JPH0455884A - Remote teaching system - Google Patents

Abstract

PURPOSE:To allow the restoration of received images against a transmission path error by transmitting an image signal for refreshing at a predetermined period from an image band compressing device of a studio station when a control circuit is used for voice communication and the image refresh request signal for the image signal error from other remote station cannot be received. CONSTITUTION:A control means 14 to control the image band compressing device 12 of the studio station 1 so as to transmit the image signal for refreshing at the predetermined period when the control circuit is used in the voice communication from one station of the remote stations 2, 3 to the studio station 1 and the image refresh request signal for the image signal error from the other one station of the remote stations 2, 3 cannot be received. The transmission of the control data to the studio station 1 is possible in this way even if the voices are allotted to the remote stations 2, 3 of some plate. The image signals are thus restored.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a broadcasting type distance education system using a satellite, in which a plurality of remote stations are connected to a studio station.

[Conventional technology]

When transmitting image information using an image band compression device,
To recover a received image from a transmission path error, (1) a periodic refresh method in which the transmitting section of the image band compression device periodically sends a refresh image signal, and (2) an image refresh method that is sent from the receiving section of the image band compression device. A demand refresh method is known in which a request is made to the transmitter. Each method has its advantages and disadvantages.The periodic refresh method has a relatively large amount of information in the refresh image signal, resulting in poor compression ratio, but the demand refresh method, which does not require any particular control, has no effect on the compression ratio. Although it is small, it has the characteristic of requiring control.

Conventionally, this type of distance education system uses a demand refresh method, in which a remote station requests an image refresh from a studio station using a control line.

[Problem to be solved by the invention]

The above-described conventional distance education system uses a demand refresh method, in which an image refresh request is sent from a remote station to a studio station as control data using a return line. However, since the line is shared with voice,
If audio is assigned to some remote station, there is a drawback that control data cannot be sent to the studio station and the received image cannot be restored.

[Means to solve the problem]

The distance education system of the present invention consists of a studio station and a plurality of remote stations each equipped with a camera, a monitor, a microphone, a speaker, an image band compression device, and a control device, and the studio station and the remote stations are connected via a satellite line. In a distance education system in which control data and audio from the remote station are switched and operated using the same control line, the control line is used for voice communication from one of the remote stations to the studio station. If an image refresh request signal corresponding to a received image error cannot be received from another of the remote stations, the image band compression device of the studio station is configured to send a refresh image signal at a predetermined cycle. It has a control means for controlling.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the system configuration of an embodiment of the present invention.

In FIG. 1, the distance education system of this embodiment includes a studio station 1 on the instructor's side, a satellite ground station 4 connected to the studio station 1, a satellite 7 that relays signals from the satellite ground station 4, and a satellite 7 that relays signals from the satellite ground station 4. The student-side remote station 2 receives the signal from the satellite 7 via the satellite ground station 5, and the student-side remote station 3 receives the signal from the satellite 7 via the satellite ground station 6. .

Studio station 1 has camera 8 and microphone 1 for the instructor.
0, a monitor 9 for the camera 8, a speaker 11 for listening to audio from the students, band compression of the image signal from the camera 8, multiplexing of the audio signal from the microphone 10, and transmission to the satellite ground station 4. An image band compression bag M12 having a function of transmitting refresh images at predetermined intervals, a control panel 13 operated by the instructor, a control device 14 that controls the entire studio station 1, and a control signal or voice from the satellite ground station 4. After receiving the signal, the control device 14 side or the speaker 11
It has a switch section 15 that switches to the side.

The remote station 2 is a satellite ground station 5. an image band compression device 16 that receives and demodulates the signal from the computer, one monitor that displays the demodulated image signal, a speaker 21 that amplifies the demodulated audio signal, a microphone 21 for students, and a remote station 2. It is configured to include a control device 17 that controls the whole, and a switch section 18 that receives a signal from the control device 17 or the microphone 21 and switches to the one that receives the signal.

Remote station 3 also has the same configuration as remote station 2.

Next, the operation of this embodiment will be explained.

In this embodiment, explanation will be given assuming that the screen to be transmitted is one screen in the case of the studio station 1 where the instructor is located and the remote station 2.3 where the students are located.

First, the lecturer's video and audio are captured by the lecturer camera 8 and lecturer microphone 10, sent to the image band compression device 12 of the studio station, and encoded and multiplexed by the image band compression device 12 of the studio station 1. is sent to the satellite ground station 4 of the remote station 2, 3 via the satellite 7.
.
It will be sent to 20 students and delivered to the students. The transmission monitor 9 of the studio station 1 displays the video taken by the lecturer camera 8.

Normally, the signals sent from the remote stations 2 and 3 to the studio station 1 are control data, and the switch unit 15 of the studio station 1 and the switch units 18 of each of the remote stations 2 and 3 are tilted toward the control device 17, and the control data is sent from the remote stations 2 and 3 to the studio station 1. It forms a bus for transmitting data. In this case, the image refresh request signal output from the image band compression device 116 of each of the remote stations 2 and 3 is transmitted to each of the remote stations 2 and 3 via the switch unit 18 of each of the remote stations 2 and 3. is sent to satellite ground stations 5 and 6, and sent to studio station 1 via satellite 7.
The satellite reaches the ground station 4 of the studio station, and the switch part 1 of the studio station]
5 to the control device 14, and the control device 14 issues an image refresh request to the image band compression device 12.

On the other hand, when audio is sent from the remote stations 2 and 3 to the studio station 1, the process is as follows.

Considering the case where the remote station 2 is made to speak, the control device 14 of the studio station 1 moves the switch unit 15 to the speaker 11 side according to instructions from the operation panel 13 operated by the instructor, and transmits control data to the instructor using the image band compression bag W12. are sent to the respective control devices 17 of the remote stations 2 and 3 through the same route as the video and audio of The control device 17 puts the switch unit 18 of the remote station 3 into a state where nothing is connected. With the above control, the voice of the student on remote station 2 is transmitted to remote station 2.
is captured by the microphone 21 of the remote station 2, sent to the satellite ground station 5 of the remote station 2 via the switch unit 18 of the remote station 2, reaches the satellite ground station 4 of the studio station 1 via the satellite 7, and is transmitted to the satellite ground station 4 of the studio station 1 via the satellite 7. The signal is sent to the speaker 11 via the switch section 15, and transmitted to the instructor by the speaker 11. The same applies to the case where the remote station 3 is made to speak.

Here, as is clear from the above, when audio is assigned to the remote stations 2 and 3, the image refresh request signal output from the image band compression device 16 of each of the remote stations 2 and 3 is transmitted to the studio station 1. It can be seen that the image refresh request cannot be sent to the image band compression device 12 of the studio station 1 because the image does not reach the control device 14 . Therefore, the control device 14 of the studio station 1 uses the image band compression device 12.
On the other hand, when remote station 2 or remote station 3 speaks, the image band compression device 12 of studio station 1 is periodically operated in refresh mode, and when remote station 2 or remote station 3 does not speak, studio station The first image band compression bag W12 is controlled to operate in the demand refresh mode.

〔Effect of the invention〕

As explained above, the present invention provides a method for controlling the image of the studio station when the control line is used for voice communication from one remote station to the studio station and an image refresh request signal for a received image error cannot be received from another remote station. By having a control means in the studio station that controls the band compression device to send out refresh image signals at predetermined intervals, it is possible to recover the received image in response to a transmission path error even when audio is assigned to a remote station. This has the effect of eliminating lecture interruptions that would otherwise occur due to the inability to see the received image at the remote station, and making it possible to conduct lectures smoothly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the system configuration of an embodiment of the present invention. 1...Studio station, 2,3...Remote station, 4...
・Satellite ground station, 5.6...Satellite ground station, 7...Satellite, 8...Camera, 9...Monitor, 10...Microphone, 11...Speaker, 12...Image Band compression device, 13... Operation panel, 14... Control device, 15.
... Switch section, 16... Image band compression device, 17.
...Control device, 18...Switch unit, 19...Monitor, 20...Speaker, 21...Microphone.

Claims (1)

[Claims] It consists of a studio station each equipped with a camera, a monitor, a microphone, a speaker, an image band compression device, and a control device, and a plurality of remote stations, and the studio station and the remote stations are connected by a satellite line, and the control from the remote stations is performed. In a distance education system in which data and audio are switched and operated using the same control line, the control line is used for voice communication from one of the remote stations to the studio station, and another of the remote stations The studio station includes a control means for controlling the image band compression device of the studio station to send a refresh image signal at a predetermined period when an image refresh request signal corresponding to a received image error cannot be received from one station. A distance education system characterized by having.