Facsimile and static presentation processing – Facsimile – Auxiliary signal
Reexamination Certificate
1999-04-01
2002-04-16
Williams, Kimberly A. (Department: 2622)
Facsimile and static presentation processing
Facsimile
Auxiliary signal
C358S442000, C358S468000, C379S100170
Reexamination Certificate
active
06373597
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a facsimile signal transmission system for enhancing facsimile signal transmission efficiency in facsimile communication in an international public switched network, an intra-enterprise communication network, etc.
In a facsimile signal transmission system, a DCS signal, an EPT signal, a training signal, a TCF signal, an image signal, and a control signal of facsimile signals are output from a transmission facsimile terminal to a reception facsimile terminal in sequence, whereby the facsimile signals are transmitted.
The DCS signal is a digital command signal of a facsimile signal output from the transmission facsimile terminal. It is output after a digital identification signal (DIS) of a facsimile signal output from the reception facsimile terminal is received. The capabilities of the reception facsimile terminal (modulation system, modulation speed, receivable original picture sizes, resolution, etc.,) are recognized according to the received DIS and are compared with the capabilities of the transmission facsimile terminal for judging communicatable capabilities. The judgement result is returned to the reception facsimile terminal as the DCS signal.
The EPT signal is an echo protect tone signal for instructing an echo canceller existing in a transmission path for facsimile communication to stop the operation. After the signal is received, the echo canceller existing in the transmission path stops the echo cancel operation.
The training signal is a signal for training a reception section (demodulation section) in the reception facsimile terminal so as to correctly receive the image signal and the TCF signal.
According to the signal, a synchronizing circuit, an adaptive equalizer, and the like in the demodulation section are trained for the functions required for correctly receiving the image signal.
The TCF signal is a training check signal for checking to see if the circuits, etc., are trained correctly by the training signal so that later the image signal can be received correctly. It is a signal with “0” data modulated for 1.5 seconds and is used to determine whether or not “0” can be received correctly for a given time at the reception facsimile terminal.
The image signal is a signal for indicating original picture data.
The control signal includes the DCS signal, an EOP signal, etc. The EOP signal is a signal for indicating the end of original data transmission.
After the signals are transmitted and received, a facsimile communication termination procedure is executed.
A flag signal is transmitted before the facsimile control signals (DCS signal, EOP signal, etc.,) other than the TCF signal or the image signal. It is a synchronizing signal for receiving the control signals. The flag signal is a signal with “7E” data modulated for one second.
An example of facsimile signal transmission equipment in a related art is a digital circuit multiplication equipment (DCME) applied to an international public switched network. Facsimile signal transmission system for DCME is described in ITU-T Recommendation G.766 and a part of the facsimile signal transmission system in the digital circuit multiplication equipment is shown in
FIGS. 17
to
20
.
FIG. 17
is a flowchart in the facsimile signal transmission system for transmission DCME to output a DCS signal, an EPT signal, a training signal, And a TCF signal output from a transmission facsimile terminal to reception DCME.
FIG. 18
is a flowchart in the facsimile signal transmission system for the reception DCME to output the DCS signal, the EPT signal, the training signal, and the TCF signal of the facsimile signals output from the transmission DCME to a reception facsimile terminal.
FIG. 19
is a flowchart in the facsimile signal transmission system for the transmission DCME to output an image signal and a control signal output from the transmission facsimile terminal to the reception DCME.
FIG. 20
is a flowchart in the facsimile signal transmission system for the reception DCME to output the image signal and the control signal of the facsimile signals output from the transmission DCME to the reception facsimile terminal.
Next, the operation will be discussed.
First, a transmission system of the DCS signal, the EPT signal, the training signal, and the TCF signal in the DCME will be discussed. For convenience of the description,
FIG. 21
shows a transmission sequence of these signals between the transmission facsimile terminal and the reception facsimile terminal.
The transmission facsimile terminal sends the DCS signal, one of facsimile control signals, indicating the capabilities of the transmission facsimile terminal such as the modulation system, the modulation speed, and receivable image resolution in accordance with transmission sequence defined in ITU-T Recommendation T.30, then sends the EPT signal for 185 ms to 200 ms in a silent time of 75 ms±20 ms and subsequently sends the training signal and the TCF signal in a silent time of 20 ms to 25 ms.
As shown in
FIGS. 17 and 21
, the transmission DCME detects the end of the DCS signal, then sends an IDLE message signal indicating the end of the DCS signal to the reception DCME. Subsequently, the transmission DCME sends an EPT massage signal after detecting the EPT signal, an END_EPT message signal after detecting the end of the EPT signal, a TRAINING message signal after detecting the training signal, and a FAX_DATA message signal after detecting the end of the training signal to the reception DCME (ST
80
to ST
87
). After this, the transmission DCME sends the TCF signal to the reception DCME.
On the other hand, as shown in
FIGS. 18 and 21
, after receiving the EPT message signal from the transmission DCME (ST
91
), the reception DCME sends the EPT signal to the reception facsimile terminal (ST
92
) until reception of the END_EPT message signal (ST
93
). Next, after receiving the TRAINING message signal from the transmission DCME (ST
94
), the reception DCME sends the training signal to the reception facsimile terminal (ST
95
) until reception of the FAX_DATA message signal (ST
96
).
Next, a transmission system of the image signal and the control signal in the DCME will be discussed. For convenience of the description,
FIG. 22
shows a transmission sequence of these signals between the transmission facsimile terminal and the reception facsimile terminal. It shows a sequence for transmitting an original of only one page between the facsimile terminals as an example.
The transmission facsimile terminal sends facsimile image signal corresponding to one page of facsimile image, then sends a flag signal in a silent time of 75 ms±20 ms and subsequently an end-of-procedures signal (EOP signal), one of the facsimile control signals.
As shown in
FIGS. 19 and 22
, the transmission DCME detects the end of the image signal (ST
100
), then sends an IDLE message signal indicating the end of the image signal to the reception DCME (ST
101
). Subsequently, the transmission DCME detects the flag signal (ST
102
), then sends a SIGNALLING message signal (ST
103
), then sends flag and EOP signals.
On the other hand, as shown in
FIGS. 20 and 22
, the reception DCME receives the SIGNALLING message signal from the transmission DCME (ST
111
), then sends the flag signal and the EOP signal received from the transmission DCME to the reception facsimile terminal.
Since the facsimile signals are thus transmitted between transmission and reception facsimile terminals in the facsimile signal transmission system in the related art, it is feared that the time interval of facsimile signal sent from the transmission facsimile terminal defined in Recommendation T.30 may not be held. Specifically, in
FIG. 21
, it is feared that the EPT message signal may arrive at the reception DCME after the expiration of 95 ms or more because of detection delay of the EPT signal in the transmission DCME and sending delay of the EPT message signal to the reception DCME. In this case, the time interval between the DCS signal sending end and the EPT signal
Horie Nobuyoshi
Suzuki Shigeaki
Mitsubishi Denki & Kabushiki Kaisha
Williams Kimberly A.
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