JPS631156A - Facsimile control processing system - Google Patents

Abstract

PURPOSE:To attain sure retransmission by providing a delay time detection circuit and a repeat sending time setting circuit setting a time sending a repeat signal corresponding to the detected delay time. CONSTITUTION:The delay time detection circuit 7 detects the delay time of a line connected between a sending side and a receiving side. The repeat sending time setting circuit receiving the notice of the delay time calculates an optimum time width returning a repeat signal to the sending side and sets it. If an error is detected by a CRC calculation circuit 5 in a frame (j) sent from the sending side, the repeat sending time setting circuit receiving the notice of an error signal commands the sending time of a repeat signal having an optimum set time width and sends the result to the sending side via a line. The repeat detection circuit 3 detecting the said repeat signal sends the signal again from the frame (j) detecting the error.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a facsimile control processing system that performs retransmission when an error is detected in the received data for each frame received on the receiving side. A CRC calculation circuit that detects errors, a delay time detection circuit that detects the delay time between the transmitting side and the receiving side, and a repeat transmission time setting that sets the time to transmit the repeat signal in accordance with the detected delay time. A circuit is provided, and when an error is detected in the received data for each frame by the CRC calculation circuit, a repeat signal is returned to the transmitting side for a predetermined time set by the repeat transmission time setting circuit to detect the error. The frame is retransmitted starting from the detected frame.

[Industrial application field]

The present invention provides a facsimile control processing method configured to set the repeat signal transmission time in response to signal delays that occur when satellite lines are used in facsimile communication that detects errors and retransmits each frame. It is related to.

[Conventional technology]

Conventionally, this is a facsimile control processing method in which the receiving side detects errors in the data transmitted for each frame, and if an error is detected, a repeat signal is sent back to the transmitting side and retransmission starts from the frame where the error occurred. There is. In this facsimile control processing method, as shown in FIGS. 4 and 5,
The image data and CRC signal for each frame transmitted from the transmission buffer 1 and the CRC calculation circuit 2 to the line are received by the reception buffer 4 on the receiving side, and are supplied to a demodulation circuit etc. as image data for each frame. , recorded as an image. Further, regarding the CRC signal received by the reception buffer 4, a CRC calculation circuit 5 calculates whether or not there is an error in the received image data. If an error is detected, an error signal is notified to the repeat sending circuit 6-1, and a repeat signal is sent back from the receiving side to the transmitting side.For example, as shown in FIG. 5(A),
If an error is detected by the CRC calculation circuit 5 when frame (3) is received, a repeat signal is sent to the transmitting side while receiving frame (4) as shown in Fig. 5 (a) and (b). It will be sent back. The repeat detection circuit 3 that received this repeat signal detects the frame (3) in which the error occurred.
) as shown in the figure.

(Problems to be Solved by the Invention) Conventionally, the transmission time of repeat signals and training signal transmission times explained using FIG. (
When using a multi-channel line), there was a problem in that communication could not be established due to delays in signals propagating through the line.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a CRC calculation circuit that detects errors in received data, a delay time detection circuit that detects a delay time between the transmitting side and the receiving side, and a delay time detection circuit that corresponds to the detected delay time. and a repeat transmission time setting circuit for setting the time for transmitting the repeat signal, and for a predetermined time set by the repeat transmission time setting circuit.
A repeat signal is sent back to the sending side.

Means for solving the problems will be explained using the principle configuration of the present invention shown in FIG.

In FIG. 1, a repeat detection circuit 3 detects repeat signals from a line.

The reception buffer 4 temporarily stores signals received via the line.

The CRC calculation circuit 5 calculates whether or not there is an error in the received signal.

The repeat sending circuit 6 sends the repeat signal back to the transmitting side.

The delay time detection circuit 7 detects the delay time of a line connected between the sending side and the receiving side. The repeat transmission time setting circuit 8 sets an optimum repeat time based on the delay time detected by the delay time detection circuit 7.

[Effect]

The configuration explained using FIG. 1 is adopted, and first, the delay time detection circuit 7 detects the delay time of the line. This delay time is determined by transmitting a repeat signal to the repeat detection circuit 3 on the transmitting side and transmitting the frame i (
i interrupts the transmission of frames 1 to n), and is calculated based on the time until the interruption of the transmission of frame i is detected by the delay time detection circuit 7 via the line. The repeat transmission time setting circuit 8 that has received the notification of this delay time calculates and sets the optimum time width for returning the repeat signal to the transmitting side. In this state, if the CRC calculation circuit 5 detects an error in the frame j transmitted from the transmitting side, the repeat transmission time setting circuit 8 that has been notified of this error signal will set the repeat transmission time setting circuit 8 to have the set optimal time width. The repeat signal sending circuit 6 is instructed to send out the repeat signal and sends it to the sending side via the line. The repeat detection circuit 3 that detected this repeat signal retransmits the frame j starting from the frame j where the error was detected.

〔Example〕

Next, the principle structure and operation of the present invention will be explained in detail using FIGS. 1 to 3.

First, the operation of the configuration shown in FIG. 1 will be explained using FIG. 2.

In FIG. 2, the repeat signal (■) in the figure indicates the signal sent to the line from the repeat sending circuit 6 on the receiving side. Since it has been calculated that an error has occurred in the reception of the image data, this means that a repeat signal is sent to the line from the repeat output path 6. The time t during which this repeat signal is sent out is shown in the figure.
shall be.

■The repeat signal in the diagram is the one sent from the receiving side.
This shows a state detected by the repeat detection circuit 3 on the transmitting side, which means that it took time t1 for the repeat signal to reach the transmitting side from the receiving side.

The ■ frame signal in the figure means that the transmission buffer 1 on the transmitting side received the repeat signal notification at ■ in the figure while transmitting the next frame (4), and therefore interrupted the transmission of the frame (4). are doing.

■Frame in the figure The signal is sent to the receiving side as ■Frame (4) in the figure.
indicates that a signal has been received. The time t2 shown in the figure is the time required for the signal of frame (4) to reach the receiving side from the transmitting side.

Based on the time t and time t2 calculated above,
The delay time required for a repeat signal to propagate through the line is calculated by the delay time detection circuit 7 in FIG.
As shown using the dotted line in ■ in the figure,
) The repeat signal is set by the repeat sending time setting circuit 8 in FIG. 1 so that the repeat signal is continuously sent out even after the signal of ) is interrupted, thereby ensuring that the repeat signal is detected. becomes possible.

Next, the operation of setting the delay time of the repeat signal will be explained in detail using FIG.

FIG. 3(a) shows a state in which delay time is detected.

In the figure, the repeat signal (2) indicates a signal sent from the repeat sending circuit 6 on the receiving side as a waveform having the time t as shown in the figure.

The frame signal ``■'' in the figure shows a state in which the repeat signal is detected by the transmitting side at ``■'' in the figure, and then the transmission of frame (4) is interrupted and detected by the receiving side.

Here, TI in the figure indicates the time from when a repeat signal is sent from the receiving side to the transmitting side until the interruption of the signal of frame (4) reaches the receiving side.

In the manner described above, the line delay time T1 is detected.

Next, FIG. 3(b) shows a state in which the delay time T and the time for transmitting the Karari beat signal are set.

In the figure, ``Repeat signal'' indicates a state in which the repeat signal is set to the optimum time T by the repeat sending time setting circuit 8. This is based on the delay time T detected at ■ in the figure, and lengthens the illustrated time T2 so that the repeat signal is sent even after frame (4) in the frame signal ■ in the figure is interrupted. This is the setting.

In this way, even after the signal of frame (4) is no longer detected on the receiving side, a repeat signal is sent out on the line,
This ensures that the repeat signal is detected. This ensures retransmission by returning the repeat signal.

〔Effect of the invention〕

As explained above, according to the present invention, a CRC calculation circuit that detects errors in received data, a delay time detection circuit that detects a delay time between the sending side and the receiving side, and a CRC calculation circuit that detects errors in received data, a delay time detection circuit that detects a delay time between the sending side and the receiving side, and a and a repeat transmission time setting circuit for setting the time for transmitting the repeat signal, and the repeat signal is returned to the transmitting side for a predetermined time set by the repeat transmission time setting circuit. Therefore, the transmission time of the repeat signal can be automatically and optimally set to match the delay time of the line, and retransmission can be reliably performed.

[Brief explanation of the drawing]

FIG. 1 is a principle configuration diagram of the present invention, FIG. 2 is an operation timing chart of the present invention, FIG. 3 is an explanatory diagram of the operation of the present invention, and FIG.
The figure shows a configuration diagram of the conventional system, and FIG. 5 shows an operation time chart of the conventional system. In the figure, 1 is a transmission buffer, 2.5 is a CRC calculation circuit, and 3
4 represents a repeat detection circuit, 4 a reception buffer, 6 a repeat transmission circuit, 7 a delay time detection circuit, and 8 a repeat transmission time setting circuit.

Claims (1)

[Claims] A facsimile control configured to send a retransmission signal back to the transmitting side and retransmitting the frame starting from the frame in which the error was detected, when an error is detected in received data for each frame received at the receiving side. The processing method includes a CRC calculation circuit (5) that detects errors in received data, a delay time detection circuit (7) that detects a delay time between the sending side and the receiving side, and this delay time detection circuit (7). a repeat transmission time setting circuit (8) for setting a time for transmitting a repeat signal in accordance with the delay time detected by the CRC;
When an error is detected in the received data for each frame by the calculation circuit (5), a repeat signal is returned to the transmitting side for a predetermined time set by the repeat transmission time setting circuit (8), and the corresponding A facsimile control processing method characterized in that a frame in which an error is detected is retransmitted.