
KX-FT21RS
6.6.MODEM SECTION
6.6.1.FUNCTION
The unit uses a 1 chip modem (IC1), enabling it to act as an interface between the control section for FAX sending and receiving, and the telephone line. During a sending operation, the digital image signals are modulated and sent to the telephone line. During a receiving operation, the analog image signals which are received via the telephone line are demodulated and converted into digital image signals. The communication format and procedures for FAX communication are standardized by
It can be controlled by writing commands from the ASIC (IC1) to the register in the modem (IC1).
This modem (IC1) also sends DTMF signals, generates a call tone (from the speaker), and detects busy tones, dial tones and DTMF.
Overview of Facsimile Communication Procedures
1.ON ITU-T (International Telecommunications´ Union.)
The No. XIV Group of
2.Definition of Each Group
·Group I (G1)
Transmission for about 6 minutes at scanning line density of 3.85 lines/mm.
·Group II (G2)
Using reduction technology in the modulation/demodulation format, an
Methods to suppress redundancy are not used. Determined in 1976.
·Group III (G3)
A method of suppressing redundancy in the image signal prior to modulation is used. An
Determined in 1980.
·Group IV (G4)
Transmission is via the data network. A method is provided for suppressing redundancy in signals prior to transmission, and
The scope of these facsimile applications is not limited simply to transmission of written statements. Through symbiotic linkages with other communication methods, it can be expected to expand to include integrated services.
3.Facsimile Call Time Series
As shown in the following diagram, the facsimile call time series is divided into five phases.
Phase A : Call setting
Call setting can be manual/automatic.
Phase B :
Phase B is a
Phase C : Message transmission
Phase C is the procedure for transmitting facsimile messages.
Phase D : Post message procedure
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