dCS 900E / 902E User Manual Manual for Software Versions 1.3x to 1.5x
dCS Ltd 12
th
June 2000
Manual part no: DOC0029021E1 Page 14 Document No: OS-MA-D0002-902.1E1
Contact dCS on + 44 1799 531 999 email to: more@dcsltd.co.uk
(inside the UK replace + 44 with 0) web site: www.dcsltd.co.uk
Overload Indicator (Overload LED)
This overload LED lights for a few seconds when the set overload level is
exceeded by a signal peak. The detection circuitry monitors both input and
digital filtering circuitry for overload conditions. The analogue input sensitivity
trims mounted on the rear panel should be set so that the overload indicator
does not light on signal peaks.
The overload indication given by the dCS 900 / 902 is comprehensive. The
detection circuitry monitoring the digital filter does not simply check the final
output word but all the data from which the output word is formed. If any of these
overload (this may not be apparent from the output data), an overload is flagged.
The filter itself has sufficient numerical accuracy that if the input data is not
overloaded, the filter computations cannot generate an overload - only a raw
data overload can cause an error. The overload indication is thus much more
accurate than any external meter based indication - for this reason it is stored in
the AES/EBU validity bit for later reference.
Menu Set -
The Set button is used with the other menu buttons (white type on the front
panel). See the section “The Software – The Menu” on page 18.
Master/Slave Menu Down
The Master/Slave button is dual function – on its own (blue type on the front
panel) it sets the clocking mode (master or slave). With the other menu buttons
(white type on the front panel) it is the menu Down button.
In Master mode, the calibrated voltage controlled crystal oscillators (VCXOs)
inside the unit generate an accurate sample rate. The LED labelled Master will
be lit to indicate this. If a Master Clock is available, this may be connected to the
Reference In connector (for AES/EBU reference) or the Clk In connector (for
SDIF-2 Word Clock). To slave the unit to the Master Clock, press the
Master/Slave button. The unit will attempt to lock to the Reference - this will
take a few seconds. If lock is achieved, the Slave LED will light up brightly and
the Master LED will turn off. To return to Master mode, press the Master/Slave
button again.
If both AES Reference and Word Clock are connected, pressing the
Master/Slave button cycles through the sequence:
Master ... AES Reference ... Word Clock ... Master ... etc.
If the active reference source is lost, the unit will select the next option in the
sequence.
If the Auto-Slave option (see page 21) is turned On the unit will automatically
slave when a suitable reference is connected. If both AES Reference and Word
Clock are connected, AES Reference takes priority. Word Clock may be
selected by pressing the Master/Slave button – it moves down the priority list.
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