JPH0530079A - Spectrum diffusion modulator - Google Patents

Abstract

PURPOSE:To provide the SS demodulator for multiple SS communication enabling efficient high-speed data transfer without deteriorating SS communication characteristics. CONSTITUTION:Serial transmission data is converted into parallel data by means of a serial-parallel converter 1 and applied to each parallel data multiplier 2-1 to 2-4. The data is diffused and modulated by a phase-corrected delay PN signal from delay devices 9-1 to 9-4 by the multipliers 2-1 to 2-4. Each modulation signal is delayed by delay devices 3-1 to 3-4, and added by an adder 5. The output is modulated with carrier wave by a multiplier 6, and transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum modulator suitable for a system for multiple SS communication.

[0002]

2. Description of the Related Art The present invention has previously proposed a spread spectrum modulator used in an SS communication system in Japanese Patent Application No. 3-31631.

FIG. 3 shows the above apparatus. In the figure, 1 is a serial-parallel converter, 2-1 to 2-4 are multipliers, 3-1 to 3-4 are delay devices, and 4 is a PN. A code generator, 5 is an adder, 6 is a multiplier, 7 is a carrier signal generator,
8 is an antenna.

The transmission data is serial-parallel converter 1.
After being serial-parallel converted by, the parallel data is spread by the PN code in the multipliers 2-1 to 2-4. The spread data is delayed by the delay units 3-1 to 3-4 having different delay times (τ1 to τ4) so that the data can be temporally separated in the demodulation unit. The delayed data are added by the adder 5, modulated by the carrier wave by the multiplier 6, and transmitted from the antenna 8.

FIG. 4 shows a change in code due to the above operation. Here, the PN code length modulated by the transmission data and S
Since it is not necessary to synchronize with the gate of the convolver of the S receiver, as shown in FIG. 5, one or more spreading codes are assigned to one transmission data, here, two cycles are assigned.

In the multiplex communication device using the SS modulator having the above-mentioned configuration, the transmitter side (modulator) does not modulate the reference signal (PN code with data, for example, a state of "all 1", which is called a sounder). ) And information signal (data)
And synthesize and send. At the transmitting side, the input high-speed data is serial-parallel converted and spread-modulated for each channel. And these modulated signals are
A spread spectrum modulated signal that does not depend on the above-mentioned data, for example, each channel is sequentially delayed with reference to the phase of the sounder, the delay signals of the spread spectrum modulated signals that are the sounders are combined, and a high frequency carrier signal is applied thereto and transmitted.

On the receiving side, the received signal is correlated with a single correlator. The PN code used for the reference signal of the correlator is selected so that a correlation spike occurs when the data is "1", for example. The output of the correlator is different from the conventional method, and for example, the correlation spike by the sounder is output at the beginning, and subsequently the correlation spike of the delayed data channel is output serially.

[0008]

Now, in order to transmit data more efficiently without impairing the characteristics such as the anti-interference characteristic of the SS communication system, the processing time (gate) of the convolver and the diffusion are required. There is a method of allocating one spreading code cycle to one transmission data under the same time length of one code cycle. However, when the method of allocating one data to one cycle of the spreading code is made to correspond to the multiplexing SS method of the prior application, there arises a problem of deterioration of the correlation peak level in the correlation processing in the demodulation system.

Next, the mechanism of occurrence of the deterioration of the correlation peak level in the case of making the above correspondence will be described.

The spreading code corresponding to each data multiplexed in this way is correlated with the reference signal by the convolver in the demodulation section. Assuming that the spread code for the sounder signal and the reference signal match as shown in FIG. 6, the correlation peak becomes maximum at this time, and the correlation amount is set to 7 (the received signal is realistically shown in FIG. In order to make it easier to understand the relationship of the spreading code corresponding to each data, it is shown separately without adding each spreading code).

Next, as shown in FIG. 7, when the spread code obtained by spreading the first data and the reference signal match, the correlation amount is 6.5.
And the correlation decreases. The amount of decrease becomes larger as the amount of delay increases. In this way, the deterioration of the correlation amount appears. Therefore, in a demodulation system that performs data demodulation based on the magnitude of the correlation amount, data error and deterioration of interference resistance occur.

An object of the present invention is to efficiently transmit high-speed data without deteriorating the characteristics of SS communication when one data length is assigned to one spreading code period length equal to the convolver processing time in a multiplexed SS communication device. It is an object of the present invention to provide a spread spectrum modulator having a spread code phase array that enables the above.

[0013]

In order to achieve the above object, the SS modulator of the present invention comprises serial-parallel conversion means for converting serial transmission data into n (n is an integer of 2 or more) parallel signals. , A PN code generator for generating a PN code, a first delay means for generating n delayed PN codes by dividing the PN code by a predetermined time, and based on n delayed PN codes shifted by a predetermined time. And a modulation means for modulating each of the n parallel signals to obtain n modulation signals, and a second delay for delaying each of the n modulation signals to obtain n modulation signals deviated by a predetermined time. The gist is that it is provided with a means and a synthesizing means for synthesizing the PN code and the n modulated signals.

[0014]

In the SS modulator of the present invention, each parallel data after conversion is spread-modulated by the n phase-corrected delayed PN codes and then delayed to shift the codes.

[0015]

Embodiments of the present invention shown in the drawings will be described below.
FIG. 1 shows an embodiment of an SS modulator according to the present invention, in which the same reference numerals as those in FIG. The PN code is sent to each of the multipliers 2-1 to 2-4 via these delay devices.

After the reference code and the spreading code of the sounder match, in order to make the spreading code of each data completely match the reference code on the convolver gate, the spreading code of the sounder and the spreading code of each data are matched. The delay time and the code phase of the spread code of each data must be changed.
If the delay amount of the spread code of the sounder and the data is α1, the phase relationship Ui (t) of the spread code of each data is

[0017] αi: delay time of each information channel, β: 1 chip time of PN code, U0 (t): PN code for sounder.

For this reason, in addition to the conventional delay units 3-1 to 3-4 for shifting the spread code, delay units 9-1 to 9-4 for correcting the phase of the spread code are required. .. On the transmission side, first, serial-parallel converter 1 converts serial data into parallel data. These data are
The PN code whose code phase is changed by each of the delay units 9-1 to 9-4 is spread by the multipliers 2-1 to 2-4,
Further, after different delay times are given by the delay units 3-1 to 3-4 for shifting the codes, the respective codes are added by the adder 4 and are transmitted as one signal.

2A and 2B show the correlation states of the sounder code and the reference code and the first data code and the reference code.

[0020]

As described above, according to the present invention, the spreading codes corresponding to the respective data, which are multiplexed in the modulation system, are completely matched with the reference codes on the gate of the convolver. Since the phase of each spreading code is changed according to the delay amount of the spreading code corresponding to the data, S
The characteristics of S communication are not deteriorated, and efficient high-speed data transmission becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the above embodiment.

FIG. 3 is a block diagram showing a conventional SS modulator.

FIG. 4 is an operation explanatory diagram of the apparatus of FIG.

FIG. 5 is a diagram showing a relationship between a data table and a PN code length.

FIG. 6 is a diagram showing a relationship between a PN code and a reference signal for a sounder signal.

FIG. 7 is a diagram showing a relationship between a PN code and a reference signal for a sounder signal.

[Explanation of symbols]

 1 Serial-parallel converter 2-1 to 2-4 Multiplier 3-1 to 3-4 Delay device 4 PN code generator 5 Adder 6 Multiplier 9-1 to 9-4 Delay device

Claims (1)

Claims: 1. A serial-parallel conversion means for converting serial transmission data into n (n is an integer of 2 or more) parallel signals, a PN code generator for generating a PN code, and First delay means for shifting the PN code by a predetermined time to create n delayed PN codes and n delay signals that are shifted by a predetermined time are used to modulate the n parallel signals, respectively. Modulation means for obtaining a plurality of modulated signals, second delay means for delaying each of the n modulated signals to obtain n modulated signals shifted by a predetermined time, and the PN
A spread spectrum modulator comprising: a synthesizing unit for synthesizing a code and n modulated signals.