JP2931231B2 - Infrared multiplex transmission system and infrared receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an infrared multiplex transmission system for multiplexing digital data divided into a plurality of channels and transmitting the multiplexed data by infrared rays, and an infrared receiving apparatus used in the system.

[0002]

2. Description of the Related Art Conventionally, a plurality of guide broadcasts are broadcast at a specific place such as an exhibition hall, and when a visitor switches a switch of a receiver to listen to one of the guide broadcasts, or at an international conference. Simultaneously broadcast interpreters for multiple countries,
When listening to the interpretation of one native language, for example, a time division multiplex transmission system in which two or more different broadcasts are carried on one radio wave and a frequency multiplex system in which different frequencies are assigned to each broadcast and transmitted are used. Have been.

[0003] FM multiplex broadcasting is also a kind of the above-described one, and frequency division multiplexes two or more different broadcasts, and performs FM modulation for transmission.

FIG. 7 shows a block diagram of an FM receiver 100 which receives this FM multiplex broadcast and receives a specific broadcast. The FM receiver 100 selects a channel and converts the signal into an intermediate frequency IF. Is amplified by the IF amplifier circuit 102.

[0005] Further, the limiter circuit of the limiter / detection circuit 103 limits the amplitude so that the signal level becomes equal, and the detection circuit demodulates the FM multiplex signal into a voice multiplex signal.

A multiplex demodulation circuit 104 connected downstream of the limiter / detection circuit 103 separates this audio multiplexed signal into individual broadcast signals, outputs them in parallel, and amplifies them in an amplifier circuit 105.

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

[0008]

[Problems to be solved by the invention]

However, when multi-channel broadcasting is transmitted by such FM multiplex broadcasting, since radio waves are used as a transmission medium, the broadcasting is not limited to a specific place in the exhibition hall, the international conference hall, but to the outside of the area. Leakage of radio waves, secret meetings, etc., we can not keep the secrets of the meeting contents,
In addition, since radio waves leak to the outside of the area, there is a risk of interference with broadcasting at other venues and the like, and there is a risk of receiving noise from outside.

In particular, when the frequency multiplexing method is adopted, interference with radio waves outside the area is unavoidable, and there has been a problem when the apparatus is used in such a specific area.

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

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and there is no leakage of a transmission signal from a specific area to the outside, there is no possibility of interference with a signal outside the area, and multiplex transmission is performed. It is an object of the present invention to provide an infrared multiplex transmission system and an infrared receiver that can increase the number of channels.

[0013]

In order to solve the above problems, an infrared multiplex transmission system according to claim 1 comprises:
It comprises a plurality of infrared transmitters for transmitting infrared signals in mutually different frequency bands and an infrared receiver for receiving the infrared signals. Each infrared transmitter transmits two or more individual digital data signals input in parallel. A time-division multiplexing circuit unit which is arranged in a time slot different for each word of a digital data signal and is a serial digital signal, and FSK-modulates the serial digital signal with a carrier frequency in a frequency band different from that of another infrared transmitting apparatus. An FSK modulation circuit section and an infrared light emitting circuit section for transmitting a serial digital signal subjected to FSK modulation as an infrared signal are provided. The infrared receiving apparatus receives the infrared signal, performs photoelectric conversion, and performs FS.
An infrared light receiving circuit unit for use as a K combined signal, a plurality of tuning circuit units for tuning to FSK modulation frequencies of different infrared transmitters, and one of the plurality of tuning circuit units are selected, and a specific infrared signal is selected from the FSK combined signal. A switch circuit for outputting a FSK modulated signal of the transmitting apparatus, an FSK demodulating circuit for demodulating a serial digital signal from the FSK modulated signal, and a source separating circuit for separating the serial digital signal into a digital data signal of one word unit and outputting the digital data signal And a unit.

Further, in the infrared multiplex transmission system according to the second aspect, the infrared transmitting apparatus includes an AD converter for converting an analog signal input as voice into a digital data signal, and the infrared receiving apparatus converts the digital data signal into an analog signal. Characterized in that it is provided with a DA converter for converting the audio output into the audio output.

Further, in the infrared receiving apparatus according to the third aspect, a plurality of serial digital signals are FSK-modulated at different carrier frequencies in different frequency bands at the same time, and a plurality of infrared signals are simultaneously received and specified from the plurality of infrared signals. An infrared receiver that FSK demodulates the serial digital signal of the above and individually receives time-division multiplexed digital data signals from the serial digital signal, the infrared receiver simultaneously receives a plurality of infrared signals, An infrared light receiving circuit unit that performs photoelectric conversion to generate an FSK composite signal, a plurality of tuning circuit units that tune to FSK modulation frequencies of different infrared signals,
A switch circuit for selecting one of the plurality of tuning circuits and outputting an FSK modulation signal in a specific infrared signal from the FSK composite signal; an FSK demodulation circuit for demodulating a serial digital signal from the FSK modulation signal; A source separation circuit for separating a signal into individual digital data signals and outputting the separated digital data signals.

Further, the infrared receiving apparatus according to a fourth aspect of the present invention is characterized in that the infrared receiving apparatus further comprises a DA converter for converting the individually output digital data signal into an analog signal.

[0017]

According to a first aspect of the present invention, an infrared transmitting apparatus time-division multiplexes two or more digital data signals input in parallel and then transmits them as FSK-modulated infrared signals.

Infrared signals transmitted from a plurality of infrared transmitters in the same manner are transmitted to the FSK modulation circuit sections at different carrier frequencies from those of the other infrared transmitters.
K modulation is performed.

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

In the infrared receiving device, an infrared signal is received by an infrared light receiving circuit and photoelectrically converted 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 transmitting apparatus, and outputs the FSK demodulation circuit. A demodulator for demodulating the serial digital signal of the specific infrared transmitter.

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

Therefore, after a large number of digital data signals are time-division multiplexed, they can be frequency-multiplexed and transmitted.

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

Therefore, an audio 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. An infrared receiving device for individually receiving a time-division multiplexed digital data signal from a serial digital signal, wherein the infrared receiving circuit unit simultaneously receives a plurality of infrared signals, photoelectrically converts the signals, and
SK composite signal.

When one of the plurality of FSK tuning circuits is selected by the switch circuit, the FSK modulation signal is tuned to one selected FSK modulation frequency from the FSK composite signal, and an FSK modulation signal is output. The circuit section converts the serial digital signal corresponding to the specific infrared signal to FSK
Demodulate.

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

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

According to a fourth aspect of the present invention, there is provided an infrared transmitting apparatus comprising:
In the converter, the separated 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 EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a 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, and different channels of transmission signals from 1 to N are respectively assigned to the infrared transmitters, and different analog signals from a to m sources are assigned to each infrared transmitter. The data is input to the division multiplexing circuit unit 10.

The time-division multiplexing circuit 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.

If the sources of the analog signals a to m input to the infrared transmitting apparatus 1 to which the N channels are assigned are ChN-a, ChN-b... ChN-m, the time division multiplexing circuit 10 , Input terminals 11, 11... Corresponding to the number of each source, and corresponding analog signals (ChN-a, ChN-b.
−m) are 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 speech at an international conference for each country, and constitutes one program for each source. Further, two broadcast sources may be assigned to L and R for one broadcast program to provide stereo broadcast.

A low-pass filter 12 and an amplifier 13 are connected to a stage subsequent to each of the input terminals 11 to cut high frequencies in analog signals from respective sources and amplify the analog signals.

The output side of the amplifier 13 is an AD converter 1
4 to convert the amplified analog signal into an 8-bit digital signal.

A shift register 15 is connected to the subsequent stage of each AD converter 14, and the shift register 15
As shown, the shift register 15 corresponding to the source Nm
With −m being the lowest stage, the shift registers 15-a corresponding to the source Na in the upper stage are sequentially connected in series.

In the uppermost stage, a shift register 15 is provided.
−H are connected in series, and the output is connected to an FSK modulation circuit section 21 via an amplification circuit 20 described later.

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

That is, the output of the first frequency divider 17 is
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 each shift register 15, and the output signal of each AD converter 14 is changed by a sampling pulse every sample period (1 / fs). Sampled into
The digital data of each stage sampled and stored in the shift register is moved to the next stage for each stage by a data shift pulse.

The sampling frequency fs is, for example, 15 if the sound is to be transmitted with a transmission characteristic of about AM radio.
KHz.

As shown in the figure, at the time of sampling, the lower 13 bits of the shift register 15-H are set to "H" by an input from a format setting circuit (not shown).
, And the other shift registers 15-a,.
The top row of m and the row 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 bits of digital data of each source separated by.

That is, the digital data of each source is
The eight bits are arranged in time slots at 10-bit intervals, which are different in word units, with one byte as a word unit.

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

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

The FSK modulation is performed based on carrier frequencies in different frequency bands for each infrared transmitting apparatus 1.

For example, a one-channel infrared transmitting apparatus ₁₁
In performs FSK modulation at a carrier frequency of 3MHz and 6 MHz, in the infrared transmission device 1 ₂ of 2 channels, 9 MHz and 12MHz different from the band of the carrier frequency
FSK modulation is performed at the carrier frequency of.

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

As shown in FIG. 1, an infrared signal from each infrared transmitting device 1 is
0, but as described above, the infrared transmitter 1
Since the FSK modulation is performed at a different carrier frequency every time, the frequency is different for each infrared transmitting apparatus.

FIGS. 2 and 5 show the configuration of the infrared receiving apparatus 30 for receiving the infrared signal.

In this embodiment, the infrared receiving device 30
Is to prepare program broadcasts according to the number of recipients,
The number does not matter.

A large number of infrared signals having different frequencies transmitted from the infrared transmitters 1 are simultaneously received by the photodiodes 31 serving as the infrared light receiving circuit, and converted into photoelectrically converted FSK composite signals.

Since the output of the photodiode 31 is weak, an amplifying / waveform shaping circuit 32 is connected to the output side of the photodiode 31 to amplify the FSK composite signal and then adjust the waveform to a predetermined 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 circuits 34 tune each of the FSK composite signals to the carrier frequency of any one of the infrared transmitting devices,
This is an SK modulation signal. Switch circuit unit 35
Selects one of the plurality of FSK tuning circuit units 34 and outputs an FSK modulation signal of the infrared transmitting apparatus corresponding to the selected FSK tuning circuit unit 34. Switch circuit section 3
5 is connected to an FSK detection circuit section 33 which is an FSK demodulation circuit section.
A serial digital signal is demodulated from the K modulated signal.

[0060] For example, when selected by the switch circuit 35 to FSK tuning circuit unit 34 _N for ChN as in FIG. 2, FS
The FSK modulation signal is output by tuning to the carrier frequency of the infrared transmitting apparatus 1 _N to which the channel N is assigned from the K combined signal, and the FSK detecting circuit 33 converts the FSK modulated signal to the infrared transmitting apparatus 1 _N as shown in FIG. Serial digital signal (b) is demodulated.

The switch circuit section 35 is manually selected, but the switching of the switch circuit may be performed by using any of electronic circuits and mechanical components such as a slide switch.

The number of FSK tuning circuits 34 does not need to be equal to the number of infrared transmitters 1 and may be smaller.

The output side of the FSK detection circuit unit 33 is connected to the source separation circuit unit 36, and the FSK detection circuit unit 3
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 the present 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 33 is input to the m-th DA converter 37-m and the first counter 38.

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

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

The first counter 38 is for synchronizing with the serial digital signal to take out a break of one cycle (1 / fs), and detects a head pulse from the input serial digital signal.

That is, since the serial digital signal is provided with a head pulse in which 13-bit "H" is continuous at the beginning, the first counter 38 keeps "H" while the clock is counted for a certain period of time. , 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 upon receiving a head pulse signal, shifts the data in each DA converter 37 and the shift register 43 to the next stage. Output pulse.

The third counter 42 is provided for each DA converter 3
7 and outputs a latch pulse.

The third counter 42 counts the data shift pulse and sends the data to each DA converter 37 from a to m.
When 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 transmitting apparatus 1 _N to which the channel N is assigned is transmitted to the source separation circuit section 36.
When receiving the latch pulse, the digital data of ChN-a is supplied to the DA converter 37-a, and the digital data of ChN-b is supplied to the DA converter 37-b.
The digital data of ChN-m is input to the DA converter 37-m.

Each DA converter 37 converts the digital data into a digital signal, 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 its output side.

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 configured as described above, a specific source (for example, Ch2-b)
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 second digital data from the head of the serial digital signal is obtained.

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.
5 ± 1.5 MHz.

In order to receive the Ch2-b program broadcast, the infrared receiver 30 scans the switch circuit 35 in advance and tunes to the frequency of 10.5 ± 1.5 MHz.
Keep selecting the use FSK tuning circuit unit 34 _2.

Amplified waveform shaping circuit 3 of infrared receiver 30
2 includes the infrared signal transmitted from another infrared transmitting apparatus 1,
h2 FSK tuning circuit section 34 ₂ and FSK demodulation circuit section 33
Accordingly, it is possible to demodulate the serial digital signals of an infrared transmission device 1 ₂ from FSK composite 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 41
1 outputs a data shift pulse. Every time this data shift pulse is input, the serial digital signal moves from the DA converter 37-m to the DA converter 37-a via the shift register 43 sequentially.

When the digital data of Ch2-b is shifted to the DA converter 37-b, the third counter 42
Outputs a latch pulse from the DA converter 37-b.
Performs DA conversion of the Ch2-b digital data.

The output timing of the latch pulse can be determined by a set value previously set in the third counter 42 by a digital switch or the like (not shown), and by specifying the number of shifts up to a specific DA converter 37, Digital data of an arbitrary 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 external headphones or the like.

In the above embodiment, the infrared transmitter 1
Has been described with respect to N infrared transmitters that are individually separated, but the present invention is not limited to this. For example, an infrared signal modulated by a plurality of carrier frequencies may be transmitted from one infrared transmitter.

Also, in the example described above, the transmission signals input to each infrared transmitting apparatus 1 have the same number of transmission signals a to m, but the number of input terminals of each infrared transmitting apparatus 1
Further, 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, the infrared signal transmitted from the infrared transmitter is an FSK-modulated infrared signal, so that the transmission signal is excellent in directivity and does not leak out of the area.

Therefore, the transmission signal does not leak outside the area at a specific place in the exhibition hall, in the international conference hall, or the like, and the secret of the conference contents can be kept in a closed conference or the like.

Also, since the FSK-modulated infrared signal is transmitted in the same manner, there is no danger of interference from outside the area, and even if noise is received from outside the area, demodulation can be performed without error because the FSK modulation method is used. it can.

Further, since transmission is performed using infrared signals, there is no interference with signals outside the area, and the time division multiplexing method and the frequency division multiplexing method can be used together.

Therefore, since a 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 an international conference. There is no such thing.

According to the second and fourth aspects of the present invention, 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 apparatus according to the present invention.

[0095]

[Brief description of the 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 the infrared receiving device 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;

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

FIG. 6 is a waveform chart showing an output signal (b) of the FSK demodulation circuit unit 34;

FIG. 7 is a block diagram showing a conventional FM receiver for receiving FM multiplex broadcasting.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 infrared transmitting device 10 time division multiplexing circuit unit 14 AD converter 21 FSK modulation circuit unit 23 infrared light emitting circuit unit 30 infrared receiving device 31 infrared light receiving circuit unit 33 FSK demodulation circuit unit (FSK detection circuit unit) 34 FSK tuning circuit Unit 35 switch circuit unit 36 source separation circuit unit 37 DA converter

Claims (4)

(57) [Claims] 1. An infrared transmitting device (1) for transmitting infrared signals in different frequency bands and an infrared receiving device (30) for receiving the infrared signals. Two or more individual digital data signals input in parallel are converted into one of the digital data signals.
A time-division multiplexing circuit unit (10) which is arranged in a time slot different for each word and is a serial digital signal, and a serial digital signal is FSK-modulated at a carrier frequency in a frequency band different from that of the other infrared transmitting apparatus (1). FSK
A modulation circuit section (21); and an infrared light emitting circuit section (23) for transmitting an FSK-modulated serial digital signal as an infrared signal. The infrared receiving apparatus (30) receives the infrared signal and performs photoelectric conversion. Infrared light receiving circuit section (31) for generating an FSK composite signal
And selecting one of the plurality of tuning circuits (34) for tuning to the FSK modulation frequency of the different infrared transmitting device (1) and one of the plurality of tuning circuits (34), and transmitting a specific infrared signal from the FSK composite signal. A switch circuit section (35) for outputting an 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 a digital data signal of one word unit and outputting the digital data signal. 2. The infrared transmitting apparatus (1) includes an AD converter (14) that converts an analog signal input as voice into a digital data signal, and the infrared receiving apparatus (30) includes:
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, wherein a plurality of serial digital signals are FSK-modulated at different modulation frequencies, a plurality of infrared signals are simultaneously received, and a specific serial digital signal is FSK-demodulated from the plurality of infrared signals. An infrared receiving device (30) for individually receiving time-division multiplexed digital data signals from the device, the infrared receiving device (30) receiving a plurality of infrared signals simultaneously, photoelectrically converting the signals, An infrared light receiving circuit section (31), a plurality of tuning circuit sections (34) for tuning to FSK modulation frequencies of different 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 a FSK modulation signal in a specific infrared signal from the signal, and an FSK for demodulating a serial digital signal from the FSK modulation signal
An infrared receiver comprising: a demodulation circuit section (33); and a source separation circuit section (36) for separating a serial digital signal into individual digital data signals and outputting the digital data signal. 4. An infrared receiver (30) for converting a digital data signal output individually to an analog signal.
The infrared receiver according to claim 3, further comprising an A converter (37).