Vocality User Manual
User Manual for V200
Valid for V08_08.02 or V08_48.02
Page 83 of 114
this clock comes from the RXC pin.
TXC The RXC clock comes from whatever source has been selected for the TXC
direction. In the particular case where the port is in DTE mode and the TXC clock
has been set to "RXC", then this option uses the TXC port pin.
PLL Derived from a Phase-locked Loop, ie. the clock source is generated internally
(synchronised to GC1 or GC2) and does not come from an external pin.
Note: In DTE mode, there is only one clock output pin available (TT) and TT always
carries the clock associated with TXD. Although the use of a locally generated (PLL)
clock in the Rx direction is permitted, it is unlikely to give reliable operation
because the phase relationship between the PLL and the received data is not
defined. To ensure reliable operation, an external clock which is synchronous to the
received data must always be provided.
DBA As PLL, but the PLL rate can be automatically and dynamically varied in real time to
meet bandwidth demands. (Applies to ports being used in Tributary mode only).
Table 5-8 Receive Clock settings
5.14.8 Transmit Clocks
The TXC signal is also selected from several possible modes:
EXT The external interface. In DCE mode the clock is taken from the TT input pin. In DTE
mode the TXC pin is used.
RXC The TXC clock comes from whatever source has been selected for the RXC
direction. In the particular case where the port is in DTE mode and the RXC clock
has been set to "TXC", then this option uses the RXC port pin.
PLL Derived from a Phase-locked Loop, ie. the clock source is generated internally
(synchronised to GC1 or GC2) and does not come from an external pin.
DBA As PLL, but the PLL rate can be automatically and dynamically varied in real time to
meet bandwidth demands. (Applies to ports being used in Tributary mode only).
TTP
The TXC output pin is driven by a PLL, but the CPU actually latches data based on
the TT input pin. A clock must be externally supplied on this input.
TTD
As for TTP mode, but the PLL rate can be dynamically varied (as per DBA, applies to
ports being used in Tributary mode only).
Table 5-9 Transmit Clock settings
5.15 Setting clocks on the Digital Voice card
This section explains how you can setup the Digital Voice card (p/n 68155) to use an
external clock source as the transmit clock.
