NEC NEFAX 671, Руководство по обслуживанию

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S-157
7. Fax Protocols
7-1. G3 ECM (G3 Error Correction Mode)
• G3 ECM is the error correction system newly recommended by Consultative Committee
of International Telephone & Telegraph of 1988.
• By G3 ECM, documents are divided into blocks (called partial page) for transmission. If
any error takes place in any frame (one partial page consists of 256 frames) on a partial
page, the receiving party generates the retransmit request with erroneous frame num-
bers.
Here is an example where frame 1 and frame 3 are subjected to error:
Transmis- Receiving
Partial page
(High-speed Modem
Signal)
300 dps Modem Signal
Re-transmission for
error (High-speed
modem Signal)
300 dps Modem Signal
Error
Note: If one page end
and consists of plural
number of partial pages,
PPS.
NULL signal is transmit-
ted from the transmis-
sion side.
Re-transmit request
(MCF is repeated if
there is no error)
Re-transmission
Partial page end
Message check
(Received without error)
4507M501AA
Partial page end and
End procedure