JPS62247642A - Synchronizing system for code communication - Google Patents

Abstract

PURPOSE:To ensure the stabilized communication by actuating a pseudo random num ber generator with the clock of a master station to spread and modulate signals for wire transmission of them and extracting the clock out of the received signal at a slave station to actuate the pseudo random number generator for spread and demodulation of signals. CONSTITUTION:A master station 12 modulates 34 a carrier wave 19 with the clock of a clock generator 33 to send it to a line 11 and also actuates a pseudo random number generator 14 for production of pseudo random number trains t1, t2... While a slave station 13a demodulates 35 the wave 19 with the signal received from the line 11 and actuates the generator 14 with the clock reproduced by a clock reproducer 36 for production of pseuso random number trains t1, t2... synchronous with the station 12. A common line signal 17 is spreaded and modulated 16 by the random number train t1 and the wave 19 is transmitted to the line 11 after balanced modulation 18. The common line signal received by the station 13a is demodulated 22 and spreaded and demodulated 21 by the random number train t2. The random number trains t3, t4... are allocated for information propert to each slave station and then used for spread/modulation and spread/demodulation like the common line signal. Thus reference clock can be surely reproduced.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention uses a pseudo-random number generator provided at each station in a coded communication method that transmits signals through a wired transmission line using a spread spectrum communication method, that is, a pseudo-random number sequence. Regarding a synchronization method for synchronization.

``Prior art'' Wired signals such as the so-called LAN method, the home bus method for controlling the switches of electrical devices in the home and intercom, and the control signal communication method for controlling various lights in the vehicle. By using the spread spectrum communication method proposed in the field of wireless communication for transmission, it is resistant to noise, does not introduce noise to the outside world, and maintains confidentiality.Furthermore, since it is wired transmission, it is possible for each station to It is easy to synchronize the provided pseudo-random number generators, and therefore reliable signal transmission can be performed with a relatively simple configuration.

In order to perform spread spectrum communication reliably in this way, the premise is that the pseudo-random number sequences for spread spectrum modulation and spread spectrum demodulation (spectrum despreading) used by each station are transmitted between the two stations attempting to communicate. It is to synchronize with.

An object of the present invention is to provide a synchronization method that can reliably synchronize pseudo-random number generators provided in each station in a wired code communication system that performs spread spectrum.

"Means for Solving the Problem" According to the present invention, one master station and at least one slave station are branch-connected to a wired transmission line, and each of these master stations and slave stations has the same pseudo-random number generator. At each station, a spread modulator performs spread spectrum modulation of the signal using a pseudo random number sequence obtained from the pseudo random number generator, and the spread spectrum modulation output modulates the carrier wave in the modulator for wired transmission. A demodulator demodulates the signal from the cable transmission line, and the demodulated output is subjected to spread spectrum demodulation using a pseudorandom number sequence from a pseudorandom number generator using a spread 1M modulator, and a demodulated signal is extracted.

The master station is provided with a clock generator, and the pseudo-random number generator of the master station is operated by the reference clock from the clock generator, and the carrier wave is modulated for clock by the reference clock from the JJ ifl clock generator. modulates the signal and sends it to the wired transmission line. On the other hand, in the slave station, the clock demodulator demodulates the Ijl signal,
A clock regenerator uses the demodulated output to regenerate a clock synchronized with the reference clock, and the regenerated clock operates the pseudo-random number generator of the slave station. In this way, on the wired transmission path, the portion where the signal transmission spectrum does not exist, that is, the frequency of the carrier wave, is changed to r4. When the frequency of the reference clock is fo, the spectrum for signal transmission on the wired transmission line mainly exists between fc±f0, and no spectrum exists at frequency fc±f0. On the other hand, the output of the clock modulator is f in the case of amplitude modulation.
, and f.

Only three spectra of ±'. are generated, the clock can be extracted without being affected by the spread spectrum modulation output of the signal, and the pseudo random number generators between each station can be operated correctly in synchronization.

"Example" The present invention will be described in detail with reference to FIG.

A master station 12 and a plurality of slave stations 13a and 13b are branch-connected to a power line transmission line 1) such as a telephone stranded wire, a power line, an electric light line, a waveguide, a coaxial cable, or an optical fiber. Each of these stations is provided with a pseudo-random number generator 1514, for example a so-called shift register type M-sequence generator, and as will be explained later, these pseudo-random number generators 14 operate synchronously, so that their taps tl+L2=j! ... generate pseudo-random number sequences with different codes, and synchronized pseudo-random number sequences with the same code are obtained from the same tap between stations.

In this example, each station is connected for information transmission using a common line signal, and exchange is performed to disconnect the connection, and the information signal is transmitted using a pseudo-random number sequence with a different code. . In this example, the transmission of the common channel signal is performed using a full-duplex communication method, and pseudorandom number sequences of two common codes are commonly assigned to each station for common channel signal transmission. In this example tap LI+L
! This is a case where a pseudo-random number sequence of v1 is applied for common line signal transmission, and at each station, the pseudo-random number sequence of tap 1° is supplied to the common signal modulator 16 through the switching circuit 15, and the common signal from the terminal 17 is Spread spectrum modulation of line signals. The modulated output is subjected to balanced modulation of a carrier wave from a carrier wave 19 in a signal modulator 18, and the modulated output is supplied to the wired transmission line 1).

Further, the pseudorandom number sequence from tap t2 is supplied to the common line signal demodulator 21 through the switching circuit 15. The modulated signal from the a-line transmission line 1) is demodulated by the signal demodulator 22, and its demodulated output is A common line signal is subjected to spread spectrum demodulation in a common line signal demodulator 21 and a common line signal is obtained at a terminal 23.

A station that wishes to communicate switches the switching circuit 15 and supplies a pseudorandom number sequence with two taps to the common line signal modulator 16 to transmit the common line signal. This common channel signal is transmitted by a so-called packet method, that is, by specifying the other party, and at the other party's station, a pseudo-random number sequence from tap t is always supplied to the common channel signal demodulator 21. , the common line signal from each station can be demodulated, and the demodulated output is manually input to the controller 24, which determines whether the signal is for that station or not, and only accepts or accepts the common line signal for that station and makes a call. be exposed. A response to the call is made using a pseudo-random number sequence from tap 1. In this way, when the other party is called using the common line signal and it is possible to communicate with each other, in this example, the communication is It is transmitted using a pseudo-random number sequence of information codes.

That is, in this example, tap t3- j4+ tS
. For example, the master station is assigned a pseudo-random number sequence with tap t, and the pseudo-random number sequence is supplied to the information demodulator 25, and the slave stations 13a and 13b each have tap L4.
+tS pseudo-random number sequences are assigned, and these pseudo-random number sequences are supplied to the information demodulator 25 of each slave station.

Furthermore, in each station, a code 'LA selection circuit 26 selects a pseudorandom number sequence other than the pseudorandom number sequence (tap L1.t2) for the common line signal of the pseudorandom number generator 14 and the pseudorandom number sequence for information assigned to the own station. Then, the selected pseudo-random number sequence can be supplied to the information modulator 27.

As mentioned earlier, when it is confirmed that two stations, for example, 13a and 13b, can communicate with each other by the common line signal, the controller 24 can communicate with the slave station 13a by receiving the common line signal. The code selection circuit 2 generates a pseudo-random number sequence for information based on the tap t assigned to the side slave station 13b.
6 is selected and supplied to the information modulator 25, and in the slave station 13b, a pseudorandom number sequence from the tap t assigned to the slave station 13a is selected by the code selection circuit 26 and supplied to the information modulator 25.
Supply to 27.

In these slave stations, the information from the terminal 28 is spread spectrum modulated in the information modulator 27 using a pseudorandom number sequence from the code selection circuit 26, and the modulated output is sent to the information modulator 29 to generate a carrier wave from the carrier wave generator 19. It is balanced modulated and supplied to the wired transmission line 1). Also, wired transmission line 1
) is demodulated by the information demodulator 3L, and the demodulated output is spread spectrum demodulated by the information demodulator 25 using a pseudorandom number sequence uniquely assigned to that station,
The demodulated information signal is output to terminal 32. In this way, information can be mutually transmitted between the two slave stations 13a and 13b using the uniquely assigned pseudorandom number sequence.

The premise that such communication can be performed is that the pseudo random number generators 14 of each station are synchronized with each other, but in this invention, in order to achieve this synchronization, one master station 12 is provided with a clock. A generator 33 is provided, and the pseudo random number generator 14 of the master station 12 is operated by the reference clock from the clock generator 333. The reference signal from this clock generator 33 is also supplied to a clock modulator 34, which modulates the output of a carrier wave 19 for supplying a spread spectrum modulated signal to the wired transmission line 1).
supply to Wired transmission line 1 in slave stations 13a and 13b
) is demodulated by a clock demodulator 35 to obtain a reference clock, the demodulated reference clock is used to regenerate the clock by a clock regenerator 36, and the regenerated clock is used to activate the pseudo-random number generator 14 of the slave station. Operate.

Therefore, the pseudo random number generator 14 of the master station 12 and the slave station 13a.

It operates in clock synchronization with the pseudo random number generator 13b.

For frame synchronization, for example, a reset signal is generated by a reset signal generator 37 from a reference clock in the master station 12, and the pseudo random number generator 14 is reset by the reset signal, and the reset signal is transmitted to the reset signal transmitter 3.
8, modulates the carrier wave, and supplies it to the wire transmission line 1), and receives the reset signal modulation signal from the wired transmission line 1) by the reset signal receiver 39 to demodulate the reset signal, The pseudo-random number generator 14 of the slave station is reset by the demodulated signal.

The spectrum of the output of the carrier wave modulated by the spread spectrum modulation signal, that is, the output of the modulator 18.29, is the carrier wave frequency as shown in Fig. 2A, where fc is the frequency of the carrier wave, and fo is the clock frequency of the pseudorandom number sequence. [
The majority exists in the ±f0 band centered on C, and further spreads upward and downward in each ro band, although the level is small.

Therefore, the spectrum does not exist at the frequency position f, ±n fo (n=1.2.3·=). On the other hand, the spectrum of the output of the clock modulator 34 is only fc, f, +:f, as shown in FIG. 2B.

Therefore, the output signal of this clock modulator 34 is transmitted on the wired transmission line 1) without being influenced by the modulation signal of other signals, and the reference clock can be reliably detected at each slave station. Each pseudo-random number generator 14 can be correctly synchronized.

The carrier wave is clocked by the modulator 3 using this reference clock.
In order to perform modulation at 8, frequency modulation is not limited to amplitude modulation as in the previous example.

In the case of frequency modulation, the spectrum of the modulated output is fc±n
A spectrum is generated at fo, and in this case also, a spectrum is generated only at positions where the spectrum of the modulated output signal of the spread spectrum signal does not exist, so that the reference clock can be reliably detected. Alternatively, when performing amplitude modulation as shown in FIG. 2C, not only the amplitude modulation of the reference clock with respect to the carrier wave fc, but also a signal obtained by amplitude modulating the carrier wave of frequency fc + 3f with the reference clock may be synthesized and output. In short, the reference clock is reliably regenerated at each slave station by transmitting the reference clock transmission spectrum in the vacant part of the output spectrum where the carrier wave is modulated with the spread spectrum modulation signal. Can be done. The carrier wave generators 19 of each station are synchronized with each other.

In addition, in Figure 1, the information is tI! For signal transmission, a connection operation for information transmission using a pseudo-random number sequence for information was performed using a common channel signal, and each station was assigned a pseudo-random number sequence for information with a unique code. For example, each time a request for information transmission occurs in the master station 12, a vacant pseudo-random number sequence for information transmission may be assigned to the two stations. In the case of mere control, the information modulators 27, 29, the information demodulators 25, 31, etc. can be omitted. For example, controlling the lighting of various lamps inside the vehicle,
In such cases, it is sufficient to support only a simple switch control signal, and the pseudo-random number generator 14 may be used, for example, by writing a pseudo-random number sequence into RAM or ROM, and reading it out repeatedly using a reference clock. By shifting the phase, pseudorandom number sequences with different codes can be obtained.

"Effects of the Invention" As described above, according to the present invention, signals are transmitted using the spread spectrum communication method, and in order to obtain the benefits of the spectrum communication method and use a wired transmission path, it is possible to synchronize the pseudo random number generator. It can be easily done and easily configured, in which case the presence of a spectrum for the transmission of a reference clock in a part of the spectrum of a spread spectrum modulated signal in a wired transmission line is not present for its synchronization. Therefore, the reference clock can be reliably regenerated in the slave station, and stable communication becomes possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining its operation. 1): Wired transmission line, 12: Master station, 13a, L3b: Slave station, 14: Pseudo-random number generator, I6: Diagonal unit for common line signal as a spreading modulator, 18.29: (A minute modulator for,
21: Common channel signal demodulator as a spreading demodulator, 25:
Information demodulator as a spreading demodulator, 27... Information modulator as a spreading modulator, 22.31: Signal demodulator,
24: Controller, 26: Code selection circuit, 33: Clothes generator, 34: Chronograph modulator, 35: Chronograph demodulator, 36: Clothes regenerator.

Claims (1)

[Claims] (1) One master station and at least one slave station are connected to a wired transmission path, and each of these master stations and slave stations is provided with a pseudorandom number generator of the same configuration, and each station uses the pseudorandom number generator The signal is spread spectrum modulated by a spread modulator using a pseudorandom number sequence obtained from
Further, a spread demodulator performs spread spectrum demodulation, modulates a carrier wave with the modulation output from the spread modulator, and sends it to the wired transmission line, demodulates the modulated carrier wave from the wired transmission line and supplies it to the spread demodulator. This code communication system includes a clock generator that generates a reference clock in the master station, supplies the reference clock to the pseudo-random number generator of the master station to operate it, and a clock generator that operates the pseudo-random number generator of the master station. a clock modulator that modulates the carrier wave with a reference clock and sends it to the wired transmission line; a clock demodulator that demodulates the reference clock modulation signal from the wired transmission line in the slave station; A code communication synchronization system comprising a clock regenerator which regenerates a clock synchronized with the reference clock from the output signal of the clock demodulator and operates a pseudo random number generator of the station using the regenerated clock.