Sample Rate; Lock Indication - Apogee BIG BEN User Manual

BIG BEN – User's Guide
Navigating the Front Panel -
The better the input reference
signal, the smaller the phase
differences between that input
and Big Ben's ultra-stable output . If
these phase differences are less than 1
degree (as depicted in FIGURE 1), the
NARROW and WIDE LEDs light. If, on
the other hand, these phase differences
increase to a point where a loss of lock
may occur (as depicted in FIGURE 2),
the Narrow LED will extinguish, leaving
only the WIDE LED lit. Though Big Ben's
output will remain remarkably stable, loss of
NARROW lock indicates a stability problem
with the input reference signal, caused by
excessive jitter or electrical failure.
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FIGURE 1
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FIGURE 2
Note that Apogee's use of
Wide and Narrow terminology
differs from that of other
manufacturers, who use "narrow" to
designate a clock reference running
precisely at standard rates, and "wide"
to designate a clock reference running at
any varispeed rate.
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APOGEE ELECTRONICS
4
4) SAMPLE RATE – When CLOCK SOURCE is set to INTernal or
VIDEO, SAMPLE RATE displays the frequency of the internally gen-
erated clock, and may be set to a frequency of 44.1 -192 kHz.
When CLOCK SOURCE is set to any other value (AES1, AES2, S/P
COAX, OPTICAL, OPTION or WC), SAMPLE RATE displays the
frequency detected at the selected input.
5) Lock Indication LEDs – Big Ben's lock status to the selected
CLOCK SOURCE is indicated with a group of 5 LEDs; the following
states are indicated:
•
•
•
•
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continued
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Blinking Green Arrow – Big Ben is not locked to the selected
CLOCK SOURCE.
Solid Green Arrow + "WIDE LOCK" displayed – Big Ben is locked
to the selected CLOCK SOURCE, but the quality of the input
signal is questionable.
Solid Green Arrow + Blue Dot + "NARROW LOCK" displayed
– Big Ben has achieved the most precise lock possible.
Blinking Green Arrow + Blue LED solidly lit – Big Ben is no
longer locked to the selected CLOCK SOURCE (indicated by
the Blinking Green Arrow) but has entered Surelock mode and is
transmitting a stable clock nevertheless (indicated by the solidly
lit Blue LED.