JPH11122216A - Spread spectrum communication receiver and its synchronization establishment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the spread spectrum communication receiver and its synchronization establishment method where the throughput of the entire system is improved and synchronization is established at a high speed with high accuracy. SOLUTION: Upon the receipt of a rough mode status signal whose status is set to '1' and a control signal representing correlation peaks from a timing generating means 104, a phase control means 105 executes control of a phase shift means 107 in the rough synchronization mode. When number of detection times of correlation peaks reaches a prescribed number of times, the status of the rough synchronization mode is set to '0' and the status of the fine synchronization mode is set to '1'. Then the timing generating means 104 counts number of times of detection of correlation peaks, that is, number of times of phase control in the fine synchronization mode, and when the detection of the correlation peaks reaches a prescribed number of times, an output of a control signal from the timing generating means 104 to the phase control means is stopped from that point of time till the end of reception of PCM data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication receiving apparatus and a method for establishing synchronization thereof, and more particularly to a spread spectrum communication receiving apparatus for performing reproduction clock synchronization and a method for establishing synchronization thereof.

[0002]

2. Description of the Related Art A spread spectrum wireless communication system uses a pseudo-noise (Pseudo N
oise: PN) It is spread over a wide band on the frequency axis by a code sequence, converted into a radio frequency (RF) signal, and transmitted.

In a receiver used in such a communication system, the signal level of an RF signal to be received greatly varies depending on a distance from the transmitter and an obstacle, so that automatic gain adjustment (Auto Gain) is performed.
Control: AGC) means is provided to perform gain control in the reception transmission path so that the signal level of the baseband signal is always substantially constant, convert the reception signal into a baseband signal, and convert the same PN code as that of the transmission side. It is configured to demodulate data by using and despreading.

FIG. 6 is a block diagram showing a general configuration of a conventional spread spectrum communication receiver.

[0005] In the figure, a signal received by an antenna 601 is input to a high frequency processing unit 602. This received signal is converted into a baseband signal after one or more times of frequency conversion through processing such as amplification and filtering in the high frequency processing unit 602. High frequency processing unit 6
02 is connected to the demodulation unit 603 and the synchronization unit 604. Further, the high frequency processing unit 602 includes an automatic gain adjustment circuit (AGC) (not shown) that controls the signal level of the baseband signal output to the demodulation unit 603 to be constant.

In the synchronizing section 604, generally, a surface acoustic wave (Su
rface Acoustic Wave (SAW) Correlation between a received signal and a local reference PN code generated on the receiving side is performed using an analog correlator such as a convolver or a SAW matched filter or a digital correlator such as a digital matched filter. The code timing is extracted from the output, and clock synchronization is established by a delay lock loop (DLL) or the like. The clock signal generated by the synchronizing unit 604 and the code generation timing signal whose synchronization with the clock signal has been established are input to the demodulating unit 603.

The demodulation section 603 generates a reference spreading code sequence using the clock signal input from the synchronization section 604 and a code generation timing signal in which synchronization with the clock signal has been established. The baseband signal input from 602 is spread spectrum demodulated. The data subjected to the spread spectrum demodulation in this manner is output as demodulated data.

In a spread spectrum communication system in which data such as image data is made into a burst and wireless communication is performed in a time-division manner, in order to receive and demodulate a data burst, a data burst to be received is required. It is necessary to establish synchronization at high speed. In this case, for example, FIG.
As shown in FIG.
In this case, a so-called packet communication system in which a preamble 702 made up of a pilot code for synchronization or the like is added before the transmission is performed.

When a large amount of digital data (eg, image data) is transmitted wirelessly in response to recent multimedia applications, the data is subjected to code division multiplexing (Code Division Multiplexing) in order to improve data throughput. Division
Multiplex: CDM).

[0010] Here, the CDM system is one of spread spectrum communication systems used for improving data throughput, and is performed by spreading and multiplexing data using N codes which are orthogonal to each other. This is a method of transmitting. Specifically, for example, as shown in FIG.
(CDM data) 801 transmitted in accordance with the preamble method includes a preamble 80 including a synchronization pilot code and the like.
2 is added. When the CDM data 801 is received and demodulated, the receiving apparatus adjusts the gain and synchronization during reception while receiving the preamble 802 transmitted before the CDM data 801, and
A method of maintaining the gain and synchronization at a constant value during reception of M data has already been proposed (for example, see Japanese Patent Application Laid-Open No.
No. 7126).

FIG. 9 shows a conventional configuration of a synchronizing unit 604 employing a DLL (delay lock loop) used in a spread spectrum communication system for transmitting data in a burst form in a time division manner as described above. FIG.

In FIG. 1, a correlating means 901 performs a correlation operation between a received signal and a PN code for local reference. For example, an analog correlator such as a SAW convolver or a SAW matched filter or a digital correlator such as a digital matched filter is used. A vessel or the like is used. The correlation means 90
If a digital correlator is used as 1, the PN code chip rate is high, so that an A / D converter (not shown) in the receiving unit performs sampling at the PN code chip rate or about twice as high as the PN code chip rate. Often. The output of the correlation means 901 is delayed and subtracted by the delay / addition means 902 to generate an S curve as shown in FIG.

FIG. 10 is a diagram showing an example of an S-curve generated by the synchronization section 604. This S-curve is approximately drawn, and when a digital correlator is used as the correlating means 901, the S-curve is acquired as, for example, a value sampled every １ ／ chip.

Note that the example shown in FIG.
The output of 1 is delayed by one chip and subtracted, but the amount of delay is not limited to one chip. In FIG. 9, the output of the correlation means 901 is configured to be delayed and subtracted.
It is also possible to use two correlating means and delay the local reference PN code of one of the correlating means to generate an S curve.

The correlation output delayed by the delay / adder 902 is input to the peak detector 903. When the level of the correlation output becomes equal to or higher than a predetermined level, the correlation output at that time is detected as a correlation peak by the peak detection means 903. The detected correlation peak is input to the timing generation unit 904.

While the correlation peak is being detected, the timing generator 904 controls the operation of the phase controller 905. The phase control means 905 calculates the zero cross point of the S curve (for example, the timing of 1/2 chip in FIG. 10).
The phase shift means 907 controls the phase of the reference signal oscillating means 906 in the direction of delaying the phase if the S curve is positive, and in the direction of advancing the phase if negative.
Control.

During the period when the preamble 802 is being received, the number of times the correlation peak is detected by the peak detecting means is counted by the timing generating means 904. After the predetermined number of correlation peaks are detected, that is, after the predetermined number of phase controls are performed, the synchronization unit 6
The state of 04 is maintained as it is. Therefore, while the CDM data 801 transmitted after the preamble 802 is being received, the clock signal and the code generation timing signal are output with the reception gain and the synchronization kept at constant values.

As described above, the clock frequency output from the synchronization section 604 matches the clock frequency sent from the transmitting side very accurately, so that data for a relatively long period is reproduced with a small phase error. be able to.

However, the synchronization section 604 configured as described above is affected by, for example, the time constant of the ACG circuit built in the synchronization section 604, and the correlation detection level in the initial stage of data burst reception is affected. There is an unstable period. For this reason, conventionally, a clock signal has been obtained by shifting the phase of the reference oscillation signal by a fixed amount in accordance with the positive / negative information of the zero cross point of the S curve shown in FIG.

FIG. 11 is a diagram showing the relationship between the zero-cross point and the amount of phase shift in a conventional spread spectrum communication receiver.

In the figure, the horizontal axis is a digital value indicating the level of the zero cross point of the S curve, and the vertical axis is the phase shift amount of the reference signal by the phase shift means 907. The direction of the phase shift by the phase shift means 907 is adjusted by the phase control means 905 when the phase control means 905 receives the control signal of the timing generation means 904.
Here, in consideration of the resolution, a phase shifter 907 having a resolution of 1/10 T (T: clock cycle) is used, so that 1/10 T is used for each phase adjustment.
Are shifted.

[0022]

However, in the above-described phase shift, since only a fixed amount is shifted, there is a disadvantage that it takes a very long time to pull in a distant phase difference. In particular, in a spread spectrum communication receiving apparatus which performs data communication in a burst manner in a time-division manner, if the time spent for synchronizing the clock signal becomes longer, the preamble 802 is set in advance.
It is necessary to lengthen the transmission period of the system, and there is a problem that the throughput of the entire system is reduced. Further, as the resolution of the phase shift is increased to improve the accuracy of clock synchronization, the time spent for synchronization pull-in becomes longer, and it has been difficult to achieve high-speed and high-accuracy synchronization.

The present invention has been made in view of the above problems, and provides a spread spectrum communication receiver capable of realizing high-speed and high-accuracy synchronization and improving the system throughput, and a method of establishing the synchronization. The purpose is to do.

[0024]

In order to achieve the above object, a spread spectrum communication receiver according to a first aspect of the present invention comprises: a correlation unit for performing a correlation operation between a received signal and a local reference code on a receiving side; Delay means for delaying the output signal;
A phase lock unit configured to shift the phase of a reference oscillation signal on the receiving side according to a level difference between an output signal level of the correlation unit and a level of an output signal of the delay unit and output the same. A spread communication receiver, comprising: peak detection means for detecting a correlation peak from an output signal of the correlation calculation means; and timing for generating a synchronization pull-in mode according to the number of times of detection of the correlation peak detected by the peak detection means. Generating means;
A shift amount control unit that controls a shift amount of the phase shift unit according to the synchronization pull-in mode generated by the timing generation unit.

According to a second aspect of the present invention, there is provided the spread spectrum communication receiving apparatus according to the first aspect, wherein the correlating means comprises a digital matched filter.

According to a third aspect of the present invention, in the spread spectrum communication receiver according to the first or second aspect, the synchronization pull-in mode generated by the timing generation means is an initial pull-in mode and a fine adjustment mode. In two modes.

According to a fourth aspect of the present invention, in the spread spectrum communication receiving apparatus of the third aspect, the shift amount control means determines a shift amount when the synchronization pull-in mode is the initial pull-in mode. The shift amount is made larger than the shift amount when the synchronization pull-in mode is the fine adjustment mode.

According to a fifth aspect of the present invention, in the spread spectrum communication receiving apparatus according to the third aspect of the present invention, when the synchronization pull-in mode is the initial pull-in mode, the amount of shift is as follows. It is characterized in that the shift amount is almost twice the shift amount in the fine adjustment mode.

According to a sixth aspect of the present invention, in the spread spectrum communication receiver according to the first or second aspect, the synchronization pull-in mode generated by the timing generation means includes a plurality of initial pull-in modes and at least a plurality of initial pull-in modes. It is characterized by a single fine adjustment mode.

According to a seventh aspect of the present invention, in the spread spectrum communication receiving apparatus according to the sixth aspect, the shift amount control means determines a shift amount when the synchronization pull-in mode is the initial pull-in mode. The shift amount is set larger than the shift amount when the synchronization pull-in mode is the fine adjustment mode.

In the spread spectrum communication receiving apparatus according to an eighth aspect of the present invention, in the spread spectrum communication receiving apparatus according to the sixth aspect, when the synchronization pull-in mode is the initial pull-in mode, the amount of shift is as follows. The shift amount is approximately twice or more of the shift amount in the fine adjustment mode.

In the spread spectrum communication receiving apparatus according to a ninth aspect, in the spread spectrum communication receiving apparatus according to the third aspect, when the correlation peak is less than a predetermined value, the timing generating means sets the synchronization pull-in mode as the synchronization pull-in mode. An initial pull-in mode is generated, and when the correlation peak is equal to or more than the predetermined value, the fine adjustment mode is generated as the synchronization pull-in mode.

According to a tenth aspect of the present invention, there is provided a method for establishing synchronization in a spread spectrum communication receiving apparatus, comprising: a correlating means for performing a correlation operation between a received signal and a local reference code on a receiving side; Spread spectrum communication having a delay locked loop comprising phase shift means for shifting and outputting the phase of the receiving-side reference oscillation signal in accordance with the level difference between the output signal level of the correlation means and the output signal level of the delay means. A method for establishing synchronization of a receiving device, comprising: detecting a correlation peak from an output signal of the correlation calculating means; generating a plurality of synchronization pull-in modes according to the number of times of detection of the detected correlation peak; The shift amount of the phase shift means is controlled according to the pull-in mode.

According to a eleventh aspect of the present invention, there is provided a method for establishing synchronization of a spread spectrum communication receiving apparatus according to the tenth aspect, wherein the plurality of generated synchronization pull-in modes are an initial pull-in mode and a fine adjustment mode. Mode.

According to a twelfth aspect of the present invention, in the method for establishing synchronization of the spread spectrum communication receiving apparatus according to the eleventh aspect, when the synchronization pull-in mode is the initial pull-in mode and the fine adjustment mode is used. The shift amount is controlled to be larger.

According to a thirteenth aspect of the present invention, in the method for establishing synchronization of the spread spectrum communication receiving apparatus according to the eleventh aspect, when the synchronization pull-in mode is the initial pull-in mode, the shift amount is set in the synchronization pull-in mode. Is approximately twice the shift amount in the fine adjustment mode.

According to a fourteenth aspect of the present invention, in the method for establishing synchronization of the spread spectrum communication receiving apparatus according to the tenth aspect, the generated plurality of synchronization pull-in modes include a plurality of initial pull-in modes and at least one time. Is a fine adjustment mode.

According to a fifteenth aspect of the present invention, there is provided a method for establishing synchronization of a spread spectrum communication receiving apparatus according to the fourteenth aspect, wherein the synchronous pull-in mode is the initial pull-in mode and the fine adjustment mode. The shift amount is set to be larger than the shift amount.

According to a sixteenth aspect of the present invention, in the method of establishing a synchronization of the spread spectrum communication receiving apparatus according to the fourteenth aspect, when the synchronization pull-in mode is the initial pull-in mode, the shift amount is the synchronization pull-in mode. Is approximately twice or more the shift amount in the fine adjustment mode.

According to a seventeenth aspect of the present invention, in the method for establishing synchronization of the spread spectrum communication receiving apparatus according to the eleventh aspect, when the correlation peak is less than a predetermined value, the initial pull-in mode is set as the synchronization pull-in mode. And generating the fine adjustment mode as the synchronization pull-in mode when the correlation peak is equal to or more than the predetermined value.

[0041]

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

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. Note that the spread spectrum communication receiving apparatus according to the present embodiment can be realized by a configuration similar to that of the above-described conventional spread spectrum communication receiving apparatus (FIG. 6).

FIG. 1 is a block diagram showing a delay locked loop (De-Loop) built in a spread spectrum communication receiver according to the present embodiment.
FIG. 3 is a diagram illustrating a configuration of a synchronization unit 604 having a lay lock loop (DLL) (hereinafter, referred to as “DLL”).

In the figure, a correlation means 101 performs a correlation operation between a received signal and a PN signal for local reference, and for example, a surface acoustic wave (Surface Acoustic Wave: SAW,
An analog correlator such as a convolver or a SAW matched filter, or a digital correlator such as a digital matched filter is used. When a digital correlator is used as the correlating means 101, the chip rate of the PN code is high, so that the A / D converter (not shown) of the receiving unit uses the chip rate of the PN code or its 2
It is often sampled at about twice the frequency.

The output of the correlation means 101 is input to the delay / addition means 102, and the delay / addition means performs delay subtraction processing, thereby generating an S curve as shown in FIG.

This S curve is approximately drawn.
When a digital correlator is used as the correlating means 101, it can be obtained, for example, as a value sampled every clock (= １ ／ chip).

The S curve shown in FIG. 10 is obtained by subtracting the correlation means 101 by delaying one code chip.
The delay amount is not limited to one chip. In FIG. 1, the output of the correlating means 101 is configured to be delayed and subtracted. However, two correlating means are provided, and an S curve is generated by delaying the local reference PN code of one of the correlating means. May be configured.

The correlation output delayed by the delay / adder 102 is input to the peak detector 103. When the level exceeds a predetermined level, the correlation output at that time is detected as a correlation peak by the peak detecting means 103. The detected correlation peak is input to the timing generation unit 104.

FIG. 2 is a timing chart showing an example of the output timing of the signal output from the timing generating means 104. FIG. 2A shows the timing at which the detected correlation peak is input. 2 (b) shows a timing at which a control signal for controlling the phase control means is output, and FIGS. 2 (c) and 2 (d) show that the mode is the coarse synchronization mode or the fine synchronization mode, respectively. The timing at which the status is output is shown.

When the correlation peak is input, the timing generation means 104 sets the status of the coarse synchronization mode to "1", and outputs the mode status signal and a control signal corresponding to the input correlation peak to the phase control means. Output to 105. Upon receiving the mode status signal in which the status of the coarse synchronization mode is set to “1”, the phase control unit 105
Executes the control of the phase shift means 107 in the coarse synchronization mode.

The timing generation means 104 counts the number of times a correlation peak is detected, that is, the number of times the phase coarse synchronization control is performed. When the number of correlation peak detections reaches a predetermined number, the timing of the coarse synchronization mode is changed to " 0 "and the status of the fine synchronization mode is set to" 1 ". In the example shown in FIG. 2, the control in the coarse synchronization mode is performed four times. The number of times can be appropriately set in accordance with the final phase shift amount that has to be pulled in at the time of the pull-in operation. However, at the end of the pull-in operation, the most distant phase difference can be almost pulled in. It is desirable to set the phase shift amount to the size.

Even after the status of the fine synchronization mode is set to "1", the timing generation means 104 counts the number of times a correlation peak is detected, that is, the number of times phase control is performed in the fine synchronization mode. When the number of correlation peak detections reaches a predetermined number, the output of the control signal from the timing generation unit 104 to the phase control unit is stopped from that point until the end of the reception of the PCM data. Therefore, while the PCM data is being received, the clock signal and the code generation timing are output with the reception gain and the synchronization kept at constant values.

As described above, since the clock frequency output from the synchronization section 604 matches the clock frequency transmitted from the transmitting side very accurately, the data can be reproduced with a small phase error in the data of a relatively long section. It becomes possible.

When a mode status signal and a control signal are input by the timing generation unit 104, the phase control unit 105 performs shift control of the phase of the reference signal oscillation unit 106 according to the pull-in mode indicated by the mode status at that time. Thus, the shift amount of the phase shift means 107 is adjusted. Note that the reference signal oscillating means 106 includes a crystal oscillator or the like, and one having an output frequency accuracy of about 1 ppm to several ppm is desirable.

The phase shift amount of the phase shift means 107 is
The phase is changed by the phase control unit in accordance with the pull-in mode indicated by the mode status signal input by the timing generation unit 104.

FIG. 3 is an explanatory diagram showing the relationship between the phase shift amount of the phase shift means 107 and the zero-cross point.

As shown in FIG.
In the case where the mode status signal input by No. 04 indicates the coarse synchronization mode, when the correlation output level at the zero-cross point of the S curve (for example, the timing of チ ッ プ chip in FIG. 10) is positive, + ＴT (T Is the clock cycle), and-相関 T if the correlation output level is negative,
The phase shift amount is adjusted so as to shift the phase of the reference signal oscillation means 106. Also, when the mode status signal indicates the fine synchronization mode, the correlation output level at the zero-cross point of the S curve is + 1 / 10T each time the correlation output level is positive, and -110T each time the correlation output level is negative. The phase shift amount is adjusted so as to shift the phase of the reference signal oscillation means 106.

In this embodiment, in consideration of the final synchronization accuracy, a phase shift means having a resolution of 1 / 10T is used, and in the coarse synchronization mode, a double phase shift amount is used. However, a desired amount of phase shift can be adopted by appropriately selecting the resolution according to the synchronization accuracy desired by the system. That is, the amount of phase shift in the coarse synchronization mode can be set to an appropriate value depending on the time and accuracy that can be given to the pull-in in the coarse synchronization mode.

As described above, according to the present embodiment, the phase shift amount used in the synchronization pull-in performed when the clock signal is generated from the reference signal is set to an appropriate value regardless of the final synchronization accuracy. Can be set to Therefore, it is possible to shorten the time required for synchronization pull-in, and to realize a high-speed and high-accuracy circuit for clock synchronization without using any special device, thereby improving the system throughput. Will be able to do it.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. 4 and FIG. Note that the configuration of the synchronization section 604 incorporated in the spread spectrum communication receiving apparatus according to the present embodiment can be realized by the configuration shown in FIG. 1 of the above-described first embodiment. Will be described with reference to FIG.

FIG. 4 is a timing chart showing an example of the output timing of the signal output from the timing generation means 104 according to the present embodiment. FIG. 4A shows the timing at which the detected correlation peak is input. FIG. 4B shows a timing at which a control signal for controlling the phase control means 105 is output.
(C) and FIG. 4 (d) show the timing at which the status indicating the first coarse synchronous mode and the second coarse synchronous mode are output, respectively, and FIG. 4 (e) shows the fine synchronous mode. This indicates the timing at which the status indicating the presence of the event is output.

When the correlation peak is input, the timing generator 104 sets the status of the first coarse synchronization mode to “1”, and outputs the mode status signal and a control signal corresponding to the input correlation peak. Phase control means 105
Output to "1" for the status of the first coarse synchronization mode
Is received, the phase control means 105 controls the phase shift means 107 in the first coarse synchronization mode.

The timing generation means 104 counts the number of times a correlation peak is detected, that is, the number of times the phase coarse synchronization control is performed. When the number of correlation peak detections reaches a predetermined number, the first coarse synchronization mode is started. The status is set to "0", the status of the second coarse synchronization mode is set to "1", and this mode status signal and a control signal corresponding to the input correlation peak are output to the phase control means 105. .
Upon receiving a mode status signal in which the status of the first coarse synchronization mode is set to “1”, the phase control unit 105
Executes the control of the phase shift means 107 in the second coarse synchronization mode.

In the example shown in FIG. 4, the control in the first coarse synchronization mode and the control in the second
Has been done times. The number of times can be set as appropriate according to the final phase shift amount that needs to be pulled in during the pull-in operation.

Further, the timing generation means counts the number of times the correlation peak is detected, and when the number reaches a predetermined number, sets the status of the second coarse synchronization mode to “0” and changes the status of the fine synchronization mode to “0”. The mode status signal is set to “1” and a control signal corresponding to the input correlation peak is output to the phase control unit 105. When receiving the mode status signal in which the status of the fine synchronization mode is set to "1", the phase control means 105 controls the phase shift means 107 in the fine synchronization mode.

Even after the status of the fine synchronization mode is set to "1", the timing generation means 104 counts the number of times a correlation peak is detected, that is, the number of times phase control is performed in the fine synchronization mode. When the number of correlation peak detections reaches a predetermined number, the output of the control signal from the timing generation unit 104 to the phase control unit is stopped from that point until the end of the reception of the PCM data. Therefore, while the PCM data is being received, the clock signal and the code generation timing signal are output with the reception gain and the synchronization kept at constant values.

As described above, since the clock frequency output from the synchronization section 604 matches the clock frequency transmitted from the transmitting side very accurately, the data can be reproduced with a small phase error in the data of a relatively long section. It becomes possible.

On the other hand, when the mode status signal and the control signal are input by the timing generation unit 104, the phase control unit 105 shifts the phase of the reference signal oscillation unit 106 according to the synchronization pull-in mode indicated by the mode status at that time. The phase shift means 107 is controlled
Adjust the shift amount of.

The phase shift amount of the phase shift means 107 is
The phase is changed by the phase control unit in accordance with the pull-in mode indicated by the mode status signal input by the timing generation unit 104.

FIG. 5 is an explanatory diagram showing the relationship between the phase shift amount of the phase shift means 107 and the zero cross point.

As shown in FIG.
In the case where the mode status signal input by 04 indicates the first coarse synchronization mode, + 2 // when the correlation output level at the zero cross point of the S curve (for example, the timing of １ ／ chip in FIG. 10) is positive. 5T (T is a clock cycle), -2 / 5T when the correlation output level is negative
The phase shift amount is adjusted so that the phase of the reference signal oscillating means 106 is shifted each time. When the mode status signal input by the timing generation unit 104 indicates the second coarse synchronization mode, the correlation output level at the zero crossing point of the S curve (for example, the timing of チ ッ プ chip in FIG. 10) is positive. In some cases, + ／ T (T is a clock cycle) at a time, and when the correlation output level is negative,
The phase shift amount is adjusted so as to shift the phase of the reference signal oscillation means 106 by 5T. When the mode status signal indicates the fine synchronization mode, and when the correlation output level at the zero cross point of the S curve is positive, + 1 /
When the correlation output level is negative for each 10T, -1/1
The phase shift amount is adjusted so as to shift the phase of the reference signal oscillation means 106 by 0T.

In this embodiment, in consideration of the final synchronization accuracy, phase shift means having a resolution of 1 / 10T is used, and in the first coarse synchronization mode, the phase shift amount is four times as large as this. In the second coarse synchronization mode, the double phase shift amount is adopted. However, a desired phase shift amount can be adopted by appropriately selecting the resolution according to the synchronization accuracy desired by the system. That is, the amount of phase shift in the coarse synchronization mode can be set to an appropriate value depending on the time and accuracy that can be given to the pull-in in the coarse synchronization mode.

In this embodiment, the shift amount for clock synchronization is changed using three types of synchronization pull-in modes. However, it is needless to say that the number of modes is not limited to this. Nor.

As described above, according to the present embodiment, the phase shift amount in the initial phase synchronization pull-in is adjusted according to the phase shift amount that must be finally synchronized regardless of the final synchronization accuracy. In addition, since the amount of phase shift is changed stepwise, the synchronization pull-in time can be significantly reduced, and the speed and precision of the circuit for clock synchronization can be increased without using special equipment. And the throughput of the system can be improved.

[0075]

As described above, according to the spread spectrum communication receiving apparatus of claim 1 or the method of establishing synchronization of the spread spectrum communication receiving apparatus of claim 10, a correlation peak is detected from an output signal of the correlation calculating means. Then, a plurality of synchronization pull-in modes are generated in accordance with the number of times the detected correlation peak is detected, and the shift amount of the phase shift means is controlled in accordance with the generated synchronization pull-in mode. The amount of phase shift used can be set to an appropriate value regardless of the final synchronization accuracy. Therefore, it is possible to shorten the time required for synchronization pull-in, and to realize a high-speed and high-accuracy circuit for clock synchronization without using any special device, thereby improving the system throughput. Is obtained.

According to the spread spectrum communication receiving apparatus of claim 3 or the method of establishing synchronization of the spread spectrum communication receiving apparatus of claim 11, the plurality of synchronization pull-in modes generated include an initial pull-in mode and a fine adjustment mode. Since the mode is the two mode, the phase shift amount can be set to two kinds of stepwise values. Therefore, it is possible to shorten the time required for synchronization pull-in, and to use a special device for clock synchronization. It is possible to achieve an effect that the speed of the circuit is increased and the accuracy is increased, and the throughput of the system can be improved.

According to the spread spectrum communication receiving apparatus of claim 4 or claim 5 or the method for establishing synchronization of the spread spectrum communication receiving apparatus of claim 12 or claim 13, the synchronous pull-in mode is the initial pull-in mode. In addition, since the shift amount is controlled to be larger than that in the fine adjustment mode, when the synchronization pull-in is started, the pull-in is performed with a large shift amount, and thereafter, the fine adjustment is performed with a small shift amount. Therefore, it is possible to achieve an effect that further higher speed and higher precision of clock synchronization can be realized and the throughput of the system can be improved.

According to the spread spectrum communication receiving apparatus of claim 6 or the method for establishing synchronization of the spread spectrum communication receiving apparatus of claim 14, the plurality of synchronization pull-in modes generated include a plurality of initial pull-in modes and at least one Since this is the fine adjustment mode, the clock synchronization can be further speeded up and the accuracy can be increased, and the effect that the system throughput can be improved can be obtained.

According to the spread spectrum communication receiving apparatus of claim 7 or claim 8 or the method of establishing synchronization of the spread spectrum communication receiving apparatus of claim 15 or claim 16, the synchronous pull-in mode is the initial pull-in mode. Since the shift amount is set larger than that in the fine adjustment mode, when the synchronization pull-in is started, the pull-in is performed with a large shift amount, and thereafter, the fine adjustment is performed with a small shift amount. Therefore, it is possible to achieve an effect that further higher speed and higher precision of clock synchronization can be realized and the throughput of the system can be improved.

According to the spread spectrum communication receiving apparatus of claim 9 or the method of establishing synchronization of the spread spectrum communication receiving apparatus of claim 17, when the correlation peak is less than a predetermined value, the initial pull-in mode is set as the synchronization pull-in mode. Is generated, and when the correlation peak becomes equal to or more than the predetermined value, the fine adjustment mode is generated as the synchronization pull-in mode, so that when the synchronization pull-in is started, the pull-in is performed with a large shift amount, and thereafter, Fine adjustment with a small shift amount. Therefore, it is possible to achieve an effect that further higher speed and higher precision of clock synchronization can be realized and the throughput of the system can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a synchronization unit having a delay lock loop, which is built in a spread spectrum communication receiver according to a first embodiment of the present invention.

FIG. 2 is a timing chart illustrating an example of an output timing of a signal output from a timing generation unit.

FIG. 3 is an explanatory diagram showing a relationship between a phase shift amount of a phase shift means and a zero cross point.

FIG. 4 is a timing chart illustrating an example of an output timing of a signal output from a timing generation unit according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a relationship between a phase shift amount of a phase shift unit and a zero cross point.

FIG. 6 is a block diagram showing a general configuration of a conventional spread spectrum communication receiver.

FIG. 7 is an explanatory diagram showing a configuration of data transmitted by a so-called packet method which is conventionally employed.

FIG. 8 is an explanatory diagram showing a configuration of data transmitted by a conventionally adopted CDM method.

FIG. 9 is a block diagram showing a conventional configuration of a synchronizing unit employing a delay lock loop, which is used in a spread spectrum communication system for transmitting data in a burst form in a time division manner.

FIG. 10 is a diagram illustrating an example of an S curve generated in a synchronization unit.

FIG. 11 is a diagram illustrating a relationship between a zero-cross point and a phase shift amount in a conventional spread spectrum communication receiver.

[Explanation of symbols]

 Reference Signs List 101 correlation means 102 delay / addition means (delay means) 103 peak value detection means 104 timing generation means 105 phase control means (shift amount control means) 107 phase shift means 604 synchronization section

Claims (17)

[Claims] 1. Correlation means for performing a correlation operation between a received signal and a local reference code on a receiving side, delay means for delaying an output signal of the correlation means, output signal level of the correlation means and output signal of the delay means And a phase shift means for shifting and outputting the phase of the reception-side reference oscillation signal in accordance with the level difference between the received signal and the output signal of the correlation operation means. Peak detection means for detecting a correlation peak from a signal; timing generation means for generating a synchronization pull-in mode in accordance with the number of times of detection of the correlation peak detected by the peak detection means; and the synchronization generated by the timing generation means Shift amount control means for controlling a shift amount of the phase shift means according to a pull-in mode. Spread spectrum communication receiver. 2. The spread spectrum communication receiving apparatus according to claim 1, wherein said correlating means comprises a digital matched filter. 3. The spread spectrum communication receiving apparatus according to claim 1, wherein the synchronization pull-in mode generated by the timing generation means is an initial pull-in mode and a fine adjustment mode. 4. The shift amount control means sets a shift amount in a case where the synchronization pull-in mode is the initial pull-in mode to be larger than a shift amount in a case where the synchronization pull-in mode is the fine adjustment mode. The spread spectrum communication receiver according to claim 3, wherein 5. The shift amount when the synchronization pull-in mode is the initial pull-in mode is approximately two times the shift amount when the synchronization pull-in mode is the fine adjustment mode.
4. The spread spectrum communication receiving device according to claim 3, wherein the number is doubled. 6. The spread spectrum communication reception according to claim 1, wherein the synchronization pull-in mode generated by the timing generation means is a plurality of initial pull-in modes and at least one fine adjustment mode. apparatus. 7. The shift amount control means sets the shift amount when the synchronization pull-in mode is the initial pull-in mode to be larger than the shift amount when the synchronization pull-in mode is the fine adjustment mode. 7. The spread spectrum communication receiving apparatus according to claim 6, wherein: 8. The shift amount when the synchronization pull-in mode is the initial pull-in mode is approximately 2 times the shift amount when the synchronization pull-in mode is the fine adjustment mode.
7. The spread spectrum communication receiver according to claim 6, wherein the number is twice or more. 9. The timing generation unit generates the initial pull-in mode as the synchronization pull-in mode when the correlation peak is less than a predetermined value, and generates the synchronization when the correlation peak becomes equal to or more than the predetermined value. 4. The spread spectrum communication receiving apparatus according to claim 3, wherein the fine adjustment mode is generated as a pull-in mode. 10. Correlation means for performing a correlation operation between a received signal and a receiving-side local reference code, delay means for delaying an output signal of the correlation means, an output signal level of the correlation means, and an output signal of the delay means. And a phase shifter for shifting and outputting the phase of the receiving-side reference oscillation signal in accordance with the level difference between the level and the level. Detecting a correlation peak from the output signal of the means, generating a plurality of synchronization pull-in modes according to the number of times the detected correlation peak is detected, and controlling a shift amount of the phase shift means according to the generated synchronization pull-in mode. A synchronization establishing method. 11. The plurality of synchronization pull-in modes to be generated include an initial pull-in mode and a fine adjustment mode.
The method according to claim 10, wherein the mode is a mode. 12. The synchronization establishing method according to claim 11, wherein when the synchronization pull-in mode is the initial pull-in mode, the shift amount is controlled to be larger than in the fine adjustment mode. 13. The shift amount when the synchronization pull-in mode is the initial pull-in mode is substantially twice the shift amount when the synchronization pull-in mode is the fine adjustment mode. 12. The synchronization establishment method according to item 11. 14. The plurality of synchronization pull-in modes generated are a plurality of initial pull-in modes and at least one fine adjustment mode.
Synchronization establishment method described. 15. A shift amount when the synchronous pull-in mode is the initial pull-in mode is larger than a shift amount in the fine-adjustment mode.
4. The synchronization establishment method according to 4. 16. A shift amount when the synchronization pull-in mode is the initial pull-in mode is substantially twice or more than a shift amount when the synchronization pull-in mode is the fine adjustment mode. Claim 1
4. The synchronization establishment method according to 4. 17. When the correlation peak is less than a predetermined value, the initial pull-in mode is generated as the synchronization pull-in mode, and when the correlation peak is equal to or more than the predetermined value, the fine adjustment is performed as the synchronization pull-in mode. The method for establishing synchronization according to claim 11, wherein a mode is generated.