JP3197581B2 - Spread spectrum receiver, spread spectrum transmitter, and spread spectrum communication system - Google Patents

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 for converting a signal into a signal having a band much wider than the band of the signal.

[0002]

2. Description of the Related Art A spread spectrum system is sometimes used for communication because of its excellent interference resistance and confidentiality.
The spread spectrum communication method is described in detail in "Spread Spectrum Communication System", Science and Technology Publishing Company (1988), but will be briefly described below.

[0003] The spread spectrum communication system includes a direct spread system (DIRECT SEQUENCE) and a frequency hopping system (FREQ
UENCY HOPPING), but first the direct spreading method will be described.

FIG. 8 is a diagram showing a configuration of a conventional spread spectrum communication. In the figure, 10 is a transmitting station, 20 is a receiving station, and 30 is an interference wave source.

[0005] In the transmitting station 10, the carrier wave is transmitted by the carrier modulating unit 11 in the form of PSK (PHASE SHIFT KEYING), FM
(FREQUENCY MODULATION), AM (AMPLITUDE MODULATI)
After primary modulation such as ON) is performed, secondary modulation (spread modulation) is performed by multiplying by a spreading code far wider than the transmission data. The spread-modulated signal is power-amplified by the transmission unit 13 and radiated from the antenna 14 as a radio wave.

On the other hand, in the receiving station 20, the high-frequency signal input from the antenna 21 is subjected to high-frequency amplification and band limitation in the receiving section 22 and spread and demodulated in the spread demodulation section 23.
This spread demodulation is to demodulate the received signal by multiplying it by the same spread code as that on the transmitting side. Then, the carrier wave demodulation unit 24 reproduces the data except for the carrier wave.

FIG. 9 is a diagram showing a spectrum of a signal of each unit in spread spectrum communication having the configuration shown in FIG.

As shown in FIGS. 1A and 1B, the spectrum of the signal after passing through the spread modulator 12 is much wider than the spectrum of the signal after passing through the carrier modulator 11. As a result, the power density per unit frequency is significantly reduced, and interference with other communications is avoided. When the spread demodulation section 23 of the receiving station 20 demodulates using the same spreading code as used in the modulation at the transmitting station, the signal can be reproduced as shown in FIG. When demodulation is performed using a spreading code different from that used in the modulation at the station, the information remains spread and cannot be reproduced, as shown in FIG. For this reason, when signals in which a plurality of pieces of transmission information are modulated with different spreading codes are present in the same frequency band, each transmission information is demodulated with the same spreading code as in the modulation operation of each piece of transmission information. Can reproduce information.

[0009] On the other hand, the spread spectrum communication system of the frequency hopping system is a system in which a carrier frequency modulated by information is randomly and discretely switched in a given band to spread the band over a wide band.

[0010] Such a spread spectrum communication system is as follows.
Because the signal band is spread, the power density is low, it is difficult to interfere with other communications, and at the same time, it is hard to be interfered by other, and the random access multiplex communication in the same frequency band is possible. When it is increased, the quality of the received signal is improved (the ratio of the frequency band B before the frequency spread of the information to the frequency band W after the spread is calculated by the processing gain Gp = W
/ B).

However, the conventional spread spectrum communication system has the following problems.

Generally, in wireless communication, the influence of an interference wave existing in a transmission space is a serious problem. In the spread spectrum communication method, a signal is spread over a wide band, so that a transmission space requires a wide frequency band, and is affected by all interference waves in the frequency band of the transmission space. In the spread spectrum communication system, at the time of reception, a received signal is multiplied by a spread code, so that an interference wave is spread over a wide band. For this reason, when the power of the interference wave is small, there are few problems, but when the power is large, the spreading effect has a large adverse effect and significantly deteriorates the reception quality.

For example, in recent years, wireless L
Although there is an attempt to build an AN, this band poses a serious problem because its frequency overlaps with large amplitude radiation from microwave ovens.

[0014]

As described above, in the conventional spread spectrum communication system, the transmission space requires a wide frequency band, and is affected by all the interference waves in the frequency band of this transmission space. In particular, when the power of the interference wave is large, the present invention has a problem of significantly deteriorating the reception quality. The present invention has been developed to solve such a problem, and reduces the influence of the interference wave to reduce the communication power. It is an object of the present invention to provide a spread spectrum communication system capable of improving quality.

[0015]

According to a first aspect of the present invention, there is provided a spread spectrum communication system for widening a signal to be transmitted and transmitting the signal from a transmitting station to a receiving station using radio waves. Te, comprising an interference wave detecting means for detecting an interference wave in the transmission space of the radio wave, when the interference wave is detected by the interference wave detecting means, the interference
High and low frequency bands based on wave frequency
The signal to be communicated is divided and spread spectrum.
And performing spread spectrum demodulation on the signal transmitted from the transmitting station to reproduce the signal to be communicated. Also, a second invention is a spread spectrum transmitting apparatus in a spread spectrum communication system for transmitting a signal to be transmitted in a wide band and transmitting the signal using a radio wave, wherein the transmission of the radio wave provided in the own device or other than the own device is provided. When the interference wave is detected by the interference wave detection means for detecting the interference wave in space, the interference wave is detected based on the frequency of the interference wave.
Should communicate between high and low frequency bands
It is characterized by comprising transmitting means for dividing the signal, spreading the spectrum and transmitting the divided signal . Also, a third invention is a spread spectrum receiving apparatus in a spread spectrum communication system for transmitting a signal to be communicated over a wide band and using radio waves, wherein the transmission of the radio waves provided in the own apparatus or other than the own apparatus is provided. When the interference wave is detected by the interference wave detecting means for detecting the interference wave in space, the interference wave
High frequency band and low frequency band
The signal to be communicated is divided and spread spectrum.
It is characterized by comprising reproducing means for performing spread spectrum demodulation on a plurality of signals to be transmitted and reproducing the signals to be communicated.

[0016]

In the spread spectrum communication system of the present invention, when an interference wave in the transmission space is detected, the interference wave is removed or the signal is transmitted while avoiding the band of the interference wave.

[0017] Therefore, the influence of the interference wave can be reduced, and high quality communication can be performed.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

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

In FIG. 1, reference numeral 100 denotes a transmitting station, 200 denotes a receiving station, and 300 denotes an interference wave generating source such as a microwave oven.

The transmitting station 100 converts the carrier into transmission data by 1
A carrier modulation unit 110 for performing the next modulation (PSK, FM, AM, etc.), a spread modulation unit 120 for performing a spread modulation by multiplying the carrier-modulated signal by a predetermined spreading code, and a signal subjected to the spread modulation A transmission unit 130 that performs power amplification of
An antenna 140 that emits a signal subjected to power amplification as a radio wave.

The receiving station 200 includes an antenna 210 for inducing a high-frequency signal from a radio wave, an interference wave detecting unit 230 for detecting an interference wave mixed in the received signal, and an interference wave detecting unit 230.
An interference wave removing unit 240 for removing the interference wave detected in step 1, a spread demodulation unit 250 for performing spread demodulation on the received signal from which the interference wave has been removed, and a carrier wave demodulation for the spread demodulated signal. And a carrier demodulation unit 260 that reproduces

Next, the operation of the spread spectrum communication system having the above configuration will be described.

In the transmitting station 100, the carrier wave is subjected to primary modulation such as PSK, FM, or AM by the carrier data in the carrier modulation section 110, and then multiplied by a predetermined spreading code in the spread modulation section 120 to perform secondary modulation ( (Spreading modulation), and is converted into a signal having a much wider band than the transmission data. The spread-modulated signal is power-amplified in transmitting section 130 and radiated from antenna 140 as a radio wave.

On the other hand, in the receiving station 200, the antenna 210
The high-frequency signal input from is subjected to high-frequency amplification, band limitation, and the like in the receiving unit 220. And the interference wave detector 23
At 0, the presence of an interference wave generated from the interference wave generation source 300 such as a microwave oven and mixed into the received signal is detected. Then, the interference wave removing section 240 removes the interference wave mixed into the received signal. The received signal from which the interference wave has been removed is subjected to spread demodulation by multiplying the received signal from the spread demodulation section 250 by the same code sequence as the code sequence obtained when spread modulation is performed by the transmitting station, and the transmission signal superimposed on the carrier wave is transmitted by the carrier wave demodulation section 260. The data is played.

FIG. 2 is a block diagram showing a detailed configuration of the interference wave detecting section 230 and the interference wave removing section 240 which are characteristic parts of the present invention of the receiving station 200 shown in FIG.

As shown in FIG.
Is a band-pass filter 231 having a variable center frequency.
And a level detector 232, and detects an interference wave by detecting a signal level at each center frequency while changing a center frequency of the bandpass filter 231 by a control signal.

Further, the interference wave removing section 240 follows the phase change of the interference wave signal mixed in the received signal, and oscillates a signal having the same frequency as the interference wave signal.
41 and a phase shift circuit 24 for making the phase of the signal oscillated by the phase locked loop circuit 241 and the phase of the interference signal the same.
2, a variable gain amplifier 243 that amplifies the signal output from the phase shift circuit 242, a switch 244 that turns on and off the output of the variable gain amplifier 243 by a signal from the interference wave detection unit 230, A subtraction circuit 245 for taking a difference between the output signal and the output signal of the switch 244;
It has a multiplication circuit 246 for multiplying the output signal of the subtraction circuit 245 and the output signal of the phase shift circuit 242, and an integration circuit 247 for integrating the output signal of the multiplication circuit 246 and extracting only low-frequency components.

Further, a phase locked loop circuit (PLL) 2
41 is a multiplier 241a which is a phase comparator, a loop filter 241b, and a voltage controlled oscillator (VCO) 241c.
It is composed of Further, the loop filter 241b is formed of, for example, a complete integration filter. The details of the operation of the PLL are described in, for example, "How to Use PLL-IC (Sanyo Publishing)".

Next, the operation of the receiving station having the configuration shown in FIG. 2 will be described.

The output signal of the receiving section 220 is represented by the following equation, which represents the signal X (t).

X (t) = S (t) + I (t) I (t) = Asin (ω ₀ t + θ) where S (t) is a desired signal and I (t) is a device such as a microwave oven, for example. The interference wave radiated from. A indicates the amplitude of the interference wave, ω ₀ indicates the angular frequency of the interference wave, and θ indicates the phase of the interference wave.

The signal X (t) is input to the interference wave detector 230 and the phase locked loop circuit 241. The phase locked loop circuit 241 synchronizes with the input periodic signal, and outputs a signal having the same frequency as that of the input and with noise suppressed to the VCO 241.
Output from c.

At this time, the output signal V of the VCO 241c
(T) is shown as follows.

V (t) = cos (ω ₀ t + θ) The phase locked loop circuit 241 synchronizes with the interference wave I (t),
I (t) and V (t) have a phase shift of 90 degrees. The VCO output V (t) is input to the phase shift circuit 242 and
Output signal U (t) of the phase shift circuit 242 after the phase shift
Becomes

U (t) = sin (ω ₀ t + θ) The output signal W (t) of the variable gain amplifier 243 is as follows.

W (t) = G sin (ω ₀ t + θ) (G
Is the gain of the variable gain amplifier) The output signal W (t) of the variable gain amplifier 243 is
44. The switch 244 is off when there is no interference wave, shuts off the signal W (t), and is on when there is an interference wave, passes the signal W (t) and inputs it to the subtraction circuit 245. At this time, the output signal of the subtraction circuit 245 is as follows for Y (t). Y (t) = X (t) −W (t) = S (t) + (A−G) sin (ω ₀ t + θ) The signal U (t) and the signal Y are output by the multiplication circuit 246.
(T) and the output signal E of the multiplication circuit 246.
(T) is as follows.

E (t) = U (t) · Y (t) = S (t) · sin (ω ₀ t + θ) + (AG) sin ² (ω ₀ t + θ) = S (t) · sin ( ω ₀ t + θ) + (AG) (1−cos 2 (ω ₀ t + θ)) / 2 Further, when the signal E (t) is input to the integration circuit 247, the signal E (t) is obtained by the low-pass characteristic of the integration circuit 247. ) Only passes through, and the output signal e (t) of the integration circuit 247 is as follows.

E (t) = (A−G) / 2 Further, the gain G of the variable gain amplifier 243 is determined by the signal e (t).
Is controlled as follows.

When e (t)> 0, that is, when A> G, G is increased.

If e (t) <0, that is, if A <G, G is decreased.

By controlling in this way, G is controlled so that e (t) = 0, that is, A = G.

When the control is performed so that A = G, the output signal Y (t) of the subtraction circuit 245 becomes Y (t) = S (t), the interference wave is removed, and the desired signal S (t) is converted. Obtainable.

The signal S (t) is input to the spread demodulation unit 250 and the carrier wave demodulation unit 260, where the data is reproduced by spread demodulation and carrier wave demodulation.

In the embodiment described above, the phase shift circuit 242
Although a fixed phase shift circuit with a phase shift is used, it is also possible to more accurately remove interference waves by using a variable phase shift circuit. When a plurality of interference waves exist, desired characteristics can be obtained by providing a plurality of similar circuits. The interference wave removing unit 240 can be realized by an analog circuit or a digital circuit. Further, the present invention is effective not only in a communication system using a wideband signal such as a spread signal in a spread spectrum communication in which a desired signal S (t) is used, but also in a communication system using a narrowband signal. The spread spectrum communication system may be a direct spread system or a frequency hopping system.

FIG. 3 is a diagram showing a configuration of a spread spectrum receiver according to another embodiment of the present invention.

In the figure, 400 is an antenna, 410
Is a receiver for amplifying and band-limiting the high-frequency signal induced by the antenna 400, 420 is an interference frequency detector for detecting the frequency of the interference signal mixed into the received signal, and 430 is detected by the interference frequency detector 420 5 shows a band rejection filter that attenuates an interference wave by changing a center frequency according to the obtained interference wave frequency.

In the embodiment shown in FIG. 2, the output of the phase locked loop circuit 241 is controlled, an amplitude signal having the same frequency and phase as the interference wave is generated, and the interference signal is subtracted from the received signal to remove the interference wave. In, the frequency of the interference wave is detected by the interference wave frequency detection unit 420, and the center frequency of the band rejection filter 430 is controlled so as to match the frequency of the interference wave, thereby removing the interference wave.

Further, in the embodiment shown in FIGS. 2 and 3, the interference wave is detected and removed at the receiving station, but if the transmitting station or the receiving station detects the interference wave, the transmission or the reception is stopped. You may do it.

FIG. 4 is a block diagram showing a configuration of a spread spectrum communication system according to still another embodiment of the present invention. In this embodiment, an interference wave is detected on the transmission side or the reception side, and if there is an interference wave, the frequency of the interference wave is detected and transmitted on the transmission side using a band other than the frequency of the interference wave. In the figure, 500 is a transmitting station,
Reference numeral 600 denotes a receiving station.

The transmitting station 500 includes a data division section 510 for dividing transmission data into two series of low-speed data strings D1 and D2.
, A carrier modulation section 520 that performs carrier modulation on the data stream D1, a spread modulation section 530 that performs spread modulation on the signal modulated by the carrier modulation section 520, and performs carrier modulation on the data stream D2. Carrier modulation unit 54
0, a spread modulator 550 that performs spread modulation on the signal carrier-modulated by the carrier modulator 540, an adder 560 that adds output signals of the spread modulator 530 and the spread modulator 550, and an adder 560. A transmitting unit 570 that performs power amplification of the added signal, an antenna 580 that emits an output signal of the transmitting unit 570 as a radio wave, and a duplexer 5 that is interposed between the transmitting unit 570 and the antenna 580.
85 and the interference wave received by the antenna 580.
5 and an interference wave detection unit 590 for detecting the interference wave via the control unit 5.

The receiving station 600 includes an antenna 610 for inducing a high-frequency signal from a radio wave, a receiving section 620 for performing high-frequency amplification and band limitation of the high-frequency signal induced by the antenna 610, and a signal output from the receiving section 620. A band pass filter 630 that passes only a specific band of the band,
640, spread demodulation sections 650 and 660 for spreading and demodulating the received signals band-limited by band pass filters 630 and 640, and carrier demodulation for carrier demodulating the signals spread and demodulated by spreading demodulation sections 650 and 660. Units 670 and 680, a data combining unit 690 that combines data demodulated by carrier wave demodulating units 670 and 680 to reproduce transmission data, and an interference wave detecting unit 695 that detects an interference wave from a signal received from receiving unit 620. And

Next, the operation of the spread spectrum communication having the above configuration will be described.

If no interference wave is detected by interference wave detecting section 590 of transmitting station 500, transmitting station 10 shown in FIG.
Data transmission is performed using the same configuration as described above. Receiving station 600
However, similarly, when no interference wave is detected by the interference wave detection unit 695, data reception is performed using the same configuration as the receiving station 20 shown in FIG. When an interference wave is detected by the interference wave detection units 590 and 695, data is transmitted and received using the configuration shown in FIG.

Now, the interference wave detector 590 of the transmitting station 500
First, the transmission data D is divided by the data division unit 510 into two series of data strings D1 and D2.

FIG. 5 is a diagram showing transmission data D, divided data strings D1 and D2, and the spectra of these data strings.

FIG. 7A shows the transmission data D and its spectrum, and FIG. 7B shows the divided data strings D1 and D2 and their spectra. As shown in these figures, assuming that the frequency bandwidth of the original transmission data D is b0, the bandwidths of data D1 and data D2, b1 and b2 are b0
1 = b2 = b0 / 2.

Next, the carrier wave of frequency f1 is modulated by the data sequence D1 in the carrier wave modulator 520. On the other hand, the carrier wave of the frequency f2 is modulated by the data sequence D2 in the carrier modulation section 540.

FIG. 6 is a diagram showing the spectrum of a signal after carrier wave modulation, and f0 indicates the frequency of the picture interference wave.

Further, spread modulation is performed on the signal after carrier modulation by spread modulation sections 530 and 550 to widen the band and lower the power density.

FIG. 7 is a diagram showing the spectrum of a signal after spread modulation. As shown in the figure, by appropriately selecting the frequencies f1 and f2 of the carrier wave and the data transfer speed with respect to the frequency f0 of the interference wave, it becomes possible to transmit data without overlapping with the band of the interference wave. .

The case where an interference wave is detected by interference wave detecting section 695 in receiving station 600 will be described. In this case, the band-pass filter 630 passes a frequency band lower than the frequency f0 of the interference wave, and the band-pass filter 640 passes a frequency band higher than the frequency f0 of the interference wave. In the spread modulation section 650, the signal passing through the band-pass filter 630, that is, the frequency f of the interference wave
Spread demodulation is performed for frequencies lower than 0. Further, spread modulation section 660 performs spread demodulation on the signal passed through band-pass filter 640, that is, a frequency higher than frequency f0 of the interference wave, using the same code sequence used in transmitting station 500. That is, spread modulation section 650 performs spread demodulation on data sequence D1, and spread modulation section 660 performs spread demodulation on data sequence D2. Then, carrier demodulation sections 670 and 680 perform carrier demodulation on the signals spread and demodulated by spread modulation sections 650 and 660, and demodulate data sequence D1 and data sequence D2, respectively. The data combining section 690 combines the data sequence D1 and the data sequence D2 to reproduce the transmission data D.

The two spread modulators 5 of the transmitting station 500
The 30, 550 spreading code strings may be the same or different. Alternatively, two carrier modulation signals may be combined and then spread-modulated collectively.

The above embodiment has been described using the direct spreading method. However, a frequency hopping spreading method of selecting a frequency signal and hopping with a spreading code pattern so as not to overlap with the detected interference wave frequency may be used. In the above-described embodiment, the case where there is one interference wave has been described. However, even when there are a plurality of interference waves, data is divided so as to avoid the frequency band of the interference wave, the carrier frequency is determined, and spread modulation is performed. You can do it. Further, the division of the data is not limited to two, and the data can be divided into three or more and transmitted.

In the case of the embodiment shown in FIG.
N, the transmitting station and the receiving station are used in a relatively close state, such as N, so that the interference wave from the interference wave
When the transmitting station and the receiving station are separated, the transmitting station can detect the interference wave but the receiving station cannot detect the interference wave. When the transmitting station and the receiving station are separated in this way, an interference wave detection unit is provided only in the transmitting station, and when the transmitting station detects an interference wave, a pilot signal indicating interference wave detection is transmitted and the receiving station transmits the pilot signal. When the pilot signal is received, reception with the configuration of the receiving station 600 shown in FIG. 4 may be started.

Further, the transmitting station may transmit using a band other than the frequency of the interference wave, and the reception side may remove the interference wave.

As described above, in the above-described embodiment, the interference wave mixed in the received signal is removed or the spread modulated signal is transmitted while avoiding the frequency band of the interference wave. It is hard to receive and high quality communication can be performed.

[0068]

Since the spread spectrum communication system of the present invention, according to the present invention so that transmitted signals to avoid the band of interference Watarunami if it detects an interference wave transmission space to reduce the influence of interference waves, high High quality communication can be performed. Also,
Stop transmission or reception if an interference wave is detected.
Can also be.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a detailed configuration of an interference wave detecting unit and an interference wave removing unit which are characteristic parts of the present invention of the receiving station shown in FIG.

FIG. 3 is a diagram showing a configuration of a spread spectrum receiving apparatus according to another embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a spread spectrum communication system according to still another embodiment of the present invention.

FIG. 5 shows transmission data D, divided data strings D1, D
FIG. 2 is a diagram showing the spectrum of these data strings.

FIG. 6 is a diagram illustrating a spectrum of a signal after carrier wave modulation.

FIG. 7 is a diagram showing a spectrum of a signal after spread modulation.

FIG. 8 is a diagram showing a configuration of a conventional spread spectrum communication.

9 is a diagram illustrating a spectrum of a signal of each unit in spread spectrum communication having the configuration illustrated in FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 100 ... Transmission station 110 ... Carrier modulation part 120 ... Spreading modulation part 130 ... Transmission part 140 ... Antenna 200 ... Reception station 210 ... Antenna 220 ... Reception part 230 ... Interference wave detection part 240 ... Interference wave removal part 250 ... Spread demodulation part 260 ... Carrier demodulation unit 300 ... Interference wave generation source

 ──────────────────────────────────────────────────続 き Continuing from the front page (73) Patent holder 000003078 Toshiba Corporation 72-72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inventor Ryuji Kono 1202-9 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Shinichi Tachikawa 5154 Katagai-cho, Ojiya-shi, Niigata (72) Inventor Hiroshi Kobayashi 70 Yanagimachi, Yuki-ku, Kawasaki-shi, Kanagawa Toshiba Inside Yanagimachi Plant (72) Inventor Shoichiro Yamazaki 70, Yanagimachi, Sachi-ku, Kawasaki City, Kanagawa Prefecture Inside Toshiba Yanagimachi Plant (56) References JP-A-63-276926 (JP, A) JP-A-63-127632 (JP) , A)

Claims (3)

(57) [Claims] 1. A spread spectrum communication system for broadening a signal to be transmitted and transmitting the signal from a transmitting station to a receiving station using radio waves, comprising: an interference wave detecting means for detecting an interference wave in a transmission space of the radio waves. When an interference wave is detected by the interference wave detection means, a high frequency band based on the frequency of the interference wave
The signal to be communicated is divided into
A spread- spectrum communication system , wherein the signal transmitted from the transmitting station is spread, and the signal to be communicated is reproduced by performing spread-spectrum demodulation on the signal transmitted from the transmitting station. 2. A spread-spectrum transmission apparatus in a spread-spectrum communication system for transmitting a signal to be transmitted in a wide band and transmitting the signal using a radio wave, wherein the signal is transmitted in a transmission space of the radio wave provided in the own device or other than the own device. On the stage where the interference wave is detected by the interference wave detection means for detecting the interference wave, the frequency of the interference wave is used as a reference.
Signals to be communicated between high and low frequency bands
A spread spectrum transmitting apparatus, comprising: transmitting means for dividing the spectrum and transmitting the divided spectrum . 3. A spread spectrum receiving apparatus in a spread spectrum communication system for transmitting a signal to be communicated over a wide band and using radio waves, wherein the radio wave is transmitted in a transmission space of the radio waves provided in the own device or other than the own device. On the stage where the interference wave is detected by the interference wave detection means for detecting the interference wave, the frequency of the interference wave is used as a reference.
Signals to be communicated between high and low frequency bands
A spread- spectrum receiving apparatus comprising: a reproduction unit that performs spread-spectrum demodulation on a plurality of signals that are divided and spread and transmitted, and reproduces the signals to be communicated.