Chapter 4: Getting Started
Planning the Timing
Part No. 24001157
VersaMux-4000 Operation & Installation Guide
Page 4-13
Revision C
Planning the Timing
The VersaMux-4000 is equipped with various timing options which enable it to
adapt to almost any network configuration. Your configuration may vary due to
your network design. This section provides an overview of typical VersaMux-4000
clocking configurations as a guide to adapting the VersaMux-4000 to your
network.
The VersaMux-4000 can accept timing from one of the following sources:
•
Aggregate (NRZ interface)
•
Any of the Port interfaces (up to four choices)
•
External Clock Input
•
The VersaMux-4000 internal oscillator
The VersaMux-4000 NRZ interface (aggregate) is software set to either DTE or DCE
(
Mode
parameter in the
Aggregate
sub-menu). This directly affects the Transmit
Clock Source operation (
TxClkSrc
parameter in the
Aggregate
sub-menu).
Selecting the
Internal
option (for the
Clk-Ref
parameter) causes the VersaMux-
4000 to develop the reference from its internal oscillator (ac/- 20-ppm).
Aggregate Timing
In most cases the VersaMux-4000, in DTE mode, will recover the master clock (also
known as the Primary Reference Source or PRS) from the transmission uplink
equipment via the aggregate interface (NRZ).
Aggregate Timing, VersaMux = DTE
illustrates a typical timing configuration where the VersaMux-4000
recovers its master clock from the Rx Clock (Receiver Signal Element Timing - DCE
Source) on the aggregate interface (
ClkRef
parameter set to
Aggregate
). It uses
the Tx Clock signal from the DCE device (Transmit Signal Element Timing- DCE
Source) to clock the Transmitted Data out to the DCE (
TxClkSrc
parameter set to
TxClkIn
). In addition, the VersaMux-400 uses the Tx Clock DCE signal to generate
the Tx Clock DTE signal to the DCE (Transmit Signal Element Timing- DTE Source).
Figure 4-14
VersaMux-4000 (DTE) Typical Network Timing Configuration
DCE Device
(IE: Satellite
Modem)
ClkRef
NRZ Interface
Transmitted Data
Tx Clock (DCE)
Tx Clock (DTE)
Rx Clock (DCE)
Rx Data
Primary
Reference
Source (PRS)
VersaMux-4000 (DTE)
Mode = DTE
ClkRef = Aggregate
TxClkSrc = TxClkIn
Port Interfaces
