JPH0786984A - Pseudo-noise code generator in spread spectrum communication - Google Patents

Abstract

(57) [Abstract] [Purpose] A PN code in a spread spectrum communication apparatus can be arbitrarily changed during communication. [Structure] PN code generators 30, 50 are provided with MPUs 31, 5
1 and flash memories 32 and 52 are provided. A plurality of types of PN codes of arbitrary length are set and written in the flash memory in advance, and the PN code changed based on the protocol between transmission and reception at the start of communication and MP is used.
The software of U was read from the flash memory to perform spread modulation and spread demodulation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pseudo noise (PN) code generator used in a transmitter / receiver of spread spectrum communication.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing essential parts of a transmitting side device and a receiving side device in spread spectrum communication. On the transmission side, the carrier wave is modulated by the signal input by the primary modulator 1 and input to the spread spectrum modulator 2. The spread spectrum modulator 2 spread-modulates the primary-modulated signal with the PN code from the PN code generator 3 and transmits it from the antenna. On the receiving side, the received wave is demodulated by the spread demodulator 4 with the same PN code input from the PN code generator 5 as on the transmitting side. An unnecessary wave component is removed from the spread demodulation output by a band pass filter (BPF) 6, demodulated by a secondary demodulator 7, and a reproduction signal is output. FIG. 3 is an example of a conventional partial configuration of the PN code generators 3 and 5 in FIG. 2, which is an n-stage shift register including flip-flops FF _{1 to} FF _n .

[0003]

As described above, since the conventional PN code generator sets a predetermined PN code by using the n-stage shift register, the hardware is fixed. Therefore, when setting various kinds of PN codes, there is a disadvantage that the number of n-stage shift registers corresponding to the number of setting codes must be provided or the hardware must be changed each time to manufacture. Further, when the code length is long, a shift register having a number of stages proportional to the length is required, and there is a problem that the price increases. An object of the present invention is to eliminate the above-mentioned conventional drawbacks and problems, and to arbitrarily change many kinds of PN codes set in advance by one piece of hardware. Moreover, the code length is arbitrarily changed to keep secret. An object is to provide a pseudo-noise code generator capable of highly efficient communication.

[0004]

A pseudo noise generator of the present invention includes a flash memory, a write controller for writing a pseudo noise code in the flash memory, and a read controller for reading the pseudo noise code from the flash memory. , A plurality of kinds of pseudo noise codes for spread modulation and spread demodulation of spread spectrum communication are written in the flash memory in advance by the write controller, and a pseudo noise code designated at the start of communication and at the time of communication is read by the read controller. And a microprocessor unit for reading and outputting.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a main part of a transmission / reception apparatus to which an embodiment of the present invention is applied. In the figure, 1, 2,
4, 6 and 7 show the same parts as in the conventional case of FIG. 30 and 5
Reference numeral 0 represents the PN code generator of the present invention. The PN code generators 30 and 50 of the present invention include microprocessor units (MPU) 31 and 51 including ROM and RAM, flash memories 32 and 52, and write controllers 33 and 5, respectively.
3 and read controllers 34 and 54. In the present invention, a plurality of types of PN codes defined for both transmission and reception are generated in the MPUs 31 and 51 corresponding to the communication state, and written in the flash memories 32 and 52 in advance by the write controllers 33 and 53. At the time of spread modulation on the transmission side, the MPU 31 reads the PN code from the flash memory 32 by the read controller 34 and gives it to the spread modulator 2. Similarly, during spread demodulation on the receiving side, MPU
The read controller 54 reads out the same PN code as that on the transmitting side from the flash memory 52 by the read controller 54 and supplies it to the spread demodulator 4. The flash memory used in the present invention is a type of EEPROM capable of electrically erasing the stored contents and writing new data.
As compared with M, the number of rewrites is not limited, the rewrite speed is fast, and the chip area is small and inexpensive, so that a large number of PN codes can be rewritten and stored. The setting of the PN code and the change during communication will be described by way of example. Table 1 below shows an example of setting nine types of PN codes.

[0006]

[Table 1]

PN codes A, B and C in Table 1 are PN codes having a short code length to be used at the time of line connection, and A → B →
Retry on the condition of C → A → ……. A line is connected with the same code with a difference in the number of retries between the transmitting side and the receiving side. When the connection is completed, the communication is performed with the code (1) at the time of communication corresponding to the code. For example, when connected by B, E is used. The codes G, H, and I at the time of communication (2) are codes of other patterns, respectively, and when the line condition is not good during communication at the time of communication (1), the sending side gives a notice to the receiving side. After that, the code is changed to the corresponding code at the time of communication (2). It can be seen that in order to generate nine kinds of PN codes as shown in Table 1 in the conventional configuration, nine kinds of n-stage shift registers are necessary and not practical.

[0008]

By implementing the present invention, various types of PN codes can be set and written in the flash memory in advance, and the PN code used by the software of the MPU can be changed. The PN code can be changed in real time, and the reproduced voice quality is good and highly confidential communication is possible. In addition, the PN code length can be shortened when the communication is connected and the long code can be used when the connection is completed by software, which is effective in shortening the synchronization time and has an extremely large practical effect. .

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of a transceiver to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram of a main part of a conventional transceiver.

FIG. 3 is a configuration example diagram of an n-stage shift register used in a conventional PN code generator.

[Explanation of symbols]

 1 Primary Modulator 2 Spreading Modulator 3, 5 PN Code Generator 4 Spreading Demodulator 6 BPF 7 Secondary Demodulator 30, 50 PN Code Generator 31, 51 MPU 32, 52 Flash Memory 33, 53 Write Controller 34, 54 lead controller

Claims (1)

[Claims] 1. A flash memory, a write controller for writing a pseudo-noise code to the flash memory, a read controller for reading the pseudo-noise code from the flash memory, and spread modulation and spreading for spread spectrum communication in the flash memory. Spread spectrum including a microprocessor unit in which a plurality of types of pseudo-noise codes for demodulation are written in advance by the write controller, and pseudo-noise codes designated at the start of communication and at the time of communication are read and output by the read controller Pseudo-noise code generator in communication.