DCD-8 User Manual
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DCD-8 User Manual
11. Defining the rate: Set, Auto & Learn
Part of the DCD-8’s great flexibility comes from the fact that the rate generated does not have
to match the rate of the reference. Different frequencies can be cross-locked if necessary.
This is done through the use of the SET, AUTO and LEARN functions.
11.1. RATE MENU
In the Rate menu, the DCD-8 offers a choice between SET and AUTO:
- SET lets the user select a specific rate;
- AUTO mirrors the Reference menu (i.e. with a 48k reference, the output is 48K).
Keep in mind that, when locked to an external reference, the DCD-8 always tracks small
variations (see examples in 11.5 below).
NOTE: Auto is not available if the reference selected is Internal or Video.
11.2. REFERENCE MENU
In the Reference menu, the DCD-8 offers a choice between LEARN and SET:
- with LEARN, the DCD-8 measures the input reference and determines it’s rate;
- with SET, the user defines the expected rate.
Most of the time LEARN will work fine. However, at times, the user may choose SET to be
sure the DCD-8 does not misinterpret an input frequency which is slightly incorrect. The
SET mode may also be chosen for more fail-safe operation, in that there is no chance that
the DCD-8 will re-define a frequency which drifts over time.
To illustrate this, let’s look at a reference frequency of 95,950Hz. This frequency is slightly
below the standard 96k rate but slightly above the pulled down 96k (95,904Hz).
- If the DCD-8 interprets this as 96k, it will run slow by 0.052%;
- if it interprets it as a pulled down 96k, it will run fast by 0.047%
In SET mode, the user can make that choice; in LEARN mode, the DCD-8 automatically
selectes the closest frequency, i.e. the pulled down 96K in this case.
11.3 ABOUT USING THE SET MODE FOR THE REFERENCE
When SETTING the rate of the reference, there is the possibility that the selected rate will
not match the measured rate (actual rate). If that is the case, the DCD-8 will still lock to the
reference but the output frequency will be adjusted proportionately.
WARNING: When using this function, the user can potentially mislead the DCD-8 and
affect the output frequency, even if that is also SET. This could be done intentionally, but
caution should be used here.
For example, if the input reference is SET for PAL, and NTSC video reference is connected,
the output frequency SET at 44100Hz will actually be 52867Hz (44100 x 29.97/25).
NOTE: You can make a change to User X, go have a look at User Y, then come back
to User X and your change will still be there, whether saved or not. Of course, if you
leave the menu, you will lose any unsaved data, as usual.
8.19. MENU 99: DCD-8 SOFTWARE VERSION
Menu 99 displays the unit’s software version number and its FireWire serial num-
ber. The FireWire serial number is pre-programmed at the factory and cannot be
changed. Identification over FireWire has to be different for each DCD-8 so that
more than one of them can co-exist on the same bus.
IMPORTANT NOTE: Remember to always press the [
enter
] key to save your settings prior
to exiting a menu or to exiting the SET UP mode. No change will take place until the [
enter
]
key is pressed.
9. Non-Volatile Storage
The DCD-8 has 4 user presets and a factory default preset (see menu 92).
In addition, it has non-volatile memory holding the current settings. This includes all DCD-8
settings such as rate and reference selections as well as output assignments. This memory
is continuously updated so that, when the unit is turned on, it is in the same condition as it
was when powered down.
NOTE: You should wait approximately 10 seconds after a change was entered before pow-
ering down, to allow for the flash memory to be updated.
10. Lock Status
The lock status of the DCD-8 is displayed in the center of the LCD display. Below are
the 7 different possibilities and what they indicate:
NO REF
Reference missing
UNLOCKED
Unable to lock
SLEW
PLL is trying to lock
LOCKED --
Loose Lock
LOCKED -
Lock confirmation phase
LOCKED
Good and locked
HOLDING
Holding last known frequency after lock failure
The DCD-8 always tries to lock to it’s input. Once the rate has been established (SET
or LEARN), if the reference is off speed by more than 10%, it switches to SLEW.
Note that with video, the 10% rule applies to the horizontal frequency and not the
frame rate.
