JPS61212963A - Method for controlling facsimile reception section - Google Patents

Abstract

PURPOSE:To decrease the reception error by deciding the data signal speed based on both the result of discrimination of a TCF signal and of data signal detection at no signal. CONSTITUTION:When a line is connected, a reception station sends a DIS signal representing the capability of a terminal station. Then a DCS signal representing the transmission condition from a transmission station is received and the detection of data signal (CD) is discriminated at a signal pause period after the end of the DCS signal. Then a high speed sequence TCF from the transmission station is received and when the CD signal is set, since it shows that the line has much noise, even when the result of discrimination of the TCF signal is successful, the ETT signal is sent back while the data signal speed is other than 4,800BPS to inform difficulty of communication. Thus, the possibility of reception error is reduced even during a picture is received.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of controlling a receiving section in a facsimile.

(Prior Art) Conventionally, a facsimile receiving section control method has been disclosed in Recommendation T, 30 of the International Telegraph and Telephone Advisory Committee, the contents of which are shown in FIGS. 4 and 5.

FIG. 4 shows a communication sequence between a terminal station A and a terminal station B connected by a telephone line. FIG. 5 is a flowchart explaining the procedure signal control of terminal station A.

A facsimile receiver control method according to the prior art will be described below with reference to FIGS. 4 and 5.

After the facsimile IJs of terminal station A and terminal station B are connected face-to-face via telephone lines, for example, when transmitting facsimile data from terminal station B to terminal station A, as shown in Figure 4, terminal station A A "1DNS" signal is transmitted from the B terminal station to the A terminal station, and then a "DCS" signal is transmitted from the B terminal station to the A terminal station, and then a "TCF" signal is transmitted. "
The "DIS" signal is a signal indicating the capability of the terminal station, and this signal includes the data signal rate that can be received.

The "DCS" signal is a command signal that instructs the transmission conditions in response to the "") Included in the content.Usually 1N) It is indicated by the common highest data signal rate possessed by the ISJ signal sending station and the local terminal.

The "TCF" signal is a high-speed signal sequence that tests whether facsimile data communication from the B terminal station to the A terminal station can be performed at this data signal speed. That is, “T
The CFJ signal is received by terminal station A, and checked to see if there are sufficiently few errors with respect to a predetermined data signal. Based on this result, the A terminal side determines whether the TCFJ signal is Pa5s (successful) or Fail (failure). If Pa5s, the B terminal station
"'CI" RJ times the signal is sent back, and the data signal speed of the "TCF" signal is transferred to step 7 of the 11) A-TA, J (image data) receiving layer.

If Pa17! If so, l-F'T for the B terminal station side.
It sends a TJ signal to notify that it is difficult to communicate at that data signal speed.

The B terminal station side uses the l'-F T T J signal to return the communication sequence to the same "1) C8" signal transmission as shown in Fig. 4 [TCFJ (whether to repeat the transmission of the "DCS" with the signal speed set one step lower
” signal and sends 1TCFj signal at the same data signal speed as the data signal speed set with the “1) C8] signal.
~, proceed with the steps. With the above control, from the B terminal station to the A
Communication of facsimile IJ data to the terminal station is based on the "r (J" Automatically selected.

(Problem to be solved by the invention) However, in the control method described above, r'I'cFJ
Since the data signal speed is selected by checking only the signal, if the signal-to-noise ratio (hereinafter referred to as S/N ratio) of the telephone line is poor, the "TCF" signal or 4Pass (successful) may not be received while the image is being received. There is a possibility that receiving errors will cause problems which are very dog-like.

The present invention aims to improve the above problems.

(Means for Solving the Problems) A feature of the present invention that achieves the above object is that the transmitting side transmits DO8 indicating the transmission conditions and the subsequent TCF' signal for testing the signal speed of facsimile communication to the receiving side. send to 1
-1 The receiving side receives a CFR signal indicating that communication is possible, or an F'T signal indicating that communication is not possible, according to the result of the error in the TCF signal.
In a facsimile system that returns an 'I' signal,
The receiving side has a means for determining on/off of data signal detection (CD) during the signal pause period between the DO8 signal and the TCF signal, and determines the on/off determination result of the CD, the determination result of TCF', The present invention also provides a method for controlling a facsimile receiving unit that determines a data transmission speed that causes fewer errors in received images based on the relationship between the data transmission speed and the data transmission speed.

(Function) According to the present invention, the determination result of the TCF signal and the C
Based on both of the determination results in I), the optimum data signal speed with few errors is determined. Therefore, the conventional disadvantage of determining the line state only by the TCF signal and causing an error when the S/N ratio is poor is eliminated.

(Embodiment) FIG. 1 is a control flow diagram showing an embodiment of this invention.
The dotted line portion is added to the figure. "DCS"
The end of the signal is detected, and it is determined whether the "CD" output signal is ON or OFF during the signal pause period until the next "TCF" signal is received. The l'-CDJ signal is originally for detecting the receivable signal level in the receiving section, and the signal level received through the telephone line is detected by this "CD".
If it is determined to be F, it will not be possible to receive it normally, and if the line noise is determined to be ON as a 1'-CDJ output signal, the line noise will be judged as a signal and there is a possibility that reception will not be possible. , indicating that there is a lot of noise on the line.

If 1-CDJ detection is ON during the signal pause period, “TCF
” Even if the signal judgment result is Pa5s, if the data signal speed is 9600 BPS or 72008 PS, C
Since the quadrature amplitude phase modulation method is recommended by the CITT V29ter (hereinafter referred to as V29), it can be expected that errors in received images are likely to occur due to noise.

Therefore, after "CD" detection is ON during the signal pause period, f'
Even if the judgment result of T"cF" J1m is Pa5s,
When the data signal speed is 9600/7200BPS,
[Send I'TTJ signal. Data signal rate is 48
For 0013PS or 2400BPS, CCI
Since it is a quadrature phase modulation method shown in TTV27ter (hereinafter referred to as V27), it is more resistant to noise than V29, so in the case of V27, it returns the l'-CFJ signal and prepares to receive image data. .

FIG. 2 shows the control flow diagram of FIG. 1 in a matrix.

FIG. 6 is an example of a device block diagram, and 51 is an input/output point (LINE) to the telephone line of the facsimile device.

52 is a signal distributor, 56 is a transmission signal modulation section, 54 is a control section, and 55 is a reception signal demodulation section.

“DIJ”, “CIi”R, which is the transmission signal to the other station
J.

1F'J"Tj times signal, which is given from the control section to the transmission signal modulation section by 56, and is the received signal from the opposite station rD
CSJ IT CFJ Signal 1'j: 57 K Yo'
) The received signal fJij' is given to the control section from the f1 section. The received signal demodulation section includes a "CD" circuit section 58
The "CD" output signal is input to the control unit, and the determination result of this signal, the determination result of TCF', and the matrix of data transmission rate are controlled by the software of the control unit, and the "CF'" output signal is sent to the other station. J signal or "F 'II' T
Return either J signal and proceed with the procedure.

The above explanation is based on the "TCF" signal and the "DC
The present invention can also be applied to the signal pause period between the "TCF" signal and the option signal 1'-NSSJ signal of the same recommendation.

(Effects of the Invention) As described above, according to the present invention, the following effects can be obtained.

1) CC by just changing the control flow on the receiving side
Improvements and methods can be implemented without compromising compatibility with ITT 1:', 30.

In other words, if the SZN ratio of the telephone line is poor, V29's "TCF
” signal is Pa5s l, even if [F'TTJ signal is returned, data signal rate is V27 and 1'-TC
The FJ signal is executed until Pa5s, and communication can be performed at a data signal speed with few reception errors.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the control flow of the facsimile receiving section according to the present invention, FIG. 2 is a diagram showing the flow in a matrix, FIG. 6 is a block diagram of the facsimile receiving section according to the present invention, and FIG. 4 is a diagram showing the control flow of the facsimile receiving section according to the present invention. FIG. 5 is a diagram showing a conventional control flow. 51; Telephone line input/output point, 52; Signal distributor, 53; Transmission signal modulation section, 54; Control section, 55; Reception signal demodulation section Patent applicant Oki Electric Industry Co., Ltd. Patent application agent Patent attorney Megumi Yamamoto Figure 1 You are Figure 2 Figure 3 s (CFR/FTT) 52CNT INES5 (DC5/TCF) R (CD) Figure 4

Claims (1)

[Claims] The transmitting side transmits a DCS indicating transmission conditions and a TCF signal that tests the signal speed of the subsequent facsimile communication to the receiving side, and the receiving side determines whether communication is possible according to the result of an error in the TCF signal. CFR signal to notify or F to notify that communication is not possible
In a facsimile system that returns a TT signal, the receiving side has means for determining whether data signal detection (CD) is on or off during the signal pause period between the DCS signal and the TCF signal, A method for controlling a facsimile receiving unit, characterized in that a data transmission rate with fewer errors in received images is determined based on the relationship between the determination result, the TCF determination result, and the data transmission rate.