JPH08274741A - Infrared ray multiplex transmission system and infrared ray reception device - Google Patents

Abstract

PURPOSE: To provide an infrared ray multiplex transmission system and infrared ray reception device which never leaks a transmitted signal to the outside from a specific area, has no possibility of interference with signals outside the area, and can increase the number of channels of transmission by multiplexing. CONSTITUTION: Plural infrared ray transmission devices 1 multiplex multichannel digital signals by time division, make FSK modulation, and transmit the results as infrared ray signals. Each infrared ray transmission device make FSK modulation with a carrier frequency different from others, so that infrared ray reception device 30 receives the infrared ray signals which are frequency-multiplexed after time-division multiplexing. The multichannel digital signals are sent with the FSK-modulated infrared ray signals, so no sent signal leaks from the specific area and no interference with the outside is caused. Further, the frequency multiplexing is usable in combination with the time-division multiplexing, so the number of transmission channels can be increased.

Description

Detailed Description of the Invention

The present invention relates to an infrared multiplex transmission system that multiplexes digital data divided into a plurality of channels and transmits the infrared rays, and an infrared receiver used in the system.

[0002]

2. Description of the Related Art Conventionally, when a plurality of guide broadcasts are broadcast at a specific place such as an exhibition hall and a visitor switches a receiver selector switch to listen to one of the guide broadcasts, or at an international conference. Simultaneously broadcast interpreters from multiple countries,
For example, when listening to an interpreter in one's own language, a time division multiplex transmission method in which two or more different broadcasts are carried on one radio wave and transmission, or a frequency multiplex method in which a different frequency is assigned to each broadcast and transmitted is used. Has been.

FM multiplex broadcasting is also a kind of this, in which two or more different broadcasts are frequency-division multiplexed and FM-modulated and transmitted.

FIG. 7 is a block diagram of an FM receiver 100 that receives this FM multiplex broadcast and receives a specific broadcast. The signal is selected by the FM front end 101 and then converted to an intermediate frequency IF. Is amplified by the IF amplifier circuit 102.

Further, the limiter circuit of the limiter / detection circuit 103 limits the amplitude so that the signal levels become equal, and the detection circuit demodulates the FM multiplex signal into a voice multiplex signal.

In the multiplex demodulation circuit 104 connected to the subsequent stage of the limiter / detection circuit 103, this audio multiplexed signal is separated into individual broadcast signals, which are output in parallel and amplified by the amplifier circuit 105.

After that, a specific broadcast signal is selected and received from the broadcast signals output by the amplifier circuit.

[0008]

[Problems to be Solved by the Invention]

However, when transmitting multi-channel broadcasting by such FM multiplex broadcasting, since radio waves are used as a transmission medium, it is not limited to a specific place of the exhibition hall, the inside of the international conference hall, but also outside the area. Radio waves are leaking, and at private meetings, etc., the content of the meeting cannot be kept secret,
In addition, there is a risk that radio waves may leak to the outside of the area, causing interference with broadcasting at other venues, and also noise from the outside.

In particular, when the frequency multiplexing system is adopted, interference with radio waves outside the area cannot be avoided, which has been a problem when used in such a specific area.

For this reason, there is a problem that the time division multiplexing method and the frequency multiplexing method cannot be used together, and the number of channels that can be simultaneously transmitted is limited.

The present invention has been made in order to solve the above-mentioned problems, and a transmission signal does not leak from a specific area to the outside, there is no fear of interfering with a signal outside the area, and the signals are multiplexed and transmitted. An object of the present invention is to provide an infrared multiplex transmission system and an infrared receiving device capable of increasing the number of channels.

[0013]

In order to solve the above problems, in the infrared multiplex transmission system according to claim 1,
The infrared transmitter includes a plurality of infrared transmitters that transmit infrared signals of different frequency bands and an infrared receiver that receives the infrared signals. Each infrared transmitter transmits two or more individual digital data signals input in parallel. , The serial digital signal is FSK-modulated by arranging it in different time slots in units of one word of the digital data signal and making it a serial digital signal at a time division multiplexing circuit section and a carrier frequency in a frequency band different from other infrared transmitters. The infrared receiving device includes an FSK modulation circuit unit and an infrared light emitting circuit unit that transmits an FSK-modulated serial digital signal as an infrared signal, and the infrared receiving device receives the infrared signal and photoelectrically converts the infrared signal.
Infrared light receiving circuit section for K combined signal, a plurality of tuning circuit sections for tuning to FSK modulation frequencies of different infrared transmitters, and one of the plurality of tuning circuit sections are selected, and a specific infrared ray is selected from the FSK combined signal. A switch circuit unit that outputs an FSK modulated signal of the transmitter, an FSK demodulation circuit unit that demodulates a serial digital signal from the FSK modulated signal, and a source separation circuit that separates and outputs the serial digital signal into a digital data signal in units of one word. And a section.

Further, in the infrared multiplex transmission system according to claim 2, the infrared transmitter comprises an AD converter for converting an analog signal inputted by voice into a digital data signal, and the infrared receiver comprises the digital data signal as an analog signal. It is characterized in that it is provided with a DA converter for converting to a voice output.

In addition, in the infrared receiver of the present invention, a plurality of infrared signals in which a plurality of serial digital signals are FSK-modulated at carrier frequencies of different frequency bands are simultaneously received and identified from the plurality of infrared signals. Of the serial digital signal of FSK demodulation to individually receive the time-division-multiplexed digital data signal from the serial digital signal, wherein the infrared receiving device simultaneously receives a plurality of infrared signals, An infrared light receiving circuit section that photoelectrically converts into an FSK composite signal, and a plurality of tuning circuit sections that tune to different FSK modulation frequencies of infrared signals,
A switch circuit section that selects one of a plurality of tuning circuit sections and outputs an FSK modulated signal in a specific infrared signal from the FSK combined signal, an FSK demodulating circuit section that demodulates a serial digital signal from the FSK modulated signal, and a serial digital signal And a source separation circuit section for separating a signal into individual digital data signals and outputting the signals.

Further, the infrared receiver according to claim 4 is characterized by comprising a DA converter for converting the individually output digital data signals into analog signals.

[0017]

According to the first aspect of the invention, the infrared transmitter transmits the FSK-modulated infrared signal after time-division multiplexing of two or more digital data signals input in parallel.

Infrared signals similarly transmitted from a plurality of infrared transmitters are subjected to FS at carrier frequencies different from those of other infrared transmitters in their respective FSK modulation circuit sections.
K modulated.

Since the infrared signal transmitted from the infrared transmitter is FSK-modulated infrared light, it has excellent directivity, the transmission signal does not leak outside the area, and noise is not received from outside the area.

In the infrared receiving device, the infrared receiving circuit section receives the infrared signal and photoelectrically converts it into an FSK composite signal.

When one of the plurality of FSK tuning circuit sections is selected by the switch circuit section, the FSK tuning circuit section tunes to the carrier frequency which is the FSK modulation frequency of the corresponding specific infrared transmitter, and the FSK demodulation circuit. In part, the serial digital signal of this particular infrared transmitter is demodulated.

This serial digital signal is further output as an individual digital data signal in the source separation circuit section, and a specific digital data signal is selected from this and received.

Therefore, a large number of digital data signals can be time-division multiplexed and then frequency-multiplexed for transmission.

According to a second aspect of the present invention, the analog signal voice-input to the infrared transmitter is converted into a digital data signal, and the digital data signal output from the source separation circuit unit in the infrared receiver is output as an analog voice signal. To be converted.

Therefore, the voice signal which is an analog signal can be multiplexed and transmitted.

According to a third aspect of the present invention, a plurality of infrared signals in which a plurality of serial digital signals are FSK modulated at different modulation frequencies are simultaneously received, and a specific serial digital signal is FSK demodulated from the plurality of infrared signals. And an infrared receiving device for individually receiving time-division-multiplexed digital data signals from a serial digital signal, wherein the infrared receiving circuit section simultaneously receives a plurality of infrared signals and photoelectrically converts them.
The SK composite signal.

When one of the plurality of FSK tuning circuit sections is selected by the switch circuit section, an FSK modulated signal is output in synchronization with one FSK modulation frequency selected from the FSK synthesized signal, and the FSK demodulated signal is FSK demodulated. The serial digital signal corresponding to a specific infrared signal is FSK in the circuit section.
Demodulate.

Thereafter, in the source separation circuit section, this serial digital data signal is separated into individual digital data signals.

Therefore, even if a large number of digital data signals are transmitted by superposing time division multiplexing and frequency multiplexing, they can be individually received from the separated digital data signals.

The invention of claim 4 is the DA of the infrared transmitter.
In the converter, the separately output digital data signal is converted into an analog signal, so that each digital data signal can be received as an analog signal.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a plurality of infrared transmitters 1 ₁ , 1 ₂ , ... 1 _N according to an embodiment of the present invention.

In the illustrated example, N infrared transmitters are shown. Channels of different transmission signals from 1 channel to N channels are respectively assigned, and analog signals of different sources a to m are assigned to each infrared transmitter. It is adapted to be inputted to the division multiplexing circuit unit 10.

The time-division multiplexing circuit section 10 converts an analog signal of a to m sources input in parallel into a serial digital signal, and its configuration will be described with reference to FIG.

When the sources of the analog signals a to m input to the infrared transmitter 1 to which N channels are assigned are ChN-a, ChN-b, ..., ChN-m, the time division multiplexing circuit section 10 has , And input terminals 11, 11 ... Corresponding to the number of respective sources are provided, and the corresponding analog signals (ChN-a, ChN-b ...
-M) is input in parallel.

Each of these sources ChN-a, ChN-b
.. The ChN-m analog signal is, for example, an audio signal obtained by interpreting a statement at an international conference for each country, and constitutes one program for each source. Also, two sources may be assigned to L and R for one broadcast program to make a stereo broadcast.

A low-pass filter 12 and an amplifier 13 are connected to the respective input terminals 11 after the input terminal 11 to cut the high frequency band in the analog signal of each source and amplify the analog signal.

The output side of the amplifier 13 is the AD converter 1
It connects to the input of 4 and converts the amplified analog signal into an 8-bit digital signal.

A shift register 15 is connected to the stage subsequent to each AD converter 14, and the shift register 15 is
As shown, the shift register 15 corresponding to the source N-m
With -m as the lowermost stage, the shift registers 15-a corresponding to the source N-a in the upper stage are sequentially connected in series.

The shift register 15 is provided at the uppermost stage.
-H is connected in series, and its output is connected to the FSK modulation circuit section 21 via the amplifier circuit 20 described later.

On the other hand, the clock signal output from the oscillator 16 is frequency-divided by the first frequency divider 17, the second frequency divider 18, and the third frequency divider 19 which are connected in series, and each is AD.
Outputs clock, data shift pulse, and sampling pulse.

That is, the output of the first frequency divider 17 is A
It is connected to the clock input terminal of the D converter 14 and outputs a clock signal for AD conversion.

The outputs of the second frequency divider 18 and the third frequency divider 19 are connected to the respective shift registers 15, and the output signals of the respective AD converters 14 are sampled by sampling pulses at every sampling period (1 / fs). Is sampled in
The digital data of each stage that is sampled and stored in the shift register is moved to the next stage for each stage by the data shift pulse.

The sampling frequency fs is, for example, 15 if voice is transmitted with a transmission characteristic of AM radio.
KHz.

As shown in the figure, at the time of sampling, the lower 13 bits from the lower stage of the shift register 15-H are "H" by the input from the format setting circuit (not shown).
And other shift registers 15-a, ... 15-
The uppermost stage of m and the stage immediately below it are “L” and “H”.

Therefore, the signal (a) sequentially output from the shift register 15-H by the data shift pulse becomes a serial digital signal as shown in FIG. 4, and after the 13-bit head pulse, "L" and "H". 8-bit digital data of each source separated by is continuous.

That is, the digital data of each source is
8 bits are used as a word unit of 1 byte, and are arranged in time slots having 10-bit intervals which are different for each word.

As shown in FIG. 1, the output of the time division multiplexing circuit unit 10 of each infrared transmitter 1 is connected to the input of the amplifier circuit 20. The amplifier circuit 20 adjusts the output level of the serial digital signal to the voltage level of the voltage controlled oscillator (not shown) in the FSK modulation circuit unit 21 connected to the subsequent stage.

The FSK modulation circuit section 21 converts the serial digital signal shown in FIG. 4 into an FSK (Frequency Shift) signal.
Keying) Modulate.

This FSK modulation is performed based on the carrier frequency in the frequency band different for each infrared transmitter 1.

For example, one-channel infrared transmitter 1 ₁
FSK modulation is performed at carrier frequencies of 3 MHz and 6 MHz, and in the 2-channel infrared transmitter 1 ₂ which is different from the carrier frequency band, 9 MHz and 12 MHz.
FSK modulation is performed at the carrier frequency of.

On the output side of the FSK modulation circuit section 21, the LED driver 22 and the infrared L which is an infrared light emission circuit section are respectively provided.
Since the ED 23 is connected, the LED driver 22
Drives and controls the infrared LED 23 according to the FSK-modulated serial digital signal.

As shown in FIG. 1, the infrared signals from the infrared transmitters 1 are transmitted by the infrared receivers 3 with the same configuration.
Although it is transmitted toward 0, as described above, the infrared transmitter 1
Since the FSK modulation is performed with a different carrier frequency for each, the frequency is different for each infrared transmitter.

2 and 5 show the structure of the infrared receiver 30 which receives this infrared signal.

In this embodiment, the infrared receiver 30 is used.
Is for preparing program broadcasting according to the number of recipients,
The number does not matter.

A large number of infrared signals of different frequencies transmitted from the infrared transmitters 1 are simultaneously received by the photodiode 31, which is an infrared light receiving circuit section, and become photoelectrically converted FSK composite signals.

Since the output of the photodiode 31 is weak, an amplifier / waveform shaping circuit 32 is connected to the output side of the photodiode 31 to amplify the FSK synthesized signal and then adjust the waveform to a constant level. I do.

The amplification / waveform shaping circuit 32 further includes a plurality of F
It is connected to the SK tuning circuit section 34.

The plurality of FSK tuning circuit sections 34 are tuned to the carrier frequency of one of the infrared transmitters from the FSK composite signal, and the FSK in the infrared transmitters are tuned.
This is an SK modulated signal. Switch circuit section 35
Selects any one of the plurality of FSK tuning circuit sections 34 and outputs the FSK modulated signal of the infrared transmitter corresponding to the selected FSK tuning circuit section 34. Switch circuit section 3
The output of 5 is connected to the FSK detection circuit unit 33 which is the FSK demodulation circuit unit, and the FS is detected in the FSK detection circuit unit 33.
A serial digital signal is demodulated from the K modulation signal.

For example, when the FSK tuning circuit section 34 _N for ChN is selected by the switch circuit section 35 as shown in FIG.
From the K composite signal, the FSK modulated signal is output in tune with the carrier frequency of the infrared transmitter 1 _N to which the channel N is allocated, and the FSK detection circuit unit 33 outputs the FSK modulated signal from the infrared transmitter 1 _N as shown in FIG. The serial digital signal (b) is demodulated.

Although the switch circuit section 35 is manually selected, any of mechanical components such as an electronic circuit and a slide switch may be used for switching the switch circuit.

The number of FSK tuning circuit sections 34 does not have to match the number of infrared transmitters 1, and may be smaller than this.

The output side of the FSK detection circuit section 33 is connected to the source separation circuit section 36, and the FSK detection circuit section 3 is connected.
The signal of each source is output from the serial digital signal demodulated in 3.

FIG. 5 is a block diagram showing the structure of the source separation circuit section 36. The source separation circuit section 36 of this embodiment further includes a DA converter 37, a low-pass filter 44, and an amplifier circuit 45.

The serial digital signal output from the FSK detection circuit section 33 is input to the m-th DA converter 37-m and the first counter 38.

The DA converter 37 is the infrared transmitter 1.
The DA converters 37, the number of which corresponds to the number of sources a to m of the analog signal input to, are connected to each other via the shift register 43.

On the other hand, the second counter 41 and the third counter 42 are further connected in series to the first counter 38, and each of the counters 38, 41, 42 receives the clock signal divided by the oscillator 39. Therefore, it is connected to the frequency divider 40.

The first counter 38 is for extracting a 1-cycle (1 / fs) delimiter in synchronization with the serial digital signal, and is for detecting a head pulse from the input serial digital signal.

That is, since the serial digital signal is provided with a head pulse having a continuous 13-bit “H” at the beginning, it is “H” while the first counter 38 counts clocks for a certain period of time. , A head pulse is detected, and a head pulse detection signal is output to the second counter 41.

The output of the second counter 41 is connected to each DA converter 37 and the shift register 43, and when the head pulse signal is received, the data shift for moving the data in each DA converter 37 and the shift register 43 to the next stage. Output pulse.

The third counter 42 is used for each DA converter 3
It is connected to 7 and outputs a latch pulse.

The third counter 42 counts the data shift pulse and sends it to each DA converter 37 from a to m.
When the digital data corresponding to each of the sources moves, a latch pulse is output at that timing.

The serial digital signal of the remote control transmitter 1 _N to which the channel N is assigned is the source separation circuit section 36.
When the latch pulse is received, the DA converter 37-a receives the ChN-a digital data, and the DA converter 37-b receives the ChN-b digital data.
The digital data of ..., And the digital data of ChN-m are input to the DA converter 37-m.

Each DA converter 37 DA-converts these digital data and outputs an analog signal to an external headphone or the like via a low-pass filter 44 and an amplifier circuit 45 connected to the output side thereof.

That is, the serial digital signal is output in parallel from each amplifier circuit 45 as an analog signal (ChN-a, ChN-b ... ChN-m).

Next, using the infrared multiplex system thus configured, a specific source (for example, Ch2-b)
The case of transmitting the program broadcast will be described.

[0077] Ch2-b analog signal is for transmission in the infrared transmission device 1 ₂ channel 2 is assigned is input to the corresponding input terminal 11 of the infrared transmission device 1 _2.

This analog signal is transmitted to the infrared transmitter 1 ₂
After being AD-converted by the time division multiplexing circuit section 10, the serial digital signal becomes the second digital data from the beginning.

The serial digital signal is FSK-modulated and transmitted as an infrared signal.

[0080] In this case, FSK modulation circuit 21 of the infrared transmission device 1 ₂ uses the carrier frequency of 9MHz and 12 MHz, so modulating the serial digital signal, the frequency of the infrared rays transmitted from the infrared transmitter 1 ₂ 10.
It is 5 ± 1.5 MHz.

In the infrared receiver 30, in order to receive the program broadcast of Ch2-b, the switch circuit section 35 is scanned in advance and Ch2 is tuned to the frequency of 10.5 ± 1.5 MHz.
The FSK tuning circuit section 34 ₂ for use is selected.

Amplified waveform shaping circuit 3 of infrared receiver 30
The FSK composite signal output from 2 includes an infrared signal transmitted from another infrared transmitting device 1, but C
h2 FSK tuning circuit section 34 ₂ and FSK demodulation circuit section 33
Thus, the serial digital signal of the infrared transmitter 1 ₂ can be demodulated from the FSK combined signal.

When a serial digital signal is input to the source separation circuit section 36, a head pulse detection signal is output from the first counter 38 to the second counter 41 and the second counter 4
1 outputs a data shift pulse. Each time this data shift pulse is input, the serial digital signal sequentially moves from the DA converter 37-m to the DA converter 37-a via the shift register 43.

When the digital data of Ch2-b is shifted to the DA converter 37-b, the third counter 42
Latch pulse is output from the DA converter 37-b
Then, the digital data of Ch2-b is DA converted.

The output timing of this latch pulse can be determined by a set value preset in the third counter 42 by a digital switch (not shown) or the like, and by designating the number of shifts up to a specific DA converter 37, Digital data of any source in each channel can be separated in the DA converter 37.

[0086] The DA converted analog signal is the same as the analog signal of Ch2-b input to the infrared transmission device 1 _2, cut the high frequency noise by the low pass filter 44, the signal amplified by the amplifier circuit 45 Then, the program broadcast of Ch2-b can be received by an external headphone or the like.

In the above embodiment, the infrared transmitter 1
In the above description, N individual infrared transmitters are separated, but the present invention is not limited to this, and an infrared signal modulated by a plurality of carrier frequencies may be transmitted from one infrared transmitter, for example.

Further, although the transmission signals input to each infrared transmitting device 1 are described as an example in which the same number of transmission signals a to m are input, the number of input terminals of each infrared transmitting device 1,
The number of sources of the input transmission signal may be different for each infrared transmitter 1.

[0089]

As described above, according to the present invention, since the infrared signal transmitted from the infrared transmitter is an FSK-modulated infrared signal, the directivity is excellent and the transmission signal does not leak outside the area.

Therefore, the transmission signal does not leak to the outside of the area in a specific place of the exhibition hall, the international conference hall, etc., and the confidentiality of the conference contents can be kept in a private conference.

Similarly, since the FSK-modulated infrared signal is transmitted, there is no fear of interference with the outside of the area, and even if noise is received from outside the area, the FSK modulation method allows demodulation without error. it can.

Furthermore, since the infrared signal is used for transmission, there is no interference with signals outside the area, and the frequency division multiplexing method can be used in combination with the time division multiplexing method.

Therefore, since a large number of digital data signals can be time-division multiplexed and then frequency-multiplexed and transmitted, the number of transmission sources can be further increased, and the number of sources is insufficient due to simultaneous interpretation at international conferences. There is no such thing.

According to the inventions of claims 2 and 4, even if the signal to be transmitted is an analog signal, it can be received using the infrared multiplex transmission system or the infrared receiving device according to the present invention.

[0095]

[Brief description of drawings]

FIG. 1 shows a plurality of infrared transmitters 1 according to an embodiment of the present invention.
It is a block diagram of.

FIG. 2 is a block diagram of an infrared receiver 30.

FIG. 3 is a block diagram showing a configuration of a time division multiplexing circuit unit 10.

FIG. 4 is a waveform diagram showing an output signal (a) of the time division multiplexing circuit unit 10.

5 is a block diagram showing a configuration of a source separation circuit section 36. FIG.

FIG. 6 is a waveform diagram showing an output signal (b) of the FSK demodulation circuit section 34.

FIG. 7 is a block diagram of an FM receiver for receiving a conventional FM multiplex broadcast.

[Description of Reference Signs] 1 infrared transmitter 10 time division multiplexing circuit 14 AD converter 21 FSK modulation circuit 23 infrared light emitting circuit 30 infrared receiver 31 infrared light receiving circuit 33 FSK demodulating circuit (FSK detection circuit) ) 34 FSK tuning circuit section 35 Switch circuit section 36 Source separation circuit section 37 DA converter

Claims (4)

[Claims] 1. An infrared transmitter (1) for transmitting infrared signals of different frequency bands, and an infrared receiver (30) for receiving the infrared signals, each infrared transmitter (1) comprising: Two or more individual digital data signals input in parallel are converted into one digital data signal.
The serial digital signal is FSK-modulated with a carrier frequency in a frequency band different from that of the time division multiplexing circuit unit (10) which is arranged in different time slots on a word-by-word basis to generate a serial digital signal and another infrared transmitter (1). FSK
A modulation circuit section (21) and an infrared emission circuit section (23) for transmitting an FSK-modulated serial digital signal as an infrared signal are provided, and an infrared receiving device (30) receives the infrared signal and photoelectrically converts it. Infrared light receiving circuit part (31) for converting into FSK composite signal
And a plurality of tuning circuit units (34) that tune to the FSK modulation frequencies of different infrared transmitters (1) and one of the plurality of tuning circuit units (34), and transmit a specific infrared signal from the FSK composite signal. A switch circuit section (35) for outputting the FSK modulated signal of the device (1), and an FSK for demodulating a serial digital signal from the FSK modulated signal
An infrared multiplex transmission system comprising: a demodulation circuit section (33); and a source separation circuit section (36) for separating a serial digital signal into digital data signals of one word unit and outputting the digital data signal. 2. The infrared transmitting device (1) comprises an AD converter (14) for converting an analog signal input by voice into a digital data signal, and the infrared receiving device (30) comprises:
The infrared multiplex transmission system according to claim 1, further comprising a DA converter (37) for converting a digital data signal into an audio output of an analog signal. 3. A serial digital signal, which simultaneously receives a plurality of infrared signals in which a plurality of serial digital signals are FSK-modulated at different modulation frequencies, and FSK demodulates a specific serial digital signal from the plurality of infrared signals. An infrared receiving device (30) for individually receiving time-division-multiplexed digital data signals, wherein the infrared receiving device (30) receives a plurality of infrared signals at the same time, photoelectrically converts them, and performs an FSK composite signal. The infrared light receiving circuit section (31), a plurality of tuning circuit sections (34) that tune to different FSK modulation frequencies of infrared signals, and one of the plurality of tuning circuit sections (34) are selected, and FSK synthesis is performed. A switch circuit unit (35) for outputting an FSK modulated signal of a specific infrared signal from the signal, and an FSK for demodulating a serial digital signal from the FSK modulated signal
An infrared receiver comprising a demodulation circuit section (33) and a source separation circuit section (36) for separating and outputting a serial digital signal into individual digital data signals. 4. The infrared receiver (30) converts the individually output digital data signals into analog signals.
The infrared receiver according to claim 3, further comprising an A converter (37).