Oki OKIFAX4550 Maintenance Manual page 295

(6) PC-FAX TX
Figure A.5 (6/13) shows the signal route in PC-FAX TX mode.
The data encoded and HDLC framed in PC is input to LVC161284 and IOGA6 via the parallel
I/F to be transferred to the DRAM under the control of DMA.
The stored encoded data is output from DRAM to the MODEM under the control of CPU. After
modulation, the picture signal "S" is sent to the NCU board as the transmission data. The
transmission data "S" goes through the amplifier and is sent to the telephone line L1 and L2 via
the transformer T1 as high speed signal.
(7) PC-FAX RX
Figure A.5 (7/13) shows the signal route in PC-FAX RX mode.
In the PC-FAX RX mode, the high-speed picture signal arriving from the telephone line at L1 and
L2 of NCU passes through the transformer T1 and the amplifier and is input to the MODEM as
"R" signal. After demodulation by modem, received binary data is sent from the MODEM to
DRAM, under the control of CPU.
The data written into the DRAM is transferred to the LVC161284 and IOGA6 by the DMA to be
output to PC via parallel I/F. The PC deframes and decodes the received data to convert it into
image data.
(8) ISDN-G3 TX mode
Figure A.5 (8/13) shows the signal route of this mode.
The signal route from the image sensor to the LC821033, DRAM, CPU, IOGA6 and MODEM is
the same as that of the item (2), "G3 send mode". The analog signal "S" encoded and modulated
in the MODEM is sent to the G4N board as the send signal. The analog signal is converted into
the digital signal by the PCM codec on the G4N board to be sent to an ISDN line.
(9) ISDN-G3 RX mode
Figure A.5 (9/13) shows the signal route of this mode.
The high-speed digital image signal received from an ISDN line is converted to analog signal by
the PCM Codec on the G4N board. The converted analog signal is then input to the modem on
the MCNT as "R" signal. The signal route from the modem to the LED head is the same as that
of the item (3) "G3 receive mode".
The signal demodulated by the modem is decoded by the CPU and stored into the DRAM. The
signal is then converted into print data by the IOGA6 (printer control) to be transferred to the LED
head as HDATA3~0.
(10) ISDN PC-FAX G3 TX mode
Figure A.5 (10/13) shows the signal route of this mode.
The signal route from the PC to the modem is the same as that described in item (6) "PC-FAX
TX". The data encoded and HDLC framed in the PC is transferred to the DRAM via the parallel
I/F, LVC161284, IOGA6 and DMA. The signal is then transferred to the modem by the CPU.
The modulated analog signal "S" is sent to the G4N board, where the signal is converted into
digital signal to be output to an ISDN line.
(11) ISDN PC-FAX G3 RX MODE
Figure A.5 (11/13) shows the signal route of this mode.
The high-speed digital image signal received from an ISDN line is converted to analog signal by
the PCM Codec on the G4N board. The converted analog signal is then input to the modem on
the MCNT as "R" signal. The signal route from the modem to PC is the same as that of the item
(7) "PC-FAX RX".
The received binary data demodulated by the modem is sent to the DRAM via the CPU and
transferred to the IOGA6 by the DMA to be output to the PC via parallel I/F. The PC deframes
and decodes the received data to convert it into image data.
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