NEC ND-71762(E) system manual Sub-Source Office, Clock Extraction and Backup Routes

GENERAL INFORMATION FOR CCIS

5.2.2Sub-Source Office

The Sub-Source Office extracts carrier clocks (24DTI: 1.544 MHz/30DTI: 2.048 MHz) from the DTI opposing to the Source Office and supplies them to the PLO/OSC (High Precision Oscillator) in the user office.

In preparation for complete clock down from the Source Office, the Sub-Source Office is provided with external oscillators (EXT. OSC) for backup. Figure 2-12 shows the routes for carrier clock extraction and for backup clocks.

Figure 2-12 Clock Extraction and Backup Routes

This figure shows an example of the clock supply routes when the PLO0 is in ACT side.

Clock receiving route

(max. 4 routes)

From DTI

External

OSC 0

External

OSC 1

For Backup

	Two systems each
	ACT
PLO 0
(PH-CK17)
/OSC 0
(PA-CK14)
	32.768 MHz
	8 kHz (FH)

To Switch

System side

ACT CLOCK

Change Synchronization

PLO 1

(PH-CK17)

/OSC 1

(PA-CK14)

Note: The OSC (PA-CK14) card is used for the 1-IMG system only. The PLO (PH-CK17) card is used for the 4-IMG system.

ND-71762 (E)CHAPTER 2

Page 17

Issue 2