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DIALING/COMMUNICATION CONTROL
3 - 15
3
- Probing/Ranging (Phase 2)
Examines the line characteristics and sets the parameters for the modulation related items such
as the modulating speed.
Transmitter
Receiver
Signal name Abbreviation Function Remarks
INFO sequence INFO0c Informs the modem capability
such as modulating speed
and frequency transmission
capability (two frequency
bands (high and low) used to
examine the line characteris-
tics), and requests for adjust-
ing.
Transmission rate: 600 bps
Tone B B Synchronization between the
modems by 1200 Hz tone sig-
nal
B
is a signal that shifts the
phase B 180°.
Tone B B
Line probing signal L1 L1 Tone signal to analyze the line
characteristics by probing
Probing is to examine the line
characteristics.
Tone signal between 150
Hz and 3,750 Hz in units of
150 Hz
Line probing signal L2 L2
Signal name Abbreviation Function Remarks
INFO sequence INFO0a Informs the modem capability
such as the modulating speed
and frequency transmission
capability.
Transmission rate: 600 bps
Tone A A Synchronization between the
modems by 2,400 Hz tone
signal
A
is a signal that shifts the
phase A 180°.
Tone A A
INFO sequence INFO0h Based on the analysis of the
line probing signal sent from
the transmitter, it informs the
pre-emphasis filter and modu-
lating speed to be used for the
data transmission.
Transmission rate: 600 bps