JPH0446427A - Spread spectrum communication equipment - Google Patents

Abstract

PURPOSE:To realize synchronization acquisition comparatively simply when a demodulation station demodulates a signal from a modulation station and to attain the signal demodulation by sending a code series from the demodulation station to the modulation station, using the code series to modulate a data and sending the result from the modulation station to the demodulation station. CONSTITUTION:A code series is generated by a pseudo noise generator PNG and multiplied with a 2nd carrier frequency fB in a 3rd mixer MA and the result is sent from a 1st transmission antenna ANTA1 to a modulation station. A 4th mixer MB1 of the modulation station eliminates the carrier frequency fB from the signal received by an antenna ANTB1 to extract the code series, The extracted code series is superimposed on a data at a 5th mixer MB2 and the result is sent to a 2nd mixer MA2 through a same path as that for data transmission. Then a code series among the code series generated from the generator PNG only through a delay device DL is fed to the mixer MA2 and the synchronization acquisition is realized by adjusting the delay time of the delay device DL to extract the data.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a spread spectrum communication device capable of selective calling and code division multiplex communication, and particularly relates to an improvement in synchronization acquisition in a direct spread system.

<Prior art> A spread spectrum communication device is disclosed in, for example, “Latest Spread Spectrum Communication System J (by R.C. Dixon, translated by Tateno et al. (1978)).The spread spectrum communication system uses selective calling and code division. Because multiplex communication is possible, when receiving measurement signals from a large number of distributed detection terminals such as air conditioning control equipment or industrial control equipment, and sending command signals to the operating terminal so that a predetermined target value is achieved, It has the potential to be used effectively. Conventionally, a communication method called data highway was used, but there is a need for new technology that can provide the same functionality at a lower cost.

FIG. 2 is a block diagram of a conventional device. In FIG. 0, a carrier wave oscillator 10 is an oscillator that generates a center frequency of a signal, and provides, for example, a specific frequency in a radio frequency band. The pseudo-noise generator 12 is a circuit that generates a code sequence having noise-like characteristics, and the code bit rate is approximately M
The balanced modulator 14 transmits the carrier wave oscillator 1 according to the code sequence supplied from the pseudo-noise generator 12.
A circuit that modulates a carrier wave of 0, a simple two-phase phase change If
(PSK: Phase 5hift Keyin
o) Pulse amplitude modulation (P A M ; Pu1s
e Amplitude Modulation), frequency deviation keying (FSK; FreQuenC
Spread spectrum communication, which may also be referred to as y ShiftKeying, is communication that uses signals spread over a much wider frequency band than the minimum band required to transmit the information to be sent. In binary phase modulation, the bandwidth of the main rope is twice the tarok frequency of the modulating signal, and information on the side ropes is also required to accurately transmit waveform information, so it is difficult to compare the speed of the code sequence. and the bandwidth is 2
It will more than double. The signal modulated by the balanced modulator 14 is transmitted from the antenna ANTA.

Antenna ANT6 receives this signal. The carrier wave oscillator 20 outputs a carrier wave /if having the same frequency and phase synchronization as the carrier wave oscillator 10, and a third party who does not have this information cannot decipher the pseudo noise generator 22.
is a circuit that generates a code sequence at the same speed and in the same phase as the pseudo noise generator 12. The balanced modulator 24 is a circuit that modulates the carrier wave of the carrier wave oscillator 20 with the code sequence of the pseudo noise generator 22. The mixer 26 is a circuit that multiplies the received signal of the antenna ANTB and the modulated signal of the balanced modulator 24.
When the codes on the transmitting side and the receiving side are synchronized, the phase-inverted carrier wave is phase-shifted by 180 degrees and the carrier wave is restored. The bandpass filter 28 is a circuit that allows only baseband modulated carrier waves to pass. Therefore, since the frequency band of the unsynchronized input signal is spread by the mixer 26, other signal components after passing through the bandpass filter 28 are attenuated.

FIG. 3 is a waveform diagram explaining the operation of the device shown in FIG.
) is the carrier wave output from the carrier wave oscillator 10, (B) is the code sequence generated by the pseudo-noise generator 12, (C) is the modulated carrier wave output from the balanced modulator 14, and (0) is the antenna A.
The received signal of the NTB, (E) is the reference code of the pseudo noise generator 22, and (F) is the carrier wave demodulated by the mixer 26.

Here, RF stands for radio frequency (Padio Frequency).
cy). Mixer 26 and bandpass filter 2
8 extracts synchronized signal waves and suppresses interfering signals.

<Problem to be solved by the invention> However, the synchronization port F#l of the receiver (carrier wave oscillator 2
When a sliding correlator with the simplest configuration is adopted as the pseudo noise generator 22), there is a problem in that it takes a long time to acquire synchronization. To solve high-speed acquisition, SA
Devices that use W filters or digital signal processing have the problem that the device itself becomes larger and the cost increases, and if a large number of devices need to be installed, such as in the case of detection terminals, the cost competitiveness is lost.

The present invention has solved these problems, and an object of the present invention is to provide a spread spectrum communication device that does not require a circuit for synchronization acquisition.

<Means for Solving the Problems> The present invention, which achieves the above object, includes the following components.

The demodulation station includes a first oscillator (LOA1) that generates a first carrier frequency (fA), a first receiver that multiplies the received signal of the first receiving means (ANTA2) and the output signal of the first oscillator. A mixer (M^1), a pseudo-noise generator (PNG) that generates a code sequence, a delay device (DL) that delays the code sequence output from this pseudo-noise generator by a specified time,
A second mixer (
MA2), a second oscillator (LOA2) that generates a second carrier frequency (/8), and a third mixer (MAo) that multiplies the output signal of this second oscillator by the code sequence output from the pseudo-noise generator. ), and has a first transmitting means (ANTA1) for transmitting the signal modulated by the third mixer.

The modulation station includes a third oscillator (LOB1) that generates a signal of the same frequency as the second carrier frequency (/8), a received signal of the second receiving means (ANTB1), and an output signal of the third oscillator. a fourth mixer (MB1) that multiplies the output signal of the fourth mixer and the input data; a fifth mixer (MB2) that multiplies the output signal of the fourth mixer and the input data;
A fourth oscillator (L) generates a signal of the same frequency as fA).
OB2), a sixth mixer (MB3) that multiplies the output signal of the fourth oscillator and the output signal of the fifth mixer, and a second transmitting means (A) that transmits the signal modulated by the sixth mixer. N Ta 2 ).

Functions Each component of the present invention has the following functions. The first oscillator and the third oscillator generate a first carrier frequency and are used for transmission from the second transmitting means to the first receiving means,
Used for data transmission.

The second oscillator and the fourth oscillator generate a second carrier frequency, which is used for transmission from the first transmitting means to the second receiving means, and used for synchronization acquisition.

The delay device uses phase information of the code sequence of the pseudo-noise generator to provide the time delay necessary for synchronization. The first to sixth mixers add or remove carrier frequency and code sequence information from the data.

<Example> The present invention will be explained below using the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. Here, a case is shown in which wireless communication is used for transmission and reception. In the figure, the transmitting station has the following components. The first oscillator (LOA1) has a first carrier frequency (fA)
occurs. The first receiving antenna (ANT^2) receives a signal containing data. The first mixer (M
A1) multiplies the received signal of the first receiving antenna and the output signal of the first oscillator. Pseudo noise generator (PNG
) generates a code sequence containing phase information necessary for synchronization. The delay device (DL>) delays the code sequence output from this pseudo-noise generator by a specified time, and the amount of delay is variable.The second mixer (MA2) is delayed by this delay device. The code sequence is multiplied by the output signal of the first mixer to demodulate the pig.The second oscillator (LOA
2) generates the second carrier frequency (/8),
It is desirable for communication to be optically separated from the first carrier frequency. The third mixer (MAo) multiplies the output signal of the second oscillator by the code sequence output from the pseudo noise generator. The first transmitting antenna (ANTA1) transmits the signal modulated by the third mixer to the modulating station, and transmits information necessary for synchronization.

The modulation station includes the following elements: Third oscillator (LO
) generates a signal having the same frequency as the second carrier frequency (/8). The second receiving antenna (ANTB1) is
A signal sent from a first transmitting antenna is received. Fourth
The mixer (MB1) multiplies the received signal of the second receiving antenna and the output signal of this third oscillator. The fifth mixer (MB2) multiplies the output signal of the fourth mixer and the input data. The fourth oscillator (L
O82) generates a signal having the same frequency as the first carrier frequency (fA). A sixth mixer (MB3) multiplies the output signal of this fourth oscillator and the output signal of the fifth mixer. The second transmitting antenna (ANTB2) transmits the signal modulated by the sixth mixer to the first receiving antenna.

The operation of the device configured in this manner will be described next. The data is sent to the modulation station, multiplied by the code sequence extracted by the fourth mixer in the fifth mixer, and multiplied by the code sequence extracted by the fourth mixer in the sixth mixer.
is multiplied by the carrier frequency (/^) and sent from the second transmitting antenna during demodulation. During demodulation, the first receiving antenna receives the signal, the first mixer removes the first carrier frequency component, the second mixer removes the code sequence component, and data is extracted.

The code sequence is generated by a pseudo-noise generator, multiplied by a second carrier frequency (fB) by a third mixer, and sent from the first transmitting antenna during demodulation. During demodulation, the second
A fourth mixer removes the second carrier frequency component from the signal received by the receiving antenna, and extracts a code sequence. The extracted code sequence is superimposed on the data in the fifth mixer and sent to the second mixer along the same route as the data transmission.

Of the code sequences generated by the pseudo-noise generator, those that have passed through the delay device are sent to the second mixer. Synchronous acquisition is achieved by adjusting the delay time of the delay device, creating a state in which data can be retrieved.

In the above embodiment, the communication between the modulation amount and the demodulation was explained using wireless communication as an example, but it may be wired or an optical fiber may be used. In the case of wired communication, the transmitting means is the transmitter and the receiving means is the receiver. Therefore, multiple transmissions and receptions are performed simultaneously in a specific frequency band. In the case of optical fiber, it is preferable to use an electro-optical converter as the transmitting means and a photoelectric converter as the receiving means, and data restoration is performed electronically.

Various methods such as two-phase phase shift modulation, pulse amplitude modulation, frequency deviation keying, etc. can be adopted as the method after modulation of the mixer.

<Effects of the Invention> As explained above, according to the present invention, a code sequence is sent between the demodulations and the modulation amount, and data is modulated by this code sequence and sent from the modulation amount between the demodulations. When demodulating the signal from the modulated amount, the propagation delay between stations is determined and the code sequence between the demodulations is used to relatively easily achieve synchronization acquisition and demodulate the signal.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention, and FIG.
The figure is a block diagram of the configuration of a conventional device, and FIG. 3 is a waveform diagram illustrating the operation of the device of FIG. 2. ANT...antenna (transmission/reception means), DL...delay device, LO...oscillator, M...mixer, PNG...
- Pseudo noise generator, f...carrier frequency. Figure 3 (D demodulation '91k PF cheekli?le■几

Claims (1)

[Claims] A first oscillator (
LO_A_1), a first mixer (M_A_1) that multiplies the received signal of the first receiving means (ANT_A_2) and the output signal of this first oscillator, a pseudo noise generator (PNG) that generates a code sequence, and this pseudo noise Delay device (DL) that delays the code sequence output from the generator by a specified time
, a second mixer (M_A_2) that demodulates data by multiplying the code sequence delayed by the delay device and the output signal of the first mixer, and a second oscillator (M_A_2) that generates a second carrier frequency (f_B). LO_A_2), a third mixer (M_A_0) that multiplies the output signal of the second oscillator by the code sequence output from the pseudo-noise generator, and a first transmitting means for transmitting the signal modulated by the third mixer. (ANT_
A_1), a third oscillator (LO_B_1) that generates a signal of the same frequency as the second carrier frequency (f_B), a received signal of the second receiving means (ANT_B_1), and the third oscillator. a fourth mixer (M_B_1) that multiplies the output signals of
a fifth mixer (M_B_2) that multiplies the output signal of the fourth mixer and the input data; a fourth oscillator (LO_B_2) that generates a signal of the same frequency as the first carrier frequency (f_A); Modulation comprising a sixth mixer (M_B_3) that multiplies the output signal of the fourth oscillator and the output signal of the fifth mixer, and second transmitting means (ANT_B_2) that transmits the signal modulated by this sixth mixer. A spread spectrum communication device comprising: a station; and a spread spectrum communication device.