JPH0740700B2 - Communication method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a communication method using a line where an echo occurs.

[Prior Art] A conventional facsimile apparatus transmits an initial identification signal and then receives an echo of the initial identification signal transmitted by itself, so that the pre-procedure is not established, and therefore facsimile transmission is performed. There is a problem that it may not be possible.

For example, as shown in Fig. 4 (1), when the device sends NSF (non-standard function identification signal) / CSI (non-call terminal identification signal) / DIS (digital identification signal), DIS is echoed. The above may be received by the own device. In this case DIS
The 9th bit of is "0" (no original), so DCN
(Disconnect command signal) is immediately sent to open the line.

On the other hand, in the above conventional device, as shown in FIG. 4 (2), when the device itself sends NSF / CSI / DIS, DIS may be received as an echo to detect the V21 signal. In this case, no significant signal is detected, so NSF / CSI / DI
Send S immediately. In the same manner, the signal transmission may be repeated, and at this time, the initial identification timer (30-40
Second), the DCN is sent and the line is released.

[Object of the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks of the conventional example and to provide a communication method that does not erroneously recognize an echo signal of a signal transmitted from the device itself as a procedure signal.

Embodiment of the Invention FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, an NCU (network control unit) 2 is connected to a terminal of the telephone line 2a in order to use the telephone network for data communication and controls the connection of the telephone switching network and the data communication path. It is a device for switching to or holding a loop.

If the signal level from the control circuit 28 is “0”, the NCU 2 connects the telephone line 2a to the telephone 4 side, and the control circuit 28
If the signal level from the device is "1", the telephone line 2a is connected to the facsimile device (the circuit on the right side of the NCU 2 in FIG. 1). Under normal conditions, the telephone line 2a is connected to the telephone 4
Connected to the side.

The hybrid circuit 6 separates a transmission system signal and a reception system signal, and the transmission signal from the addition circuit 18 is NC.
The signal sent to the telephone line 2a via U2, and the signal sent from the other party are sent to the demodulators 20 and 22 via NCW2.

The reading circuit 8 sequentially reads an image signal for one line in the main scanning direction from a transmission original and creates a signal train representing binary black and white. The image pickup device such as a CCD (charge coupled device) and an optical system. It consists of and.

The encoding circuit 10 encodes the binary data output by the reading circuit 8 (MH (Modified Huffman) encoding or
MR (Modified Read) encoding) circuit.
The modulation circuit 12 is a modulator that performs modulation based on the well-known CCITT recommendation V27ter (differential phase modulation) or V29 (quadrature modulation).

When the 1100 Hz sending circuit 14 receives the sending command pulse from the control circuit 28, it sends a 1100 Hz signal for 3 seconds, and when the signal sending is completed, sends a sending completion pulse to the control circuit 28. . The modulator 16 is a circuit that performs modulation based on CCITT Recommendation V21.

The V21 demodulator 20 is a circuit that performs demodulation based on CCITT Recommendation V21. The demodulator 22 is a demodulator that performs demodulation based on CCITT recommendation V27ter (differential phase modulation) or V29 (quadrature modulation).

The decoding circuit 24 is a circuit for decoding the demodulated data from the demodulator 22 (MH decoding or MR decoding). Recording circuit
26 is the decoded white and black signals sequentially for each line,
It is a circuit to record.

When the control circuit 28 receives the first command in the transmitting state, it detects a flag that continues for 2 bytes, and then when it receives byte data other than the flag, only once.
This is a circuit for transmitting 1100 Hz for 3 seconds, which prevents the partner device from receiving NSF / CSI / DIS echoes, and is a circuit for performing control to prevent the pre-procedure from becoming impossible.

In this embodiment, the 1100 Hz tonal signal is transmitted as a collision signal, but this does not cause the other device to malfunction even if the 1100 Hz tonal signal is transmitted after detecting the CED signal and the DIS signal. This is because

In other words, as can be seen by considering the case of automatic transmission, the first signal sent after call connection during automatic transmission is 11
00Hz CNG (calling tone) signal, and this CNG signal is DI
May collide with S signal. Therefore, DIS signal and 1100Hz
It is configured so as not to malfunction even if it collides with the signal of.

Next, the operation of the above embodiment will be described.

FIG. 2 is a flow chart showing the control operation of the control circuit 28, and FIG. 3 is a diagram showing an example of the communication procedure in the above embodiment.

In FIG. 2, first, the control circuit 28 outputs a signal of level "0" to the NCU 2 to turn off the CML and connect the telephone line 2a to the telephone 4 side (S32).

Then, in the initial identification procedure, it is transmitted only once 11
"0" is set to F110TR, which indicates whether or not a 00 Hz signal is transmitted (for 3 seconds) (S34).

It is determined whether or not it is in the transmission state (S36), and if it is not in the transmission state, other processing is performed (S38).

In the transmitting state, the control circuit 28 outputs a signal of level "1" to turn on the CML, and the telephone line 2a
To the facsimile device side (S40).

Then, the timer T1 is set to 35 seconds (S42), it is determined whether or not a 2-byte continuous flag pattern is detected (S44), and when a 2-byte continuous flag is detected, 2-byte data is set. Check whether the previous 1-byte data is a flag pattern and the other 1-byte data is a byte data other than the flag pattern (ie,
Whether or not the address field is detected) is determined (S46). As a result, when the address field is not detected, it is determined whether the timer T1 has timed out (S48). Even if the two-byte continuous flag is not detected in S44, the process of S48 is performed.

When the timer T1 has not timed out, the process returns to step S44, and when the timer T1 has timed out, the process returns to S32.

When the address field is detected (S46), F
It is determined whether 110TR is “0” (1100 Hz is not transmitted) (S50). When F110TR is "0" (1100Hz is not sent), 1100Hz is sent for 3 seconds, and the V21 signal sent by the other device is destroyed. Specifically, the control circuit 28
Sends a sending command pulse to the circuit 14, the circuit 14 sends a signal of 1100 Hz for 3 seconds (S52), and when the circuit 14 generates the sending completion pulse, the sending of the signal of 1100 Hz ends, so the flag S110TR is set to " 1 ”is set (S54).

When F110TR is not "0" (transmitting 1100Hz), the pre-procedure is performed (S56), image transmission is performed (S58),
Perform the post-procedure (S60). Then, in the case of multi-page reception (S62), the process returns to the process when the EOM (message end signal) is received (S42) or the process when the MPS (multi-page signal) is received (S58). If multi-page reception is not performed (EOP (procedure end signal) is received), the process returns to S32.

In the above practical example, when the first command is received in the transmission state, a continuous flag of 2 bytes is detected, and then, when byte data other than the flag is received, the 1100Hz signal is sent for 3 seconds only once. I am sending it out.

As a result, the receiver receives the NSF / CSI / DIS transmitted by itself.
The echo of is destroyed by the signal of 1100Hz, and it becomes impossible to receive NSF / CSI / DIS. For this purpose, the above NSF / CSI /
NSF / CSI / DIS is retransmitted after DIS transmission is completed or after 3 seconds or 4.5 seconds have elapsed. Where in this case
There will be no signal for a certain period of time, so the retransmitted NSF / CSI /
No echo is generated for DIS. This establishes the pre-procedure.

Further, in the above embodiment, the initial identification signal sent by the other device, as a condition for causing a predetermined signal to collide, other than the above embodiment, for example, a CED signal is detected (the echo suppressor is disabled by the CED signal. Become ABLE)
The condition may be set, and only in this case, signal collision may be performed.

In the above-described embodiment, the echo DIS signal is 1100H
Although the z tonal signal is collided, it is not limited to the 1100 Hz tonal signal, and any signal may be used as long as it is not erroneously recognized as a significant procedure signal by the other device.

Further, although the facsimile apparatus has been described as an example in the present embodiment, generally in a data communication apparatus, when performing data communication, a data communication procedure is performed to set a communication mode. The procedure signal of this data communication procedure may return an echo procedure signal from the line as in the case of the facsimile machine. In this case also, as described in this embodiment,
A malfunction can be prevented by colliding a specific signal with the echo procedure signal to destroy the echo procedure signal.

[Effects of the Invention] According to the present invention, the calling side and the called side are line-connected using a line in which an echo is generated, and an initial identification signal is transmitted from the called side device, and the calling side is called. In a communication method in which a signal similar to the initial identification signal may be transmitted from the side, at the time when the echo of the initial identification signal occurs, in order to destroy the echo of the initial identification signal, from the calling side Since a predetermined tonal signal is transmitted on the line, the called device receives the echo sent by itself and the received echo does not establish the communication procedure with the calling device, and the calling device It is possible to eliminate the adverse effect that the device cannot communicate with the called device.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a flow chart showing the operation of the control circuit in the above embodiment. FIG. 3 is a diagram showing an example of a communication procedure in the above embodiment. FIG. 4 is a diagram showing a procedure between conventional facsimile machines. 2 ... NCU, 4 ... telephone, 14 ... 1100Hz transmission circuit, 28 ... control circuit.

Claims (1)

[Claims] 1. An echo generating line is used to connect a calling side and a called side to each other, an initial identification signal is transmitted from the called side device, and the initial identification signal is sent from the calling side. In a communication method in which a signal similar to the above is sometimes transmitted, a predetermined tonal is transmitted on the line from the calling side in order to destroy the echo of the initial identification signal when the echo of the initial identification signal occurs. A communication method characterized by transmitting a signal.