Motorola T1/E1 manual Frequency off-set by clock type, Master and Secondary Clocks

Canopy T1/E1 Multiplexer				September 2004
			T1/E1 Multiplexer FPGA Version 3.4
		Table 10: Frequency off-set by clock type
	Clock	Frequency Off-set
		(accuracy over 24	Time to First
	Type	hours)	Frame Slip	Application
	Stratum 1	1 x10-11	1 every 72 days	Gateway Office
	Clock
	Stratum 2	1x10-10	1 every 3.5 hours	Toll Center
	Clock
	Stratum 3	3.7x10-7	1 every 6 minutes	Central Office
	Clock		or
			255 in 24 hours
	Stratum 4	3.2x10-6	Up to 1 frame slip	Customer Premises Equipment
	Clock		every 4 seconds in	(PBX, Channel Banks, Routers)
			free-run

The Canopy T1/E1 Multiplexer does not have an internal oscillator. Therefore, the unit must be synchronized to a T1/E1 bit stream in order to accurately pass T1/E1 traffic. The Canopy T1/E1 Multiplexer may be configured to synchronize to a near-end or far-end Canopy T1/E1 Multiplexer.

Master and Secondary Clocks

The clock on each Canopy T1/E1 Multiplexer must be correctly configured to prevent frame slips. Each of the four (4) T1/E1 ports may be configured as the Master clock source or the Secondary clock source. Any port may be set to Master and any port may be set to Secondary, however there may only be one (1) Master and one (1) Secondary clock setting per unit.

Note: If neither the Master or Slave port is active, then the system will start at Port 1 and search in logical order until it finds an active T1/E1 port, at which time it will assume this to be the Master clock source.

Two scenarios are shown below, one scenario with Port 1 set to Master and Port 2 set to Secondary. The second scenario shows Port 1 set to Secondary and Port 3 set to Master.

Figure 7: Master and secondary clock settings (top view)

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