JPS61290830A - Spread spectrum communication equipment - Google Patents

Abstract

PURPOSE:To stabilize synchronizing eliminating influences of leaking in of signals of an oscillator for the transmission carrier of own station at the time of receiving by continuing the oscillating action of an oscillator for the transmission career at the time of receiving, and at the same time, changing SS code to a value that is attenuated by reverse spread, for instance, fixed value such as '0' or '1', even when the code leaks to a receiving side. CONSTITUTION:When receiving, an antenna 22 is switched to the receiving side R. However, signal leakage occurs at the part of a switching unit and other circuits and wiring. Accordingly, when a transmission carrier 9 is generated in own station at the time of receiving, the transmission carrier 9 of own station is inputted to the receiving side. For instance, the operation of an SS code generator 4 is stopped by transmission reception switching signal 24 to stop outputting to a multiplier 8 which is modulator of the SS code. As transmission data are not outputted at the time of receiving, an output signal 25 of EOR 7 after diffusion becomes a fixed value signal of '0' or '1', and the output signals of a modulator 8 become the carrier 9 itself, and become the signals very narrow in a frequency band width. Accordingly, even when the signal 9 leaks to the receiving side, the signals is attenuated by the reverse diffusion, and little influence is given to reproduced data 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a spread spectrum communication device using a half-duplex communication method.

[Background of the invention]

faster synchronization in full-duplex communication methods that perform simultaneous communication using waves, and unidirectional communication methods that perform communication in only one direction;
I was trying to stabilize and stabilize. In this case, in the full-duplex communication system, once synchronization is achieved, that state can be maintained, so stabilization is relatively easy.

However, in the half-duplex communication method, in which communication is performed alternately by switching the transmitting and receiving states using a single carrier wave, it is difficult to maintain a stable synchronized state because the transmitting and receiving states are switched. There has been a demand for stabilization of synchronization in SS communications using half-duplex communications.

[Purpose of the invention]

The present invention was made in view of the above-mentioned demands, and
An object of the present invention is to provide an SS communication device that can achieve synchronization stabilization in half-duplex communication.

[Summary of the invention]

At the time of reception, the device of the present invention continues the oscillation operation of the transmission carrier oscillator, and changes the SS code to a value that is attenuated by despreading even if it leaks to the receiving side, for example, a constant value of 0 or 1, This is intended to stabilize synchronization while eliminating the influence of signal leakage from the transmit carrier oscillator of the own station during reception.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the SS communication device according to the present invention. The side of the arrow A indicates the transmitting side, and the side of the arrow indicates the receiving side, with a point ia in between. First, on the transmission side, the output signal 9 of the transmission carrier wave oscillator 1 is divided by the frequency divider 2 to create a clock pulse 3 for generating the SS code, and the SS code generator 4 generates the SS code 5. The transmission data '6 is processed by a multiplier or an exclusive OR circuit, here an exclusive OR circuit (hereinafter referred to as E).
(abbreviated as OR) 7, and further multiplier 8 spreads the carrier wave 9.
After modulating the signal, it is transmitted through a filter 10. Here, the transmission carrier wave oscillator 1 continues its oscillation operation not only during transmission but also during reception. On the receiving side, the received signal is amplified by an amplifier 27 and is converted into a local oscillation signal 14 of the VCO 12 by a carrier-locked loop formed by a multiplier 11, a voltage controlled oscillator (hereinafter abbreviated as vCO) 12, and a vCO controller 13. It synchronizes the received signal carrier wave and performs synchronous demodulation.Furthermore, the frequency of the local oscillation signal 14 is divided by a frequency divider 15 to produce a clock pulse 17 of the receiving side SS code, and the synchronization is detected by an SS code synchronization detector 18. , SS code generator 19
After activating the SS code 16 and creating an SS code 16 synchronized with the transmitting side, the received signal is despread by a multiplier or FORl (here, EOR 20) and data 21 is reproduced.

In half-duplex communication, the antenna switching device 23 is activated by the transmission/reception switching signal 24, and the antenna 22 is switched to the transmitting side T or the receiving side R. During reception, the antenna 22 is switched to the reception side R, but there is signal leakage at the switch 23, other circuits, and wiring, and therefore, even during reception, if the transmission carrier 9 is generated at the own station, the antenna 22 is switched to the reception side R. The transmitted carrier wave 9 of the station is input to the receiving side. Therefore, for example, the operation of the SS code generator 4 is stopped by the transmission/reception switching signal 24, and the output to the multiplier 8, which is the modulation section of the SS code, is stopped. In addition, since the transmitted data is not output during reception, the output signal 25 of the EOR 7 after spreading becomes a constant value signal of O or 1, and the output signal of the modulator 8 remains as the carrier wave 9, and becomes an extremely narrow signal with one frequency bandwidth. . Therefore, even if this signal 9 leaks to the receiving side, it is attenuated by despreading and has almost no effect on the reproduced data 21.

Figures 2 to 4 show the signal spectra of each part of the circuit of the present invention, of which Figure 2 shows the received signal a1 and the leakage signal (
The transmitted carrier signal 9)a2 is shown.

Both signals al and a2 pass through a multiplier 11 that performs synchronous demodulation, and become as shown in FIG. In FIG. 3, bl is a received signal and b2 is a leakage signal, which is despread by the EOR 20 and becomes as shown in FIG. Since the SS codes of the received signal b1 match, the data is correctly reproduced by despreading to become 01 in FIG. Attenuates as shown in 02 in Figure 4.

A specific example of means for stopping the output to the multiplier 8, which is the modulation section of the SS code, is shown in FIGS. 5 and 6.

The example shown in FIG. 5 is the clock pulse 3 of the SS code generator 4.
The example shown in Fig. 6 is SS
This is a method in which code 5 is stopped by an AND circuit 27. In the method illustrated in FIG. 5, it is uncertain whether the SS code 5 stops at 0 or 1. On the other hand, in the method illustrated in FIG. 6, the signal 51 is always O, and in this case, the AND circuit 2
If 7 is replaced with a NAND circuit, the signal color 1 becomes 1. Note that the methods shown in FIGS. 5 and 6 may be used in combination.

In this way, the device of the present invention described above is configured to
By stopping the signal 5, there is no need to stop the operation of the transmission carrier wave oscillator 1, and therefore, the frequency fluctuation of the transmission carrier wave 9 when switching to transmission is eliminated, and synchronization can be stabilized.

Note that the present invention is not limited to the method of setting the SS code 5 to a constant value of O or 1 as in the above embodiment, but may also adopt a method of changing the SS code 5 completely different from that on the receiving side. In short, it is sufficient that the SS code 5 has a value that is attenuated to such an extent that even if it leaks to the receiving side during reception, it will not affect the reproduced data 21 by despreading.

〔Effect of the invention〕

As described above, according to the present invention, since the oscillation operation of the transmitting carrier wave oscillator is not stopped during reception, there is no frequency fluctuation of the transmitting carrier wave when switching between reception and transmission, and stable synchronization can be maintained. There is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the device of the present invention, FIGS. 2 to 4 are diagrams showing spectra of various signals in FIG. 1, and FIGS. 5 and 6 are respectively diagrams showing the device of the present invention. In S
FIG. 7 is a block diagram showing a specific example of means for stopping output of the S code to the modulation section.

Claims (1)

[Claims] 1. On the transmitting side, the transmitting data is spread by a spread spectrum code having a frequency bandwidth sufficiently wider than that, and further modulating a carrier wave with the signal and transmitting it, and on the receiving side, the transmitted data is In a half-duplex communication type spread spectrum communication device that reproduces data by synchronously demodulating and despreading the received signal using the same spread spectrum code as the side and a local oscillation signal synchronized with the carrier wave, the transmitted carrier wave is The present invention is characterized by comprising an excavation continuation means for keeping the oscillator oscillating, and a code changing means for changing the spread spectrum code at the time of reception to a value that is attenuated by despreading even if it leaks to the receiving side. spread spectrum communication equipment. 2. The spread spectrum communication apparatus according to claim 1, wherein the code changing means is code constant value conversion means for converting the spread spectrum code to a constant value. 3. The code constant value means is a means for stopping the output of the spread spectrum code to the carrier wave modulation unit to set all the spread spectrum codes thereto to 0 or 1. Spread spectrum communication device according to scope 2.