A3.7 Unc5 (Ncu) Circuit Diagram - Oki OKIOFFICE44 Service Manual

A3.7 UNC5 (NCU) Circuit Diagram
Note: The relationship between NCU and optional boards (NTIF, TEL, HOOK, etc.) are shown in
A3.11.
1. Block diagram
• Figure A3.7.1 shows a block diagram of UNC5 circuit.
2. General functions of this circuit are as follows:
1) Generates and detects signals to be exchanged with a telephone exchange or network in
Phases A and E defined by ITU T.30.
• Loop formation for call origination
• Line current detection (see note 1) before call origination
• Dial tone detection (see note 1)
• Generation of dial pulses (see note 2)
• Busy tone detection (see note 1)
• Ringing signal detection
2) Sends various data and signals from the R44/M17 board to the telephone line after amplifi-
cation.
• Picture data/Protocol/Tonal signals/PB tone, etc.
3) Sends the following signals received from the line to the R44/M17 board as data after
amplification.
• Picture data/Protocol/Tonal signals, etc.
Note 1: This procedure may be omitted depending on the dial parameters.
Note 2: MF (Multi-frequency) tone is generated by the modem and transferred to the
Board Descriptions
telephone line via the NCU board.
A - 51 OKIOFFICE 44 Serv. Man., P/N 59276801