JPH1022956A - Demodulator for am data multiplexed and modulated wave signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a demodulator for demodulating a base band digital signal based on a multiplexed digital wave signal from an AM data multiplexed and demodulated wave signal. SOLUTION: This modulator amplitude-modulates the carrier wave of a frequency fc by an analog signal wave by means of an AM modulator and demodulates a base band digital signal from the AM data multiplexed and demodulated wave signal obtained by multiplexing a digital modulated wave signal at the position of a frequency (fc+fα) and the position of a frequency (fc-fα) which are symmetrical with the carrier wave of the frequency fc as the axis of symmetry on a frequency axis. The AM data multiplexed and demodulated wave signal is synchronize-detected by a synchronizing detector 2, the carrier wave of the frequency fc is AM-modulated with a synchronizing detection output signal by an AM modulator 5, this modulated wave signal is subtracted from the AM data multiplexed and demodulated wave signal by a subtractor 6 and a subtraction output is demodulated to the base band digital signal by a data demodulation circuit B based on the data modulating system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AM data multiplexed modulated wave signal demodulator for extracting a baseband digital signal from an AM data multiplexed modulated wave signal generated by an AM data multiplexing modulator. Is
A carrier having a frequency fc, which is proposed by the present applicant, is amplitude-modulated by an AM modulator using an analog signal wave. fc-fα) and an AM data multiplexed modulated wave signal demodulation apparatus for extracting a baseband digital signal from an AM data multiplexed modulated wave signal in which a digital modulated wave signal is multiplexed.

[0002]

2. Description of the Related Art Conventional data multiplexed modulated wave signal demodulation methods are roughly classified into a time division multiplexing method and a frequency multiplexing method. In the case of the time-division method, the time at which data is multiplexed is selected to extract desired data. In the case of the frequency multiplexing method, the frequency band in which data is multiplexed is selected to extract desired data.

[0003]

However, a carrier having a frequency fc is amplitude-modulated by an AM signal using an analog signal wave, and the position and frequency of a frequency (fc + fα) that is line-symmetric on the frequency axis with the carrier having the frequency fc as an axis. (Fc-fα)
In the AM data multiplexing modulation method where the digital modulated wave signal is multiplexed at the position of, the AM signal and the data signal are multiplexed in the same frequency band and the same time, so only data is selected on both the frequency axis and the time axis. Can not do it.

An object of the present invention is to provide an AM data multiplexed modulated wave signal demodulator for demodulating a baseband digital signal based on a multiplexed digital modulated wave signal from an AM data multiplexed modulated wave signal.

[0005]

According to the present invention, an AM data multiplexed modulated wave signal demodulator according to the present invention amplitude-modulates a carrier having a frequency fc with an analog signal wave by an AM modulator, and converts the carrier having a frequency fc on a frequency axis. AM data multiplexing in which a digital modulated wave signal is multiplexed at a position of a frequency (fc + fα) and a position of a frequency (fc−fα) which are line-symmetrical with respect to an axis. A modulated wave signal demodulation apparatus, comprising: an AM modulated wave signal elimination circuit for removing an AM modulated wave signal from an input AM data multiplexed modulated wave signal; and an output from the AM modulated wave signal elimination circuit. And a data demodulation circuit for receiving the signal and demodulating it into a baseband digital signal.

According to the AM data multiplexed modulated wave signal demodulating apparatus according to the present invention, the position of the frequency (fc + fα) and the position of the frequency (fc−fα) are symmetric with respect to the carrier of the frequency fc on the frequency axis. The AM modulated wave signal is removed from the AM data multiplexed modulated wave signal in which the digital modulated wave signal is multiplexed by the AM modulated wave signal removing circuit,
A digital modulated wave signal is transmitted. Upon receiving the digital modulated wave signal, the data demodulation circuit demodulates the digital modulated wave signal into a baseband digital signal.

The AM modulated wave signal removing circuit in the AM data multiplexed modulated wave signal demodulating apparatus according to the present invention comprises:
A synchronous detector for synchronously detecting the data multiplexed modulated wave signal,
The carrier wave of frequency fc is output by the output signal from the synchronous detector.
An AM modulator for modulating the signal; and a subtraction circuit for subtracting an AM modulated wave signal output from the AM modulator from the AM data multiplexed modulated wave signal. An output of the subtraction circuit is sent to a data demodulation circuit. And

According to the AM data multiplexed modulated wave signal demodulation device according to the present invention, the position of the frequency (fc + fα) and the position of the frequency (fc−fα) are symmetric with respect to the carrier of the frequency fc on the frequency axis. The AM data multiplexed modulated wave signal in which the digital modulated wave signal is multiplexed is synchronously detected to output an AM demodulated signal composed of a frequency component on one side of the frequency fc, and the AM demodulated signal is modulated by a carrier having the frequency fc. Is done. Since the modulated wave signal is subtracted from the input AM data multiplexed modulated wave signal by the subtraction circuit, a digital modulated wave signal is output from the subtraction circuit,
The digital modulated wave signal is demodulated by a data demodulation circuit to output a baseband digital signal.

The AM modulated wave signal elimination circuit in the AM data multiplexed modulated wave signal demodulator according to the present invention sets the frequencies fu and fL to fu> fL and fu-fc = fc-f.
When L, the AM data multiplexed modulated wave signal and the frequency f
a first frequency converter for mixing and frequency-converting a signal of frequency u, a second frequency converter for mixing and frequency-converting an AM data multiplexed modulated signal and a signal of frequency fL, An arithmetic circuit for calculating a difference between an output signal from the frequency converter and an output signal from the second frequency converter is provided, and an output of the arithmetic circuit is sent to a data demodulation circuit.

According to the AM data multiplexed modulated wave signal demodulating apparatus according to the present invention, the position of the frequency (fc + fα) and the position of the frequency (fc−fα) are symmetric with respect to the carrier of the frequency fc on the frequency axis. An AM data multiplexed modulated wave signal in which a digital modulated wave signal is multiplexed is mixed with a signal of frequency fu and frequency-converted, mixed with a signal of frequency fL, and frequency-converted. The AM data multiplexed modulated wave signal frequency-converted by mixing with the signal of the frequency fu is subjected to a spectrum inversion that reverses the order of the frequency spectrum, and the difference between one frequency-converted signal and the other signal is obtained. The arithmetic circuit outputs a digital modulated wave signal from the arithmetic circuit, and the digital modulated wave signal is demodulated by the data demodulation circuit to output a baseband digital signal.

The data demodulation circuit in the AM data multiplexed modulated wave signal demodulator according to the present invention includes: a filter for extracting a frequency component exceeding a frequency based on the frequency fc from an output signal from the AM modulated wave signal removing circuit; Demodulating means for receiving an output signal of the filter and performing demodulation based on a data modulation method.

According to the data demodulation circuit in the AM data multiplexed modulated wave signal demodulator according to the present invention, the data demodulation circuit is located symmetrically on the frequency axis with respect to the frequency based on the frequency fc from the AM modulated wave signal removal circuit. The digital modulated wave signal is output to the data demodulation circuit, and a frequency component exceeding a frequency based on the frequency fc is extracted from the output digital modulated wave signal by a filter, and demodulation based on the digital modulation method is performed. The digital modulated wave signal is demodulated and a baseband digital signal is output.

The data demodulation circuit in the AM data multiplexed modulated wave signal demodulator according to the present invention includes: a filter for extracting a frequency component lower than a frequency based on the frequency fc from an output signal from the AM modulated wave signal removing circuit; Demodulation means for receiving the output signal of the filter and performing demodulation based on the data modulation method.

According to the data demodulation circuit in the AM data multiplexed modulated wave signal demodulator according to the present invention, the data demodulation circuit is located symmetrically on the frequency axis with respect to the frequency based on the frequency fc from the AM modulated wave signal removal circuit. The digital modulated wave signal is output to the data demodulation circuit, and a frequency component lower than the frequency based on the frequency fc is extracted from the output digital modulated wave signal by a filter, and demodulation based on the digital modulation method is performed. The modulated wave signal is demodulated and a baseband digital signal is output.

[0015] The data demodulation circuit in the AM data multiplexed modulated wave signal demodulator according to the present invention includes a digital demodulated wave signal output from the AM modulated wave signal elimination circuit for converting a frequency component exceeding a frequency based on the frequency fc from the digital modulated wave signal. A first filter to be extracted, first demodulation means for receiving an output signal of the first filter and performing demodulation based on a data modulation method, and a digital modulated wave signal output from the AM modulated wave signal removing circuit. A second filter for extracting a frequency component lower than a frequency based on the frequency fc, a second demodulation unit for receiving an output signal of the second filter and performing demodulation based on a data modulation method, and a first or second demodulation unit Sign inverting means for inverting the sign of the demodulated output, and adding means for adding the sign-inverted demodulated output and the non-sign-inverted demodulated output. And butterflies.

According to the data demodulation circuit in the AM data multiplexed modulated wave signal demodulator according to the present invention, the data demodulation circuit is positioned symmetrically on the frequency axis with respect to the frequency based on the frequency fc from the AM modulated wave signal removal circuit. A digital modulated wave signal is output to a data demodulation circuit, and a frequency component exceeding a frequency based on the frequency fc is extracted from the output digital modulated wave signal by a first filter, and is digitally modulated by a first demodulation unit. Since demodulation based on the scheme is performed, the digital modulated wave signal is demodulated and a baseband digital signal is output. A frequency component lower than the frequency based on the frequency fc is extracted from the digital modulated wave signal by the second filter, and demodulation based on the digital modulation method is performed by the second demodulation means.
The digital modulated wave signal is demodulated and a baseband digital signal is output. The sign of the demodulated output of the first or second demodulating means is inverted by the sign inverting means, and the demodulated output whose sign has been inverted and the demodulated output which has not been inverted are added and transmitted as a demodulated output.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An AM data multiplexed modulated wave signal demodulator according to the present invention will be described with reference to an embodiment.

FIG. 1 shows an AM according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a data multiplexed modulated wave signal demodulation device. A according to the embodiment of the present invention shown in FIG.
A description will be given of an example in which a QPSK (four-phase PSK) modulation method is used as a digital modulation method in the M data multiplexed modulated wave signal demodulation device.

An AM data multiplexed modulated wave signal demodulator according to one embodiment of the present invention removes an AM modulated wave signal from an input AM data multiplexed modulated wave signal to convert a digital modulated wave signal. It comprises an AM modulated wave signal removal circuit A to be extracted and a data demodulation circuit B for demodulating the digital modulated wave signal output from the AM modulated wave signal removal circuit A into a baseband digital signal.

First, the AM modulated wave signal elimination circuit A will be described. The AM data multiplexed modulated wave signal is supplied to the delay unit 1 to be delayed, and is also supplied to the synchronous detector 2 to which the carrier of the frequency (fc) is supplied and detected. The detection output signal from the synchronous detector 2 is supplied to a low-pass filter 3 to remove high-frequency components and to be amplified by an amplifier 4.
The amplified output signal from the low-pass filter 3 is supplied to an AM modulator 5 to which a carrier having a frequency (fc) is supplied, and is subjected to AM modulation. The subtractor 6 subtracts the modulated wave signal output from the AM modulator 5 from the AM data multiplexed modulated wave signal delayed through the delay unit 1. The delay time of the delay unit 1 is set to the sum of the respective delay times in the synchronous detector 2, the low-pass filter 3, the amplifier 4, and the AM modulator 5.

Next, the data demodulation circuit B will be described. The data modulated wave signal extracted by the AM modulated wave signal removal circuit A is supplied to a high-pass filter 7 for extracting a frequency component exceeding the frequency fc.
The demodulated signal A is obtained by receiving the output signal extracted from the digital demodulator 8 and supplying it to the digital demodulator 8 for performing demodulation based on the data modulation method.

The data modulated wave signal extracted by the AM modulated wave signal elimination circuit A is supplied to a low-pass filter 9 for extracting a frequency component lower than the frequency fc. The signal is supplied to a digital demodulator 10 that performs demodulation based on the modulation method, and is subjected to digital demodulation. The output from the digital demodulator 10 is supplied to a sign inverter 11 to perform sign inversion to obtain a demodulated signal B. The demodulated signal A and the demodulated signal B are supplied to an adder 12 to obtain a demodulated output C. Here, in the case of QPSK modulation,
In the sign inversion, since only the I signal component is inverted during modulation, only the I signal component is inverted and the sign is restored.

The operation of the AM data multiplexed modulated wave signal demodulator according to the embodiment of the present invention having the above-described configuration will be described.

Prior to the description of demodulation, an AM data multiplexed modulated wave signal supplied to the delay unit 1 and the synchronous detector 2 will be described.

The AM modulated wave signal νAM (t) when the carrier is modulated by the signal wave has a carrier amplitude of 1, a carrier angular frequency of ωc (rad / s), a modulation degree of κ, and a signal wave of νm If (t) is used, it is represented as the following equation (1).

ΝAM (t) = ｛1 + κνm (t)｝ cos ωct t Equation (1)

The I and Q digital signal sequences generated by the QPSK baseband digital signal generator are represented by In and Qn.
The digital signal sequence of In and Qn is also referred to as a dibit. Here, it is assumed that In = ± 1 and Qn = ± 1.

The output signal from the QPSK baseband digital signal generator is split into two, one of which is input to a quadrature modulator to which a carrier having a frequency (fc + fα) is supplied. ωc + ωα) (rad
/ s) is orthogonally modulated. This quadrature modulated wave signal νD
H (t) is as shown in the following equation (2).

ΝDH (t) = In cos (ωc + ωα) t + Qn sin (ωc + ωα) t Equation (2)

The other of the output signals from the QPSK baseband digital signal generator is supplied to a sign inverter, where the signs of the output signals In and Qn are inverted (−In),
It is converted to (-Qn), complex-conjugated by a complex conjugator, and converted to (-In) and (Qn). This complex signal sequence is input to a quadrature modulator to which a carrier having a frequency (fc−fα) is supplied.
−ωα) (rad / s) is subjected to quadrature modulation. This quadrature modulated wave signal νDL (t) is as shown in the following equation (3).

ΝDL (t) = − In cos (ωc−ωα) t + Qn sin (ωc−ωα) t (3)

The output signal νDH of the equations (2) and (3)
(t) and νDL (t) are added, and the digital modulated wave signal νD (t), which is the added output, is as shown in the following equation (4).

ΝD (t) = νDH (t) + νDL (t) = Incos (ωc + ωα) t + Qn sin (ωc + ωα) t−Incos (ωc−ωα) t + Qn sin (ωc−ωα) t (4)

The AM modulated wave signal νAM (t) and the digital modulated wave signal νD (t) are added, and the added output signal is output as an AM data multiplexed modulated wave signal. The AM data multiplexed modulated wave signal ν (t) is as shown in the following equation (5) from the equations (1) and (4).

Ν (t) = νAM (t) + νD (t) = ｛1 + κνm (t)｝ cos ωct + Incos (ωc + ωα) t + Qncos (ωc + ωα) t−Incos (ωc−ωα) t + Qn sin (ωc− ωα) t ... Equation (5)

Ωα is the angular frequency (rad / s) of the difference between the digitally modulated carrier and the AM modulated carrier. The AM data multiplexed modulated wave signal represented by the equation (5) is supplied to the AM modulated wave signal removal circuit A. AM modulated wave signal removal circuit A
The process of canceling the AM modulated wave signal from the AM data multiplexed modulated wave signal will be described below. First, the input AM data multiplexed modulated wave signal ν (t) is input to the delay unit 1 and also to the synchronous detector 2.

For synchronous detection in the synchronous detector 2, A
The multimodulation carrier cos ωct is multiplied by the equation (5) to perform synchronous detection. The synchronous detection output is expressed as shown in the following equation (6).

2 ｛ν (t) cos ωc t｝ = {1 + κνm (t)} + In cos ωα t + Qn sin ωα t −In cos (−ωα) t + Qn sin (−ωα) t + ｛1 + κνm (t)｝ cos 2ωc t + In cos (2ωc + ωα) t + Qn sin (2ωc + ωα) t−In cos (2ωc−ωα) t + Qn sin (2ωc−ωα) t (6)

The synchronous detection output signal is supplied to the low-pass filter 3, and the low-pass filter 3 removes high-frequency components, and the output signal from the low-pass filter 3 is represented by the following equation (7).

2 ｛ν (t) cos ωct = {1 + κνm (t)｝ + Incosωαt + Qn sin ωαt-Incos (−ωα) t + Qn sin (−ωα) t = {1 + κνm (t)} + Incos ωα t + Qn sin ωα t −In cos ωα t−Qn sin ωα t ν (t) cos ωc t = １ ／ {1 + κνm (t)} (7)

The signal shown in the equation (7) is amplified by the amplifier 4 and input to the AM modulator 5, where the carrier having the frequency (fc) is AM-modulated. Here, the amplification degree of the amplifier 4 is 2. After multiplying equation (7) by {2}, AM modulation carrier cos ωct is multiplied for AM modulation, and A
The AM modulated wave signal output from the M modulator 5 is converted to νAM ′ (t)
Is shown in equation (8).

ΝAM ′ (t) = ｛1 + κνm (t)｝ cos ωct (8)

Next, the other of the branched AM data multiplexed modulated wave signals ν (t) is delayed by the delay unit 1.
The delay time of the delay unit 1 is the sum of the delay times of the synchronous detector 2, the low-pass filter 3, the amplifier 4, and the AM modulator 5. However, for simplicity, the respective delays are not taken into consideration. The delay time of the delay unit 1 is set to 0. Therefore, the output of the delay unit 1 becomes equal to the AM multiplex signal ν (t).

The output signal from the delay unit 1 and the AM modulated wave signal νAM ′ (t) shown in the equation (8) are input to the subtractor 6, and the AM modulated wave signal νAM´
(t) is subtracted. The output signal νD (t) from the subtractor 6 is as shown in Expression (9).

ΝD (t) = ν (t) −νAM ′ (t) = Incos (ωc + ωα) t + Qn sin (ωc + ωα) t−Incos (ωc−ωα) t + Qn sin (ωc−ωα) t Equation (9) )

Accordingly, as shown in equation (9), the AM modulated wave signal removing circuit A removes the AM modulated wave signal from the AM data multiplexed modulated wave signal when the data modulation system is the QPSK modulation system, and It can be seen that only the digital modulated wave signal obtained can be extracted.

The AM in the AM modulated wave signal elimination circuit A according to the embodiment of the present invention configured as described above.
FIG. 2 schematically shows the process of removing the modulated wave signal. 2, the AM data multiplexed modulated wave signal input to the AM modulated wave signal elimination circuit A is shown as a in FIG. The AM data multiplexed modulated wave signal is synchronously detected by the synchronous detector 2 to become a detection output signal shown in FIG.
The signal A, which is AM-modulated in the AM modulator 5 and shown in FIG.
It becomes an M modulated wave signal. A output from the AM modulator 5
The M modulated wave signal is subtracted in the subtractor 6 from the AM data multiplexed modulated wave signal. As a result, the AM modulated wave signal is removed from the AM data multiplexed modulated wave signal and the subtracter 6
2 outputs a digital modulated wave signal as shown in FIG.

Next, the AM data multiplexed modulated wave signal
The demodulation of the digital modulated wave signal from which the M modulated wave signal has been removed in the data demodulation circuit B will be described. The output signal from the subtractor 6, that is, the digital modulated wave signal νD
(t) is branched into two, one is input to the high-pass filter 7 and the other is input to the low-pass filter 9.

From the high-pass filter 7 to which the input digital modulated wave signal νD (t) is input, an AM of frequency fc is output.
Only the digital modulated wave signal in the higher frequency band than the carrier passes. Therefore, the digital modulated wave signal νD of equation (9)
The output νDU (t) when (t) is input is given by the following equation (10).
become that way. νDU (t) = Ιn cos (ωc + ωα) t + Qn sin (ωc + ωα) t Equation (10)

The digital modulated wave signal νDU (t) shown in the equation (10) is input to the digital demodulator 8 and the carrier (ωc + ω
α) (rad / s) digital demodulation (here QPSK demodulation)
Is done. The outputs are denoted by ΙA and QA, and are shown in the following equations (11) and (12). This is the demodulated signal A. ΙA = Ιn Equation (11) QA = Qn Equation (12)

Next, from the low-pass filter 9 to which the digital modulated wave signal νD (t) is input, only the digital modulated wave signal in the lower frequency band than the AM carrier having the frequency fc passes.
Therefore, the output νDL (t) when the digital modulated wave signal νD (t) of the equation (9) is input is as shown in the following equation (13). νDL (t) = − Ιn cos (ωc−ωα) t + Qn sin (ωc−ωα) t Equation (13)

The digital modulated wave signal νD (t) shown in the equation (13) is input to the digital demodulator 10 and the carrier (ωc−
ωα) (rad / s) and is digitally demodulated (here, QPSK demodulated). The outputs are denoted by ΙB ′ and QB ′, and are shown in the following equations (14) and (15). ΙB ′ = − Ιn Equation (14) QB ′ = Qn Equation (15)

Since the sign of only the 域 signal component of the low-frequency digital modulated wave signal is inverted at the time of AM data multiplex modulation as described above,
The sign of the signal component is restored. The outputs of the sign inverter 11 are denoted by ΙB and QB, and are shown in the following equations (16) and (17). This is the demodulated signal B. ΙB = −ΙB ′ = Ιn Equation (16) QB = QB ′ = Qn Equation (17)

Next, the demodulated signal A and the demodulated signal B are added in the adder 12 to become a demodulated signal C, (ΙC, QC), which are shown in the following equations (18) and (19). ΙC = ΙA + ΙB = 2Ιn Equation (18) QC = QA + QB = 2Qn Equation (19)

Therefore, digital data, that is, a baseband digital signal is obtained from the digital modulated wave signal in the data demodulation circuit B.

The demodulated signals A, B and C are baseband digital signals, and the data demodulation circuit B demodulates the baseband digital signal from the digital modulated wave signal. In addition,
As is apparent from the above, since three baseband digital signals are output, even if a component of one baseband digital signal is crushed due to interference of other radio waves, frequency fading, or the like, The baseband digital signal of the system having the best reception state can be selected.

Next, an AM data multiplexed modulated wave signal demodulator according to a first modification of the embodiment of the present invention will be described.

FIG. 3 is a block diagram showing a configuration of an AM data multiplexed modulated wave signal demodulator according to a first modification of the embodiment of the present invention. First embodiment of the present invention
The AM data multiplexed modulated wave signal demodulator according to the modified example includes an AM modulated wave signal elimination circuit C and a data demodulation circuit B.

The AM modulated wave signal removing circuit C will be described. The AM data multiplexed modulated wave signal has an oscillation frequency (3f
The signal is supplied to the frequency converter 15 together with the signal of c / 2), the frequency is converted to a frequency that is 1/2 of the carrier frequency fc, and the frequency conversion output is supplied to the low-pass filter 16 to remove high frequency components. The AM data multiplexed modulated wave signal is supplied to a frequency converter 17 together with a signal of an oscillation frequency (fc / 2), frequency-converted to a frequency that is half the carrier frequency fc, and a frequency-converted output is supplied to a low-pass filter 18. To remove high frequency components.

Thus, the frequency of the output signal of the low-pass filter 16 and the frequency of the output signal of the low-pass filter 18 are converted to the same frequency. Low-pass filter 1
6 and the output signal of the low-pass filter 18 are supplied to a subtractor 19, which subtracts the output signal of the low-pass filter 18 from the output signal of the low-pass filter 16.

The operation of the AM-modulated-wave signal removing circuit C according to the first modification having the above-described configuration will be described.

Since the AM data multiplexed modulated wave signal ν (t) represented by the equation (5) is frequency-converted by the frequency converter 15 to a frequency which is の of the carrier frequency fc, the AM represented by the equation (5) is converted. In the data-multiplexed modulated wave signal ν (t), c
os (ωc + ωc / 2) t = cos 3/2 · ωct. The result of this multiplication is as shown in the following equation.

2 ｛ν (t) cos 3/2 · ωct = {1 + κνm (t)｝ cosωct / 2 + Incos (ωc / 2 + ωα) t−Qn sin (ωc / 2 + ωα) t-Incos (ωc / 2−ωα) t−Qn sin (ωc / 2−ωα) t + ｛1 + κνm (t)｝ cos 5ωc / 2 · t + Incos (5ωc / 2 + ωα) t + Qn sin (5ωc / 2 + ωα) t−Incos (5ωc / 2−ωα) t + Qn sin (5ωc / 2−ωα) t

From this signal, a high-frequency component (image component) is removed by a low-pass filter 16. This is shown in the following equation (20) as νUPPER (t). νUPPER (t) = 1/2 ｛1 + κνm (t)｝ cosωc / 2 · t + ／ ｛Incos (ωc / 2 + ωα) t−Qn sin (ωc / 2 + ωα) t−Incos (ωc / 2−ωα) t−Qn sin (ωc / 2−ωα) t｝ Equation (20)

Since the AM data multiplexed modulated wave signal ν (t) represented by the equation (5) is frequency-converted by the frequency converter 17 to a half frequency of the carrier frequency fc, the AM represented by the equation (5) is converted. In the data-multiplexed modulated wave signal ν (t), c
os (ωc / 2) t is multiplied. The result of this multiplication is as shown in the following equation.

2 ｛ν (t) cos (ωc / 2) t｝ = {1 + κνm (t)｝ cos (ωc / 2) t−Incos (ωc / 2 + ωα) t + Qn sin (ωc / 2 + ωα) t + Incos ( ωc / 2−ωα) t + Qn sin (ωc / 2−ωα) t + ｛1 + κνm (t)｝ cos3ωc / 2 · t + Incos (3ωc / 2 + ωα) t + Qn sin (3ωc / 2 + ωα) t−Incos (3ωc / 2−ωα) t + Qn sin (3ωc / 2−ωα) t

High frequency components (image components) are removed from this signal by the low-pass filter 16. Letting this be νLOWER (t), νLOWER (t) is: νLOWER (t) = 1/2 ｛1 + κνm (t)｝ cos ωc / 2 · t + ／} − In cos (ωc / 2 + ωα) t + Qn sin ( ωc / 2 + ωα) t + Incos (ωc / 2−ωα) t + Qn sin (ωc / 2−ωα) t｝ (21)

ΝLOWER (t) is subtracted from νUPPER (t) in the subtractor 19. Digital subtracted wave signal ν
Assuming that D (t), the digital modulated wave signal νD (t) is given by νD (t) = νUPPER (t) −νLOWER (t) = Incos (ωc / 2 + ωα) t + Qn sin (ωc / 2 + ωα) t-In cos (ωc / 2−ωα) t + Qn sin (ωc / 2−ωα) t (22)

As is apparent from equation (22), the AM modulated wave signal removing circuit C removes the AM modulated wave signal from the AM data multiplexed modulated wave signal when the data modulation system is the QPSK modulation system. It can be seen that only the multiplexed digital modulated wave signal is extracted.

The AM in the AM modulated wave signal elimination circuit C
FIG. 4 schematically shows the process of removing the modulated wave signal. In FIG. 4, the AM data multiplexed modulated wave signal input to the AM modulated wave signal elimination circuit C is indicated as shown in FIG. The AM data multiplexed modulated wave signal is frequency-converted and filtered by the frequency converter 15 and the low-pass filter 16 to become a frequency converted output signal shown in FIG.
The frequency is converted and filtered by the low-pass filter 18 to obtain a frequency-converted output signal shown in FIG. The frequency conversion signal shown in FIG. 4C is subtracted from the frequency conversion signal shown in FIG. As a result, the AM modulated wave signal is removed from the AM data multiplexed modulated wave signal, and the subtracter 19 outputs a digital modulated wave signal as shown in FIG.

The frequency of the digital modulated wave signal extracted by the AM modulated wave signal elimination circuit C is different from that of the digital modulated wave signal extracted by the AM modulated wave signal elimination circuit A, and is converted to another frequency. Therefore, the data demodulation circuit B must perform demodulation matching this frequency. The digital modulated wave signal extracted by the AM modulated wave signal removal circuit C is converted into a data demodulation circuit B.
And demodulate it into a baseband digital signal, the frequency of the carrier supplied to the digital demodulator 8 is {(fc / 2) + fα}, and the frequency of the carrier supplied to the digital demodulator 10 is {(fc / 2) It may be -fα−.

In the AM modulated wave signal removing circuit C,
Although the frequency is converted to the frequency of fc / 2, it can be converted to another frequency. In this case, assuming that a frequency higher than the frequency fc is fn and a frequency higher than the frequency fc is fL, fu−fc = fc−fL,
The frequencies fu and fL may be set.

Although the case where the data modulation system is the QPSK modulation system has been described above, the case of another modulation system will be described.

The case where the data modulation method is the ASK modulation method will be described. First, the AM data multiplexed modulated wave signal ν (t) when the ASK modulation method is used for digital modulation will be described.

An AM modulator modulates a carrier having a frequency fc with a signal wave. On the other hand, the ASK baseband digital signal output from the ASK baseband digital signal generator is supplied to the first balanced modulator and supplied to the frequency (fc + f
The carrier of α) is balanced-modulated with an ASK baseband digital signal. On the other hand, the ASK baseband digital signal output from the ASK baseband digital signal generator is supplied to a sign inverter to invert the sign.

ASK whose sign is inverted in the sign inverter
The baseband digital signal is supplied to the second balanced modulator, and the carrier having the frequency (fc−fα) is balanced-modulated with the output signal from the sign inverter. The output signal from the AM modulator, the output signal from the first balanced modulator, and the output signal from the second balanced modulator are added and transmitted as an AM data multiplexed modulated wave signal.

The AM modulated wave signal νAM (t) output from the AM modulator has a carrier amplitude of 1, a carrier angular frequency of ωc (rad / s), a modulation factor of κ, and a signal wave of νm (t). ), ΝAM (t) = ｛1 + κνm (t)｝ cos ωct (23)

The signal sequence generated by the ASK baseband digital signal generator is represented by an. Here, it is assumed that an = 0 or 1.

This signal is split into two, one of which is input to a first balanced modulator to which a carrier of frequency (fc + fα) is supplied, and modulates a carrier of cos (ωc + ωα) t. The output signal νDH (t) of the first balanced modulator is as follows: νDH (t) = ancos (ωc + ωα) t (24)

The sign of the other signal sequence an is inverted by the sign inverter and converted to a signal sequence (-an). The second signal sequence is supplied with a carrier having a frequency (fc−fα).
And modulates the carrier of cos (ωc−ωα) t. The output signal νDL (t) is as follows: νDL (t) = − an cos (ωc−ωα) t (25)

The AM modulated wave signal νDH (t) and νDL (t) are added, and the digital modulated wave signal νD (t) which is the added output is added.
ΝD (t) = νDH (t) + νDL (t) = ancos2 (ωc + ωα) t−ancos (ωc−ωα) t Expression (26)

Next, the AM modulated wave signal νAM (t) and the digital modulated wave signal νD (t) are added, and the AM data multiplexed modulated wave signal ν (t) becomes ν (t) = νAM (t) + νD (t) = {1 + κνm (t)} cosωct + ancos (ωc + ωα) t−ancos (ωc−ωα) t (27)

Here, in the AM modulated wave signal elimination circuit C of FIG. 3, the inputted AM data multiplexed modulated wave signal represented by the equation (27) is inputted to the frequency converter 15 and 17 is input. Frequency converter 1
In step 5, the input AM data multiplexed modulated wave signal is frequency-converted to half the frequency fc. for that reason,
cos (ωc + ωc / 2) t = cos3ωc / 2 t is ν (t)
(Expression 27) is multiplied, and the high-frequency component is removed by the low-pass filter 16. Therefore, the term of the image component (frequency equal to or higher than the angular frequency ωc) can be omitted. This is ν
As UPPER (t), νUPPER (t) is given by the following equation (28).

2νUPPER (t) = 2 ｛ν (t) cos · 3 / 2ωc (t)｝ = {1 + κνm (t)｝ cos · ωc / 2 · t-an cos (ωc / 2 + ωα) t + an cos (ωc / 2-ωα) t Therefore, νUPPER (t) = 1 / 2１ ／ 1 + κνm (t)｝ cosωc / 2 · t + 1/2 ／ -ancos (ωc / 2 + ωα) t + ancos (ωc / 2-ωα) t ｝ …… Equation (28)

In the frequency converter 17, the input equation (2)
The AM data multiplexed modulated wave signal shown in 7) is converted to a frequency f
The frequency is converted to half the frequency of c. So cos
ωc / 2 · t is multiplied by ν (t), and a low-pass filter 18
Removes high frequency components. Therefore, the term of the image component (frequency equal to or higher than the angular frequency ωc) can be omitted. Assuming that this is νLOWER (t), νLOWER (t) is given by the following equation (29).

2νLOWER (t) = 2 ｛ν (t) cosωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t + an cos ｛(ωc / 2) + ωα｝ t−an cos ｛(ωc / 2 ) −ωα｝ t Therefore, νLOWER (t) = 1 / 2１ ／ 1 + κνm (t)｝ cosωc / 2 · t + 1/2 ｛ancos ((ωc / 2) + ωα) t−ancos ((ωc / 2) − ωα) t｝ Equation (29)

When νUPPER (t) and νLOWER (t) are input to the subtracter 19, and the output is a digital modulated wave signal νD (t), the following equation (30) is obtained. νD (t) = νLOWER (t) −νUPPER (t) = an cos ｛(ωc / 2) + ωα｝ t-an cos ｛(ωc / 2) -ωα｝ t (30)

Accordingly, as is apparent from the equation (30), the AM modulated wave signal removing circuit C is removed from the AM data multiplexed modulated wave signal when the data modulation system is the ASK modulation system.
, The AM modulated wave signal is removed, and a multiplexed digital modulated wave signal is extracted.

The case where the data modulation method is the FSK modulation method will be described. First, the AM data multiplexed modulated wave signal ν (t) when the FSK modulation method is used for digital modulation will be described.

A carrier having a frequency fc is AM-modulated by a signal wave by an AM modulator. The FSK baseband digital signal output from the FSK baseband digital signal generator is supplied to a first FSK modulator, and cos (ωc +
ωα + Δω) t carrier, cos (ωc + ωα−Δω) t
Is FSK-modulated with the FSK baseband digital signal. On the other hand, the FSK baseband digital signal is supplied to a sign inverter to invert the sign.

FSK whose sign is inverted in the sign inverter
The baseband digital signal is supplied to a second FSK modulator, where a carrier of −cos (ωc−ωα + Δω) t, −cos (ω
The carrier of c + ωα−Δω) t is FSK-modulated by the FSK baseband digital signal output from the sign inverter 19. The output signal from the AM modulator, the output signal from the first FSK modulator, and the output signal from the second FSK modulator are added, and the added signal is added to the AM data multiplexed modulated wave signal ν (t). Is sent out.

The AM modulated wave signal νAM (t) output from the AM modulator has a carrier amplitude of 1, a carrier angular frequency of ωc (rad / s), a modulation factor of κ, and a signal wave of νm (t). )
It is expressed by the following equation (31). νAM (t) = ｛1 + κνm (t)｝ cos ωct t Equation (31)

The signal sequence an is generated by the FSK baseband digital signal generator. Here, it is assumed that an = ± 1.

This signal sequence an is input to the first FSK modulator, and modulates the carrier of cos (ωc + ωα ± Δω) t. The output signal νDH (t) from the first FSK modulator is as follows: νDH (t) = cos (ωc + ωα + Δωan) t (32)

The signal sequence an is input to a sign inverter, inverted in sign, and converted to (−an). This signal sequence is input to the second FSK modulator, and -cos
Modulate the carrier at (ωc−ωα ± Δω) t. Second F
The output signal νDL (t) from the SK modulator is as follows: νDL (t) = − cos (ωc−ωα−Δωan) t (33)

This signal νDH (t) and νDL (t) are added, and
The digital modulated wave signal νD (t) as an addition output is νD (t) = νDH (t) + νDL (t) = cos (ωc + ωα + Δωan) t−cos (ωc−ωα−Δωan) t (34) ).

The AM modulated wave signal νAM (t) and the digital modulated wave signal νD (t) are added, and the AM data multiplexed modulated wave signal ν (t) becomes ν (t) = νAM (t) + νD ( t) = {1 + κνm (t)} cos ωct + cos (ωc + ωα + Δωan) t−cos (ωc−ωα−Δωan) t (35)

In the AM modulated wave signal elimination circuit C of FIG. 3, the inputted AM data multiplexed modulated wave signal represented by the equation (35) is inputted to the frequency converter 15 and also inputted to the frequency converter 17. Is done. In the frequency converter 15,
The input AM data multiplexed modulated wave signal is frequency-converted to half the frequency fc. Therefore, cos (ω
c + ωc / 2) t = cos3ωc / 2 · t is ν (t) (Equation 3
5), and the low-pass filter 16 removes high frequency components. Therefore, the term of the image component (frequency equal to or higher than the angular frequency ωc) can be omitted. This is νUPPER (t)
Is shown in the following equation (36).

2νUPPER (t) = 2 ｛ν (t) cos3ωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t−cos (ωc / 2 + Δωan + ωα) t + cos (ωc / 2−Δωan−ωα) t νUPPER (t) = １ ／ {1 + κνm (t)} cosωc / 2 · t + ／} − cos (ωc / 2 + Δωan + ωα) t + cos (ωc / 2−Δωan−ωα) t｝ (36)

The input AM data multiplexed modulated wave signal is frequency-converted by the frequency converter 17 into a frequency half the frequency fc. Therefore, cosωc / 2 · t is multiplied by ν (t), and the low-pass filter 18 removes high frequency components. Therefore, the term of the image component (frequency equal to or higher than the angular frequency ωc) can be omitted. This is νLOWER (t),
This is shown in the following equation (37).

2νLOWER (t) = 2 ｛ν (t) cosωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t + cos (ωc / 2 + Δωan + ωα) t−cos (ωc / 2−Δωan−ωα ) TνLOWER (t) = 1/2 ｛1 + κνm (t)｝ cosωc / 2 · t + ／ ｛cos (ωc / 2 + Δωan + ωα) t−cos (ωc / 2−Δωan−ωα) t｝ (37) )

The difference between νUPPER (t) and νLOWE (t) is subtracted by a subtractor 1
9, the subtraction output is the digital modulated wave signal νD
If (t) is used, it becomes as shown in Expression (38). νD (t) = νLOWER (t) −νUPPER (t) = cos (ωc / 2 + Δωan + ωα) t−cos (ωc / 2−Δωan−ωα) t (38)

Therefore, as is apparent from equation (38), the AM modulated wave signal removing circuit C is removed from the AM data multiplexed modulated wave signal when the data modulation system is the FSK modulation system.
, The AM modulated wave signal is removed, and a multiplexed digital modulated wave signal is extracted.

The case where the data modulation method is the 8-phase PSK modulation method will be described. The AM data multiplexed modulated wave signal ν (t) when the 8-phase PSK modulation method is used for digital modulation will be described first.

An AM modulator modulates a carrier having a frequency fc with a signal wave. The initial phase of the carrier wave cos (ωc + ωα) t is changed by the first phase shifter and the second phase shifter to (+ π /
8) radian, (-π / 8) radian phase shift, 8-phase PS
PS output from K baseband digital signal generator
PSK in K baseband digital signal (an, bn, cn)
First based on the phase of the baseband digital signal (cn)
, Or one of the output carriers from the second phase shifter is selected, and the selected carrier cos (ωc +
ωα) t and PSK baseband digital signal (an, bn, c
The dibit (an, bn) in n) is supplied to the first quadrature modulator, and the phase-shifted carrier wave cos (ωc + ωα) t is quadrature-modulated by the dibit (an, bn).

On the other hand, the eight-phase PSK baseband digital signal output from the eight-phase PSK baseband digital signal generator is supplied to a sign inverter to invert the sign, and the sign is inverted of the eight-phase PSK baseband digital signal (−). an, -b
n, -cn), that is, dibits in tribits (-a
n, -bn) is supplied to a complex conjugator to take a complex conjugate and convert it into dibits (-an, bn). Carrier cos (ωc−
8-phase PSK baseband digital signal whose sign is inverted by (+ π / 8) radian and (-π / 8) radian in the initial phase of ωα) t by a third phase shifter and a fourth phase shifter Select one of the output carrier from the third phase shifter or the output carrier from the fourth phase shifter based on the phase of the PSK baseband digital signal (-cn) in (-an, -bn, -cn) Then, the selected carrier wave cos (ωc−ωα) t and the dibit (−an, bn) output from the complex conjugate are supplied to the second quadrature modulator, and the phase-shifted carrier wave cos (ωc−ωc−ωα) is supplied.
ωα) t is orthogonally modulated by dibits (−an, bn).

The AM modulated wave signal output from the AM modulator 1, the output signal from the first quadrature modulator, and the output signal from the second quadrature modulator are added together. The transmitted signal is transmitted as an AM data multiplexed modulated wave signal.

The AM modulated wave signal νAM (t) output from the AM modulator has an AM carrier amplitude of 1 and an angular frequency of ωc
(Rad / s), the modulation factor is κ, and the signal wave is νm (t), it is expressed by the following equation (39). νAM (t) = ｛1 + κνm (t)｝ cosωct t (39) The signal sequence generated by the eight-phase PSK baseband signal generator
Represented by an, bn and cn. Here, it is assumed that an, bn, and cn = 1.

A carrier cos ｛(ωc) whose initial phase is selected based on the phase of the PSK baseband digital signal (cn)
+ Ωα) t + (π / 8) · cn｝ is dibit (an, bn)
Are orthogonally modulated. The output signal νDH (t) is shown in the following equation (40). νDH (t) = an cos ｛(ωc + ωα) t + (π / 8) ・ cn｝ + bn sin ｛(ωc + ωα) t + (π / 8) ・ cn｝ Equation (40)

On the other hand, the tribits (an, bn, cn) are sign-inverted and converted to (-an, -bn, -cn), and the dibits (-an, -bn) are converted to dibits (-an, -bn) by the complex conjugator. −an, bn). The carrier cos {(ωc-ωα) t- (π / 8) · cn} whose initial phase is selected based on the phase of the PSK baseband digital signal (−cn) is quadrature-modulated by dibits (−an, bn). . The output signal νDL (t) is shown in the following equation (41). νDL (t) = − an cos ｛(ωc−ωα) t− (π / 8) · cn｝ + bn sin ｛(ωc−ωα) t− (π / 8) · cn｝ Equation (41)

The νDH (t) and νDL (t) are added, and the added output is a digital modulated wave signal νD (t), which is represented by the following equation (42). νD (t) = νDH (t) + νDL (t) = an cos ｛(ωc + ωα) t + (π / 8) · cn｝ + bn sin ｛(ωc + ωα) t + (π / 8) · cn｝ −an cos ｛(ωc −ωα) t− (π / 8) · cn｝ + bn sin {(ωc−ωα) t− (π / 8) · cn} Equation (42)

The AM modulated wave signal νAM (t) output from the AM modulator and the digital modulated wave signal νD (t) are added, and the added output is the AM data multiplexed modulated wave signal ν (t). Thus, the following equation (43) is obtained. ν (t) = νAM (t) + νD (t) = ｛1 + κνm (t)｝ cosωct + an cos ｛(ωc + ωα) t + (π / 8) · cn｝ + bn sin ｛(ωc + ωα) t + (π / 8) cn｝ −an cos ｛(ωc−ωα) t− (π / 8) · cn｝ + bn sin ｛(ωc−ωα) t− (π / 8) · cn｝ Equation (43)

Here, the AM modulated wave signal removing circuit C shown in FIG.
In the above, the input AM data multiplexed modulated wave signal represented by the equation (43) is input to the frequency converter 15 and also to the frequency converter 17. Frequency converter 15
Then, the input AM data multiplexed modulated wave signal has a frequency f
The frequency is converted to half the frequency of c. Therefore, cos (ωc
+ Ωc / 2) t = cos3ωc / 2 · t is ν (t) (Equation 43)
And the low-pass filter 16 removes high frequency components. Therefore, the term of the image component (angular frequency ω
(frequency above c) can be omitted. This is expressed as νUPPER (t) in the following equation (44).

2νUPPER (t) = 2 ｛ν (t) cos3ωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t−an cos ｛((ωc / 2) + ωα) t + (π / 8)・ Cn｝ -bn sin ｛((ωc / 2) + ωα) t + (π / 8) ・ cn｝ + an cos ｛((ωc / 2) -ωα) t- (π / 8) ・ cn｝ -bn sin ｛ ((Ωc / 2) −ωα) t− (π / 8) · cn｝ Therefore, νUPPER (t) = 1/2 ｛1 + κνm (t)｝ cosωc / 2 · t + ／ [− an cos ｛(( ωc / 2) + ωα) t + (π / 8) · cn｝ −bn sin ｛((ωc / 2) + ωα) t + (π / 8) · cn｝] +1/2 [an cos ｛((ωc / 2) −ωα) t− (π / 8) · cn｝ −bn sin {((ωc / 2) −ωα) t− (π / 8) · cn｝] Equation (44)

In the frequency converter 17, the input AM data multiplexed modulated wave signal is converted into a half frequency of the frequency fc. Therefore, cosωc / 2 · t becomes ν (t) (Equation 43)
And the low-pass filter 18 removes high frequency components. Therefore, the term of the image component (angular frequency ω
(frequency above c) can be omitted. This is expressed as νLOWER (t) in the following equation (45).

2νLOWER (t) = 2 ｛ν (t) cosωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t + an cos ｛((ωc / 2) + ωα) t + (π / 8) · cn｝ + bn sin ｛((ωc / 2) + ωα) t + (π / 8) ・ cn｝ −an cos ｛((ωc / 2) -ωα) t- (π / 8) ・ cn｝ + bn sin ｛(( ωc / 2) −ωα) t− (π / 8) · cn｝ Therefore, νLOWER (t) = 1/2 ｛1 + κνm (t)｝ cosωc / 2 · t + 1/2 [an cos ｛((ωc / 2 ) + Ωα) t + (π / 8) · cn｝ + bn sin ｛((ωc / 2) + ωα) t + (π / 8) · cn｝] +1/2 [−an cos ｛((ωc / 2) −ωα) t− (π / 8) · cn｝ + bn sin ｛((ωc / 2) −ωα) t− (π / 8) · cn｝] Equation (45)

The difference between νUPPER (t) and νLOWER (t) is obtained, and the output is output as a digital modulated wave signal νD (t). The digital modulated wave signal νD (t) is represented by the following equation (46). νD (t) = νLOWER (t) −νUPPER (t) = ancos ｛((ωc / 2) + ωα) t + (π / 8) · cn｝ + bn sin ｛((ωc / 2) + ωα) t + (π / 8) ・ cn｝ -an cos ｛((ωc / 2) -ωα) t- (π / 8) ・ cn｝ + bn sin ｛((ωc / 2) -ωα) t- (π / 8) ・ cn｝ …… Equation (46)

Therefore, as is apparent from equation (46), the AM when the data modulation method is the 8-phase PSK modulation method is used.
The AM modulated wave signal is removed from the data multiplexed modulated wave signal in the AM modulated wave signal removing circuit C, and the multiplexed digital modulated wave signal is extracted.

The case where the data modulation method is the 16-phase PSK modulation method will be described. AM data multiplexed modulated wave signal ν when 16-phase PSK modulation method is used for digital modulation
(t) will be described first.

An AM modulator modulates a carrier wave of frequency fc with a signal wave by AM. The initial phase of the carrier wave cos (ωc + ωα) t is changed by the first phase shifter and the second phase shifter to (+ π /
8) radian, (−π / 8) radian phase shift, 16 phase P
P output from the SK baseband digital signal generator
Based on the phase of the PSK baseband digital signal (cn) in the SK baseband digital signal (an, bn, cn, dn), the output carrier from the first phase shifter or the output carrier from the second phase shifter Select one of the selected carrier co
The initial phase of s (ωc + ωα) t is changed by the fifth phase shifter and the sixth phase shifter to (+ π / 16) radian, (−π / 1
6) Based on the phase of the PSK baseband digital signal (dn) in the PSK baseband digital signal (an, bn, cn, dn) output from the 16-phase PSK baseband digital signal generator, which is shifted in radian phase. 5 and the output carrier from the sixth phase shifter are selected, and the selected carrier cos (ωc + ωα) t and PS are selected.
Providing dibits (an, bn) in the K baseband digital signals (an, bn, cn, dn) to a first quadrature modulator;
The transferred carrier cos (ωc + ωα) t is converted into a dibit (a
n, bn).

On the other hand, the eight-phase PSK baseband digital signal output from the eight-phase PSK baseband digital signal generator is supplied to a sign inverter to invert the sign, and the sign is inverted for the eight-phase PSK baseband digital signal (−). an, -b
The dibits (-an, -bn) in (n, -cn, -dn) are supplied to a complex conjugator to take a complex conjugate to obtain the dibits (-an, -bn).
bn). The initial phase of the carrier wave cos (ωc−ωα) t is changed to (+ π / 8) by the third and fourth phase shifters.
Radian, (−π / 8) radian phase-shifted and sign-inverted 16-phase PSK baseband digital signal (−an, −b
n, -cn, -dn), based on the phase of the PSK baseband digital signal (-cn), selects one of the output carrier from the third phase shifter or the output carrier from the fourth phase shifter. The initial phase of the selected carrier wave cos (ωc−ωα) t is set to (+ π / 16) by the seventh phase shifter and the eighth phase shifter.
Radian, (-π / 16) radian phase shift, 16 phase PS
PS output from K baseband digital signal generator
K baseband digital signal (-an, -bn, -cn, -d
n) based on the phase of the PSK baseband digital signal (−dn) in the output carrier from the seventh phase shifter or the eighth
One of the output carriers from the phase shifter is selected, and the selected carrier cos (ωc + ωα) t and the dibit (−−) in the PSK baseband digital signal (−an, −bn, −cn, −dn) are selected.
an, -bn) to the second quadrature modulator to convert the phase-shifted carrier cos (ωc-ωα) t into dibits (-an, bn)
To perform quadrature modulation.

The AM modulated wave signal output from the AM modulator 1, the output signal from the first quadrature modulator, and the output signal from the second quadrature modulator are added, and the sum is added by an adder 35. The transmitted signal is transmitted as an AM data multiplexed modulated wave signal.

The AM modulated wave signal νAM (t) output from the AM modulator has an AM carrier amplitude of 1 and an angular frequency of ωc
(Rad / s), the modulation factor is κ, and the signal wave is νm (t), it is expressed by the following equation (47). νAM (t) = {1 + κνm (t)} cosωct t (47) The signal sequence generated by the 8-phase PSK baseband signal generator is
Represented by an, bn, cn, and dn. Where an, bn, cn, dn = ±
Let it be 1.

PSK baseband digital signal (cn),
(dn) The phase is selected based on the phase of (dn) Carrier cos ｛(ωc + ωα) t + (π / 8) · cn + (π
/ 16) · dn｝ is quadrature-modulated by dibits (an, bn). The output signal νDH (t) is shown in the following equation (48). νDH (t) = an cos ｛(ωc + ωα) t + (π / 8)） cn + (π / 16) ・ dn｝ + bn sin ｛(ωc + ωα) t + (π / 8) ・ cn + (π / 16) ・ dn｝ … Equation (48)

PSK baseband digital signals (an, b
n, cn, dn) are sign inverters (-an, -bn, -cn, -d
n). Dibits (-an, -bn)
Is input to the complex conjugator and converted into dibits (−an, bn). PSK baseband digital signal (-cn),
The carrier cos {(ωc−ωα) t− (π / 8) · cn} whose phase is selected based on the phase of (−dn) is quadrature-modulated by dibits (−an, bn). The output signal νDL (t) is shown in the following equation (49). νDL (t) = − an cos ｛(ωc−ωα) t− (π / 8) · cn− (π / 16) · dn｝ + bn sin ｛(ωc−ωα) t− (π / 8) · cn− (Π / 16 · dn｝ ... Equation (49)

The νDH (t) and νDL (t) are input to the adder 34 and added. The output digital modulated wave signal νD (t) is represented by the following equation (50). νD (t) = νDH (t) + νDL (t) = ancos ｛(ωc + ωα) t + (π / 8) · cn + (π / 16) · dn｝ + bn sin ｛(ωc + ωα) t + (π / 8) · cn + (Π / 16) ・ dn｝ -an cos ｛(ωc-ωα) t- (π / 8) ・ cn- (π / 16) ・ dn｝ + bn sin ｛(ωc-ωα) t- (π / 8)・ Cn− (π / 16) ・ dn｝ ... Equation (50)

The AM modulated wave signal νAM (t) output from the AM modulator 1 is added to the digital modulated wave signal νD (t), and the added output is an AM data multiplexed modulated wave signal ν (t). , AM data multiplexed modulated wave signal ν (t) is given by the following equation (5)
It becomes like 1). ν (t) = νAM (t) + νD (t) = {1 + κνm (t)} cosωct + an cos ｛(ωc + ωα) t + (π / 8) · cn + (π / 16) · dn｝ + bn sin ｛(ωc + ωα) t + (π / 8) ・ cn + (π / 16) ・ dn｝ -an cos ｛(ωc-ωα) t- (π / 8) ・ cn- (π / 16) ・ dn｝ + bn sin ｛(ωc-ωα ) T− (π / 8) · cn− (π / 16) · dn｝ Equation (51)

Here, the AM modulated wave signal removing circuit C shown in FIG.
, The input AM data multiplexed modulated wave signal represented by the equation (51) is input to the frequency converter 15 and also to the frequency converter 17. Frequency converter 15
Then, the input AM data multiplexed modulated wave signal has a frequency f
The frequency is converted to half the frequency of c. Therefore, cos (ωc
+ Ωc / 2) t = cos3ωc / 2 · t is ν (t) (Equation 51)
And the low-pass filter 16 removes high frequency components. Therefore, the term of the image component (angular frequency ω
(frequency above c) can be omitted. This is expressed as νUPPER (t) in the following equation (52).

2νUPPER (t) = 2 ｛ν (t) cos3ωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t−an cos ｛((ωc / 2) + ωα) t + (π / 8)・ Cn + (π / 16) ・ dn｝ -bn sin ｛((ωc / 2) + ωα) t + (π / 8) ・ cn + (π / 16) ・ dn｝ + an cos ｛((ωc / 2) -ωα) t- (π / 8) ・ cn- (π / 16) ・ dn｝ -bn sin ｛((ωc / 2) -ωα) t- (π / 8) ・ cn- (π / 16) ・ dn｝ ΝUPPER (t) = 1/2 ｛1 + κνm (t)｝ cosωc / 2 · t + ／ [− an cos ｛((ωc / 2) + ωα) t + (π / 8) · cn + (π / 16) Dn｝ −bn sin ｛((ωc / 2) + ωα) t + (π / 8) · cn + (π / 16) · dn｝] + 1/2 [an cos ｛((ωc / 2) -ωα) t − (Π / 8) · cn− (π / 16) · dn {−bn sin {((ωc / 2) −ωα) t− (π / 8) · cn− (π / 16) · dn} ...... formula (52)

In the frequency converter 17, the input AM data multiplexed modulated wave signal is converted into a half frequency fc. Therefore, cosωc / 2 · t becomes ν (t) (Equation 50)
And the low-pass filter 18 removes high frequency components. Therefore, the term of the image component (angular frequency ω
(frequency above c) can be omitted. This is represented by equation (53) as νLOWER (t).

2νLOWER (t) = 2 ｛ν (t) cosωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t + an cos ｛((ωc / 2) + ωα) t + (π / 8) · cn + (π / 16) ・ dn｝ + bn sin ｛((ωc / 2) + ωα) t + (π / 8) ・ cn + (π / 16) ・ dn｝ -an cos ｛((ωc / 2) -ωα) t − (Π / 8) · cn− (π / 16) · dn｝ + bn sin ｛((ωc / 2) −ωα) t− (π / 8) · cn− (π / 16) · dn｝ Therefore, νLOWER (t) = 1/2 {1 + κνm (t)} cosωc / 2 · t + 1/2 [an cos ｛((ωc / 2) + ωα) t + (π / 8) · cn + (π / 16) · dn + Bn sin ｛((ωc / 2) + ωα) t + (π / 8) · cn + (π / 16) · dn｝] + ／ [-an cos ｛((ωc / 2) -ωα) t- (π /8).cn-(.pi./16).dn {+ bn sin} ((. Omega.c / 2)-. Omega..alpha.) T-(. Pi./8).cn-(.pi./16).dn}] Equation (53)

The difference between νUPPER (t) and νLOWER (t) is obtained, and the output is output as a digital modulated wave signal νD (t). The digital modulated wave signal νD (t) is represented by the following equation (54). νD (t) = νLOWER (t) −νUPPER (t) = ancos ｛((ωc / 2) + ωα) t + (π / 8) · cn + (π / 16) · dn｝ + bn sin ｛((ωc / 2 ) + Ωα) t + (π / 8) ・ cn + (π / 16) ・ dn｝ -an cos ｛((ωc / 2) -ωα) t- (π / 8) ・ cn- (π / 16) ・ dn｝ + Bn sin {((ωc / 2) −ωα) t− (π / 8) · cn− (π / 16) · dn} (54)

Therefore, as is apparent from equation (54), A in the case where the data modulation method is the 16-phase PSK modulation method.
The AM modulated wave signal removal circuit C removes the AM modulated wave signal from the M data multiplexed modulated wave signal, and extracts a multiplexed digital modulated wave signal.

The case where the data modulation system is a multi-carrier using the 4-phase PSK modulation system will be described. First, an AM data multiplexed modulated wave signal ν (t) when a multi-carrier is used by using a four-phase PSK modulation method for digital modulation will be described.

An AM modulator modulates a carrier having a frequency fc with a signal wave. On the other hand, the 4-phase PSK baseband digital signal (# 1n, Q1n, # 2n, Q2n) output from the 4-phase PSK baseband digital signal generator is branched into two, and the four-phase PSK baseband digital signal (# 1n, Q1
n) and the carrier of cos (ωc + ωα) t are supplied to the first quadrature modulator, and the carrier of cos (ωc + ωα) t is
Quadrature-modulate with the SK baseband digital signal (# 1n, Q1n). Similarly, a four-phase PSK baseband digital signal
(Ι2n, Q2n) and the carrier of cos (ωc + ωβ) t are the second
, And a carrier wave of cos (ωc + ωβ) t is converted to a four-phase PSK baseband digital signal (Ι2n, Q2
Perform quadrature modulation in n).

A four-phase PSK baseband digital signal (# 1
n, Q1n, Ι2n, Q2n) are supplied to a sign inverter to invert the sign and to output a 4-phase PSK baseband digital signal (−Ι1
n, -Q1n, -Ι2n, -Q2n). The code-converted 4-phase PSK baseband digital signal (-Ι1n,-
Q1n, -Ι2n, -Q2n) are supplied to a complex conjugator, where complex conjugate is taken and a 4-phase PSK baseband digital signal
(-Ι1n, Q1n, -Ι2n, Q2n).

The 4-phase PSK baseband digital signal (-
Ι1n, Q1n) and (−Ι2n, Q2n) are branched into two, and the four-phase PSK baseband digital signal (−Ι1n, Q1n)
n) and the carrier of cos (ωc−ωα) t are supplied to the third quadrature modulator, and the carrier of cos (ωc−ωα) t is
Quadrature modulation is performed with the SK baseband digital signal (−Ι1n, Q1n). Similarly, the four-phase PSK baseband digital signal (− 信号 2n, Q2n) and the carrier of cos (ωc−ωβ) t are supplied to a fourth quadrature modulator, where cos (ωc−ωβ) t
Is converted to a 4-phase PSK baseband digital signal (-Ι2
n, Q2n).

The output signal from the AM modulator and the first, second,
The output signals from the third and fourth quadrature modulators are added, and the added signal is transmitted as an AM data multiplexed modulated wave signal.

The AM modulated wave signal νAM (t) output from the AM modulator has an AM carrier amplitude of 1 and an angular frequency of ωc
(Rad / s), the modulation factor is κ, and the signal wave is νm (t), it is expressed by the following equation (55). νAM (t) = ｛1 + κνm (t)｝ cosωct t Equation (55)

The PSK baseband digital signal generated by the four-phase PSK baseband signal generator is represented by {1n, Q1n,}
2n and Q2n. Here, Ι1n, Q1n, Ι2n, Q2n = ±
Let it be 1.

PSK baseband digital signal {1n, Q
1n and the carrier cos (ωc + ωα) t are quadrature modulated,
PSK baseband digital signal # 1n, Q1n and carrier
Cos (ωc + ωβ) t is orthogonally modulated. The combined output signal νDH (t) of the two orthogonal modulated wave signals is shown in the following equation (56). νDH (t) = Ι1n cos (ωc + ωα) t + Q1n sin (ωc + ωα) t + Ι2n cos (ωc + ωβ) t + Q2n sin (ωc + ωβ) t (56)

PSK baseband digital signal {1n, Q
1n, Ι2n, and Q2n are sign inverters (−Ι1n, −Q1n, −Ι
2n, -Q2n), and (-Ι1
n, Q1n, -Ι2n) and Q2n). PSK baseband digital signal (-Ι1n, Q1n) and carrier cos
(Ωc−ωα) t is orthogonally modulated, and the PSK baseband digital signal (−Ι2n, Q2n) and the carrier cos (ωc
−ωβ) t is orthogonally modulated. The combined output signal νDL (t) of the two orthogonal modulated wave signals is shown in the following equation (57). νDL (t) = − Ι1n cos (ωc−ωα) t + Q1n sin (ωc−ωα) t−Ι2n cos (ωc−ωβ) t + Q2n sin (ωc−ωβ) t Equation (57)

The νDH (t) and νDL (t) are added, and a digital modulated wave signal νD (t), which is an added output, is given by the following equation (5).
It becomes like 8). νD (t) = νDH (t) + νDL (t) = Ι1n cos (ωc + ωα) t + Q1n sin (ωc + ωα) t + Ι2n cos (ωc + ωβ) t + Q2n sin (ωc + ωβ) t−Ι1n cos (ωc−ωα) t + Q1n sin (ω− ωα) t−Ι2n cos (ωc−ωβ) t + Q2n sin (ωc−ωβ) t (58)

The AM modulated wave signal νAM (t) and the digital modulated wave signal νD (t) are added, and the added output AM data multiplexed modulated wave signal ν (t) is expressed by the following equation (59). become. ν (t) = νAM (t) + νD (t) = ｛1 + κνm (t)｝ cosωct + Ι1n cos (ωc + ωα) t + Q1n sin (ωc + ωα) t + Ι2n cos (ωc + ωβ) t + Q2n sin (ωc + ωβ) t−Ι1−cosω ) T + Q1n sin (ωc−ωα) t−Ι2n cos (ωc−ωβ) t + Q2n sin (ωc−ωβ) t (Equation (59))

Here, the AM modulated wave signal removing circuit C shown in FIG.
In the above, the input AM data multiplexed modulated wave signal represented by the equation (59) is input to the frequency converter 15 and also input to the frequency converter 17. Frequency converter 15
Then, the input AM data multiplexed modulated wave signal is frequency-converted to half the frequency fc. For this reason, co
s (ωc + ωc / 2) t = cos3ωc / 2 · t is ν (t)
(Expression 59) is multiplied, and the high-frequency component is removed by the low-pass filter 16. Therefore, the term of the image component (frequency equal to or higher than the angular frequency ωc) can be omitted. This is ν
As UPPER (t), νUPPER (t) is given by Expression (60).

2νUPPER (t) = 2 ｛ν (t) cos3ωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t-ΙIncos (ωc / 2 + ωα) t−Q1n sin (ωc / 2 + α) t −Ι2n cos (ωc / 2 + ωβ) t −Q2n sin (ωc / 2 + ωβ) t + Ι1n cos (ωc / 2−ωα) t −Q1n sin (ωc / 2−ωα) t + Ι2n cos (ωβ / 2−ωβ) t −Q2n sin (Ωβ / 2−ωβ) t

Therefore, νUPPER (t) = 1/2 ｛1 + κν (t)｝ cosωc / 2 · t + ／／ ｛1ncos ((ωc / 2) + ωα) t−Q1n sin ((ωc / 2) + ωα ) T−Ι2n cos ((ωc / 2) + ωβ) t−Q2n sin ((ωc / 2) + ωβ) t} +1/2 ｛Ι1n cos ((ωc / 2−ωα) t−Q1n sin (ωc / 2− ωα) t + {2n cos (ωβ / 2−ωβ) t−Q2n sin (ωβ / 2 + ωβ) t} (60)

In the frequency converter 17, the input AM data multiplexed modulated wave signal is frequency-converted to half the frequency fc. Therefore, cos (ωc / 2) t becomes ν (t)
(Expression 59) is multiplied, and the high-frequency component is removed by the low-pass filter 18. Therefore, the term of the image component (frequency equal to or higher than the angular frequency ωc) can be omitted. This is ν
As LOWER (t), νLOWER (t) is given by Expression (61).

2νLOWER (t) = 2 ｛ν (t) cosωc / 2 · t｝ = {1 + κνm (t)｝ cosωc / 2 · t + Ι1n cos ((ωc / 2) + ωα) t + Q1n sin ((ωc / 2) + Ωα) t + Ι2n cos ((ωc / 2) + ωβ) t + Q2n sin ((ωc / 2) + ωβ) t-Ι1n cos ((ωc / 2) -ωα) t + Q1n sin ((ωc / 2) -ωα) t- Ι2n cos ((ωβ / 2) −ωβ) t + Q2n sin ((ωβ / 2) −ωβ) t

Therefore, νLOWER (t) = 1/2 ｛1 + κνm (t)｝ cosωc / 2 · t + 1 / 2ｃ1n cos ((ωc / 2) + ωα) t + Q1n sin (ωc / 2) + ωα) t + I2n cos ((Ωc / 2) + ωβ) t + Q2n sin ((ωc / 2) + ωβ) t｝ +1/2 ｛−Ι1n cos ((ωc / 2) −ωα) t + Q1n sin ((ωc / 2) −ωα) t − {2n cos (ωβ / 2−ωβ) t + Q2n sin ((ωβ / 2) −ωβ) t} Equation (61)

The difference between νUPPER (t) and νLOWER (t) is calculated, and assuming that the output is a digital modulated wave signal νD (t),
Equation (62) is obtained. νD (t) = νLOWER (t) −νUPPER (t) = Ι1n cos (ωc + ωα) t + Q1n sin (ωc + ωα) t + Ι2n cos (ωc + ωβ) t + Q2n sin (ωc + ωβ) t−Ι1n cos (ωc-ωα) t + Q1n sin (ω) ωα) t−Ι2n cos (ωc−ωβ) t + Q2n sin (ωc−ωβ) t (Equation (62))

Therefore, as is apparent from the equation (62), the AM data multiplexed modulated wave signal when the data modulation method uses the multi-carrier of the 4-phase PSK modulation method is as follows.
The AM modulated wave signal removal circuit C removes the AM modulated wave signal and extracts a multiplexed digital modulated wave signal.

As described above, the AM modulated wave signal removal circuit C removes the AM modulated wave signal irrespective of the data modulation method, and extracts the multiplexed digital modulated wave signal. The digital modulated wave signal output from the AM modulated wave signal removal circuit C is supplied to the data demodulation circuit B and demodulated into a baseband digital signal.

When the digital modulated wave signal output from the AM modulated wave signal removing circuit C is converted to another frequency, the frequency for demodulation in the data demodulation circuit B is changed to the frequency corresponding to the converted frequency. It is necessary to match.

If differential encoding is performed for AM data multiplex modulation, the low-pass filter 8 in the data demodulation circuit B
A delay detection method can be adopted by connecting a delay detector to the next stage of the signal inverter and connecting a delay detector to the next stage of the sign inverter 12.

Even when a modulation method other than QPSK is used for digital modulation, the data can be demodulated by the data demodulation circuit B. At that time, the high-pass filter 7, the low-pass filter 9, the digital demodulators 8, 10 and the sign inverter 11 of the data demodulation circuit B can be handled by the following.

The high-pass filter 7 is a high-pass filter that passes only the digital modulated wave signal higher than the AM carrier, and the low-pass filter 9 is the low-pass filter that passes only the digital modulated wave signal lower than the AM carrier. As a filter, the digital demodulator 8 is a digital demodulator based on a digital modulation method, receives a digital modulated wave signal modulated by a carrier higher than the AM carrier, and outputs a digital baseband signal sequence. As a digital demodulator, the digital demodulator 10 is a digital modulator based on a digital modulation method and receives a digital modulated wave signal modulated by a carrier in a lower frequency band than an AM carrier to form a digital baseband signal sequence. A sign demodulator 11 is an AM data multiplexing modulator. And inverted sign inverter to reverse the inverted digital baseband signal sequence, an adder 1
Reference numeral 2 denotes an adder that adds two digital baseband signal sequences.

When the digital modulated wave signal is converted into a different frequency as shown in the AM modulated wave signal removing circuit C, the high-pass filter 7, the low-pass filter 9, and the digital demodulators 8 and 10 are connected to each other. This can be dealt with by adjusting to the converted frequency. Specifically, the AM carrier is similarly frequency-converted, and A
In the case of the M modulated wave signal elimination circuit C, the AM carrier is ω
The high-pass filter 7, the low-pass filter 9, and the digital demodulators 8 and 10 may be configured assuming that they are at c / 2 · (rad / s).

[0159]

As described above, the AM according to the present invention is described.
According to the data multiplexed modulated wave signal demodulation device, the digital modulated wave signal can be extracted by removing the AM modulated wave signal from the AM data multiplexed modulated wave signal. Demodulated to obtain digital data, that is, a baseband digital signal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an AM data multiplexed modulated wave signal demodulator according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining the operation of an AM modulated wave signal removal circuit in the AM data multiplexed modulated wave signal demodulator according to one embodiment of the present invention;

FIG. 3 shows A according to a first modification of the embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of an M data multiplexed modulated wave signal demodulation device.

FIG. 4 shows A according to a first modification of the embodiment of the present invention.
FIG. 9 is a schematic diagram for explaining the operation of an AM modulated wave signal removal circuit in the M data multiplexed modulated wave signal demodulator.

[Explanation of symbols]

 A and CAM modulated wave signal removal circuit B Data demodulation circuit 1 Delay device 2 Synchronous detector 3, 9, 16 and 18 Low-pass filter 5 AM modulator 6 and 19 Subtractor 7 High-pass filter 8 and 10 Digital demodulator 11 Code Inverter 12 Adder 15 and 17 Frequency converter

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroyuki Nagasaka 1-14-6 Dogenzaka, Shibuya-ku, Tokyo Inside Kenwood Corporation (72) Inventor Atsushi Shinoda 1-16-16 Dogenzaka, Shibuya-ku, Tokyo Kenwood Corporation Inside

Claims (6)

[Claims] An analog signal wave having a frequency fc and a carrier wave of A
The amplitude is modulated by the M modulator, and the frequency fc on the frequency axis
The baseband digital signal is demodulated from the AM data multiplexed modulated wave signal in which the digital modulated wave signal is multiplexed at the position of the frequency (fc + fα) and the position of the frequency (fc−fα) which are symmetrical with respect to the carrier wave of the axis. An AM data multiplexed modulated wave signal demodulation device, comprising: an AM modulated wave signal elimination circuit for removing an AM modulated wave signal from an input AM data multiplexed modulated wave signal; and an AM modulated wave signal elimination circuit. And a data demodulation circuit for demodulating the output from the base station into a baseband digital signal. 2. The AM data multiplexed modulated wave signal demodulating device according to claim 1, wherein the AM modulated wave signal removing circuit comprises:
A synchronous detector for synchronously detecting the M data multiplexed modulated wave signal, an AM modulator for AM-modulating a carrier having a frequency fc with an output signal from the synchronous detector, and an AM modulated wave signal output from the AM modulator. An AM data multiplexed modulated wave signal demodulation device, comprising: a subtraction circuit for subtracting from an AM data multiplexed modulated wave signal, and sending an output of the subtraction circuit to a data demodulation circuit. 3. The AM data multiplexed modulated wave signal demodulator according to claim 1, wherein the AM modulated wave signal removing circuit sets the frequencies fu and fL to fu> fL and fu−fc = fc−.
When fL, a first frequency converter for mixing and frequency-converting the AM data multiplexed modulated wave signal and the signal of frequency fu, and mixing the AM data multiplexed modulated wave signal and the signal of frequency fL, A second frequency converter for frequency conversion;
An arithmetic circuit that calculates a difference between an output signal from the first frequency converter and an output signal from the second frequency converter,
An AM data multiplexed modulated wave signal demodulation device for sending an output of an arithmetic circuit to a data demodulation circuit. 4. The AM data multiplexed modulated wave signal demodulation device according to claim 1, wherein the data demodulation circuit removes a frequency component exceeding a frequency based on the frequency fc from an output signal from the AM modulated wave signal removal circuit. An AM data multiplexed modulated wave signal demodulation device comprising: a filter to be extracted; and a demodulation means for receiving an output signal of the filter and performing demodulation based on a data modulation method. 5. The AM data multiplexed modulated wave signal demodulator according to claim 1, wherein the data demodulation circuit extracts a frequency component lower than the frequency based on the frequency fc from the output signal from the AM modulated wave signal removal circuit. An AM data multiplexed modulated wave signal demodulation device, comprising: a filter; and a demodulation unit that receives an output signal of the filter and performs demodulation based on a data modulation scheme. 6. An AM data multiplexed modulated wave signal demodulator according to claim 1, wherein the data demodulation circuit exceeds a frequency based on the frequency fc from a digital modulated wave signal output from the AM modulated wave signal elimination circuit. A first filter for extracting the frequency component obtained, a first demodulation means for receiving an output signal of the first filter and performing demodulation based on a data modulation method,
A second filter for extracting a frequency component lower than the frequency based on the frequency fc from the digital modulated wave signal output from the AM modulated wave signal elimination circuit, and receiving the output signal of the second filter and using a data modulation method Second demodulation
And a sign inverting means for inverting the sign of the demodulated output of the first or second demodulating means, and an adding means for adding the sign-inverted demodulated output and the sign-inverted demodulated output. An AM data multiplexed modulated wave signal demodulator characterized by the above-mentioned.