the despread signal generator and the frequency of the reference clock signal of the transmitter-side spread signal generator to be as close to zero as possible. Thus, it is possible to obtain a spread spectrum signal receiving apparatus capable of reducing noise of a received signal by minimizing adjacent channel interference and transmission path noise.

In order to solve the above-mentioned problems, a method of receiving a spread spectrum signal according to the present invention comprises the steps of: determining a level of a received signal obtained by despreading a spread spectrum signal with a despread signal; A phase control signal generating step for generating a phase control signal for controlling the phase of the despread signal, and a reference for controlling the frequency of a reference clock signal for generating the despread signal by a frequency control signal based on the phase control signal And a clock signal frequency control step.

Thus, by performing a stable tracking process with respect to the fluctuation of the reception level, the level of the reception signal is stabilized, the noise included in the reception signal is reduced, and the frequency of the reference clock signal for driving the despread signal generation unit is reduced. By controlling the frequency difference between the frequency of the reference clock signal and the frequency of the spread signal generator on the transmitting side to be as close to zero as possible, the amount of tracking processing is reduced, and adjacent channel interference and transmission path noise are minimized. As a result, a spread spectrum signal receiving method for reducing the noise of the received signal is obtained.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A spread spectrum signal receiving apparatus according to a first aspect of the present invention includes a despreading section for despreading a spread spectrum signal and outputting a received signal, and a received signal output from the despreading section. Signal level detecting section for detecting the level of the received signal and outputting a received level signal indicating the received signal level, a despread signal generating section for generating a despread signal based on the reference clock signal, and an output from the received signal level detecting section. A phase control unit for generating a phase control signal for controlling the phase of the despread signal output from the despread signal generation unit based on the received level signal received, and a reference clock signal input to the despread signal generation unit. A reference clock generator that generates the signal, and a reference frequency controller that controls the frequency of the reference clock signal generated by the reference clock generator based on the phase control signal output from the phase controller. In which it was decided to have a.

According to this configuration, the reference clock signal (transmission reference clock signal) output from the reference clock generation unit of the spread spectrum signal transmission apparatus based on the gradient of the integrated value of the phase control signal output from the phase control unit at predetermined time intervals. And a reference clock signal (reception reference clock signal) output from a reference clock generator of the spread spectrum signal receiving apparatus, and the reference of the spread spectrum signal receiving apparatus is determined according to the gradient of the integrated value of the phase control signal. By controlling the frequency of the clock generation unit, the frequency of the reception reference clock signal matches the frequency of the transmission reference clock signal, and the phase difference generated between the spread signal and the despread signal is reduced to zero as much as possible. This has the effect of reducing tracking processing.

According to a second aspect of the present invention, in the spread spectrum signal receiving apparatus according to the first aspect, the reference frequency control section fetches a phase control signal output from the phase control section to perform phase control. A least square error slope calculator for calculating an average time rate of change of the phase of the despread signal by obtaining a slope of the signal at a predetermined time interval by linear approximation using a least square error calculation, and an average time change of the phase of the despread signal A sign determination unit that outputs a sign determination signal indicating a positive or negative sign of the rate; and a reference frequency control signal generation unit that generates a reference frequency control signal based on the sign determination signal. The frequency of the reference clock signal is controlled by a reference frequency control signal.

With this configuration, the slope of the integrated value of the phase control signal at a predetermined time interval is obtained by the least square error calculation, so that the reception level signal is greatly affected by noise and the phase control signal contains much noise. Even in the situation, it has the effect of accurately calculating the slope of the integrated value of the phase control signal and improving the stability of the frequency control signal.

According to a third aspect of the present invention, in the spread spectrum signal receiving apparatus according to the first aspect, the reference frequency control section fetches a phase control signal output from the phase control section to perform phase control. A point-to-point linear interpolation unit for calculating an average time change rate of the phase of a despread signal by applying a point-to-point linear interpolation operation to an integrated value of a signal at a predetermined time interval; A sign determination unit that outputs a sign determination signal indicating the sign of the average time change rate of the phase of the determined despread signal, and a reference frequency control signal generation unit that generates a reference frequency control signal based on the sign determination signal. And the reference clock generator controls the frequency of the generated reference clock signal by a reference frequency control signal.

According to this configuration, the slope of the integrated value of the phase control signal at the predetermined time interval can be obtained with a small amount of calculation such as obtaining the slope of the integrated value of the phase control signal at the predetermined time interval by linear interpolation between two points. It has the action of:

According to a fourth aspect of the present invention, in the spread spectrum signal receiving apparatus according to the first aspect, the reference frequency control section fetches a phase control signal output from the phase control section to perform phase control. A phase control signal slope calculator for calculating a slope of the signal at a predetermined time interval, a slope comparator for calculating an average time change rate of the phase of the despread signal based on the slope output from the phase control signal slope calculator, When the absolute value of the average time rate of change of the phase of the despread signal is large, the frequency of the reference clock signal output from the reference clock generator is greatly changed, and the absolute value of the average time rate of change of the phase of the despread signal is obtained. Is smaller, the reference frequency control signal generator for slightly changing the frequency of the signal output from the reference clock generator is provided.

With this configuration, the frequency difference between the transmission reference clock signal and the reception reference clock signal can be quickly and stably controlled by performing frequency control corresponding to the absolute value of the gradient of the integrated value of the phase control signal at predetermined time intervals. This has the effect of canceling.

According to a fifth aspect of the present invention, in the spread spectrum signal receiving apparatus according to the first aspect, the reference frequency control section takes in the phase control signal output from the phase control section and outputs the phase control signal. A phase control signal integrator for obtaining an integrated value of the phase control signal; a phase comparator for outputting a phase comparison signal indicating whether or not the integrated value output from the phase control signal integrator has exceeded a predetermined threshold; and A reference frequency control signal generator for generating a reference frequency control signal, wherein the reference clock generator controls the frequency of the generated reference clock signal based on the reference frequency control signal.

With this configuration, the frequency of the reception reference clock signal is controlled when the integrated value of the phase control signal exceeds a predetermined threshold of the phase control comparison unit in accordance with the frequency difference between the transmission reference clock signal and the reception reference clock signal. This has the effect of quickly and stably canceling the frequency difference between the transmission reference clock signal and the reception reference clock signal with a simple circuit configuration.

A spread spectrum signal receiving apparatus according to a sixth aspect of the present invention is the spread spectrum signal receiving apparatus according to any one of the first to fifth aspects, wherein the received level signal output from the received signal level detecting section is indicated. A reception level drop detection unit that outputs a reception level drop signal when the reception signal level drops rapidly, and a reference frequency lock when the rate of time change of the frequency indicated by the frequency control signal output from the reference frequency control unit is small. A reference frequency lock detection unit for outputting a signal, and a phase control signal output from the phase control unit when the reference frequency lock signal is output from the reference frequency lock detection unit and the reception level reduction signal is output from the reception level reduction unit. For a short time.

With this configuration, in a situation where the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal are almost the same, the phase difference of the despread signal will be small even if the tracking process is stopped for a short time. Because the signal level is very small, if the received electric field strength changes rapidly due to fading, etc., the phase control signal is cut off to prevent an increase in the phase difference between the spread signal and the despread signal due to incorrect control in the tracking process. Has the effect of maintaining the quality of the received signal.

According to a seventh aspect of the present invention, there is provided the spread spectrum signal receiving apparatus according to any one of the first to sixth aspects, wherein the reference clock signal output from the reference clock generating unit is inputted. The radio device uses a reference clock signal as a radio signal frequency conversion, a carrier signal reference signal and / or a modulation / demodulation unit reference signal.

With this configuration, the reference clock signal is used not only as the spread signal generator or the despread signal generator, but also as the reference clock signal for the carrier signal generator so that the frequency of the reception reference clock signal can be reduced. , The difference between the frequencies of the carrier signals becomes extremely small, and the IF-BPF bandwidth in the intermediate frequency band can be optimally designed. By reducing the number, the selectivity is improved, and further, by minimizing the equivalent noise bandwidth, the amount of noise is minimized, thereby improving the quality of the received signal.

According to a eighth aspect of the present invention, there is provided a method for receiving a spread spectrum signal, comprising the steps of: determining a level of a received signal obtained by despreading a spread spectrum signal with a despread signal; A phase control signal generating step for generating a phase control signal for controlling the phase of the spread signal, and a reference clock signal frequency control for controlling the frequency of the reference clock signal for generating the despread signal by a frequency control signal based on the phase control signal And a step.

According to this configuration, the frequency difference between the frequency of the reception reference clock signal and the frequency of the transmission reference clock signal is reduced to zero as much as possible, thereby reducing tracking processing.

According to a ninth aspect of the present invention, in the spread spectrum signal receiving method according to the eighth aspect, the reference clock signal frequency control step includes the step of adjusting the slope of the phase control signal at a predetermined time interval to a least square error. An average time change rate calculating step of obtaining an average time change rate of the phase of the despread signal by obtaining a linear approximation using an operation; A code determination signal generation step to be generated, and a frequency control step of controlling the frequency of the reference clock signal based on the code determination new word so that the average time rate of change of the phase of the despread signal becomes infinitely zero. Things.

With this configuration, the slope of the integrated value of the phase control signal at a predetermined time interval is obtained by the least square error calculation, so that the reception level signal is greatly affected by noise and the phase control signal contains much noise. Even in the situation, it has the effect of accurately calculating the slope of the integrated value of the phase control signal and improving the stability of the frequency control signal.

According to a tenth aspect of the present invention, in the method for receiving a spread spectrum signal according to the eighth aspect, the frequency control step of the reference clock signal comprises despreading from an integrated value of the phase control signal at a predetermined time interval. An average time change rate calculating step of calculating an average time change rate of a signal phase by a two-point linear complement operation, and a sign of the average time change rate of a phase of a despread signal obtained by a two-point linear complement operation. And a frequency control step of controlling the frequency of the reference clock signal based on the code determination signal such that the average time change of the phase of the despread signal becomes infinitely zero. It was decided to have.

With this configuration, the slope of the integrated value of the phase control signal at the predetermined time interval can be obtained with a small amount of calculation such as obtaining the slope of the integrated value of the phase control signal at the predetermined time interval by linear interpolation between two points. This has the effect that the processing time can be reduced and the circuit scale can be reduced.

According to an eleventh aspect of the present invention, in the method for receiving a spread spectrum signal according to the eighth aspect, the step of controlling the frequency of the reference clock signal comprises the step of controlling the phase of the phase control signal at a predetermined time interval. A signal slope calculating step; an average time change rate calculating step of calculating an average time change rate of the phase of the despread signal from the slope; and a reference clock signal when the absolute value of the average time change rate of the phase of the despread signal is large. When the absolute value of the time change rate of the phase of the despread signal is small, the frequency of the reference clock signal is slightly changed so that the average time change rate of the phase of the despread signal is infinite. A frequency control step of controlling the frequency of the reference clock signal so as to be zero.

With this configuration, the frequency difference between the transmission reference clock signal and the reception reference clock signal can be quickly and stably controlled by performing frequency control corresponding to the absolute value of the gradient of the integrated value of the phase control signal at predetermined time intervals. This has the effect of canceling.

According to a twelfth aspect of the present invention, in the spread spectrum signal receiving method of the eighth aspect, the reference clock signal frequency control step includes an integrated value calculating step of obtaining an integrated value of the phase control signal. A comparison determination step of determining whether the integrated value of the phase control signal has exceeded a predetermined threshold value and determining in which of the positive or negative phase direction the integrated value of the phase control signal has been integrated;
Having a frequency control step of controlling the frequency of the reference clock signal based on the comparison determination result in the comparison determination step to control the average time rate of change of the phase of the despread signal to be infinitely zero. It was done.

According to this configuration, the frequency of the reception reference clock signal can be easily controlled by controlling the frequency of the reception reference clock signal when the integrated value of the phase control signal exceeds a predetermined threshold according to the frequency difference between the transmission reference clock signal and the reception reference clock signal. With a simple circuit configuration, the frequency difference between the transmission reference clock signal and the reception reference clock signal is quickly and stably canceled.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS. In each of the embodiments described below, the spread spectrum system is direct spread (DS / SS), and multiplexing of each channel is not performed by code division multiple access (CDMA), but by frequency division multiple access (FDMA). ).

(Embodiment 1) FIG.1 is a block diagram showing a spread spectrum signal receiving apparatus according to Embodiment 1 of the present invention.

In FIG. 1, reference numeral 1 denotes a despreading unit for despreading the received spread spectrum signal S (t) and outputting a received signal R (t), and 2 detects the level of the received signal R (t). A reception signal level detector for outputting a reception level signal indicating the level of the reception signal R (t).
The phase control unit 5 outputs a phase control signal for controlling the phase of the despread signal input to the despreading unit 1 based on the time change of the level, and the despread signal according to the phase control signal from the phase control unit 3 , A reference clock generator for outputting a reference clock signal of the despread signal generator 5, and a despread signal based on the phase control signal output from the phase controller 3. A reference frequency control unit that obtains a time change ratio of the despread signal output from the generation unit 5, outputs a frequency control signal, and controls the frequency of the reference clock signal output from the reference clock generation unit 6. For this reason, the reference clock generator 6 has a configuration in which the oscillation frequency can be varied by the reference frequency control signal.
0 ").

FIG. 6 is a block diagram showing a spread spectrum communication system for performing two-way communication using the spread spectrum signal receiving apparatus according to the first embodiment of the present invention.

In FIG. 6, reference numeral 30 denotes a radio station serving as a main station in a two-way spread spectrum communication system; 31, a spread signal generator of the main station 30; 32, a despread signal generator of the main station 30; 30 reference clock signal generators, 3
Reference numeral 4 denotes a wireless device of the main station 30. A wireless station 35 serving as a slave station in the two-way spread spectrum communication system;
36 is a spread signal generator of the slave station 35, 37 is a despread signal generator of the slave station 35, 38 is a reference clock signal generator of the slave station 35, and 39 is a radio of the slave station 35.

FIG. 7 is a block diagram showing a spread spectrum communication system for performing one-way communication using the spread spectrum signal receiving apparatus according to the first embodiment of the present invention.

In FIG. 7, reference numeral 40 denotes a transmitting station in the one-way spread spectrum communication system;
, 41 is a spread signal generator of the transmitting station 40, 42 is a reference clock generator of the transmitting station 40, 43 is a receiving station in the one-way spread spectrum communication system, 43a is a receiving section of the receiving station 43, and 44 is a receiving section. The despread signal generator of the station 43 is a reference clock generator of the receiving station 43.

The spread spectrum signal receiving apparatus according to the present embodiment is applied to one of the master station 30 and the slave station 35 in the spread spectrum communication system for performing bidirectional communication shown in FIG. I do. In a spread spectrum communication system having a plurality of slave stations, it is assumed that the present invention is applied to each of the plurality of slave station spread spectrum signal receiving apparatuses. Also,
In the spread spectrum communication system for performing one-way communication shown in FIG. 7, the present invention is applied to the spread spectrum signal receiving device of the receiving station 43. A cordless telephone using spread spectrum communication has the configuration shown in FIG.

Hereinafter, this embodiment will be described with reference to FIGS. 1, 6, 7, and 8. FIG.

The spread spectrum signal receiving apparatus according to the present embodiment can be applied to both the two-way spread spectrum communication system and the one-way spread spectrum communication system. Except where noted, the model of the wireless communication system is a spread spectrum communication system that performs one-way communication in FIG.

The phase of the spread signal included in the received spread spectrum signal with respect to the despread signal of the receiving station 43 is
It changes due to a change in the positional relationship between the transmitting station 40 and the receiving station 43, and a change in the propagation path length due to the movement of a reflector on the propagation path. In addition, since the frequency of the transmission reference clock signal is different from the frequency of the reception reference clock signal, a phase difference corresponding to the frequency difference between the frequencies of the reference clock signals occurs over time. Particularly, in a cordless telephone, a crystal oscillator having low frequency accuracy and low stability is used as a reference clock generator 42 of the transmitting station 40 and the receiving station 43.
The crystal oscillator used for the reference clock generators 42 and 45 of the transmitting station 40 and the receiving station 43 has a frequency accuracy of several tens ppm. For these reasons, in the case of a cordless telephone, the phase change due to the frequency difference between the reference clock signals of the transmitting station 40 and the receiving station 43 is generally dominant as compared with the phase change due to the change in the propagation path length. If the rate of the phase change is large, the rate of the processing related to the tracking processing increases. When a phase difference occurs between the phase of the spread signal included in the received signal and the phase of the despread signal of the spread spectrum signal receiving apparatus, the reception level decreases according to the magnitude of the phase difference as shown in FIG. I do. The spread-spectrum signal receiving apparatus constantly monitors the time change of the reception level, and controls the phase of the despread signal output from the despread signal generator in the direction in which the reception level increases.
In the configuration shown in FIG. 1, the phase controller 3 controls the phase of the despread signal, and has the same function as the phase controller 73 in FIG. The phase control process is as shown in the flowchart of the conventional tracking process shown in FIG. The phase control unit 3 determines the magnitude of the phase control signal by comparing the received signal level in the previous tracking processing with the current received signal level.

The despread signal generator 5 changes the phase of the despread signal according to the magnitude of the phase control signal output from the phase controller 3. The value obtained by temporally integrating the phase control signal output from the phase control unit 3 is obtained when the frequency difference between the reference clock signals output from the reference clock generation units 42 and 45 of the transmitting station 40 and the receiving station 43 does not change. In this case, the frequency monotonically increases or monotonously decreases at a certain gradient while finely oscillating in the phase control cycle T seconds within the integration time. The integrated value of the phase control signal is determined by the difference between the frequency of the reference clock signals output from the reference clock generators 42 and 45 of the transmitting station 40 and the receiving station 43. Since the phase difference between the phase and the phase of the despread signal of the receiver is indicated, the slope of the integrated value of the phase control signal is determined by the reference clock generators 42 and 45 of the transmitting station 40 and the receiving station 43. It is proportional to the frequency difference of the output reference clock signal. Tracking processing period T
Is a few milliseconds (several milliseconds). Even if there is no condition that the frequency difference between the reference clock signals output from the reference clock generators of the transmitting station 40 and the receiving station 43 does not change, a general crystal oscillator can be used. Alternatively, the slope of the integrated value of the phase control signal in a short time interval of 1 second to 10 seconds can be regarded as a sufficiently straight line from the viewpoint of the time change rate of the oscillation frequency of the VCXO oscillating by applying a constant control voltage. . From the above, the inclination of the integrated value in the short time interval (1 to 10 seconds) of the phase control signal is determined by the transmitting station 40.
And the frequency difference between the reference clock signal output from the reference clock generator of the receiving station 43 and the reference clock signal.

From the above, when the sign of the slope of the integrated value in the short time interval of the phase control signal is positive (+), the reception reference clock signal output from the reference clock generation unit 45 of the reception station 43 is output. This indicates that the frequency is lower than the frequency of the transmission reference clock signal output from the reference clock generation unit 42 of the transmission station 40, and conversely, the sign of the slope of the integrated value in the short time interval of the phase control signal is negative ( In the case of-), the reference clock generator 45 of the receiving station 43
Indicates that the frequency of the reception reference clock signal output from the transmission station 40 is higher than the frequency of the transmission reference clock signal output from the reference clock generation unit 42 of the transmission station 40. That is, the relative magnitude relationship between the frequency of the reference clock signal of the transmitting station 40 and the frequency of the reference clock signal of the receiving station 43 is determined from the sign of the short-time integration value of the phase control signal. The relative frequency difference between the frequencies of the reference clock signals of the station 40 and the receiving station 43 can be obtained. Based on this principle, the reference frequency control unit 4 determines the relative frequency difference between the frequencies of the reference clock signals of the transmitting station 40 and the receiving station 43 or the frequency The magnitude relationship between the frequencies of the reference clock signals of the receiving station 43 is determined, and a frequency control signal is generated to the reception-side reception clock generator 6 on the receiving side so that the frequency difference between the reference clock signals approaches zero as much as possible. Since the receiving reference clock generator 6 on the receiving side has a configuration such as VCXO that can change the oscillation frequency with a control voltage, the above-described control is repeated to reduce the frequency of the transmitting reference clock signal on the transmitting side. The frequency difference between the reception reference clock signals on the reception side becomes relatively infinitesimally small. Here, the update period of the frequency control signal output from the reference frequency control unit 4 is sufficiently longer than the update period T seconds of the phase control signal output from the phase control unit 3, and the frequency update amount of the frequency control signal is In addition, the stability of the receiver circuit is not affected by setting it smaller than 1 ppm with respect to the nominal transmission frequency of the reception reference clock generator 6 on the reception side.

As described above, the relative frequency difference between the reference clock signal of the transmitting station 40 and the reference clock signal of the receiving station 43 is obtained from the short-time integrated value of the phase control signal, and control is performed so that the frequency difference becomes infinitely zero. Thus, a phase difference between the spread signal included in the received signal and the despread signal output from the despread signal generator 5 of the receiving station 43 is less likely to occur, and the tracking processing in the phase controller 3 can be reduced. it can.

In a spread spectrum communication system for performing bidirectional communication to which the spread spectrum signal receiving apparatus according to the present embodiment shown in FIG. 6 is applied, one of the master station 30 and the slave station 35 receives the spread spectrum signal. By applying the receiving device, the main station 3
0 and the tracking processing of the slave station 35 can be reduced. When there is a plurality of slave stations 35 while one master station 30 is used, this spread spectrum signal receiving apparatus is applied to the slave station 35 side, so that the master station 30 is similarly connected.
In addition, the tracking processing of the receiving device of the slave station 35 can be reduced.

As described above, according to the present embodiment, despreading section 1 for despreading spread spectrum signal S (t) and outputting a received signal, and receiving signal R ( a received signal level detector 2 for detecting the level of t) and outputting a received signal indicating the received signal level (determination step); a despread signal generator 5 for generating a despread signal based on the reference clock signal; A phase control signal for controlling the phase of the despread signal output from the despread signal generator 5 based on the received level signal output from the received signal level detector 2 (phase control signal generation step) The control unit 3, a reference clock generation unit 6 for generating a reference clock signal input to the despread signal generation unit 5, and a reference clock generation unit 6 based on the phase control signal output from the phase control unit 3. You By providing the reference frequency control unit 4 for controlling the frequency of the reference clock signal (reference clock signal frequency control step), the slope of the integrated value of the phase control signal output from the phase control unit 3 at a predetermined time interval can be calculated as follows. A reference clock signal (transmission reference clock signal) output from the reference clock generator of the spread spectrum signal transmitter and a reference clock signal (reception reference clock signal) output from the reference clock generator 6 of the spread spectrum signal receiver. By calculating the frequency difference and controlling the frequency of the reference clock generator 6 of the spread spectrum signal receiver according to the gradient of the integrated value of the phase control signal,
The tracking process can be reduced by making the frequency of the reception reference clock signal equal to the frequency of the transmission reference clock signal and making the phase difference between the spread signal and the despread signal as zero as possible.

(Embodiment 2) FIG. 2 is a block diagram showing a spread spectrum signal reception apparatus according to Embodiment 2 of the present invention. 1 shows a signal receiving device.

In FIG. 2, the despreading section 1, the received signal level detecting section 2, the phase control section 3, the despreading signal generating section 5, and the reference clock generating section 6 are the same as those in FIG. The description is omitted. Reference numeral 12 denotes a least-squares calculation slope calculator for calculating the slope of the integrated value of the phase control signal (the average time change rate of the phase of the despread signal) by the least-square error calculation.
Reference numeral 3 indicates whether the slope is positive (+) or negative (-) based on the sign of the slope of the integrated value of the phase control signal obtained by the least square error calculation, and outputs a sign determination signal indicating the determination result. The sign determining unit 14 is a reference frequency control signal generating unit that outputs a frequency control signal for controlling the frequency of the reception reference clock signal output from the reference clock generating unit 6 based on the sign determining signal. The above components 12 to
Reference numeral 14 forms the reference frequency control unit 4.

The operation of the thus-configured spread spectrum signal receiving apparatus will be described with reference to FIGS. FIG. 9 is a flow chart showing the operation of the spread spectrum signal receiving apparatus of FIG. 2, and shows a flow chart for calculating the gradient of the integrated value of the phase control signal when the least square calculation is used for the reference clock signal frequency control. FIG. 10 is a diagram illustrating the time change of the phase control signal, the time change of the integrated value of the phase control signal, and the slope of the integrated value of the phase control signal at a predetermined time interval according to the second embodiment of the present invention. It is a graph which shows the approximate straight line at the time of finding. In FIG. 10, the horizontal axis represents time, the vertical axis represents the phase control signal and its integrated value, 47 is a phase control signal, 48 is a characteristic line showing the time change of the integrated value of the phase control signal 47, and 49 is the phase. This is an approximate straight line obtained by calculating a least square error of the integrated value 48 of the control signal in a short time.

In FIG. 2, the least squares error slope calculator 1
In step 2, the gradient of the integrated value of the phase control signal output from the phase control unit 3 is calculated using the least square error calculation. When the tracking process is performed at a constant time interval T seconds and the phase control signal is output, the gradient α of the integral value of the phase control signal by the least square error calculation every N tracking processes is obtained by (Equation 2).

[0067]

(Equation 2)

Here, the variables A, B,
C and D are obtained by the equations of (Equation 3) to (Equation 4).

[0069]

(Equation 3)

[0070]

(Equation 4)

[0071]

(Equation 5)

[0072]

(Equation 6)

[0073]

(Equation 7)

In the least square error slope calculating section 12,
In order to determine the gradient α of the integrated value of the phase control signal (Equation 2)
It is calculated according to (Equation 7). Slope α shown in (Equation 1)
Is performed at a cycle N times the tracking processing cycle based on the phase control signal. Here, the least-square-error-slope calculating unit 12 is any of a central processing unit (hereinafter, referred to as “CPU”), a digital signal processing unit (hereinafter, referred to as “DSP”), a dedicated LSI, or a combination thereof. It consists of. Least square error slope calculator 1
At 2, initialization is first performed (S21), a phase control signal is fetched for each tracking processing cycle (S22), and A, B, C, and D are calculated by (Equation 3) to (Equation 7) (S23). ). This is repeated until the phase control signal is received N times (S24, S25).
Is calculated (S26). Here, the reference clock generator 6
Is constituted by VCXO or the like, and can change the oscillation frequency by the reference frequency control signal as described above. The reference frequency control signal generator 14 increases or decreases the reference frequency control signal in accordance with the sign of the gradient α of the integrated value of the phase control signal, and changes the frequency of the received reference clock signal output from the reference clock generator 6. . The reference frequency control signal generator 14 includes an up / down counter or register, a digital / analog converter, and a low-pass filter (hereinafter, referred to as “LPF”).

The present embodiment using the least-square error slope calculator 12 has a feature that the frequency difference between the frequency of the transmission reference clock signal of the transmitter and the frequency of the reception reference clock signal can be detected with high accuracy. Have. When the number N of times of taking in the phase control signal for calculating the gradient α of the integrated value of the phase control signal is reduced, the calculation in (Equation 2) includes a large amount of error. When the frequency of the reference clock signal is adjusted at high speed, and the number N of times of taking in the phase control signal is increased, the error included in the calculation in (Equation 2) is reduced. Adjustment of the frequency of the clock signal is delayed. When the gradient α of the integrated value of the phase control signal is large, the frequency is adjusted at high speed by reducing the number N of times of taking in the phase control signal for calculating the gradient α of the integrated value of the phase control signal. When the gradient α of the integrated value of the control signal is sufficiently small, the frequency difference is detected with high accuracy by increasing the number N of times of taking in the phase control signal. By performing the above variable control, it is possible to perform high-speed frequency adjustment and high-stability, high-precision frequency adjustment.

As described above, according to the present embodiment, the reference frequency control unit 4 takes in the phase control signal output from the phase control unit 3 and calculates the slope of the phase control signal at a predetermined time interval by the least square error calculation. The average time change rate of the phase of the despread signal is obtained by linear approximation using (Average time change rate calculation step).
And a code determination unit 13 that outputs a code determination signal indicating the sign of the average time rate of change of the phase of the despread signal (sign determination signal generation step), and generates a reference frequency control signal based on the code determination signal. (Frequency control step) The reference clock generation unit 6 includes a reference frequency control signal generation unit 14, and the reference clock generation unit 6 controls the frequency of the generated reference clock signal by the reference frequency control signal. The slope of the integrated value of the phase control signal can be obtained by the least square error calculation, and even in a situation where the received level signal is greatly affected by noise and the phase control signal contains much noise, the integrated value of the phase control signal is calculated. Can be accurately calculated, and the stability of the frequency control signal can be improved.

(Embodiment 3) FIG. 3 is a block diagram showing a spread spectrum signal receiving apparatus according to Embodiment 3 of the present invention. Show the case.

In FIG. 3, despreading section 1, received signal level detecting section 2, phase control section 3, despreading signal generating section 5, reference clock generating section 6, code judging section 13, and reference frequency control signal generating section 14 are shown in FIG. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 15 denotes a point-to-point linear interpolation unit that calculates the gradient of the integrated value of the phase control signal (the average time change rate of the phase of the despread signal) by the point-to-point linear interpolation calculation.

The operation of the thus-configured spread spectrum signal receiving apparatus will be described with reference to FIG. FIG. 11 shows the time change of the phase control signal, the time change of the integrated value of the phase control signal, and the slope of the integrated value of the phase control signal at a predetermined time interval according to the third embodiment of the present invention by linear interpolation between two points. It is a graph which shows the complementary straight line at the time of finding.
In FIG. 11, a phase control signal 47, a phase control signal 47
Is the same as that in FIG. 10, and therefore, the same reference numeral is assigned and the description is omitted. Reference numeral 50 denotes a complementary straight line of the integrated value of the phase control signal obtained by the two-point linear complementary operation.

The point-to-point straight-line complementing operation section 15 calculates an integrated value 48 of the phase control signal in a predetermined period, and generates a reference frequency control signal according to whether the integrated value is positive (+) or negative (-). The frequency control signal output from the unit 14 is increased or decreased to change the frequency of the reception reference clock signal generated by the reference clock generation unit 6. Point-to-point linear interpolation unit 1
5, the integrated value 4 of the phase control signal at a predetermined time interval
Since only 8 is required, it is desirable in terms of the number of processes. A two-point linear approximation operation circuit 1 comprising a counter circuit and a comparator.
5, which is desirable in terms of circuit scale. Thus 2
The method of obtaining the slope of the integrated value of the phase control signal using the point-to-point linear interpolation unit 15 has the characteristic that it can be realized with a simpler circuit than the method of least squares operation. However, the calculation accuracy is liable to be affected by noise and the like, and the calculation accuracy tends to be worse than the least square error calculation. In order to avoid this, the integration time for obtaining the integrated value of the phase control signal is lengthened. Also, if the accumulated time is counted by a counter,
The slope of the phase control signal can also be obtained from the integrated value of the phase control signal at predetermined time intervals.

As described above, according to the present embodiment, reference frequency control section 4 takes in the phase control signal output from phase control section 3 and applies 2 to the integrated value of the phase control signal at a predetermined time interval. The average time rate of change of the phase of the despread signal is determined by applying the point-to-point linear interpolation operation (average time-change rate calculation step).
And a sign judging unit 13 for outputting a sign judging signal indicating the sign of the average time rate of change of the phase of the despread signal obtained by the linear interpolation between two points (sign judging signal generating step).
And a reference frequency control signal generator 14 for generating a reference frequency control signal based on the sign determination signal (frequency control step). The reference clock generator 6 controls the frequency of the generated reference clock signal by the reference frequency control. The control by the signal allows the slope of the integrated value of the phase control signal at the predetermined time interval to be obtained with a small amount of calculation such that the slope of the integrated value of the phase control signal at the predetermined time interval is obtained by the linear interpolation between two points. The slope can be determined.

(Embodiment 4) FIG. 4 is a block diagram showing a spread spectrum signal receiving apparatus according to Embodiment 4 of the present invention. Shows a case where the frequency control is performed according to the magnitude of. 2 and 3, the control value of the reference frequency control signal generator 14 is set to 1 by the positive or negative sign of the gradient α of the integrated value at a predetermined time interval of the phase control signal.
The frequency of the reception reference clock signal is changed by increasing or decreasing the control amount by a plurality of times in accordance with the magnitude of the gradient, which has been increased or decreased by the control amount. This has the feature that the frequency difference between the transmission reference clock signal and the reception reference clock signal can be made close to zero as quickly as possible.

In FIG. 4, despreading section 1, received signal level detecting section 2, phase control section 3, despreading signal generating section 5, reference clock generating section 6, and reference frequency control signal generating section 14 are shown in FIGS. Therefore, the same reference numerals are given and the description is omitted. Reference numeral 16 denotes a phase control signal slope calculator for calculating the slope of the phase control signal, and reference numeral 17 denotes a slope comparator for calculating an average time change rate of the phase of the despread signal from the slope of the phase control signal.

The operation of the thus configured spread spectrum signal receiving apparatus will be described with reference to FIG. FIG. 12 is a graph showing the input / output characteristics of the slope comparison unit 17, where the horizontal axis indicates the slope α and the vertical axis indicates the amount of update of the reference frequency control signal. As the absolute value of the gradient α increases, the number of updates of the reference frequency control signal increases. In order to increase the stability of the receiver, the number of updates of the reference frequency control signal is limited so as not to increase more than a certain number as shown in FIG.

Here, if the integrated value of the phase control signal for one second is q chips, the frequency difference between the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal is theoretically approximately qHz. . Therefore, if the integrated value of the phase signal per second is calculated from the gradient α of the integrated value of the phase control signal, the frequency difference between the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal can be obtained. In principle, it is possible to reduce the frequency difference between the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal to zero as much as possible by one operation for calculating the gradient of the integrated value of the phase signal. However, since the calculation of the slope of the integrated value of the phase control signal actually includes an error component,
The frequency control amount of the reference clock generator 6 per operation must be smaller than the frequency difference obtained by the theoretical value, and the control sensitivity needs to be reduced. In this case, the count for the frequency difference obtained from the theoretical value of the frequency control is at most about 0.5. This improves the stability of the frequency control.

As described above, according to the present embodiment, reference frequency control section 4 takes in the phase control signal output from phase control section 3 and calculates the slope of the phase control signal at a predetermined time interval (phase). Control signal gradient calculating step) a phase control signal gradient calculating unit 16; an average time rate of change of the phase of the despread signal based on the gradient (average time rate of change calculating step); When the absolute value of the average time rate of change of the phase of the reference clock signal is large, the frequency of the reference clock signal output from the reference clock generator is greatly changed, and when the absolute value of the average time rate of change of the phase of the despread signal is small, Is provided with a reference frequency control signal generator 14 that slightly changes the frequency of the signal output from the reference clock generator (frequency control step), so that the Kick can be fast and cancel stably frequency difference between the transmission reference clock signal and the received reference clock signal by performing a minute frequency control according to the absolute value of the slope of the integrated value of the phase control signal.

(Embodiment 5) FIG. 5 is a block diagram showing a spread spectrum signal receiving apparatus according to Embodiment 5 of the present invention, wherein a reference frequency control unit for a received reference clock signal includes a phase integrating unit, a phase comparing unit, This shows a case where it is composed of a reference frequency control signal generator.

In FIG. 5, despreading section 1, received signal level detecting section 2, phase control section 3, despreading signal generating section 5, reference clock generating section 6, and reference frequency control signal generating section 14 are shown in FIGS. Therefore, the same reference numerals are given and the description is omitted. Reference numeral 18 denotes a phase control signal integrating unit that integrates the phase control signal, and 19 denotes a positive side of the integrated value of the phase control signal when the integrated value of the phase control signal output from the phase control signal integrating unit 18 exceeds a predetermined positive threshold + PK. Is output, and when the integrated value of the phase control signal output from the phase control signal integrator 18 exceeds a negative predetermined threshold value -PK (below), the integrated value of the phase control signal is increased. This is a phase comparison unit that outputs a phase comparison signal indicating that it has exceeded the minus side.

The operation of the thus configured spread spectrum signal receiving apparatus will be described.

As described above, the phase comparator 19 outputs a phase comparison signal indicating that the integrated value of the phase control signal has exceeded the plus or minus side. In addition, when the phase comparison signal is output from the phase comparison unit 19, the phase control signal integrator 1
Clear the integral value of 8 to zero. The reference frequency control signal generator 14 changes the reference frequency control signal in a direction in which the frequency difference between the transmission reference clock signal and the reception reference clock signal decreases according to the output of the phase comparator 19. As described above, the circuit for detecting the frequency difference between the transmission reference clock signal and the reception reference clock signal is provided by the phase control signal integrator 18.
When the frequency difference between the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal is large, the frequency matching frequency in a predetermined time increases, and the transmission reference clock signal When the frequency difference between this frequency and the frequency of the reception reference clock signal is small, the variable frequency control can be realized by a simple logic circuit such that the number of frequency adjustments in a predetermined time is reduced.

The minimum value of the set value of the predetermined threshold value ± PK is larger than the phase fluctuation width when the tracking phase is stable, and the maximum value of the set value of the predetermined threshold value ± PK is ± 1 chip (chip) of the spread signal. It is desirable to make the phase difference smaller than ()).

The phase control signal accumulating section 18 can be constituted by hardware processing using a counter or software processing using a CPU or a DSP. However, it is easier to implement a hardware configuration by using a counter. This is desirable from the viewpoint of reducing power consumption. The phase comparison unit 19 can also be configured by hardware processing using a comparator using a logic circuit or software processing using a CPU or a DSP. Is desirable from the viewpoint of reducing the size. The reference frequency control signal generator 14 can be configured by hardware processing using an up / down counter or software processing using a CPU or a DSP, but the hardware configuration can be easily realized by using an up / down counter. This is desirable from the viewpoint of reducing power consumption.

As described above, according to the present embodiment, reference frequency control section 4 takes in the phase control signal output from phase control section 3 and calculates the integrated value of the phase control signal (integrated value calculation step). A control signal integrator 18; a phase comparator 19 for outputting a phase comparison signal indicating whether the integrated value output from the phase control signal integrator 18 has exceeded a predetermined threshold (comparison determination step); A reference frequency control signal generator 14 for generating a reference frequency control signal based on the reference frequency control signal (frequency control step). The reference clock generator 6 controls the frequency of the generated reference clock signal based on the reference frequency control signal. By doing so,
When the integrated value of the phase control signal exceeds a predetermined threshold of the phase comparator 19 according to the frequency difference between the transmission reference clock signal and the reception reference clock signal, the frequency of the reception reference clock signal can be controlled. The circuit configuration can quickly and stably cancel the frequency difference between the transmission reference clock signal and the reception reference clock signal.

(Embodiment 6) FIG. 13 is a block diagram showing a spread spectrum signal receiving apparatus according to Embodiment 6 of the present invention, showing a case where a phase control signal cutoff unit is used.

In FIG. 13, despreading section 1, received signal level detecting section 2, phase control section 3, reference frequency control section 4, despreading signal generating section 5, and reference clock generating section 6 are shown in FIGS.
Therefore, the same reference numerals are given and the description is omitted. Reference numeral 20 denotes a reception level drop detection unit, reference numeral 21 denotes a reference frequency lock detection unit, and reference numeral 22 denotes a phase control signal cutoff unit.

The operation of the spread spectrum signal receiving apparatus configured as described above will be described.

The reception level drop detecting section 20 detects that the received signal level has dropped sharply in a state where the received signal level is higher than a certain level, and the reference frequency lock detecting section 21 The phase control signal cutoff unit 22 detects that the time change of the output reference frequency control signal is small and the frequency difference between the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal is close to zero. A frequency lock detection signal that indicates that the frequency difference between the frequency of the transmission reference clock signal output from the frequency lock detection unit 21 and the frequency of the reception reference clock signal is close to zero;
When the reception level decrease detection signal for notifying that the reception signal level outputted from the controller has suddenly dropped is output at the same time, the phase control signal outputted from the phase control section 3 is cut off for a short time ΔTstop.

By having such a configuration and performing such processing, when the level of the received signal R (t) suddenly drops for some reason other than the tracking processing,
It is possible to prevent the tracking processing from becoming unstable due to the decrease in the received signal level, and as a result,
The feature is that the quality of the received signal R (t) can be improved. Since the frequency difference between the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal is close to zero, the phase of the spreading code included in the reception signal R (t) and the despread signal on the reception side are reduced. The situation is such that the phase difference between the despread signals generated by the generator 5 is hardly generated. Even if the tracking processing is stopped for a short time and the phase of the despread signal is not controlled at all, there is almost no change in the reception level. That is.

Here, the short time ΔTstop, which is the time interval for stopping the tracking processing, is defined as a case where the phase control signal is continuously output in one direction (for example, in the + phase direction) and the integrated value of the phase control signal is the spread signal (or inversely). This is a time interval equal to the time required for a half of the spread signal).
When converted by the tracking processing cycle, the phase of the despread signal updated per tracking processing is Δq chip,
Assuming that the tracking cycle is T seconds, a short time ΔTstop
Is the time interval shown in (Equation 8).

[0100]

(Equation 8)

After the phase control signal is once cut off for a short time,
The control signal is not interrupted for a time interval equal to or more than twice the short time ΔTstop. This prevents the phase control signal from being cut off for a long time and becoming unreceivable. The reception level drop detection unit 20 can be realized by hardware processing including an LPF and a comparator, or software processing using a CPU or a DSP. In this case, one input of the comparator is a reception level signal output from the reception signal level detection unit 2 and the other input is a reception level signal output from the reception signal level detection unit 2 that has passed through a moving average filter. By doing so, it is possible to detect that the reception level has dropped sharply. The reference frequency lock detection unit 21 can be realized by hardware processing including a comparator that compares the magnitude of the time change of the reference frequency control signal output from the reference frequency control unit 4 or software processing using a CPU or a DSP. Can be. Further, the input signal to the reference frequency lock detection unit 21 can be set as the gradient α of the integrated value of the phase control signal in the reference frequency control unit 4. The phase control signal cutoff unit 22 is a switch for turning on / off the phase control signal, a gate circuit, or a CPU or DSP.
Can be realized by software processing using.

As described above, according to the present embodiment, even when the received electric field strength is rapidly decreased due to fading, the received signal R is changed due to a change in the reception environment despite the accurate tracking control. It is possible to prevent the tracking processing from becoming unstable due to the change in the level of (t). Further, in a receiver using the switching reception diversity circuit, it is conceivable that the reception signal level may fluctuate temporarily at the moment when the antenna is switched, but even in such a case, the phase control signal interruption according to the present embodiment is interrupted. By using the unit 22 to block the phase control signal for a certain period after the antenna switching, it is possible to prevent the tracking processing from becoming unstable due to the antenna switching. In addition, by taking the antenna switching signal into the phase control signal blocking unit 22, it is possible to more accurately detect that the antenna switching has been performed, and to prevent a tracking processing error.

(Embodiment 7) FIG. 14 is a block diagram showing a radio station having a spread spectrum signal receiving apparatus according to Embodiment 7 of the present invention, in which a reference clock generator is used as a frequency adjuster. .

In FIG. 14, reference numeral 6 denotes a reference clock generator similar to that of FIG. 1, and reference numeral 60 denotes a carrier frequency generator (not shown).
A radio station that performs spread spectrum communication using the reference clock signal output from the reference clock generation unit 6 as the reference signal is a radio device 61 excluding the reference clock generation unit 6.

The operation of the radio station 60 having the spread spectrum signal receiving apparatus thus configured will be described.

In a radio communication system or a wired communication system, a voice signal or data is transmitted by modulating a carrier signal with a baseband signal. In this case, the receiving station uses a reference signal having the same frequency as that of the transmitting station. Reception is performed by generating a carrier and converting the frequency. However, in an actual communication system, a reference signal for generating a carrier differs between a transmitting station and a receiving station. In the case of a conventional cordless telephone using spread spectrum communication, the frequency shift of the reference signal causes a shift in the carrier frequency relationship between the transmitting station and the receiving station, thereby deteriorating the receiving characteristics. The deterioration of the reception characteristic is a problem that occurs in particular when the bandwidth of the IF-BPF is widened and a design having a sufficient margin is performed to compensate for a decrease in the reception signal level and an increase in distortion due to a frequency shift. As described above, in the cordless telephone using the conventional spread spectrum signal receiving apparatus, the bandwidth of the IF-BPF is widened, and instead of compensating for the deterioration of the received signal due to the shift of the frequency relation of the carrier frequency between the transmitting and receiving stations, the adjacent band is not used. Channel interference and an increase in noise due to the widening of the noise band were caused.

In the present embodiment, the reference clock signal output from the reference clock generator 6 is used for all the reference signals of the carrier frequency generator of the transmission / reception system of the radio 61. In the present embodiment, in addition to the configuration of the radio 61, the configuration is such that the reference clock generator 6 that supplies the reference signal as described above is added, so that the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal are changed. Is almost always the same, the frequency relationship between the transmitting station and the receiving station is always maintained more accurately than in the configuration of the conventional cordless telephone. Therefore IF-
The frequency band of the BPF can be made substantially equal to the signal bandwidth, adjacent channel interference is reduced, and the noise band is narrowed. Therefore, the signal-to-noise power ratio (hereinafter, referred to as “SNR”) of the received signal is reduced. Can be max. As a result, the quality of the received signal can be improved.

By setting the IF-BPF to have a narrow band, the frequency of the transmission reference clock signal and the frequency of the reception reference clock signal greatly deviate, for example, when the power is turned on. In such a case, the receiving station that performs one-way communication or the slave station that performs two-way communication performs synchronization supplementary processing of the spread spectrum signal including the frequency scan. In the case of a cordless telephone, since the slave unit and the base unit can communicate via the charging terminal during charging, by exchanging a signal for adjusting the frequency of the reference clock signal via the charging terminal, The frequency of the IF signal can be set within the IF-BPF band without emitting radio waves. When charging is completed and the slave unit and the master unit are located at a distance from each other, a frequency adjustment signal is periodically emitted from the master unit to keep the frequency deviation of the reference clock signal within a certain value. This prevents the IF signal from completely out of the band of the IF-BPF. As described above, the frequency scan is performed when the frequency of the reference clock signal is largely deviated, and control is performed so that the frequency of the reference clock signal does not largely deviate once the frequency of the reference clock signal matches. Even if a crystal oscillator having a lower frequency accuracy than that of a conventionally used crystal oscillator is used, the quality of a received signal can be improved as compared with the conventional case.

As described above, according to the present embodiment, the radio 61 is provided for inputting the reference clock signal output from the reference clock generator 6, and the radio 61 converts the frequency of the radio signal and converts the frequency of the carrier signal. By using the reference clock signal as the reference signal and / or the reference signal of the modulation / demodulation unit, the reference clock signal can be used as a reference clock signal of the carrier signal generation unit as well as the spread signal generation unit or the despread signal generation unit. In this case, since the frequency of the reception reference clock signal substantially matches the frequency of the transmission reference clock signal, the frequency difference of the carrier signal becomes extremely small, and the intermediate frequency becomes small. IF-BP in band
The bandwidth of F can be optimally designed, the selectivity is improved by reducing adjacent frequency signal interference, and
By minimizing the amount of noise by minimizing the equivalent noise bandwidth, the quality of the received signal can be improved.

[0110]

As described above, according to the spread spectrum signal receiving apparatus of the first aspect of the present invention, a despreading section for despreading a spread spectrum signal and outputting a received signal, A reception signal level detection unit that detects a level of the output reception signal and outputs a reception level signal indicating the reception signal level; a despread signal generation unit that generates a despread signal based on the reference clock signal; A phase controller for generating a phase control signal for controlling the phase of the despread signal output from the despread signal generator based on the reception level signal output from the level detector; A reference clock generator for generating a reference clock signal, and a frequency of the reference clock signal generated by the reference clock generator based on the phase control signal output from the phase controller. A reference clock signal (transmission reference) output from the reference clock generator of the spread spectrum signal transmitter based on the slope of the integrated value of the phase control signal output from the phase controller at predetermined time intervals. A frequency difference between a clock signal) and a reference clock signal (reception reference clock signal) output from a reference clock generation unit of the spread spectrum signal receiving device is obtained, and the spread spectrum signal is received according to the gradient of the integrated value of the phase control signal. Since the frequency of the reference clock generator of the device can be controlled, the frequency of the reception reference clock signal is made to match the frequency of the transmission reference clock signal, and the phase difference generated between the spread signal and the despread signal is reduced to zero. And the advantageous effect that the tracking process can be reduced can be obtained. .

According to the spread spectrum signal receiving apparatus of the second aspect, in the spread spectrum signal receiving apparatus of the first aspect, the reference frequency control section takes in the phase control signal output from the phase control section, A least-squares-error-slope calculating unit for obtaining an average time rate of change of the phase of the despread signal by obtaining a slope of the phase control signal at a predetermined time interval by linear approximation using a least-square error calculation, and an average of the phase of the despread signal A sign determination unit that outputs a sign determination signal indicating a positive or negative sign of the time change rate, and a reference frequency control signal generation unit that generates a reference frequency control signal based on the sign determination signal, By controlling the frequency of the generated reference clock signal by the reference frequency control signal, the gradient of the integrated value of the phase control signal at a predetermined time interval can be minimized. Since it can be obtained by an error calculation, the slope of the integrated value of the phase control signal can be calculated accurately even in a situation where the reception level signal is greatly affected by noise and the phase control signal contains much noise. This has an advantageous effect that the stability of the frequency control signal can be improved.

According to the spread spectrum signal receiving apparatus of the third aspect, in the spread spectrum signal receiving apparatus of the first aspect, the reference frequency control section fetches the phase control signal output from the phase control section, A point-to-point linear interpolation unit for calculating an average time change rate of the phase of the despread signal by applying a point-to-point linear interpolation operation to an integrated value of the phase control signal at a predetermined time interval; A code determination unit that outputs a code determination signal indicating the sign of the average time change rate of the phase of the despread signal obtained by the operation, and a reference frequency control signal that generates a reference frequency control signal based on the code determination signal The reference clock generation unit controls the frequency of the generated reference clock signal by the reference frequency control signal, thereby controlling the phase control at a predetermined time interval. Since the inclination of the integrated value of the signal can be determined by linear interpolation calculation between two points, is advantageous effect that it is possible to determine the tilt of the integrated value of the phase control signals at a predetermined time interval with a small amount of calculation obtained.

According to the spread spectrum signal receiver of the fourth aspect, in the spread spectrum signal receiver of the first aspect, the reference frequency control section fetches the phase control signal output from the phase control section, A phase control signal slope calculator for calculating a slope of the phase control signal at predetermined time intervals, and a slope comparator for calculating an average rate of change in phase of the despread signal based on the slope output from the phase control signal slope calculator When the absolute value of the average time rate of change of the phase of the despread signal is large, the frequency of the reference clock signal output from the reference clock generator is greatly changed, and the average time rate of change of the phase of the despread signal is A reference frequency control signal generator for slightly changing the frequency of the signal output from the reference clock generator when the absolute value is small, Since the frequency control corresponding to the absolute value of the gradient of the integrated value of the phase control signal in the interval can be performed, the frequency difference between the transmission reference clock signal and the reception reference clock signal can be quickly and stably canceled. The advantageous effect that it can be obtained is obtained.

According to the spread spectrum signal receiving apparatus of the fifth aspect, in the spread spectrum signal receiving apparatus of the first aspect, the reference frequency control section takes in the phase control signal output from the phase control section, and A phase control signal integrator for obtaining an integrated value of the control signal; a phase comparator for outputting a phase comparison signal indicating whether an integrated value output from the phase control signal integrator has exceeded a predetermined threshold; A reference frequency control signal generating unit for generating a reference frequency control signal based on the reference frequency control signal. When the integrated value of the phase control signal exceeds a predetermined threshold value of the phase control comparison unit according to the frequency difference between the clock signal and the reception reference clock signal, the reception reference clock is output. It is possible to control the frequency of issue, advantageous effect that the frequency difference between the transmission reference clock signal and the received reference clock signal with a simple circuit configuration can be canceled faster and stably can be obtained.

According to the spread spectrum signal receiving apparatus of the sixth aspect, in the spread spectrum signal receiving apparatus of any one of the first to fifth aspects, the received level signal output from the received signal level detecting section is provided. The reception level drop detection unit that outputs a reception level drop signal when the reception signal level shown by the reference value suddenly drops, and the reference when the rate of time change of the frequency indicated by the frequency control signal output from the reference frequency control unit is small. A reference frequency lock detection unit that outputs a frequency lock signal; and a phase output from the phase control unit when the reference frequency lock signal is output from the reference frequency lock detection unit and the reception level reduction signal is output from the reception level reduction unit. By providing a phase control signal cutoff unit for cutting off the control signal for a short time, the frequency of the transmission reference clock signal and the reception In a situation where the frequency of the reference clock signal is almost the same, the phase difference of the despread signal is very small even if the tracking process is stopped for a short time, so the received electric field strength is abrupt due to fading or the like. In the case of a change, it is possible to prevent the increase in the phase difference between the spread signal and the despread signal due to erroneous control in the tracking process by blocking the phase control signal, thereby maintaining the quality of the received signal. Advantageous effects can be obtained.

According to the spread spectrum signal receiving apparatus of claim 7, in the spread spectrum signal receiving apparatus of any one of claims 1 to 6, the reference clock signal output from the reference clock generating unit is input. The radio device uses a reference clock signal as a frequency conversion of a radio signal, a reference signal of a carrier signal and / or a reference signal of a modulation / demodulation unit, so that the reference clock signal is spread or despread. Since it can be used not only as a signal generator but also as a reference clock signal for a carrier signal generator, the frequency of the received reference clock signal almost matches the frequency of the transmission reference clock signal. , The frequency difference becomes extremely small, and the IF in the intermediate frequency band
-The bandwidth of the BPF can be designed optimally, the selectivity is improved by reducing adjacent frequency signal interference, and the noise amount is minimized by minimizing the equivalent noise bandwidth. An advantageous effect that the quality of the received signal can be improved is obtained.

According to the spread spectrum signal receiving method of the present invention, the determining step of determining the level of the received signal obtained by despreading the spread spectrum signal with the despread signal, and the step of determining based on the level of the received signal A phase control signal generating step for generating a phase control signal for controlling the phase of the despread signal, and a reference clock signal for controlling the frequency of the reference clock signal for generating the despread signal by a frequency control signal based on the phase control signal By having the frequency control step, the frequency difference between the frequency of the reception reference clock signal and the frequency of the transmission reference clock signal can be made zero as much as possible, so that the advantageous effect that tracking processing can be reduced can be achieved. can get.

According to the spread spectrum signal receiving method of the ninth aspect, in the spread spectrum signal receiving method of the eighth aspect, the reference clock signal frequency control step minimizes a gradient of the phase control signal at a predetermined time interval. Average time change rate calculating step of calculating the average time change rate of the phase of the despread signal by obtaining a linear approximation using a square error operation, and sign determination indicating the positive and negative signs of the average time change rate of the phase of the despread signal A code determination signal generating step of generating a signal; and a frequency control step of controlling the frequency of the reference clock signal based on the code determination new word so that the average time rate of change of the phase of the despread signal becomes infinitely zero. As a result, the slope of the integrated value of the phase control signal at a predetermined time interval can be obtained by the least square error calculation. Even in a situation where the bell signal is greatly affected by noise and the phase control signal contains much noise, the slope of the integrated value of the phase control signal can be calculated with high accuracy, and the stability of the frequency control signal can be improved. The advantageous effect described above can be obtained.

According to the spread spectrum signal receiving method of the tenth aspect, in the spread spectrum signal receiving method of the eighth aspect, the reference clock signal frequency control step is performed based on an integrated value of the phase control signal at a predetermined time interval. Calculating an average time rate of change of the phase of the despread signal by the linear interpolation between two points; and calculating the positive and negative of the average time rate of change of the phase of the despread signal obtained by the linear interpolation between the two points A code determination signal generating step of generating a code determination signal indicating a code, and a frequency control step of controlling the frequency of the reference clock signal based on the code determination signal so that the average time change of the phase of the despread signal becomes infinitely zero. , The slope of the integrated value of the phase control signal at a predetermined time interval can be obtained by a two-point linear interpolation operation. In, it is possible to determine the tilt of the integrated value of the phase control signal at predetermined time intervals a small amount of computation, the reduction of processing time, is advantageous effect that it is possible to reduce the circuit scale is obtained.

According to the spread spectrum signal receiving method of the present invention, in the spread spectrum signal receiving method of the eighth aspect, the reference clock signal frequency control step finds a gradient of the phase control signal at a predetermined time interval. Calculating a phase control signal slope, calculating an average time change rate of the phase of the despread signal from the slope, and setting a reference when the absolute value of the average time change rate of the phase of the despread signal is large. If the frequency of the clock signal is greatly changed and the absolute value of the time change rate of the phase of the despread signal is small, the frequency of the reference clock signal is slightly changed to reduce the average time change rate of the phase of the despread signal. Frequency control step of controlling the frequency of the reference clock signal so as to be infinitely zero,
Since it is possible to perform frequency control corresponding to the absolute value of the gradient of the integrated value of the phase control signal at a predetermined time interval,
An advantageous effect is obtained that the frequency difference between the transmission reference clock signal and the reception reference clock signal can be canceled quickly and stably.

According to the spread spectrum signal receiving method of the twelfth aspect, in the spread spectrum signal receiving method of the eighth aspect, the reference clock signal frequency control step includes calculating an integrated value for obtaining an integrated value of the phase control signal. A step of determining whether the integrated value of the phase control signal has exceeded a predetermined threshold value and determining in which of the positive or negative phase direction the integrated value of the phase control signal has been integrated; Controlling the frequency of the reference clock signal based on the determination result, thereby controlling the average time rate of change of the phase of the despread signal to be infinitely zero. When the integrated value of the phase control signal exceeds a predetermined threshold value according to the frequency difference between It is possible to control the frequency of the click signal, advantageous effect that the frequency difference between the transmission reference clock signal and the received reference clock signal with a simple circuit configuration can be canceled faster and stably can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a spread spectrum signal receiving apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a spread spectrum signal receiving apparatus according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a spread spectrum signal receiving apparatus according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a spread spectrum signal receiving apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a spread spectrum signal receiving apparatus according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a spread spectrum communication system for performing two-way communication using the spread spectrum signal receiving apparatus according to the first embodiment of the present invention;

FIG. 7 is a block diagram showing a spread spectrum communication system for performing one-way communication using the spread spectrum signal receiving apparatus according to the first embodiment of the present invention;

FIG. 8 is a graph showing an autocorrelation characteristic of a spread code sequence used for spread spectrum communication.

FIG. 9 is a flowchart showing the operation of the spread spectrum signal receiving apparatus of FIG. 2;

FIG. 10 shows a time change of the phase control signal, a time change of the integrated value of the phase control signal, and a slope of the integrated value of the phase control signal at a predetermined time interval according to the second embodiment of the present invention, obtained by a least squares calculation. Graph showing the approximate straight line when

FIG. 11 is a linear interpolation between two points of a time change of a phase control signal, a time change of an integrated value of the phase control signal, and a slope of the integrated value of the phase control signal at a predetermined time interval according to the third embodiment of the present invention. Graph showing the complementary straight line obtained by

FIG. 12 is a graph showing input / output characteristics of a tilt comparison unit.

FIG. 13 is a block diagram showing a spread spectrum signal receiving apparatus according to a sixth embodiment of the present invention.

FIG. 14 is a block diagram showing a wireless station having a spread spectrum signal receiving apparatus according to Embodiment 7 of the present invention.

FIG. 15 is a block diagram showing a conventional spread spectrum signal receiving apparatus.

FIG. 16 is a flowchart showing tracking processing in a conventional spread spectrum signal receiving method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Despreading part 2 Received signal level detecting part 3 Phase controlling part 4 Reference frequency controlling part 5 Despreading signal generating part 6 Reference clock generating part 12 Least square error slope calculating part 13 Code judging part 14 Reference frequency control signal generating part 15 2 Point-to-point linear interpolation calculation unit 16 Phase control signal slope calculation unit 17 Slope comparison unit 18 Phase control signal integration unit 19 Phase comparison unit 20 Received level drop detection unit 21 Reference frequency lock detection unit 22 Phase control signal cutoff unit 30 Main station 31, 36, 41, 44 Spread signal generator 32, 37 Despread signal generator 33, 38, 42, 45 Reference clock signal generator 34, 39 Radio 35 Dependent station 40 Transmitting station 43 Receiving station 60 Radio station 61 Radio

Claims (12)

[Claims] 1. A despreading section for despreading a spread spectrum signal to output a received signal, and detecting a level of the received signal output from the despreading section and outputting a received level signal indicating the received signal level. A reception signal level detection unit, a despread signal generation unit that generates a despread signal based on a reference clock signal, and the despread signal generation unit based on the reception level signal output from the reception signal level detection unit. A phase control unit that generates a phase control signal that controls the phase of the output despread signal, a reference clock generator that generates the reference clock signal that is input to the despread signal generator,
A reference frequency control unit that controls a frequency of a reference clock signal generated by the reference clock generation unit based on the phase control signal output from the phase control unit. 2. The reference frequency control section fetches the phase control signal output from the phase control section, and obtains a slope of the phase control signal at a predetermined time interval by linear approximation using least square error calculation. A least-squares error slope calculating unit that calculates an average time change rate of the phase of the despread signal, and a code determination unit that outputs a sign determination signal indicating the sign of the average time change rate of the phase of the despread signal. A reference frequency control signal generation unit that generates a reference frequency control signal based on the sign determination signal, wherein the reference clock generation unit controls the frequency of the generated reference clock signal by the reference frequency control signal The spread spectrum signal receiving apparatus according to claim 1, wherein: 3. The reference frequency control unit fetches the phase control signal output from the phase control unit, and applies a two-point linear complement operation to an integrated value of the phase control signal at a predetermined time interval. A point-to-point linear complementation calculation unit for calculating an average time change rate of the phase of the despread signal,
A code determination unit that outputs a code determination signal indicating a positive or negative sign of an average time rate of change of the phase of the despread signal obtained by the two-point linear interpolation operation, and a reference frequency control signal based on the code determination signal And a reference frequency control signal generator for generating the reference clock signal, wherein the reference clock generator controls the frequency of the generated reference clock signal by the reference frequency control signal. Spread spectrum signal receiver. 4. A phase control signal slope calculating section for fetching the phase control signal output from the phase control section and calculating a slope of the phase control signal at a predetermined time interval; A slope comparison unit that calculates an average time change rate of the phase of the despread signal based on the slope output from the control signal slope calculation unit, and a case where the absolute value of the average time change rate of the phase of the despread signal is large. Greatly changes the frequency of the reference clock signal output from the reference clock generator, and when the absolute value of the average time rate of change of the phase of the despread signal is small, the signal output from the reference clock generator is 2. The spread spectrum signal receiving apparatus according to claim 1, further comprising: a reference frequency control signal generator for slightly changing the frequency. 5. A phase control signal integrating section for taking in the phase control signal output from the phase control section to obtain an integrated value of the phase control signal, and an output from the phase control signal integrating section. A phase comparison unit that outputs a phase comparison signal indicating whether the integrated value exceeds a predetermined threshold, and a reference frequency control signal generation unit that generates a reference frequency control signal based on the phase comparison signal, The spread spectrum signal receiving apparatus according to claim 1, wherein the reference clock generator controls the frequency of the generated reference clock signal based on the reference frequency control signal. 6. A reception level decrease detection section for outputting a reception level decrease signal when the reception signal level indicated by the reception level signal output from the reception signal level detection section sharply decreases, and the reference frequency control. A reference frequency lock detection unit that outputs a reference frequency lock signal when the rate of time change of the frequency indicated by the frequency control signal output from the unit is small, and the reference frequency lock signal is output from the reference frequency lock detection unit; A phase control signal cutoff unit that cuts off the phase control signal output from the phase control unit for a short time when the reception level reduction signal is output from the reception level reduction unit. 6. The spread spectrum signal receiving device according to any one of 1 to 5. 7. A wireless device for inputting a reference clock signal output from the reference clock generating unit, wherein the wireless device is used as a frequency conversion of a wireless signal, a reference signal of a carrier signal, and / or a reference signal of a modulation / demodulation unit. 7. The spread spectrum signal receiving apparatus according to claim 1, wherein the reference clock signal is used. 8. A determining step of determining a level of a received signal obtained by despreading a spread spectrum signal with a despread signal, and a phase control for controlling a phase of the despread signal based on the level of the received signal. A phase control signal generating step of generating a signal; and a reference clock signal frequency control step of controlling a frequency of a reference clock signal for generating the despread signal by a frequency control signal based on the phase control signal. Spread spectrum signal receiving method. 9. The reference clock signal frequency control step includes determining a gradient of the phase control signal at a predetermined time interval by linear approximation using a least square error calculation, thereby calculating an average time change rate of the phase of the despread signal. Calculating an average time rate of change, a sign determination signal generating step for generating a sign determination signal indicating the sign of the average time rate of change of the phase of the despread signal, and an average time rate of change of the phase of the despread signal. A frequency control step of controlling the frequency of the reference clock signal based on the sign determination signal so that the value of the reference clock signal becomes infinitely zero.
3. The method for receiving a spread spectrum signal according to claim 1. 10. The reference clock signal frequency control step includes the step of calculating an average time change rate of the phase of the despread signal by a linear interpolation between two points from an integrated value of the phase control signal at predetermined time intervals. A calculating step, a code determining signal generating step of generating a code determining signal indicating a positive or negative sign of an average time rate of change of the phase of the despread signal obtained by the two-point linear interpolation operation, A frequency control step of controlling a frequency of the reference clock signal based on the sign determination signal so that an average time change of a phase becomes zero as much as possible. Method. 11. The reference clock signal frequency control step includes: a phase control signal slope calculating step of obtaining a slope of the phase control signal at a predetermined time interval; and an average time change rate of the phase of the despread signal from the slope. Calculating the average time rate of change; and, when the absolute value of the average time rate of change of the phase of the despread signal is large, changing the frequency of the reference clock signal greatly; A frequency control step of controlling the frequency of the reference clock signal so that the average time change rate of the phase of the despread signal is infinitely zero by slightly changing the frequency of the reference clock signal when the value is small. 9. The method according to claim 8, comprising: 12. The reference clock signal frequency control step includes: an integrated value calculating step of obtaining an integrated value of the phase control signal; determining whether the integrated value of the phase control signal exceeds a predetermined threshold; A deciphering step of judging whether the integrated value of the control signal is accumulated in either the positive or negative phase direction, and controlling the frequency of the reference clock signal based on the result of the judging step in the deciphering step to obtain the despread signal. And a frequency control step of controlling the average time change rate of the phase to be infinitely zero.