JPS58139568A - Buffer memory controlling method - Google Patents

Abstract

PURPOSE:To always monitor the residual quantity of a receiving buffer memory and to prevent previously an overflow of the receiving buffer memory, by calculating the decoding enable time of the sending coding data at the transmitting side. CONSTITUTION:A line synchronizing signal is detected by a line synchronizing signal detector 18 out of the coding data that is delivered from a transmitting buffer memory. Then an interruption of lower ranking is applied to a microcomputer 20. Thus the present time is read by a timer 21 to calculte the time when the decoding is started. At this time point of calculation, the sending start time of the next coding data is calculated to avoid an overflow of a receiving buffer memory 6. The computer 20 delivers consecutively the fill-bit request signals until the sending start time. Then the fill is inserted by means of a fill-bit inserting device 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a buffer memory used for transmitting image signals, such as facsimile signals.

In general, facsimile machines that convert black-and-white binary images into 141st positions and transmit them are encoded in redundancy suppressed transitive mode and transmitted, so the number of bits of the phase encoded data is scanned. The length of each mountain varies greatly. Also, since there is a transmission line with a certain transmission speed and reaction between the receiver and the receiver (Nm) of this facsimile machine, there,
For these dark speed U V/: + 6h Th&,
Fewer bits? A dummy hit called a fill is inserted into the data.Then, one side is equipped with a buffer memory for temporarily storing encoded data, and this is controlled By doing so, the length of the inserted fill can be increased and the transmission time can be shortened.

A conventional method for controlling Kaede's buffer memory is shown in FIG. In the figure, an image signal read by an input section (1) is encoded in units of scanning lines by an encoding section (2). The encoded data for one eclipse line is prefixed with a line synchronization number h and sent (h buffer memory section (3)
are accumulated sequentially.

The encoded data in the transmission buffer memory unit (3) is modulated by the modulation capital (4) and transmitted to the receiver via the transmission path. At the receiver, the transmitted encoded data is recoded.
It is demodulated in step (5) and stored in reception buffer memory 5 (6). The decoding section (7) takes out the encoded data from the reception buffer memory in units of scanning lines, decodes it, and records it on recording paper in the recording section (8). In the conventional buffer memory control method, if the transmission buffer memory (3) is full, the aging section (1) and the encoding section (2)
Work + Pause, and stop writing to the send (h buffer memory (3). Conversely, when the send (Fj buffer memory (3) is empty and there is no more encoded data to send,
Sends out a dummy bit called fill.

Here, the time required for encoding (or decoding) processing for one running line is referred to as encoding (or decoding) line processing time. When the condition of the receiving buffer memory (6) is equal to or higher than that of the transmitting buffer memory (3), overflow of the receiving buffer memory (6) can be prevented by such a conventional buffer memory control method. has been made clear.

In this conventional buffer memory control method, the transfer (h
Since a fill is inserted only when the buffer memory (3) becomes empty, the transmission time can be reduced compared to the case without a buffer memory. By the way, if the encoding line processing time 1 can be made shorter, the time it takes for the transmission 11j buffer memory (3) to become empty can be shortened, and the transmission time can be further shortened. However, in the conventional buffer memory control method, when the encoding line processing time is shorter than the backward 8r line processing time, there is a risk of '3e4@buffer overflow, and in such a case, the conventional buffer memory fliII
The IIIJ method had the disadvantage that it could not be used.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above.By calculating the decodable time of the transmitted encoded data on the transmitting side, the remaining capacity of the receiving buffer memory can always be saved. The object of the present invention is to provide a buffer memory control method that can monitor and prevent overflow of the receive buffer memory.

Below, one embodiment of the present invention will be explained using the second prisoner. In the figure, the eleventh point 1a s is different from the conventional one.
On the transmitting side between the transmitting buffer memory (3) and the modulating section (4)? The feature of the present invention is that an AI section 4 is provided, and the sections other than this transmission control section (10) are the same as those in the conventional buffer memory control method.

Transmission 1III Control 5 (Ii is the code for 1 running green minute) Monitors the status of the reception buffer memory (6) for each data, and when the reception buffer memory (6) is about to overflow, sends out a fill to prevent overflow. Take steps to prevent this from happening.

Figure 8 shows transmission 1i1i 1IIT1 part G (J O)
-$1 It is a figure showing an example. Is this the send-a-go system? 1t11 (10 is a microcomputer that can handle 2-level interrupts) is the core, and a timer is used to know the current time, and a line synchronization signal is detected from the encoded data sent from the transmission buffer memory (3). The fill bit inserter q1 inserts a fill bit based on a command from a microcomputer.

The operation starts from the encoded data output from the transmission buffer memory (3) to the line output (4=ii output).
When a line synchronization signal is detected, a low-level interrupt is sent to the microcomputer. When the microcomputer receives an interrupt, it reads the current time from timers I and 4v, and measures the time when the encoded data of one eclipse force that it sent out will start to be returned to the receiver.

Then, at the calculated time, the receive buffer memory (6
) to prevent overflow, the microcomputer calculates the start date and time for sending the next behavioral data, outputs the fill bit request (ts month), and presses the fill bit pusher until it reaches %. o Push in the fill.

Also, when the transmitting buffer memory (3) is empty, an interrupt of 1 litl order is generated to the microcomputer (H) due to the empty space from the transmitting buffer memory (3), and the microcomputer (E) is The system is such that the request (N) is sent to the fill bit 44 and the fill bit is sent out.The above correct operation prevents the receive buffer memory (6) from overflowing.

Next, we briefly examine the improvement rate in transmission time when using this method. Here, for each Yuzu method shown in Fig. 4, CCITT test chart No. 1 to 8 will be described.
We will measure the transmission time and compare the improvement rate. Method α is based on the international standard G8, the encoding and decoding line processing times are both 10m5ec, the buffer memory is free, and the encoded data i for one scanning line is 96 bits (96
00 bps), the fill is set to (11).Method β is a conventional buffer memory control method in which both transmit and receive buffer memories are set to 16 bits.Method γ is In the buffer memory control method according to the present invention, the phase encoding line processing time is 5 m.
It is faster at 5ec. Furthermore, the method δ is an international standard G8 with an encoding and decoline processing time of 5 m5ec.

Further, FIG. 5 shows the improvement rate of the transmission time of other methods when the method α of FIG. 4 is used as a standard.

From the figure, we can see that the buffer memory 71i! It can be seen that the starting rate with IN is large, and the improvement rate of method γ, which is this investigation, is particularly large. Also, it is an interesting result that method γ outperforms method δ for all manuscripts, even though the decoding line processing time is longer.

As described above, according to the present invention, the transmission system post section speeds up the encoding line processing, supervises the reception buffer memory between the transmission buffer memory section and the modulation section, and adjusts the fill insertion island. By providing this, the transmission time can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a facsimile according to a conventional buffer memory control method. Fig. 4 is a comparative explanatory diagram for comparing the transmission time of each method, Fig. 5 is a diagram showing the configuration of the transmission system This shows the rate of improvement in transmission time of other methods when compared to . In the figure, (2) is the encoding section, (3) is the transmitting (M buffer memory section), (4) is the modulating section, (5) is the demodulating section, (6) is the receiving buffer memory, and (7) is the decoding section. Converting part and OO are the 1st part of the request by sending. In the figures, the same reference numerals indicate the same or corresponding parts. Agents Shimano Ii - and @I L J
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Claims (1)

[Claims] (1) In the case where the encoded tq-edited data is sent out via the transmitting side buffer memory and the selected encoded data is received and decoded via the Th side buffer memory, the above sending (Th( The same "Ay" 4m timing of each of the encoded data sent from the ll + buffer memory is detected, and the decoding start time of the encoded data is calculated from the respective transmission timing, and from this calculated time, the receiving side A buffer memory control method comprising monitoring a memory state of a buffer memory, delaying the sending of the encoded data in accordance with the memory state, and sending out dummy data.