RLH Industries 16 Channel T1 Over Ethernet Multiplexer System User Manual - 1.3 Timing Modes
Timing modes
To emulate a clear E1/T1 channel over a packet network, the RLH-TG Mux not only conveys data
stream content correctly from the source to the destination, but also passes timing. Packet networks do
not provide such built-in timing transparency mechanism as TDM networks do. RLH-TG Mux uses its
proprietary algorithm to reconstruct the E1/T1 clock at the destination. The recovered clock is of very
high quality, with low jitter and wander. Typical frequency offset is within ±5ppm, and jitter is below
0.1UI. It can be adopted in most applications. This timing mode of rebuilding the E1 clock at the
destination is called Adaptive Timing.
For applications where separate clock distribution network exists, another timing mode, Loop back
Timing, may be used for maximum clock quality.
The two timing modes of RLH-TG Mux are shown below.
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RLH-TG Mux
RLH-TG Mux
Adaptive Timing
Loopback Timing
Timing Modes
Correct timing mode setting is important for smooth operation. In most cases, setting both units to
adaptive timing mode is sufficient, but sometimes setting one unit to loop timing mode may work better.
For example, setting the RLH-TG Mux unit connected with the clock master (such as local exchange) to
loop back mode, and the other unit connected with the clock slave (such as PBX or remote module) to
adaptive mode, is probably better than setting both to adaptive modes.
One typical error in telecom applications is to connect two communication devices that are both clock
slaves. The RLH-TG Mux will not support such operation no mater how the timing modes are set.
Note: That the E1channel emulation takes several minutes to stabilize. During that period, clock drift
may exceed the limit, errors and slips may occur.
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2.
System Architecture
2.1 Block diagram
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Timing Mode Scheme Reference Diagram
Timing Mode Reference Table
Various timing setups for the two timing modes are shown in the table below. Note that setting both
units to adaptive timing mode works well for all the conditions, although the other option may work
better.
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RLH Industries, Inc. - 16 Channel T1/E1 over GE with Fiber
General Information