Spectracom 8144-DD, Инструкция по эксплуатации

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Section 3: Operation
Page 3-2 Instruction Manual 8144-DD/075020
3.1 THEORY OF OPERATION
The Model 8144-DD Clock Selector/Distribution Amplifier is a clock switch and
splitter. The input circuit can automatically or manually select a clock input, the
send that clock to distribution amplifiers. The distribution amplifiers split the clock
to twelve outputs and sends them to the rear panel connectors.
The Model 8144-DD can operate in two modes: Automatic or Manual. In
automatic mode, the primary (A) clock has priority and is selected if it is present.
If the A clock is not present, the secondary (B) clock is automatically selected.
Unit default is “switch and stay” (non-revertive switching), but can be configured
to “switch back “ (revertive switching) when the A channel returns. In manual
mode, the front panel select pushbuttons determine which channel is selected.
In automatic mode, the channels can be selected remotely by asserting an alarm
on the rear panel alarm inputs. Putting an alarm condition on the A channel
causes the unit to select channel B. An alarm on channel B causes channel A to
be selected.
In manual mode, if a channel is selected and an alarm input is asserted for that
channel, the outputs are removed. In either mode, if an alarm is asserted on
both rear panel outputs, the outputs are removed.
3.2 FRONT PANEL FUNCTIONS
The following paragraphs describe the front panel functions. Refer to Figure 3-2,
8144-DD Front Panel.
MAJOR ALARM Indicator:
A major alarm exists when both clock references are not ready (AIS or
LOS) or both alarm inputs have been activated.
This indicator can be either latched on after the occurrence of an alarm, or
on only during the alarm condition. This option is selected by internal
header H8.
If there is only one reference and internal header H7 is set to A-B, the loss
of the A reference or activation of the A alarm causes a major alarm.
A major alarm removes the outputs from the rear panel connectors.