JPH0213979B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a spread spectrum transmitter/receiver that transmits or receives various information by spread spectrum.

Conventional Structure and Problems There are various communication systems currently being researched and developed, and one of them is known as a spread spectrum communication system.

In this method, the transmitting side spreads the spectrum of a narrowband signal such as data or voice over a wide band using pseudo noise and sends it out, and the receiving side performs correlation detection (despreading) on the signal to reproduce the narrowband signal. It is. This spread spectrum communication method not only makes effective use of frequencies, but also is resistant to external interference and noise, and has high confidentiality.
In recent years, it has attracted attention as a very effective communication method.

On the other hand, there is a demand for communication by superimposing signals on existing power lines, which are not originally communication lines, because of the simplicity of not requiring new wiring work. Examples of this include devices that control or monitor home appliances by transmitting and receiving a specific frequency (approximately 120KHz) in synchronization with the power line frequency, and FM carrier interfaces that transmit and receive FM-modulated audio. It has been put into practical use.

However, since the example above uses a specific frequency, other equipment connected to the same power line (e.g.
Problems include noise from refrigerators, vacuum cleaners, etc.) and a drop in impedance at this frequency.

In the case of communication using power lines as a medium, the spread spectrum communication method does not use a specific frequency, so other equipment is connected to the same power line, and this equipment generates noise at a specific frequency. ,
Alternatively, even if there is a drop in impedance at a specific frequency, it is hardly affected, making it a particularly effective means of communication.

When using electric light lines, the frequency is 10KHz or more according to the Radio Law.
Since only the 450KHz range is available, which is a relatively low frequency band, a pace band spread spectrum method is used. The conventional spread spectrum method using power lines will be described below with reference to the drawings.

FIG. 1 shows the main block configuration of a conventional transmitting/receiving device based on the power line spread spectrum system.

In FIG. 1, 1 is a clock and synchronization signal generator that generates a clock CK and a synchronization signal SYNC, and 2 is a clock and synchronization signal generator that generates a clock CK and a synchronization signal SYNC.
a signal pseudo-noise generator that generates broadband pseudo-noise such as M-series or gold-series; 3 a modulator for spreading the spectrum of the information signal to be transmitted using the signal pseudo-noise of the signal pseudo-noise generator 2; 4; uses the clock CK and the synchronization signal SYNC generated by the clock and synchronization signal generator 1 to generate an M-sequence or gold signal that is synchronized with the pseudo noise generated by the signal pseudo noise generator 2 but different A synchronization pseudo-noise generator 4 that generates pseudo-noise (such as a sequence) is an adder that adds the signal spread by the modulator 3 and the pseudo-noise generated by the synchronization pseudo-noise generator 4. The above clock and synchronization signal generator 1, signal pseudo-noise generator 2, modulator 3, synchronization pseudo-noise generator 4, and adder 5 form a transmitting section. 6 and 6' are couplers configured with transformers or capacitors that send the output of the adder 5 to the power line of the transmission medium or receive it via the power line, and the coupler 6 receives the output of the adder 5 mentioned above. is transmitted to the power line, and the coupler 6' receives the signal superimposed on the power line. 7 is an automatic gain controller that amplifies the signal output from the coupler 6' and automatically controls the gain;
Reference numerals 8, 9, and 10 are correlation detectors that perform correlation detection by multiplying the output of the automatic gain controller 7 by a pseudo noise generated from a synchronization pseudo noise generator (described later), and 11 is generated by a voltage controlled oscillator (described later). clock CK
The synchronization required to generate three different sequences of the same pseudo-noise by one clock as the synchronization pseudo-noise generator 4 described in the transmitting section and at the same time synchronize with the signal pseudo-noise generator described later. signal
Synchronization pseudo noise generator that generates SYNC, 12,
13 and 16 are low-pass filters that pass only necessary low frequency components among the outputs of the correlation detectors 8, 10, and 9, respectively; 14 is a subtracter that subtracts the output of the low-pass filter 13 from the output of the low-pass filter 12; 15 is a voltage controlled oscillator whose oscillation frequency changes according to the output voltage of the subtracter 14; 18 is a clock generated by the voltage controlled oscillator 15 in synchronization with the synchronization signal SYNC generated by the synchronization pseudo noise generator 11;
CK, a signal pseudo-noise generator that generates the same series of pseudo-noise as the signal pseudo-noise generator 2 of the transmitting section; 17 is the output of the automatic gain controller 7 and the signal generated by the signal pseudo-noise generator 18; A correlation detector 19 performs correlation detection by multiplying by pseudo-noise, and a low-pass filter 19 extracts a necessary low-frequency component information signal from the signal despread by the correlation detector 17.

Regarding the transmitter/receiver configured as above,
The operation will be described below.

First, an information signal to be transmitted is generated by a generating means (not shown), and the information signal is sent from the generating means to the modulator 3 of the information signal transmitter. The modulator 3 modulates (spreads) the pseudo noise sent from the signal pseudo noise generator 2, and the adder 5 adds it to the pseudo noise sent from the synchronization pseudo noise generator 4. sent to the line.
Here, using the clock CK and the synchronization signal SYNC generated by the clock and synchronization signal generator 1, the pseudo noise generated by the signal pseudo noise generator 2 and the synchronization pseudo noise generator 4 is synchronized. are synchronized.

Now, the signal and synchronization pseudo noise that is spread spectrum in the transmitter and transmitted to the power line are as follows:
It is received by combiner 6' and sent to automatic gain controller 7. The automatic gain controller 7 amplifies the received signal and automatically controls its gain using the output of a low-pass filter 16 (described later) to maintain a constant level regardless of the input signal level from the coupler 6'. Send a signal. The output of the automatic control gain controller 7 is supplied to the correlation detectors 8, 9, and 10, and the output of the synchronization pseudo-noise generator 11, which generates the same pseudo-noise as the synchronization pseudo-noise generator 4 of the transmitting section ( a), (b)
and (c) respectively, and correlation detection (despreading)
be done. Here, the synchronization pseudo-noise output (b) is delayed by one clock from the synchronization pseudo-noise output (a), and similarly, the synchronization pseudo-noise (c) is further delayed by one clock from the synchronization pseudo-noise output (b). be. The output of the correlation detector 8 is the pseudo noise sent out from the synchronization pseudo noise generator 4 of the transmitting section and the synchronization pseudo noise generator 1 of the receiving section.
When the pseudo noise output (a) of 1 is in phase, it becomes a peak and decreases whether it is faster or slower than this. Therefore, when the output of the correlation detector 8 is passed through the low-pass filter 12, it becomes a triangular shape whose lower side is ±1 clock. Similarly, the signal obtained by passing the output of the correlation detector 10 through the low-pass filter 13 is passed through the low-pass filter 1.
It has a triangular shape whose lower side is ±1 clock that is two clocks later than the output of No.2. When the output of the low-pass filter 13 is subtracted by the subtracter 14 from the output of the low-pass filter 12, the output (b) of the synchronization pseudo-noise generator 11 is the output of the synchronization pseudo-noise generator 4 of the transmitter. It is 0 when it is in phase with , a positive peak when the phase is leading, and a negative peak when the phase is lagging. The output of the subtracter 14 controls the oscillation frequency of the voltage controlled oscillator 15 to clock the clock.
Generate CK. This clock CK is used as a clock for generating pseudo noise in the synchronization pseudo noise generator 11. By using such a loop, the pseudo noise output (b) generated by the synchronization pseudo noise generator 11 becomes in phase with the pseudo noise generated by the synchronization pseudo noise generator 4 of the transmitter. Such a loop is known as a delay lock loop. In the above delay lock loop, the output (b) of the synchronization pseudo-noise generator 11, which is in phase with the pseudo-noise of the transmitter synchronization pseudo-noise generator 4, is connected to the output of the automatic gain controller 7 and the correlation detector 9. The correlation is detected at
Automatic gain controller 7 so that the output of
Control with.

The signal pseudo-noise generator 18 receives the clock CK from the voltage-controlled oscillator 15 and the synchronization signal SYNC from the synchronization pseudo-noise generator 11, and synchronizes with the synchronization pseudo-noise generator 11. A pseudo noise having the same phase as that of the transmitter signal pseudo noise generator 2 is generated. A correlation detector 17 detects the correlation between the output of the signal pseudo-noise generator 18 and the output of the automatic gain controller 7, and the output is passed through a low-pass filter 19 to remove unnecessary high frequency components. I can get a signal.

According to the above configuration, since the signal pseudo-noise generators 2 and 18 are provided, the information signal can be transmitted and received by spreading it over a wide same wave number band, and it is possible to transmit and receive the information signal by spreading it over a wide same frequency band. It is less susceptible to influence, and the information signal cannot be deciphered unless the sequence of the signal pseudo noise of the transmitter is known, so it has high secrecy. Further, since the synchronization pseudo noise generators 4 and 11 are provided, there is an advantage that transmission and reception can be synchronized without being influenced by information signals.

However, in the above configuration, the information signal is directly transmitted.
Since the signal is modulated by the pseudo noise of the signal pseudo noise generator 2, it is difficult to synchronize transmission and reception using the same pseudo noise of the signal pseudo noise generator 18 in the receiving section. Pseudo-noise generators 4 and 11 are required. In addition, in order to synchronize transmission and reception, three correlation detectors 8, 9, and 10 for synchronization and automatic gain control are required in addition to the signal system, and a total of four correlation detectors are required. And the receiving device becomes complicated. Also, as mentioned above, low-pass filters 12, 13, 16, and 19 are necessary, but especially when performing spread spectrum communication using power lines as a medium, the power supply frequency (50 Hz) is higher at the station end than the signal. Or 60
Hz), it is necessary to provide sufficient high-pass filters (not shown) before entering the low-pass filters 12, 13, 16, and 19. Also, compared to high-pass filters or band-pass filters, low-pass filters have a larger DC drift due to temperature and shock noise, so be careful of this point especially when using low-pass filters in delay lock loops for synchronizing transmission and reception as described above. It also had the disadvantage that it also required

Purpose of the Invention In view of the above drawbacks, the present invention provides a spread spectrum transmission/reception system that does not require a synchronization pseudo-noise generator separate from that for signals, is less susceptible to direct current drift, and can greatly simplify the configuration. It provides equipment.

Structure of the Invention The present invention includes a first oscillator that changes an oscillation frequency according to an information signal to be transmitted, and a first oscillation signal oscillated by the first oscillator that generates a first pseudo-noise as a clock. A transmitter is equipped with a first pseudo-noise generating means, a modulating means for modulating the first oscillation signal with the first pseudo-noise, and an output means for transmitting the output of the modulating means to a transmission medium. and an input means for receiving the output of the output means via the medium, a gain controller for controlling the gain of the received signal received by the input means, and a demodulation means for demodulating the output of the gain controller. a bandpass filter that performs bandpass filtering at a constant frequency on the output of the demodulation means; and an envelope detector that performs envelope detection from the output of the bandpass filter to provide a control signal for the gain controller. , a second oscillation signal oscillated by a second oscillator is used as a clock to generate a second pseudo-noise, and the demodulation means demodulates the output of the gain controller in accordance with the second pseudo-noise. a second pseudo-noise generating means for outputting this second pseudo-noise to the demodulating means; and a second pseudo-noise generating means for outputting the second pseudo-noise to the demodulating means; The receiver is equipped with a phase comparator that controls the oscillation frequency, and the receiver side includes a gain controller, demodulation means, a bandpass filter,
and an envelope detector to form a first loop circuit, and the gain controller performs automatic gain control, and the demodulation means, a bandpass filter, a phase comparator, a second oscillator, and a second pseudo noise. The above object is achieved by forming a second loop circuit by the generating means to synchronize with the receiver side and demodulating the information signal.

Further, the present invention includes a first oscillator that changes an oscillation frequency according to an information signal to be transmitted, and a first oscillator that generates a first pseudo noise using a first oscillation signal oscillated by the first oscillator as a clock. The transmitter is equipped with a pseudo-noise generating means, a modulating means for modulating the first oscillation signal with the first pseudo-noise, and an output means for transmitting the output of the modulating means to a transmission medium, input means for receiving the output of the output means via the medium; a gain controller for controlling the gain of the received signal received by the input means; first and second demodulators for demodulating the output of the gain controller; , a third demodulating means, and the first, second,
first, second, and third bandpass filters each perform bandpass filtering at a constant frequency on the output of the third demodulating means; and envelope detection is performed from the output of the second bandpass filter to a second envelope detector for generating a control signal for the gain controller; first and third envelope detectors for performing envelope detection from the outputs of the first and third bandpass filters; , a subtracter that calculates the difference between the outputs of the third envelope detector, a second oscillator that changes the oscillation frequency according to the output signal of the subtracter, and a second oscillator oscillated by the second oscillator. The second, third, and fourth pseudo-noises are generated using the oscillation signal of generating a pseudo-noise (delayed by one clock) and outputting it so that the first, second, and third demodulation means demodulate the output of the gain controller according to each of these pseudo-noises; means are included in the receiver,
A first loop circuit is formed by a gain controller, a second demodulation means, a second bandpass filter, and a second envelope detector on the receiver side, and the gain controller performs automatic gain control. At the same time, a second loop circuit is formed by the first and third demodulating means, the first and third bandpass filters, the subtracter, the second oscillator, and the second pseudo noise generating means, The above object is achieved by synchronizing with the receiver side and demodulating the information signal.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a block configuration of a spread spectrum transmitter/receiver according to an embodiment of the present invention.

In FIG. 2, 5 is a modulator, 2 and 18 are pseudo noise generators, 6 and 6' are combiners, 7 is an automatic gain controller, 15 is a voltage controlled oscillator, and 17 is a correlation detector. This is the same configuration as shown in FIG.

On the other hand, 21 is a voltage controlled oscillator, 22 and 23 are frequency dividers, 24 is a phase comparator, 25 is a band pass filter, and 26 is an envelope detector.

In the transmitter/receiver configured as above,
The operation will be explained in detail below with reference to the waveform diagrams shown in FIGS. 2 and 3.

The information signal to be sent as shown in Figure 3a is input to the voltage controlled oscillator 21, and as shown in Figure 3b, the oscillation frequency is set to frequency ₁ when the information signal is at high level and frequency ₂ when it is at low level. generate.
(Here, ₁ and ₂ are set within the transmission bandwidth (10K to 450KHz in the case of power line transmission).) This oscillation signal is input to the frequency divider 22 and is divided into the necessary frequencies as shown in Figure 3c. The frequency is divided by a frequency division ratio (FIG. 3 shows an example of frequency division by 1/2). Using this frequency-divided signal shown in FIG. 3c as a clock, the pseudo noise generator 2 generates the pseudo noise shown in FIG. 3d. The output of the voltage controlled oscillator 21 is modulated by the modulator 5 using pseudo noise generated by the pseudo noise generator 2 to spread the spectrum. Figure 3e shows this situation.
An example of balanced modulation of FIG. 3b is shown in FIG. 3d. That is, when the output of the pseudo noise generator 2 (Fig. 3 d) is at a high level, the output of the modulator 5 (Fig. 3 e) is in phase with the output of the voltage controlled oscillator 21 (Fig. 3 b). A signal is sent out, and when the signal d in FIG. 3 is at a low level, a signal having the opposite phase to that in FIG. 3b is sent out. The output of the modulator 5 is transmitted to the power line through the coupler 6 in the same manner as described in FIG. 1, and similarly the signal from the power line is received through the coupler 6' and sent to the receiver.

In the receiving section, the automatic gain controller 7 described in FIG. 1 sends out a constant output regardless of the reception level. Although the output of the automatic gain controller 7 has the original waveform shown in FIG. 3e, it is actually modified by noise on the transmission path or by the frequency characteristics of impedance. Here, for convenience of explanation, it will be described as being the same as FIG. 3e. The pseudo-noise generator 18 is set in advance to generate pseudo-noise of the same series as the pseudo-noise generator 2 of the transmitting section, and is also synchronized by a loop to be described later.
The pseudo noise generator 2 of the transmitting section as shown in FIG. Output of automatic gain controller 7 (Fig. 3 e) and output of pseudo noise generator 18 (Fig. 3 f)
is multiplied by the correlation detector 17, and when f in FIG. This signal is transmitted at the frequency described in the transmitter section.
₁ , ₂ and the transmission speed of the information signal, and is input to a bandpass filter 25 having a corresponding frequency bandwidth, and is waveform-shaped by a waveform shaper 27, as shown in FIG. 3g. It becomes a signal. This signal of FIG. 3g and the voltage controlled oscillator 15
The oscillation signal of the voltage controlled oscillator 15 is input to the phase comparator 24, the phases of both signals are compared, and the oscillation frequency of the voltage controlled oscillator 15 is controlled by the phase difference signal.
Form a loop consistent with figure g. On the other hand, the output of the voltage controlled oscillator 15 is further transmitted to the frequency divider 2 of the transmitting section.
2 and is supplied to the frequency divider 23, and is inputted as a clock to the pseudo noise generator 18 in the same manner as explained in the transmitting section.

The pseudo noise generator 18, correlation detector 17, bandpass filter 25, and waveform shaper 2 described above
7. Through the loop of the phase comparator 24, voltage controlled oscillator 15, and frequency divider 23, the output of the receiving section pseudo noise generator 18 is synchronized with the output of the transmitting section pseudo noise generator 2. The output of the bandpass filter 25 is further supplied to an envelope detector 26,
The envelope is detected and input to the automatic gain controller 7,
Due to the loop formed by the automatic gain controller 7, the correlation detector 17, the bandpass filter 25, and the envelope detector 26, the output of the envelope detector 26 is constant, and therefore the output of the automatic gain controller 7 (third Figure e) has a constant amplitude.

Due to the action of each loop described above, the waveform shown in FIG. 3h is outputted from the phase comparator 24. This is the transmitted information signal shown in FIG. 3a, and this information signal has been demodulated.

As described above, according to this embodiment, a pseudo noise generator for synchronization is not used separately from that for signals, and moreover, only one correlation detector can perform synchronization and demodulation of information signals, and the configuration is significantly simplified compared to the conventional one. can do. Furthermore, since the bandpass filter 25 is used in the demodulation loop, a stable system that is not affected by DC drift can be achieved compared to the case where a conventional low-pass filter is used.

FIG. 4 shows a block configuration of a transmitting/receiving device in a second embodiment of the present invention.

In FIG. 4, 5 is a modulator, 2 and 18 are pseudo noise generators, 6 and 6' are combiners, 7 is an automatic gain controller, 8, 9, and 10 are correlation detectors, 14 is a subtracter, 15 and 21 are voltage controlled oscillators, 22 and 23 are frequency dividers, 25 is a band pass filter, and 26 is an envelope detector, which is the same as the configuration shown in FIG. 2. On the other hand, 28 and 29 are band pass filters, which have the same performance as the band pass filter 25. Envelope detectors 30 and 31 have the same performance as the envelope detector 26.

The operation will be explained below using FIG. 4. Note that the transmitting section has exactly the same configuration as that explained in FIG. 2, so a description thereof will be omitted.

In addition, in the receiving section, the difference in configuration from the conventional one shown in FIG. bandpass filters 25, 28, and 29 and envelope detectors 26, 30, and 31 are provided, and a frequency divider 23 having the same configuration as that explained in FIG. 2 is provided, and the pseudo noise generator for synchronization shown in FIG. 11 is replaced by a pseudo noise generator 18 (for signals) set in the same series as the pseudo noise generator 2 of the transmitting section.
(However, outputs (a), (b), and (c) are delayed by one clock as explained in FIG. 1).

First, the outputs of the correlation detectors 8, 9, and 10 are converted into correlation strength signals by the bandpass filters 28, 25, and 29 and the envelope detectors 30, 26, and 31, respectively, and the low-pass filters 12 and 10 described in FIG.
16 and 13 will be output.
Therefore, in the loop of the automatic gain controller 7, the correlation detector 9, the bandpass filter 25, and the envelope detector 26, the amplitude of the output of the automatic gain controller 7 is kept constant as explained in FIG. Also, due to the loop formed by the correlation detectors 8, 10, bandpass filters 28, 29, envelope detectors 30, 31, subtracter 14, voltage controlled oscillator 15, frequency divider 23, and pseudo noise generator 18, , the receiver pseudo-noise generator 18 can be synchronized with the transmitter pseudo-noise generator 2, similar to that described in FIG. Therefore, as explained in FIG. 2, the input of the voltage controlled oscillator 15, ie, the output of the subtracter 14, becomes the same information signal as that transmitted and is demodulated. In this case as well, there are effects similar to those of the first embodiment described above.

In addition, in the embodiments explained in FIGS. 2 and 4, the information signal was explained as a binary signal as shown in FIG. Don't bend over.

Furthermore, in the embodiments of FIGS. 2 and 4, the frequency divider 22,
23, the case where the frequency division ratio is 1 is also included. In this case, the frequency dividers 22 and 23 can be omitted.

Further, in the embodiments shown in FIGS. 2 and 4, a case has been described in which a power line is used as a transmission medium, but the transmission medium is not limited to a power line, but may also be infrared rays, ultrasonic waves, radio waves, etc.

Furthermore, in the embodiments shown in FIGS. 2 and 4, the input signal of the voltage controlled oscillator is extracted as an information signal, but the output of the bandpass filter 25 is
As already explained, since it is a frequency modulated signal, the information signal can be demodulated from the output of the bandpass filter 25 using a known frequency demodulator.

Effects of the Invention As described above, the present invention changes the oscillation frequency of a voltage controlled oscillator with an information signal, uses this oscillation signal as a clock for generating pseudo noise from a pseudo noise generator, and also uses the oscillation signal and the pseudo noise as a clock. By spreading the spectrum and transmitting it, and forming a loop with a correlation detector, bandpass filter, voltage controlled oscillator, pseudo noise generator, etc. in the receiving section, the configuration is simpler than before and is less susceptible to DC drift. It can be done, and the effects are great.

[Brief explanation of drawings]

Fig. 1 is a block wiring diagram of a conventional transmitting/receiving device using the spread spectrum method, Fig. 2 is a block wiring diagram of a spread spectrum transmitting/receiving device according to an embodiment of the present invention, Fig. 3 is a timing chart of the same device, and Fig. 4 FIG. 2 is a block diagram of a spread spectrum transmitter/receiver according to another embodiment of the present invention. 1... Clock and synchronization signal generator, 2, 4,
11, 18...Pseudo noise generator, 3...Modulator,
5... Adder, 6, 6'... Combiner, 7... Automatic gain controller, 8, 9, 10, 17... Correlation detector, 12, 13, 16, 19... Low pass filter, 14... ...Subtractor, 15, 21... Voltage controlled oscillator, 22, 23... Frequency divider, 24... Phase comparator, 25, 28, 29... Band pass filter,
26, 30, 31... Envelope detector, 27... Waveform shaper.

[Claims]

1 The transmitting side is equipped with a filter circuit having an emphasis characteristic H(f), a spectrum inverting circuit that receives the output of the filter circuit as input, and a transmitting circuit that phase-modulates the output of the inverting circuit and transmits the signal. A receiving circuit for a phase modulated wave, and an emphasis characteristic H provided on the output side of the receiving circuit that is exactly the same as that on the transmitting side.
(f); and a spectrum inversion circuit whose input is the output of the filter circuit.
On the transmitting side, the original signal to be transmitted is emphasized,
The spectrum-inverted signal is phase-modulated and transmitted, and the receiving side receives the phase-modulated wave and performs the same emphasis processing on the demodulated signal as on the transmitting side, and then spectrally inverts the resulting signal as a reproduced signal. A transmitting/receiving isomorphic emphasis reverse secret communication system characterized by the following.

Claims (1)

A first loop circuit is formed by a controller, a demodulating means, a bandpass filter, and an envelope detector, and the gain controller performs automatic gain control. 2. A spread spectrum transmitting/receiving device that forms a second loop circuit using a second oscillator and a second pseudo-noise generating means to synchronize with the transmitter side and demodulate the information signal. 2. The spread spectrum transmitting/receiving device according to claim 1, wherein the first and second oscillators are voltage controlled oscillators that change their oscillation frequencies in accordance with changes in the voltage of the information signal. 3. The first and second pseudo-noise generating means each include a frequency divider that divides the frequency of the oscillation signal oscillated by the first and second oscillators to obtain a frequency-divided signal, and a frequency divider that generates a frequency-divided signal by using the frequency-divided signal as a clock signal. The spread spectrum transmitting/receiving apparatus according to claim 1, further comprising a pseudo noise generator that generates noise. 4. The spread spectrum transmitting/receiving device according to claim 3, wherein the frequency dividing ratio of the frequency divider is 1 or less. 5. The spread spectrum transmitting/receiving device according to claim 1, wherein the output means and the input means are equipped with a transformer or a capacitor for transmitting and receiving data via a power line as a medium. 6. A first oscillator that changes an oscillation frequency according to an information signal to be transmitted, and a first pseudo-noise generator that generates a first pseudo-noise using a first oscillation signal oscillated by the first oscillator as a clock. A transmitter is provided with: a modulating means for modulating the first oscillation signal with the first pseudo noise; and an output means for transmitting the output of the modulating means to a transmission medium; input means for receiving the output of the input signal via the medium, a gain controller for controlling the gain of the received signal received by the input means, and first, second, and
a third demodulating means; first, second, and third bandpass filters that perform constant frequency bandpass filtering on the outputs of the first, second, and third demodulating means, respectively; a second envelope detector that performs envelope detection from the output of the bandpass filter and uses it as a control signal for the gain controller; and a second envelope detector that performs envelope detection from the outputs of the first and third bandpass filters. 1, a third envelope detector, and the first and third envelope detectors;
a second oscillator that changes the oscillation frequency according to the output signal of the subtracter; and a second oscillation signal oscillated by the second oscillator. The second, third,
A fourth pseudo-noise is generated (however, the third pseudo-noise is delayed by one clock each from the second pseudo-noise, and the fourth pseudo-noise is delayed by one clock from the third pseudo-noise). , pseudo noise generating means for outputting the first, second and third demodulating means to demodulate the output of the gain controller according to these pseudo noises, respectively, the receiver is equipped with A first loop circuit is formed by a gain controller, a second demodulation means, a second bandpass filter, and a second envelope detector on the side, and the gain controller performs automatic gain control, and the gain controller performs automatic gain control. A second loop circuit is formed by the first and third demodulation means, the first and third bandpass filters, the subtracter, the second oscillator, and the second pseudo noise generation means, and the receiver side A spread spectrum transmitting/receiving device that synchronizes with the information signal and demodulates the information signal. 7. The spread spectrum transmitting/receiving device according to claim 6, wherein the first and second oscillators are voltage controlled oscillators that change their oscillation frequencies in accordance with changes in the voltage of the information signal. 8 The first and second pseudo-noise generating means each include a frequency divider that divides the oscillation signals oscillated by the first and second oscillators to obtain a frequency-divided signal, and a frequency divider that generates a frequency-divided signal by using the frequency-divided signal as a clock signal. 7. The spread spectrum transmitting/receiving apparatus according to claim 6, further comprising a pseudo noise generator that generates noise. 9. The spread spectrum transmitting/receiving apparatus according to claim 8, wherein the frequency division ratios of the first and second frequency dividers are 1 or less. 10. The spread spectrum transmitting/receiving device according to claim 6, wherein the output means and the input means are equipped with a transformer or a capacitor for transmitting and receiving data via a power line as a medium.