Chapter 11, SMPTE, Sync and Offset
ALESIS M20 REFERENCE MANUAL 1.06 11-3
For example, Int Gen always generates time code when the Internal Generator TC Start Ref
parameter is set to User Set, Free Run, and the TC Input button is lit. Setting this parameter
to ABS Time generates time code only if there is a valid, ADAT-formatted tape in the
transport. Setting this parameter to TC Track generates time code only if there is valid time
code recorded on the TC track of the tape.
With the Time Code track in Input mode, the time code start point and internal generator
functions vary, as shown below.
TC
Source
Mode
Int Gen
Start Ref
Intern
Gen
status
Internal Gen will… How Time Code Starts
External N/A Disabled N/A Input time code passes through
to the output
Internal ABS
Time
Enabled Run immediately (in
Free Run mode) or when
tape is moving (in
Play/Rec mode)
Time code starts from the ABS
time + internal generator ABS
offset
Internal User Set Enabled Run immediately (in
Free Run mode) or when
tape is moving (in
Play/Rec mode)
Time code starts from the
specified time
Internal TC track Enabled Run immediately (in
Free Run mode) or when
tape is moving (in
Play/Rec mode)
Internal generator time code
starts from the TC track.
Caution: If the TC track is put into record when the internal generator is disabled and the TC track is
in Input mode, the TC track will record no time code and will erase any previous TC track time code.
11.4 CHASE REFERENCE
Chase Reference chooses between two chase (synchronization) reference options. The tape
time code playback mode automatically follows the incoming time code frame rate.
• With ABS Time mode, the M20 will chase incoming SMPTE based on its absolute time
reference (the standard ADAT-format time code).
• With Tape TC mode, the time code track recorded on tape provides the reference for
locking to incoming SMPTE. If there is no time code on tape, the tape will not chase
incoming SMPTE.
Note: In both cases, when synchronizing to optical or word clocks, the time code must be synchronous
to the sample rate (this will always be the case if synchronizing to absolute time; if synchronizing to
tape time code, the TC track must be synchronous to the clock). For the M20 to lock, you must also
make sure that the incoming time code is synchronous to the incoming word clock.
