JPH03262289A - Picture and audio signal transmitter - Google Patents

Abstract

PURPOSE:To ensure simultaneous performance between a picture signal and an audio signal by converting the picture data into an audio band signal, applying frequency division multiplying to the signal onto an audio signal and transmitting the result so as to send the picture data and the audio signal simultaneously. CONSTITUTION:A picture data read from a picture memory 103 is converted into an analog signal by a D/A converter 104 and fed to a monitor television receiver 105. Moreover, the picture data is fed to a MODEM 106 being a multi- frequency modulating and demodulating means via a data bus 115. A square signal outputted from the MODEM 106 is fed to a 2/4-wire conversion section 108 as an audio band signal via a band pass filter 107 having a pass band of 2000-2400Hz. On the other hand, an audio signal from a handset 109 is fed to a conversion section 108 via a band eliminating filter 110 eliminating the band of 2000-2400Hz. These signals are synthesized by a synthesis circuit 108 in the inside of the conversion section 108, a transmission signal is generated and fed to an analog line 200 via a hybrid circuit 108b and a line transformer 108c.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is applicable to simultaneous transmission of image data and audio signals using a low-speed, narrow-band transmission line such as a general telephone line or a wireless communication line. The present invention relates to an image/audio transmission device suitable for use in.

[Prior art] As a low-speed, narrow-band transmission line, for example, a general telephone line,
There are wireless communication lines, etc. A general telephone line will be explained below as an example.

The I5DN (Integrated Digital Communication Network) line, which has been put into service in recent years, is called a digital line, whereas the general telephone line is called an analog line, so this name will be used hereafter.

2. Description of the Related Art Still image transmission devices and monochrome still image telephones (video telephones) are already known as devices for transmitting data other than audio signals, such as still image data, over analog lines.

In all of these devices, the modulation/demodulation device (modem) for low-speed conversion and transmission of image data occupies almost the entire analog line band of 300 to 3400 Hz. Therefore, it has not been possible to frequency-division multiplex and transmit audio signals.

FIG. 6 shows a carrier waveform diagram of a commercially available videophone.

In this case, the AM-PM (amplitude phase modulation) method is adopted as the modem method, and as shown in the figure, "black" of the video signal corresponds to the maximum amplitude of the first phase, and "white" corresponds to the maximum amplitude of the second phase. The intermediate tones in between are assigned to the amplitudes divided into eight equal parts. That is, a combination of two phases and eight amplitude values performs modulation corresponding to 16 gradations of the luminance signal.

Here, if the AM-PM method is expressed mathematically, E AM-P
M = A(1+maV(t))cos(2*fct+
2rr mpV(t) 〇)V(D = Vcos
(2rr f mt): Modulation signal ma; AM modulation coefficient IB; PM modulation coefficient, and the energy distribution of the AM-PM system is spread over the entire band of the analog line.

Therefore, it is impossible to simultaneously transmit image data modulated by a modem and an audio signal in a narrow band of 300 to 3400 Hz.

One method that has been considered is to digitally encode both image data and audio signals and transmit them simultaneously by time-division multiplexing, but this method avoids the need for a large and expensive system. do not have.

On the other hand, this type of device that handles small amounts of image data rather than large amounts of image data has already been put into practical use.

This is because FSK (Freque
It is a system that can transmit handwritten figures, etc. even during a telephone call by multiplexing image data converted into cyShift Keying) signals, and has been internationally standardized as a telewriting standard. However, F.S.K.
The baud rate is low, about 300 bps, and is not suitable for transmitting image data.

[Problem to be solved by the invention] In this telewriting standard, image data can be transmitted simultaneously during a call, but F S
K has a low baud rate of about 300 bps, making it unsuitable for transmitting large amounts of data such as image data.

For example, if the brightness signal has 64 gradations and is still image data of 256 x 240 dots, the capacity will be 256 x 240 x 8 pits, so if this is transmitted at 300 bps, it will take 256 x 240 x 8 ÷ 300 dots, or 28 minutes. , it takes nearly 30 minutes to transmit one image.

On the other hand, as a modulation method, as mentioned above, the AM-PM method or Q A M ((Luadrature
If a method such as A M ) is used, the frequency component will occupy almost the entire frequency band of the analog line, so
Simultaneous transmission with audio signals is not possible.

Furthermore, when transmitting images and audio, it is necessary to first perform an operation to capture the video and then perform an operation to transmit the image, as in the conventional case.

Therefore, even when transmitting audio and having a conversation, the video capturing operation and image transmitting operation must be performed at any time, which is extremely troublesome.

SUMMARY OF THE INVENTION Accordingly, the present invention provides an image and audio transmission device that can transmit image data and audio signals simultaneously, has a high data transmission baud rate, and has improved transmission operability.

[Means for Solving the Problems] The present invention includes a multi-frequency value modulating means for converting image data into an audio band signal on the transmitting side, and a frequency used for the audio band signal from the multi-frequency value modulating means than the audio signal. A band elimination filter for removing band components, a signal synthesis means for synthesizing the audio band signal from the multi-frequency value modulation means and an audio signal from the band elimination filter to obtain a transmission signal, and a transmission start signal sending means. The receiving side includes a signal separating means for separating the voice band signal from the audio signal from the transmission signal transmitted from the transmitting side, and a multi-frequency value for converting the voice band signal from the signal separating means into image data. The apparatus includes demodulation means and means for transmitting a reception ready signal.

[Function] In the above configuration, the image data is converted into an audio band signal, frequency division multiplexed with the audio signal, and transmitted, so the image data and the audio signal can be transmitted simultaneously.

Furthermore, since image data is converted into an audio band signal by multi-frequency value modulation, it is possible to increase the baud rate of data transmission.

Prior to video transmission, the automatic transmission and manual transmission selection switch 113 is operated to switch to automatic transmission. Then, on the transmitting side, data representing the transmission start signal is read from the control data storage means 114, and is transmitted to the receiving side.

When the receiving side receives this transmission start signal, if the selection switch 113 is switched to the automatic transmission mode, the receiving side checks whether the receiving side is ready for reception or not.
When it is determined by U112 that the reception preparation is complete, data representing the reception preparation completion signal is read from the control data storage means 114 and is transmitted. C
After receiving this, the PIJII 2 takes in the image and then enters the transmission start mode.

Through such handshaking, image capture, image transmission and reception are automatically repeated in a predetermined cycle.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. This example is an example of transmission using an analog line, and image data is frequency division multiplexed into a band of 2000 to 2400H2.

In the figure, 100A and 100B are transmitting/receiving sets serving as terminal devices connected to an analog line (general telephone line) 200.

The transmitter/receiver) 100A is configured as follows.

103 is an image memory. A video signal from the video camera 101 is supplied to the image memory 103 after being converted into a digital signal of, for example, 6 bits per sample by the A/D converter 102, and image data for one screen is written therein.

Further, image data read from the image memory 103 is converted into an analog signal by a D/A converter 104 and supplied to a monitor television 105.

Further, image data read from the image memory 103 is sent via a data bus 115 to a modem 106 constituting a multi-frequency modulation/demodulation means. This modem 106 is configured as shown in FIG. 2, for example.

In the figure, a modulation counter 106a is supplied with six hits of image data representing 64 steps (gradations) from the image memory 103. This counter 106a counts down from a predetermined value in accordance with the image data. And this counter 1
From 06a, a one-cycle square wave signal having a period corresponding to the value (step) of the image data is output. That is, equal time differences are given to the period of the square wave corresponding to each step.

In this case, the period corresponding to the first step is I/2000
Hz, the period corresponding to the 64th step is 1/240
The frequency is set to 0 Hz. In other words, the frequency of the square wave at the 1st step is 2000H2, the frequency of the square wave at the 2nd step is 2005H2,..., the frequency of the square wave at the 63rd step is 2393Hz, and the frequency of the square wave at the 64th step is 2400H2. (Illustrated in Figure 4A).

Further, 106c is a waveform shaping circuit, and this waveform shaping circuit 10Gc is supplied with an audio band signal supplied from the transmitting side via the analog line 200. As will be described later, this audio band signal is a sine wave signal obtained by passing the above-mentioned square wave signal through a band pass filter having a pass band of 2000 to 2400 Hz. The waveform shaping circuit 106C reproduces the original square wave signal based on the zero crossing point of the sine wave signal.

The square wave signal from the waveform shaping circuit 106c is then supplied to a demodulation counter 106b.

As described above, the square wave signal has a period corresponding to the value (step) of the image data.

The counter 106b performs a counting operation during each cycle of the square wave signal, and the period of each cycle of the square wave signal is calculated from the count value. Then, this counter 106b outputs 6-pit image data having a value corresponding to the period, and this 6-pit image data is supplied to the image memory 103.

Returning to FIG. 1, the square wave signal output from the counter 106a of the modem 106 is passed through a bandpass filter 107 having a passband of 2000 to 2400H2.
The signal is supplied to the line converter 108 as an audio band 1 signal. This audio band signal is shown in Figure 4B.
The signal becomes a sine wave signal as shown in .

The audio signal from the handset 109 is from 2000 to 2400.
The signal is supplied to the converter 108 via a band-removal filter 110 that removes the Hz band.

The conversion unit 108 is configured as shown in FIG. 3, for example.

In the same figure, 108a is a synthesis circuit, and in this synthesis circuit 10a, the audio band signal from the bandpass filter 107 and the band-limited audio signal from the band-removal filter 110 are combined to form a transmission signal. . This transmission signal is a frequency division multiplexed signal of an audio band signal and an audio signal, as shown in FIG.

The transmission signal from the combining circuit 108a is transmitted to the hybrid circuit 1
08b and the line transformer 108C to the analog line 200.

Further, a transmission signal supplied from the transmitting side via analog line 200 is supplied to buffers 12-108d and 108e via line transformer 108C and hybrid circuit 108b.

Returning to FIG. 1, the transmission signal from the buffer 108d of the conversion unit 108 is supplied to the bandpass filter 107 to extract the voice band signal, and this voice band signal is transmitted to the modem 10.
6. Then, as described above, image data is demodulated from the audio band signal, and this is supplied to the image memory 103 via the data bus 115.

Further, the transmission signal from the buffer 108e of the conversion unit 108 is supplied to a band elimination filter 110 to extract an audio signal, and this audio signal is supplied to the handset 109.

112 is a CPU that controls the transmission mode.

Reference numeral 113 is a selection switch that can select between automatic transmission mode and manual transmission mode. Reference numeral 114 denotes a control data storage means, which stores data representing a transmission start signal (code signal) and data representing a reception preparation completion signal. Therefore, the CI) U 112, the selection switch 113, and the control data storage means 114 constitute means for sending out a transmission start signal.

When the manual transmission mode is selected, it is necessary to perform the same transmission processing operations as before, so the operation keys necessary for that transmission mode (imaging key, transmission key, etc.) are provided. ing. However, it is not illustrated.

Although the transmitter/receiver set 100A is configured as described above, the transmitter/receiver set 100B is also configured in the same manner as the transmitter/receiver set 100A. Therefore, the CPU 112, the selection switch 113, and the control data storage means 114 provided in the transmitting/receiving set (set 100B as described below) functioning as the receiving side function as means for transmitting the reception preparation completion signal.

In the above configuration, the operation will be described when, for example, the transmitting/receiving set 100A is used as the transmitting side, and the transmitting/receiving set 100B is used as the receiving side. It is assumed that the selection key 113 has been switched to the automatic transmission mode.

Prior to transmitting the video, the transmission 3-14- key 113 on the transmitting side is operated first. Then, change this to CPU1
12, the necessary data, that is, the transmission start signal, is read out from the storage means 114, and this is transferred to the data bus 1.
15 to the modem 10B for transmission.

On the receiving side, by receiving the transmission start signal, C
The PU 112 determines the state of the receiving side. Only when reception preparation is complete, a "reception preparation completion signal" is read out from the storage means 114, and this is sent to the modem 106 via the data bus 115. Sent.

On the transmitting side, upon reception of this reception ready signal, image capture and transmission and reception of the captured image and audio are repeated at predetermined timing.

Therefore, when the automatic transmission mode is selected, transmission and reception are alternately repeated in a predetermined cycle.

In contrast, automatic transmission mode is selected only on the sending side,
When manual transmission mode is selected on the receiving side,
The sending side only performs sending operations, and the receiver 5-debt only performs receiving operations.

In this way, after the handshake for the transmission/reception mode is performed, the image capture process is performed, and the mode becomes the transmission mode for the captured images and audio.

Therefore, the video signal from the video camera 101 is A/D
After being converted into a 6-bit digital signal by a converter 102, it is supplied to an image memory 103.
3, image data for one screen, for example, 256×240 dots, is written.

Then, the image data of each dot is sequentially read out from the image memory 103, and is supplied to the modem 106 via the data bus 115. A square wave signal is output.

Then, the square wave signal output from the modem 106 is filtered at 2000 to 2400 Hz by a band pass filter 107.
A sine wave signal in a frequency band of 2000 to 2400 Hz, that is, a voice band signal, is supplied to the conversion unit 10B and outputted from the handset 109. After being removed, it is supplied to the conversion unit 108.

Then, in the converting section 108, the voice band signal and the voice signal are frequency division multiplexed to form a transmission signal, and this transmission signal is supplied to the analog line 200 (transmission/reception circuit) 1
Transmitted to 00B.

Next, the operation of the transmitter/receiver I-100B will be explained.

The transmission signal transmitted from the transmitter/receiver set 100A via the analog line 200 is supplied to the band-removal filter 110 via the converter 10.
The audio signal extracted at 0 is supplied to the handset 109, and audio based on the audio signal is output.

In this case, the band rejection filter 110 has a frequency of 2000 to 240.
Since the 0Hz voice band signal is removed, the handset 10
9 does not output any unpleasant sound (sound) caused by the audio band signal.

Also, transmission/reception via analog line 200) 100
The transmission signal transmitted from A is supplied to the bandpass filter 107 via the conversion section 108, and the audio band signal extracted by the bandpass filter 107 is supplied to the modem 106.

Then, in the modem 10B, 6-bit image data is demodulated from the audio band signal. In this case, since the bandpass filter 107 removes audio signals outside the frequency band of 2000 to 2400 Hz, the modem 106 will not malfunction due to the audio signals.

Six pieces of image data demodulated by the modem 106 are supplied to the image memory 103 via the data bus 115 and written therein.

Then, 6-bit image data for each dot is sequentially read out from this image memory 103, converted into an analog signal by a D/A converter 104, and then supplied to a monitor television 105, where an image based on the image data is displayed. .

According to this example, the audio band signal obtained by numerically modulating the image data and the band-controlled audio signal are frequency division multiplexed and transmitted, so that the image data and the audio signal are Can be transmitted simultaneously.

Furthermore, according to this example, since the audio band signal is formed by modulating the image data with multiple frequency values, the baud rate of data transmission can be increased, and the image transmission time can be significantly shortened.

In other words, the frequency band used for the voice band signal is 200.
The average baud rate when using 0 to 2400 Hz is as follows.

Baud rate = 2200 x 6 = 13200b
ps Therefore, the luminance signal has 64 gradations and is 256×24
For still image data with 0 dots, 256X240X
Since the capacity is 8 pits, the transmission time is 256 x 240 x 8 ÷ 13,200 bowls, or 37 seconds. In other words, compared to telewriting using 300 baud FSK, one image can be transmitted in approximately I/40 of the time required (assuming that the image is also transmitted using the telewriting standard). .

In the above-mentioned embodiment, the image data is 6 bits, but it can be similarly configured to have any number of hits. Further, although the frequency band used for the voice band signal is 2000 to 2400 Hz, the frequency and range are not limited to this.

Further, in the above-described embodiments, the transmitting/receiving set is two-kilometres, but a structure having even more transmitting/receiving sets can be constructed in the same manner.

Furthermore, although the above-mentioned embodiments have shown transmission using an analog line, systems that simultaneously transmit image data and audio signals using other transmission media may also be used.
The same can be applied. For example, it can be applied to systems that handle image data and audio signals, such as amateur hand wireless communication, between the main body of home appliances and remote control transmitters, and security information systems that use home electric power lines (100V). can.

20- [Effects of the Invention] As explained above, according to the present invention, since the audio band signal obtained by modulating the image data and the audio signal are frequency division multiplexed and transmitted, the image data and the audio signal can be transmitted simultaneously. This makes it possible to ensure simultaneous broadcasting of images and audio.

This allows you to talk while looking at the image. Also, since there is no interruption in conversation even when transmitting images,
Conventionally, images were sent manually, but now it is possible to automatically repeat image transmission, reception, transmission, reception, etc., alternately, which simplifies the operation.

In addition, since the audio band signal is formed by multi-frequency value modulation of image data, the baud rate in data transmission can be increased, and the image transmission time can be significantly shortened, reducing the hassle of waiting time. can be reduced.

Furthermore, in this invention, an automatic sending function has been added, so
By using this function, image importing and image transmitting operations are automated, eliminating the need for conventional image importing and image transmitting operations, a feature that greatly improves the usability of the device. have

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram of a modem, Fig. 3 is a block diagram of a 2-wire/4-wire converter, and Fig.
FIG. 6 is an explanatory diagram of multi-frequency value modulation, FIG. 6 is a diagram showing the structure of a transmission signal, and FIG. 6 is a diagram showing the relationship between gradation and carrier waveform in a conventional videophone. 100A. 101 ・ Φ 102 ・ Meeting 103 ・ ・ 1041 105 ・ ・ 106 ・ ◆ 10 OB ・Transmission/reception set competition Video camera・A/D converter・Image memory・D/A converter・Monitor TV・Modem 1 22- 107・・・Band pass filter 108... 2-wire 4-wire converter 109... Handset 110... Band removal filter 112◆・No. CPU 113... Selection switch 114... Control data storage means

Claims (1)

[Claims] (1) On the transmitting side, a multi-frequency value modulation means converts image data into an audio band signal, and a band elimination filter removes components of the frequency band used in the audio band signal from the multi-frequency value modulation means from the audio signal. and signal synthesis means for synthesizing the audio band signal from the multi-frequency value modulation means and the audio signal from the band elimination filter to obtain a transmission signal, and means for sending a transmission start signal for images and audio, The receiving side includes signal separating means for separating the audio band signal from the audio signal from the transmission signal transmitted from the transmitting side; and multi-frequency value demodulation means for converting the audio band signal from the signal separating means into the image data. and means for transmitting a reception ready signal.