JPH10117222A - Data transmission system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To transmit data divided into a plurality of transmission units for each transmission unit and automatically reconnect the line even if a failure occurs in the connection state of the line. To resend the data. For example, when transmitting still image data divided into a plurality of MCUs by a half-duplex method, a line 3
When a failure occurs in the connection state of the device 2, the failure detecting means 202 of the receiving-side apparatus 2 detects the failure, and the receiving-side line disconnecting means 203 disconnects the line 3. On the other hand, the transmitting device 1
Then, the transmission-side line blocking unit 102 blocks the line 3 after the transmission processing is completed. Next, in the receiving device 2, the timer 20
1 counts the transmission processing end time in the transmitting apparatus 1 based on the transmission data amount notified in advance by the data amount notification unit 101, and the line reconnection unit 204
Are reconnected, and the retransmission request notifying unit 205 notifies the transmitting apparatus 1 of the retransmission request. Next, in the transmitting device 1, the retransmission processing unit 103 performs a data retransmission process according to the retransmission request.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for transmitting data divided into a plurality of transmission units, and more particularly, to a system for automatically reconnecting a line even if a failure occurs in the line connection state. And a data transmission system capable of transmitting data to be transmitted.

[0002]

2. Description of the Related Art In a system such as a mobile communication system or a remote monitoring system, for example, still image data or the like is transmitted via a line connected between a transmitting device and a receiving device. When still image data is transmitted by such a system, the image data is generally divided into a plurality of blocks, for example, an MCU (Minimum Coded Un).
It) performs data compression processing for each MCU and packetizes these MCUs for transmission. Also, in the above-described system, since a low-quality transmission line is used as a transmission line, errors may occur in data during transmission, or when data transmission is particularly bad, the data transmission The line between the transmitting device and the receiving device may be disconnected.

When a failure occurs in the connection state of the line as described above, the data packet is frequently retransmitted between the modems of the transmitting device and the receiving device due to the deterioration of the line condition. If the line condition further deteriorates and carrier loss in the data modem of the receiving device continues for a certain period of time or more, the operator disconnects the line once for both the transmitting device and the receiving device, and then disconnects the line again. Data transmission is performed again after connection.

[0004]

However, in the above system, the process of reconnecting the line disconnected due to the failure and retransmitting the data cannot be performed automatically. There has been a problem that the operator needs to perform an operation such as a line reconnection process or a data retransmission process in the device or the receiving device.
For this reason, when data transmission is interrupted due to a failure in the connection state of the line, the M
Since the CU is discarded, there is a problem that all MCUs must be transmitted again for still image data to be transmitted.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem. When transmitting data divided into a plurality of transmission units for each transmission unit, the transmission side apparatus and the reception side apparatus need to communicate with each other. An object of the present invention is to provide a data transmission system capable of transmitting data to be transmitted by automatically performing a line reconnection process even when a failure occurs in a connection state of a line between the lines. . Also, according to the present invention, even if a failure occurs in the connection state of the line between the transmission side device and the reception side device, the line is automatically reconnected, and the reception side device specifies the connection by a retransmission request. It is an object of the present invention to provide a data transmission system capable of retransmitting only data in a transmission unit from a transmitting device to a receiving device.

[0006]

In order to achieve the above object, in a data transmission system according to the present invention, when a failure occurs in a line connection state, reconnection processing is performed as follows. That is, for example, when still image data divided into a plurality of MCUs is used as data to be transmitted, in the transmitting apparatus, the data amount notifying unit transmits the data before transmitting the still image data to be transmitted. Is notified to the receiving side device, and the transmitting means sequentially transmits data to be transmitted for each MCU. Then, in the receiving device, the timer starts counting the end time of the data transmission process in the transmitting device based on the total amount of transmission data notified from the transmitting device, and the receiving unit transmits the data for each MCU from the transmitting device. Received data sequentially.

If a fault occurs in the line connection between the transmitting device and the receiving device during the data transmission,
In the receiving device, the failure detecting means detects a failure in the line connection state, and the receiving line disconnecting means disconnects the line with the transmitting device based on the detection of the failure by the failure detecting means. On the other hand, in the transmission-side device, the transmission-side line blocking unit blocks the line with the reception-side device based on the completion of the data transmission process for the data to be transmitted.
Next, in the receiving-side device, the line reconnecting unit disconnects the line with the transmitting-side device based on the fact that the line is disconnected by the receiving-side line disconnecting unit and the end time of the data transmission process is counted by the timer. Connected, and the retransmission request notification means is connected to the MCU via the line connected by the line reconnection means.
Of the data retransmission request including the designation of the data transmission to the transmitting apparatus. Next, in the transmitting device, the retransmission processing means retransmits the data of the specified MCU to the receiving device in accordance with the retransmission request notified from the receiving device.

As described above, since the line reconnection process is performed after guaranteeing that the line between the transmission side device and the reception side device has been completely cut off, the line can be reliably reconnected. . Therefore, even if a failure occurs in the connection state of the line between the transmitting device and the receiving device during data transmission by the half-duplex system, the line is automatically reconnected and the receiving device is reconnected. Can retransmit the data in the transmission unit specified by the transmission side device to the reception side device.

Here, the fault in the connection state of the line detected by the fault detecting means is, for example, a fault that hinders normal transmission of data for a certain period of time or longer, or a fault in the data due to the disconnection of the carrier. In order to retransmit data, such as a failure that makes it impossible to continue transmission, it is necessary to disconnect the line once and then connect the line again.

[0010] Further, as a unit of transmission of data to be transmitted, for example, a plurality of MCUs obtained by dividing one frame of image data may be used. Therefore, image data for each frame may be used as a transmission unit, and any unit may be used as the transmission unit.

In the full-duplex data transmission system according to the present invention, when a failure occurs in the connection state of the line, a reconnection process is performed as follows. That is, for example, when still image data divided into a plurality of MCUs is used as data to be transmitted, in the transmitting apparatus, the data amount notifying unit transmits the data before transmitting the still image data to be transmitted. Is notified to the receiving side device, and the transmitting means sequentially transmits data to be transmitted for each MCU. Then, in the receiving device, the receiving means sequentially receives data transmitted from the transmitting device for each MCU.

If a failure occurs in the state of the line connection between the transmitting device and the receiving device during the data transmission,
In the receiving device, the failure detecting means detects a failure in the line connection state, and the receiving line disconnecting means disconnects the line with the transmitting device based on the detection of the failure by the failure detecting means. Then, in the transmitting device, the transmitting line disconnecting means disconnects the line with the receiving device based on the disconnection of the line by the receiving device. On the other hand, in the receiving device, the line reconnecting means connects the line with the transmitting device based on the fact that the line has been cut off by the transmitting line cutoff means and the receiving line cutoff means, and the retransmission request notifying means outputs the line reconnection request. Via the line connected by the connection means, a request for retransmission of data including the designation of the MCU is notified to the transmitting apparatus. Next, in the transmitting device, the retransmission processing means retransmits the data of the specified MCU to the receiving device in accordance with the retransmission request notified from the receiving device.

As described above, since the line reconnection process is performed after guaranteeing that the line between the transmission side device and the reception side device has been completely cut off, the line can be reliably reconnected. . In a full-duplex system in which a transmission side device and a reception side device can detect a line disconnection from each other, any device grasps a state where a line between the transmission side device and the reception side device is disconnected. be able to. Therefore, even if a failure occurs in the connection state of the line between the transmitting device and the receiving device during data transmission, the line is automatically disconnected after confirming that the line has been completely disconnected. By reconnecting, the data in the transmission unit specified by the receiving device can be retransmitted from the transmitting device to the receiving device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of a data transmission system according to the present invention. The data transmission system includes a transmitting device 1 for transmitting data, a receiving device 2 for receiving data, and transmitting data. A line 3 is provided. In this example, the still image data divided into a plurality of MCUs from the transmitting device 1 via the line 3 by the half-duplex method is transmitted to the receiving device 2 for each MCU, and the connection state of the line 3 during data transmission. When a failure occurs, the data to be transmitted is retransmitted by automatically performing a line reconnection process.

The transmitting device 1 includes an image input device 11 for inputting image data, an information source encoder 12 for dividing the image data into a plurality of MCUs and compressing the data, and a transmission of data transmitted for each MCU. A pixel block disperser 13 for dispersing the order, an error detection encoder 14 for performing error detection encoding on data, and a transmitting modem 15 for modulating or demodulating data.
And a transmission-side main control unit 16 that controls various processes in the transmission-side device 1.

The image input device 11 includes image input means such as a still camera, inputs still image data, digitizes the input still image data, and outputs it to the information source encoder 12. The information source encoder 12 converts the still image data input from the image input device 11 into a plurality of MCs.
The divided MCUs are subjected to a compression coding process for each of the divided MCUs, and the compressed data for each MCU is output to the pixel block disperser 13.

The pixel block disperser 13 is configured to block the data of each MCU input from the source coder 12 so that the MCUs located nearby in the same image frame are transmitted at a time apart from each other. The MCUs are dispersed by interleaving, and the MCUs are output to the error detection encoder 14 in the dispersed order. By this distributed processing, even if errors occur consecutively in a certain range of data, such as a burst error during data transmission, in the original image data, MCUs normally received in the vicinity of each MCU can be used. Data can be left, and for an MCU in which an error has occurred, an image close to the original image can be reproduced by performing an interpolation process based on a nearby normal MCU in the receiving device 2. Note that this interpolation processing is performed by an image data interpolator 25 provided in the reception-side device 2 described later.

Further, a transmission order number is added to each of the dispersed MCUs in accordance with the transmission order. As a result, even if the transmission processing is interrupted due to the failure of the connection state of the line 3, the receiving apparatus 2 notifies the transmitting apparatus 1 of the retransmission request based on the transmission order number added to the MCU. The transmitting device 1 can transmit the MC to be transmitted.
By retaining U until the data transmission processing is completed, it is possible to retransmit only the specified MCU.

The error detection encoder 14 performs error detection encoding on the data for each MCU input from the pixel block distributor 13 and outputs the data to the transmitting modem 15. By this error detection encoding process, the error detection decoder 22 provided in the receiving device 2 can detect a code error occurring during transmission. The transmitting modem 15 is connected to the error detection encoder 1
The data for each MCU input from 4 is modulated by a method suitable for the line 3, and the modulated data for each MCU is sequentially transmitted to the receiving side device 2 via the line 3.

The transmitting-side main controller 16 includes a data amount notifying unit 101 for notifying the receiving-side device 2 of the amount of data to be transmitted, a transmitting-side line blocking unit 102 for cutting off a line between the receiving-side device 2, MCU according to the retransmission request from the receiving device 2
Retransmission processing means 10 for retransmitting each data to the receiving device 2
3 are provided.

The data amount notifying means 101 transmits the coded data length of the transmission data and the total number of MCUs before transmitting the data to be transmitted, and the number of frames to be transmitted when transmitting a plurality of frames of image data. Is transmitted to the receiving side device 2 via the line 3. Thus, the receiving device 2 can grasp the total amount of data to be transmitted prior to the data receiving process. If the transmission-side line blocking unit 102 does not receive the reception end notification from the reception-side apparatus 2 until all the data for each MCU to be transmitted has been transmitted and the specified time has elapsed, the data transmission is stopped. Assuming that the operation has not been performed normally, the line 3 to the receiving side device 2 is cut off. Here, the above-mentioned prescribed time may be arbitrarily determined, and may be determined according to the usage status of the system. The retransmission processing unit 103 retransmits the data of the specified MCU to the receiving side device 2 according to the retransmission request notified from the receiving side device 2.

The transmission-side main control unit 16 sends an AC signal to the reception-side device 2 as a response for confirming reception in the transmission processing.
K (acknowledgement) or NAK (negative acknowledgement)
When the data transmission processing is completed, a transmission end notification is transmitted to the receiving device 2. With the above apparatus, the transmitting apparatus 1 sequentially transmits the still image data to be transmitted to the receiving apparatus 2 for each MCU, and when the connection state of the line 3 fails during data transmission, the receiving apparatus 1 Data retransmission processing is performed according to a retransmission request from the device 2.

The receiving device 2 has a receiving modem 21 for modulating or demodulating data, an error detecting decoder 22 for detecting and decoding data, and an MCU distributed in the transmitting device 1 at an original position. A pixel block rearranger 23 that relocates the still image data, an information source decoder 24 that expands data for each MCU to reconstruct still image data, and an image data interpolator 25 that performs interpolation processing on the still image data. A display 26 for displaying image data and a receiving main control unit 27 for controlling various processes in the receiving device 2 are provided.

The receiving modem 21 sequentially receives data for each MCU transmitted from the transmitting device 1 via the line 3, demodulates the received data for each MCU, and outputs the data to the error detection decoder 22. I do. The error detection decoder 22 detects a code error occurring during transmission by performing error detection decoding of the data for each MCU input from the receiving modem 21 in correspondence with the transmitting device 1, and the data for each MCU is detected. To the pixel block rearranger 23. The pixel block rearranger 23 rearranges the data for each MCU input from the error detection decoder 23 in the original arrangement order by performing processing reverse to the distributed processing performed in the transmission side device 1 and rearranged. The obtained data for each MCU is output to the information source decoder 24.

The information source decoder 24 converts the data for each MCU input from the pixel block rearranger 23 into the transmission side device 1.
The still image data is reconstructed from the decompressed data for each MCU and output to the image data interpolator 25.

The image data interpolator 25 is an information source decoder 2
For the MCU in which an error has occurred during transmission among the MCUs of the still image data input from step 4, an interpolation process is performed by using a nearby normally received MCU to obtain still image data close to the original image. It reproduces and outputs the reproduced still image data to the display 26. As described above, since the MCUs are distributed by the transmitting device 1 and transmitted to the receiving device 2, even when a burst error occurs during transmission, it is necessary to effectively perform the above-described interpolation processing. Can be.

The display 26 comprises image output means such as a display screen, and displays and outputs the still image data input from the image data interpolator 25. In addition, the display 26 displays the data transmission status by sequentially displaying and outputting normally received MCU data during data transmission.

The receiving side main control unit 27 includes a timer 201 for counting time, a failure detecting means 202 for detecting a failure in the connection state of the line 3, and a receiving side for disconnecting the line 3 between the transmitting side device. There are provided a line cutoff unit 203, a line reconnection unit 204 for connecting the line 3 between the transmission side device 1, and a retransmission request notification unit 205 for notifying the transmission side device 1 of a data retransmission request.

The timer 201 counts the end time of the data transmission processing in the transmission side device 1 based on the transmission data amount notified from the transmission side device 1. That is, the timer 201 counts the end time of the transmission process from the notified transmission data amount, and after that, when the time required for the transmitting device 1 to cut off the line 3 with the receiving device 2 elapses, This time elapse is notified to the line reconnection means 204.

The fault detecting means 202 monitors the receiving modem 21 during data transmission, and if the carrier from the transmitting device 1 is disconnected for a prescribed time or more, a fault occurs in the connection state of the line 3. Then, the failure is detected, and the fact that the failure is detected is notified to the receiving-side line cutoff means 203. Here, the above-mentioned prescribed time may be arbitrarily determined, and may be determined according to the usage status of the system. When receiving the failure detection from the failure detecting means 202, the receiving line disconnecting means 203 disconnects the line 3 with the transmitting apparatus 1, and notifies the line reconnecting means 204 that the line 3 has been disconnected. .

The line reconnecting means 204 is notified that the line 3 has been cut off by the receiving line cutoff means 203, and is notified by the timer 201 that the time at which the transmitting apparatus 1 cuts off the line 3 has elapsed. Then, the line 3 is reconnected to the transmitting side apparatus 1 and the retransmission request unit 205 is notified that the line 3 has been reconnected. Retransmission request means 205
Is notified from the line reconnecting means 204 that the line 3 has been reconnected, a request for retransmission of data including the designation of the MCU via the reconnected line 3 is transmitted via the line 3 Notify to

The receiving-side main control unit 27 sends an AC signal to the transmitting-side apparatus 1 as a response for confirming reception in the transmission processing.
K (acknowledgement) or NAK (negative acknowledgement)
When the data transmission process is completed and a transmission end notification is received from the transmission side device 1, the reception end notification is transmitted to the transmission side device 1. With the above device, the receiving device 2 becomes the transmitting device 1
If the connection state of the line 3 during data transmission fails, the line 3 is reconnected to the transmission side device 1. , And notifies the transmitting device 1 of a data retransmission request.

Next, the operation of the transmitting device 1 and the receiving device 2 when a failure occurs in the line 3 during data transmission by the present system will be described with reference to the drawings. FIG.
2 shows a conceptual diagram of a data transmission process in the present system.

First, the transmitting device 1 notifies the receiving device 2 of the amount of data to be transmitted. The receiving device 2 transmits an ACK to the transmitting device 1 when the transmission data amount is normally received from the transmitting device 1, and transmits a NAK when the transmission data amount cannot be normally received. To the local device 1. When the transmission data amount is normally transmitted to the reception device 2 and an ACK is received from the reception device 2, the transmission device 1
The transmission of the still image data to be transmitted is started for each MCU.
Upon receiving the MCU transmitted first from the transmitting device 1, the receiving device 2 starts counting the end time of the data transmission process in the transmitting device 1 using the timer 201 provided.

Here, if a failure occurs in the connection state of the line 3 during data transmission and the carrier from the transmitting device 1 to the receiving device 2 is cut off for a specified time or more, the receiving device 2 Detects a failure in the connection state of the line 3 and cuts off the line 3 with the transmission side device 1. FIG. 2 shows an example in which a failure occurs during transmission of the n-th transmitted MCU (# 1-n).

On the other hand, the transmitting device 1 transmits the MCU to be transmitted.
When all data has been transmitted and the data transmission processing is completed, a transmission end notification is transmitted to the receiving device 2 and a response from the receiving device 2 is waited for. If all the data transmissions have been performed normally, a reception end notification is transmitted from the receiving device 2 to the transmitting device 1, but the data transmission is stopped due to a failure in the connection state of the line 3 during the data transmission. When the reception is interrupted, the receiving end device 2 does not transmit a reception end notification to the transmitting side device 1, and the transmitting side device 1 waits for a response from the receiving side device 2 for a specified time and then receives the notification. The line 3 with the side device 2 is cut off.

In the receiving side apparatus 2, the timer 201 counts the end time of the data transmission processing in the transmitting side apparatus 1, and when the time when the transmitting side apparatus 1 cuts off the line 3 elapses, the communication with the transmitting side apparatus 1 is started. The line 3 is reconnected, and a request for retransmission of data including designation of an unreceived MCU is notified to the transmission side device 1 via the reconnected line 3. For example, FIG.
In the case shown in (1), the receiving-side apparatus 2 performs the n-th (# 1-
n) Notify the transmitting device 1 to retransmit the subsequent MCUs. The transmitting device 1 transmits an ACK to the receiving device 2 when the data retransmission request is normally received from the receiving device 2, and transmits the ACK to the receiving device 2 when the data retransmission request cannot be normally received. The NAK is transmitted to the receiving device 2. When the transmitting apparatus 1 receives the retransmission request from the receiving apparatus 2 normally, the MCU specified by the retransmission request, that is, the nth (# 1-n) or later in FIG. Is retransmitted to the receiving device 2.

As described above, in the data transmission system according to the present invention, a failure has occurred in the connection state of the line 3 between the transmitting device 1 and the receiving device 2 during data transmission by the half-duplex system. Even in this case, the data of the transmission unit specified by the receiving device 2 is transmitted from the transmitting device 1 by performing the line reconnection process after guaranteeing that the line 3 between the two is completely disconnected. It can be retransmitted to the receiving device 2.

If a failure occurs again in the connection state of the line 3 during the data retransmission by the above system, all the data is transmitted to the transmission side by repeating the line reconnection process and the data retransmission process. The data can be transmitted from the device 1 to the receiving device 2. If data transmission cannot be performed normally even by repeating the retransmission processing, the transmission processing is terminated in the middle by preliminarily setting the upper limit number of times of performing the retransmission processing, and Also, an error display can be performed in the receiving device 2.

In the above embodiment, the failure detecting means 202 provided in the receiving side device 2 detects a failure when the disconnection of the carrier from the transmitting side device 1 continues for a specified time or longer, and detects the failure. Even if such a failure detection method is not used, a method of detecting a failure and disconnecting the line 3 when data cannot be normally received for a specified time or more is used. You may be. In this case, as shown in FIG. 3, for example, the receiving side apparatus 2 starts counting time each time each MCU is received (reception waiting time count), and receives the next MCU within a specified time. If not, the failure detection means 202 can detect the failure and cut off the line 3 with the transmitting device 1.

Further, the above-described detection of the carrier disconnection and the detection of the normal reception disconnection may be performed simultaneously. In this case, if either of the faults is detected, the line may be cut off. . Also, the faults detected include:
The failure is not limited to the above-described failure, and any failure that requires disconnecting the line once and reconnecting the line in order to perform data retransmission may be detected.

In the above embodiment, an example of data transmission by the half-duplex system has been described. However, in the case of performing data transmission by the full-duplex system, the transmitting-side apparatus 1 is connected to the receiving-side apparatus 2 via the line 3. Can be detected. Therefore, in the transmitting device 1, as shown in FIG. 4, the transmitting line disconnecting means 102 monitors the transmitting modem 15 during data transmission, and confirms that the line 3 has been disconnected by the receiving device 2. Detects and after a lapse of a specified time, a line 3 with the receiving side device 2
Can be shut off. In this case, the receiving device 2 does not need to include the timer 201, and the line reconnecting unit 204 determines that the line 3 has been disconnected by the transmitting line disconnecting unit 102 and the receiving line disconnecting unit 203. The line 3 is re-connected based on this. In other words, the line 3 is reconnected after the line 3 between the transmitting side device 1 and the receiving side device 2 is completely disconnected, so that the line 3 can be reliably reconnected.

In the above embodiment, still image data is divided into a plurality of MCUs and transmitted as data to be transmitted. However, data to be transmitted is, for example, moving image data or other media data. Alternatively, any data may be transmitted as long as the data is divided into a plurality of transmission units. Also, as for the transmission unit, not only the MCU is used as in the above-described embodiment, but also in the case of transmitting image data of a plurality of frames, any transmission unit may be used, such as each frame being a transmission unit. Good.

The line for transmitting data may be a wired line or a wireless line, and any line may be used. This invention is particularly effective when applied to data transmission using a line.

The data transmission unit in the retransmission request may be specified, for example, by notifying only the transmission order number of a certain transmission unit to the transmitting apparatus, and retransmitting the data of the transmission unit after the transmission order number notified. The transmission unit data of the plurality of transmission order numbers notified by selectively notifying the transmission order number of the plurality of transmission units to the transmitting apparatus may be performed. The transmission unit may be specified by any suitable method.

In the above embodiment, an example of a system in which data is transmitted in only one direction from a transmitting device to a receiving device as applied to, for example, a remote management system has been described. The system is provided with a plurality of communication devices having both functions of the transmitting device and the receiving device shown in the above, and these communication devices are connected to each other via a line, so that data transmission between arbitrary communication devices can be performed. Can be performed in both directions.

In the above embodiment, the data to be transmitted is subjected to compression / decompression processing, MCU distribution / relocation processing,
Although error detection coding and decoding processing and data interpolation processing have been performed, these processing does not necessarily need to be performed on data to be transmitted. In short, data to be transmitted is transmitted in a plurality of transmission units. Just do it.

When each means relating to the main control unit provided in the transmitting device and the receiving device is constituted by software, the system may be provided with a single-function communication modem, and the system can be manufactured at low cost. Can be configured.

[0049]

As described above, according to the data transmission system of the present invention, even if a failure occurs in the line connection between the transmitting device and the receiving device during data transmission. Since the reconnection process of the line is performed after guaranteeing that the line between them is completely disconnected, the data of the transmission unit specified by the receiving device must be retransmitted from the transmitting device to the receiving device. Can be.

[Brief description of the drawings]

FIG. 1 is a configuration example of a data transmission system according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining data retransmission processing according to a half-duplex method.

FIG. 3 is a diagram for explaining data retransmission processing by a half-duplex method.

FIG. 4 is a diagram for explaining data retransmission processing by a full-duplex method.

[Explanation of symbols]

1... Transmitting device, 2... Receiving device, 3... Line, 11... Image input device, 12... Information source coder, 13... Pixel block disperser, 14. , Transmitting modem, 16 transmitting main control unit, 21 receiving modem, 22 error detecting decoder, 23 pixel block rearranger, 24 source information decoding Device, 25 ... image data interpolator, 26 ...
Display unit 27 receiving main control unit 101 data amount notifying unit 102 transmitting line disconnecting unit 103
.. retransmission processing means, 201 timer, 202 fault detection means 203 receiving line cutoff means 204
..Line reconnection means, 205..Retransmission request means

Claims (2)

[Claims] 1. A data transmission system in which a transmission-side device sequentially transmits data divided into a plurality of transmission units for each transmission unit, and a reception-side device sequentially receives data for each transmission unit. Means for notifying the receiving apparatus of the total amount of the data to be transmitted prior to transmitting the data to be transmitted; transmitting means for sequentially transmitting the data to be transmitted for each transmission unit; Transmission-side line blocking means for disconnecting the line with the reception-side apparatus based on the completion of the data transmission processing, and data of the transmission unit specified in accordance with the retransmission request notified from the reception-side apparatus Retransmission processing means for retransmitting the data to the receiving device. The receiving device terminates the data transmission process in the transmitting device based on the total amount of transmission data notified from the transmitting device. A timer that counts time, a receiving unit that sequentially receives data transmitted from the transmitting device for each transmission unit, a failure detecting unit that detects a failure in a line connection state, and a failure detected by the failure detecting unit. Receiving line disconnecting means for disconnecting the line with the transmitting apparatus based on the fact that the line is disconnected by the receiving line disconnecting means and the end time of the data transmission process is counted by the timer. Line reconnecting means for connecting a line with the transmission side device; retransmission request notifying means for notifying the transmission side device of a data retransmission request including designation of a transmission unit via the line connected by the line reconnection means; A data transmission system, comprising: 2. A full-duplex data transmission system in which data divided into a plurality of transmission units is sequentially transmitted by a transmission device for each transmission unit, and data for each transmission unit is sequentially received by a reception device. The transmitting device has a data amount notifying unit that notifies the receiving device of the total amount of the data before transmitting the data to be transmitted; a transmitting unit that sequentially transmits the data to be transmitted for each transmission unit; Transmission line blocking means for blocking the line to the receiving device based on the disconnection of the line by the receiving device, and receiving the data of the specified transmission unit according to the retransmission request notified from the receiving device Retransmission processing means for retransmitting the data to the transmitting apparatus; receiving means for sequentially receiving data transmitted from the transmitting apparatus for each transmission unit; and failure of the line connection state. A receiving line disconnecting unit that disconnects a line with a transmitting device based on the detection of a failure by the failure detecting unit; and a transmitting line disconnecting unit and a receiving line disconnecting unit. A line reconnecting means for connecting a line with the transmitting apparatus based on the interruption of the line, and a request for retransmission of data including a transmission unit designation via the line connected by the line reconnecting means; A data transmission system comprising: a retransmission request notifying unit that notifies a device.