JPH05219010A - Demodulation device for spread spectrum communication - Google Patents

Abstract

PURPOSE:To shorten a synchronism acquisition time without indicating synchronism misacquisition nor enlarging the device by providing a specific cyclic integration control part. CONSTITUTION:An input signal is inputted to a sliding correlation part 5 and multiplied through a multiplier 3 by a dummy noise signal which is outputted from a dummy noise signal generation part 2 and has a phase difference from the input signal, and then the result is integrated by an integration circuit 4. Those outputs are read by the cyclic integration control part 21 to calculate the spread of all phase differences, and such a minimum frequency M' of cyclic integration that the spread of subsequent cyclic integration outputs is in a specific range is calculated on the basis of the calculated spread and sent to a cyclic integrator 8. The output of a correlation part 5 is integrated M' times by the integrator 8 and an acquisition control part 9 sends an acquisition completion signal and a synchronism end signal to a synchronism tracking part 10 according to the M'-time integration output. The synchronism tracking part 10 demodulates the data by a data demodulation part 11 and outputs the demodulated data over synchronism tracking while controlling the phase of the dummy noise signal from a dummy noise signal part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demodulator for spread spectrum communication having a cyclic integrator for averaging correlation outputs.

[0002]

2. Description of the Related Art A conventional demodulator for spread spectrum communication will be described below with reference to the drawings.

FIG. 3 is a block diagram showing the structure of a conventional demodulator for spread spectrum communication. In FIG. 3, the multiplier 3 to which the input terminal 1 to which the incoming pseudo noise signal is input and the pseudo signal generating unit 2 are connected is connected to the integrating circuit 4, and the incoming pseudo noise signal and the pseudo signal from the input terminal 1 are connected. The reception side pseudo noise signal from the generator 2 is multiplied and output to the integrator circuit 4. The multiplier 3 and the integrating circuit 4 constitute a sliding correlation unit 5, and the sliding correlation unit 5
Calculates the sum of products of the incoming pseudo-noise signal and the receiving-side pseudo-noise signal for one information data cycle with a certain phase difference, and performs the same calculation for all the phase differences of the receiving-side pseudo-noise signal sequentially. Perform synchronization acquisition. The adder 6 to which the output end of the integrating circuit 4 is connected is connected to the shift register 7, and the output end of the shift register 7 is connected to the adder 6. The adder 6 and the shift register 7 form a cyclic integrator 8, which further integrates the output from the correlator to average the correlation. Further, the capture control section 9 to which the output end of the shift register 7 is connected controls the synchronous capture based on the output from the cyclic integrator 8. Furthermore, the synchronization tracking unit 10 to which the acquisition control unit 9 and the input terminal 1 are connected is connected to the pseudo signal generation unit 2, and the output from the acquisition control unit 9 is used to generate the reception side pseudo noise from the pseudo noise signal generation unit 2. The synchronization tracking is performed so that the incoming pseudo noise signal and the receiving side pseudo noise signal are synchronized while controlling the phase of the signal. Further, the data demodulating section 11 to which the output end of the integrating circuit 4 is connected is connected to the output terminal 12, and the data demodulating section 11 demodulates the data and outputs the reproduced data from the output terminal 12. Here, the receiving side pseudo noise signal is a signal of the same phase or opposite phase as the incoming pseudo noise signal.

The operation of the conventional demodulator for spread spectrum communication configured as described above will be described below. First, the input signal SIij, which is an incoming pseudo noise signal, is input to the sliding correlation unit 5, and the multiplier 3 and the pseudo noise signal SLij having a certain phase difference from the input signal SIij of the output from the pseudo noise signal generation unit 2 After being multiplied, they are integrated by the integrating circuit 4. Then, the pseudo noise signal generator 2 sequentially outputs the pseudo noise signal SLij by changing the phase difference, and the sliding correlation unit 5 performs the same calculation operation for all N phase differences. Then, when this series of operations is further repeated and the output thereof is cyclically integrated by the cyclic integrator 8 thereafter, the output Jk of each phase difference k (1 to N) is k: phase difference between input signal and pseudo noise signal N: number of spreading chips M: number of cyclic integrations An acquisition completion signal is sent from the acquisition control unit 9 to the synchronization tracking unit 10 based on those outputs, and the synchronization tracking unit 10 controls the phase of the reception-side pseudo noise signal from the pseudo noise signal generation unit 2 while Simultaneous tracking is performed so that the noise signal and the pseudo noise signal on the receiving side are synchronized, and at the same time, the data demodulation unit 11 determines the polarity of the output of the sliding correlation unit 5 to demodulate the data and output the reproduced data from the output terminal 12. To do.

At this time, the time t required for the capture control section 9 to send the capture completion signal is t> M × N2 × T T: information data period, and the time t is less than M × N2 × T. Absent.

[0006]

However, in the above-described conventional spread spectrum communication demodulator, for example, M
Even in a high-quality transmission line that does not need to perform cyclic integration once, as in the case of a transmission line that does not need to perform cyclic integration, it takes uniformly M × N 2 × T or more time to complete the synchronization acquisition.

The present invention solves the above-mentioned conventional problems. In a high-quality transmission line in which it is not necessary to perform cyclic integration M times, synchronization is performed without increasing the false synchronization probability and without increasing the size of the device. It is an object of the present invention to provide a demodulation device for spread spectrum communication that can shorten the acquisition time.

[0008]

In order to solve the above-mentioned problems, a demodulator for spread spectrum communication of the present invention outputs a receiving side pseudo noise signal of the same phase or opposite phase as an incoming pseudo noise signal. Pseudo-noise signal generator capable of varying the phase of the reception-side pseudo-noise signal, and a correlator for performing synchronous acquisition by performing a product-sum operation of the incoming pseudo-noise signal and the reception-side pseudo-noise signal for one information data period. And a cyclic integrator that further integrates the output from the correlation unit to average the correlation, and a phase of the reception-side pseudo noise signal from the pseudo noise signal generation unit using the output from the cyclic integrator. A synchronous control unit that performs synchronous tracking so that the incoming pseudo-noise signal and the receiving-side pseudo-noise signal are synchronized while controlling the output variance from the correlation unit, and then the cyclic integration from the cyclic integrator. Where the variance of the output is The minimum cyclic integration count of the cyclic integrator to be in the range is obtained by a cyclic integral control unit for adaptively setting control.

[0009]

With the above configuration, the cyclic integration controller reads the variance of the sliding correlation output, calculates the variance of the sliding correlation output with respect to all the phase differences, and the variance value of the subsequent cyclic integral output is within the predetermined range. Since the number of cyclic integration of is adaptively reduced as much as possible,
For example, in a high-quality transmission line that does not need to perform cyclic integration M times, if the dispersion value of the cyclic integration output is within a predetermined range, the false synchronization probability is suppressed to a certain value or less, and the number of cyclic integration And the synchronization acquisition time is shortened.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the same effects as those of the conventional example are given the same reference numerals and the description thereof will be omitted.

FIG. 1 is a block diagram showing the configuration of a demodulator for spread spectrum communication in one embodiment of the present invention. In FIG. 1, the cyclic integration control unit 21 connected to the connection point between the integrating circuit 4 of the sliding correlation unit 5 and the adder 6 of the cyclic integrator 8 is connected to the shift register 7 of the cyclic integrator 8, and By calculating the variance of the sliding correlation output with respect to the phase difference and suppressing the false synchronization probability to a certain level or less, the number of cyclic integrations of the cyclic integrator 8 is adaptively reduced as much as possible within a predetermined range of the dispersion value of the cyclic integration output thereafter. The configuration is controlled so that

The operation of the demodulation device for spread spectrum communication configured as described above will be described below. First, the input signal SIij is input to the sliding correlation unit 5, and the multiplier 2 outputs the output from the pseudo noise signal generation unit 2.
Pseudo noise signal SL having a certain phase difference from the input signal SIij
After being multiplied by ij, it is integrated by the integrating circuit 4. Then, the pseudo noise signal generator 2 sequentially changes the phase difference between the input signal SIij and the pseudo noise signal SLij, and performs the same calculation operation for all N phase differences. The output Jk is, for each phase difference k (1 to N), Becomes Then, the outputs Jk are read by the cyclic integration control unit 21 and the variances of all the phase differences are calculated.

By the way, when the noise mixed in the input signal is white noise and the variance of the cyclic integral output is suppressed within a predetermined range in order to suppress the false synchronization probability, when the variance of the sliding correlation output is determined, the minimum cyclic The number of integrations is uniquely determined.

Therefore, based on the dispersion calculated by the above equation, the minimum number of times of cyclic integration M'where the dispersion of the cyclic integration output thereafter falls within a predetermined range is calculated, and the information is sent to the cyclic integrator 8. Then, the output Sk of the sliding correlation unit 5 is cyclically integrated M times by the cyclic integrator 8, and the acquisition control unit 9 sends an acquisition completion signal to the synchronous tracking unit 10 based on the output. The synchronization tracking unit 10 performs synchronization tracking while controlling the phase of the pseudo noise signal from the pseudo noise signal generation unit 2, and at the same time, the data demodulation unit 11 determines the polarity of the output of the sliding correlation unit 5 and demodulates the data. , Outputs reproduction data from the output terminal 12.

When the noise mixed in the input signal is white noise, the better the transmission path is, the smaller the variance value of the sliding correlation output is. Also, the more the number of cyclic integrations is, the more the variance value of the cyclic integration output is. Becomes smaller. That is, since the conventional cyclic integration number M is set so that synchronization can be acquired even when the transmission line is very bad, in the case of a normal transmission line, (minimum cyclic integration number M ′) <
(Conventional cyclic integration number M). At this time, the time t ′ required until the capture control unit 9 sends the capture completion signal is t ′ = M ′ × N2 × T <t, where the time t is the time required to send the conventional capture completion signal. , The synchronization acquisition time is shortened without increasing the false synchronization probability.

Although the sliding correlator 5 is used in the present embodiment, as shown in FIG. 2, one cycle of the incoming pseudo noise signal a and the reception side pseudo noise signal b stored in advance. It may be a matched filter correlating unit 31 which performs correlation acquisition for each chip at the same time with one cycle, and the matched filter correlating unit 31 has the same number of stages as the lengths of the incoming pseudo noise sequence and the receiving side pseudo noise sequence. Of the shift register 32, a multiplier 33 that multiplies the signals from the respective stages of the shift register 32, and an adder 34 that adds the outputs from the multiplier 33. The adder 34 outputs the correlation output c. .. This is a method of performing initial acquisition by performing pattern matching between the incoming pseudo noise sequence and the receiving-side pseudo noise sequence held internally.

[0017]

As described above, according to the present invention, the output variance from the correlator is calculated, and the minimum number of cyclic integrations of the cyclic integrator is adapted so that the dispersion value of the subsequent cyclic integration output falls within a predetermined range. By providing the cyclic integration control unit for performing the setting control, the synchronization acquisition time can be shortened without increasing the false synchronization probability and without making the device too large.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a demodulation device for spread spectrum communication according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a matched filter correlator of a demodulator for spread spectrum communication according to another embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional demodulator for spread spectrum communication.

[Explanation of symbols]

 2 Pseudo-noise signal generator 3, 33 Multiplier 4 Integrator circuit 5 Sliding correlator 6, 34 Adder 7, 32 Shift register 8 Cyclic integrator 9 Acquisition controller 10 Synchronous tracking unit 21 Cyclic integration controller 31 Matched filter correlator

Claims (1)

[Claims] 1. A pseudo noise signal generator capable of varying the phase of the receiving pseudo noise signal for outputting the receiving pseudo noise signal having the same phase or opposite phase as the incoming pseudo noise signal, and one information data cycle. In the meantime, a correlator that performs a product-sum operation of the incoming pseudo noise signal and the pseudo noise signal on the receiving side to perform synchronization acquisition, and a cyclic integrator that further integrates the output from the correlator to average the correlation. And synchronous tracking so that the incoming pseudo noise signal and the receiving pseudo noise signal are synchronized while controlling the phase of the receiving pseudo noise signal from the pseudo noise signal generator using the output from the cyclic integrator. Calculating the output variance from the synchronization control unit and the correlation unit, and adapting the minimum number of cyclic integrations of the cyclic integrator so that the dispersion value of the cyclic integration output from the cyclic integrator thereafter falls within a predetermined range. Integral control with dynamic setting control Spread spectrum communication demodulation device that includes a part.