JPH06204975A - Spread spectrum communication system - Google Patents

Abstract

PURPOSE:To make possible miniaturization and to reduce cost by performing spreading and transmission by two respectively different pseudo noise signals for binary information data, performing inverse spreading by one of the pseudo noise signals on a reception side and judging the presence of correlation detection output. CONSTITUTION:A transmission side is provided with pseudo noise signal generation parts 2A and 2B for generating the two pseudo noise signals A and B and a selector 3 for selecting the signals A and B spread by inputted information data. Without changing the polarity of the spreading pseudo noise signals by the information data, one of the two respectively different signals A and B of the binary information data '1' and '0' is allocated, spread and transmitted from an antenna 4. On the reception side, the inverse spreading is performed by multiplying a reception side pseudo noise signal A same as the transmission side outputted from the generation part 2A and reception signals received by the antenna 5 at an inverse spreading part 6. Thus, the information data can be reproduced just by the presence of the correlation detection output from the inverse spreading part 6.

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 system, and more particularly to a spread spectrum communication system which can be demodulated by a small and inexpensive demodulator.

[0002]

2. Description of the Related Art A conventional spread spectrum communication system is provided with a pseudo noise signal generator 2 and a spreader 3A on the transmitting side, and outputs from the pseudo noise signal generator 2 as shown in FIG. After the spread modulation for changing the polarity of the spread pseudo noise signal in accordance with the information data by multiplying the pseudo noise signal to be transmitted and the information data to be transmitted input from the terminal 1 in the spreading unit 3A, It is transmitted from the antenna 4.

On the receiving side, a pseudo noise signal generating section 2 for generating the same pseudo noise signal as on the transmitting side and a despreading section 6 are provided.
, Synchronization tracking unit 7, synchronization acquisition unit 8, and data demodulation unit 10
The despreading section 6 multiplies the receiving side pseudo noise signal output from the pseudo noise signal generating section 2 on the same side as the transmitting side by the receiving signal received by the antenna 5 to perform despreading.

In the initial stage of the despreading process, the phase difference between the received signal and the receiving side pseudo noise signal is ± 1 in the synchronization acquisition unit 8.
The output of the pseudo noise signal generator 2 on the receiving side is controlled so as to be within / 2 chips, and synchronization is acquired. When the synchronization is acquired, the synchronization tracking unit 7 controls the output of the pseudo noise signal generation unit 2 so that the reception signal and the reception-side pseudo noise signal are in phase with each other to perform the synchronization tracking.

In the synchronous tracking state as described above, a correlation detection output whose polarity changes according to the information data 1 is output from the despreading unit 6 in the cycle of the information data 1. In the data demodulation section 10, the timing of the correlation detection output is detected and the polarity is judged to reproduce the information data and output it as reproduction data from the terminal 9.

[0006]

However, in such a conventional spread spectrum communication system, in order to reproduce the information data, the timing of the correlation detection output from the despreading section is detected and its polarity is judged. There was a need.

Therefore, an object of the present invention is to provide a spread spectrum communication system capable of reproducing information data only with the presence or absence of the correlation detection output from the despreading section.

[0008]

A pseudo noise signal generator for generating two pseudo noise signals and outputs of these two pseudo noise signal generators are selected in accordance with binary information data to be transmitted. Transmitting means provided with a selector for spreading and transmitting, a despreading section for despreading a received signal, a pseudo noise signal generating section for generating a pseudo noise signal for despreading, and detection of despread output And a receiving unit provided with a synchronization tracking unit for performing synchronization tracking, and the transmission side spreads the binary information data with two different pseudo noise signals. Then, the information data is reproduced on the receiving side by despreading with one of the pseudo noise signals and determining the presence or absence of the correlation detection output.

[0009]

On the receiving side, the information data can be reproduced only by determining the presence or absence of the correlation detection output generated from the despreading section.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The spread spectrum communication system of the present invention is shown in FIG.
As shown in FIG. 2, on the transmitting side, pseudo noise signal generators 2A and 2B for generating two pseudo noise signals A and B, and a terminal 1
A selector 3 for selecting the pseudo noise signal A or B to be spread according to the input information data is provided, and binary information data “1” and “0” can be stored without changing the polarity of the spread pseudo noise signal by the information data. , And two different pseudo noise signals A or B are assigned to each of them and spread and transmitted from the antenna 4.

On the receiving side, a pseudo noise signal generator 2A for generating a pseudo noise signal A, a despreading unit 6, a synchronization tracking unit 7, a synchronization acquisition unit 8, and a data demodulation unit 10 are provided. Despreading is performed by multiplying in the despreading unit 6 the pseudo noise signal A on the receiving side that is output from the noise signal generating unit 2A and the received signal received by the antenna 5.

The synchronization acquisition and the synchronization tracking are performed in the same manner as the conventional spread spectrum communication system shown in FIG.

In the synchronous tracking state, when the information data is "1", the same pseudo noise signals A are despread, and a correlation detection output having a constant polarity is output from the despreading unit 6. To be done. When the information data is “0”, different pseudo noise signals B are despread, and the correlation detection output is not output from the despreading unit 6.

Therefore, the information data can be judged to be "1" when the correlation detection output is detected from the despreading unit 6 and "0" when it is not detected. It is output to the terminal 9 as reproduction data from 10.

The operation principle will be further described. Assuming that the pseudo noise sequences output from the pseudo noise signal generators 2A and 2B are PN _Ai and PN _Bi , respectively, the preconditions for the pseudo noise sequences used in the spread spectrum communication system are That is, as conditions for being orthogonal, ∫PN _Ai · PN _Ai di = 1 (normalized to 1 for simplification) ∫PN _Ai · PN _Bi di = 0 holds. That is, on the receiving side, PN _Ai is prepared for PN _Ai or PN _Bi , the above equation is calculated, and the output is larger or smaller than the threshold value S (0 <S <1). , It is determined whether the data is “1” or “0”.

If, on the transmitting side, the data "0" is spread with a pseudo noise sequence PN _i that does not satisfy the condition of the above equation, or one of the pseudo noise sequences A and B is pseudo noise sequence. in dispersing, the value of ∫PN _Ai · PN _i di is uncertain, it is to use two pseudo-noise sequence PN _Ai and PN _Bi.

[0017]

As is clear from the description based on the above embodiments, according to the spread spectrum communication system of the present invention,
Since the information data can be reproduced only by the presence / absence of the correlation detection output from the despreading unit, the size can be reduced, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a spread spectrum communication system of the present invention,

FIG. 2 is a block diagram showing an example of a conventional spread spectrum communication system.

[Explanation of symbols]

 1 Input Terminals 2, 2A, 2B Pseudo Noise Signal Generation Section 3 Selector 3A Spreading Section 6 Despreading Section 7 Sync Tracking Section 8 Sync Acquisition Section 9 Output Terminal 10 Data Demodulation Section

Claims (1)

[Claims] 1. A pseudo noise signal generating section for generating two pseudo noise signals, and outputs of the two pseudo noise signal generating sections are selected and spread according to binary information data to be transmitted and transmitted. Transmitting means provided with a selector, a despreading section for despreading the received signal, a pseudo noise signal generating section for generating a pseudo noise signal for despreading,
The receiving unit is provided with a synchronization acquisition unit that performs synchronization acquisition by detecting the despread output and a synchronization tracking unit that performs synchronization tracking, and the transmission side has two different two-value information data. A spread spectrum communication system characterized in that information data is reproduced by spreading and transmitting by a pseudo noise signal, despreading by one of the pseudo noise signals on the receiving side, and determining the presence or absence of correlation detection output. .