Specifications
CHAPTER 2 OPERATION AND TIMING
2-56
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1999 CANON INC. CANON SUPER G3 FAX BOARD-F1 REV.0 MAY 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
2. V.34 Modem
The high-speed modem communication procedure recommended by ITU-T is referred to as
"V.34," and may be described as follows:
a. It communicates using half-duplexing mode of a 33.6 kbps modem complying with ITU-T.
b. It automatically selects the most appropriate transmission speed (14 types; every 24000 bps
between 2400 bps and 33600 bps).
transmission speed = data speed (ITU-T recommendation) = data speed
c. It uses ECM.
d. It executes a start-up using the V.8 procedure (V.34, phase 1).
e. A V.34 modem is equipped with a modem circuit of the old recommendation to enable
connection with existing modems (upward compatible).
f. In addition to the increased modulation speed, it enables increases in overall speed (not only in
segments but also in continuous data transmission) using the following:
f.1 Pre-Emphasis Technology
It transmits data by raising the transmission level of the higher-frequency band, which is
subject to noise, thereby improving the S/N ratio.
f.2 Probing Technology
The transmitting device generates tone signals (probing tones) for use by the receiving
device to measure the characteristics of the line, thereby adapting the modem to the existing
line conditions.
g. It uses a full duplex mode for the pre-procedure/post-procedure of the V.8 and V.34 protocols,
thereby increasing the speed of executing procedures.
h. Its modulation speed (baud rate) may be 2400, 3000, or 3200 symbols/sec (required), or 2743,
2800, or 3429 symbols/sec (optional), allowing more varied choice of a data transmission speed
than past modems.
modulation speed (baud rate) = symbol speed (ITU-T recommendation)