2 synchronization of timecode, 3 pull up and pull down, 4 error bypass – Tascam RC-898 User Manual

Page 52: 5 rechase mode

Section 8.2 - Advanced timecode functions

8-6

1) From menu group 5, move the cursor to

OutTc Src

and press

SELECT

2) Use the

and

DOWN

keys to select between

the four options available:

8.2.2 Synchronization of timecode

When timecode (including MTC) is output

from a DTRS unit, it may be synchronized to
either the analog or digital outputs, depending on
which is in used at the time. This is necessary
because of the nature of the digital-to-analog cir-
cuitry employed in the DTRS units.

1) From menu group5, move the cursor to

OutTc Tmg

, and press

SELECT

2) Use the

and

DOWN

keys to select either

digital or analog synchronization for the output
timecode.

8.2.3 Pull up and pull down

When using DTRS units in NTSC telecine situa-
tions, it may be necessary to adjust the sampling
frequency fractionally, as the NTSC frame rate of
29.97 and the cinema frame rate of 24 do not form
a neat mathematical ratio.

The sampling frequencies of 44.1kHz and 48kHz
are therefore affected when the material is trans-
ferred back to film.

Accordingly, the pull up and pull down functions
are provided to allow the adjustment of sampling
frequencies to drop-frame environments.

1) From menu group 8, move the cursor to

Shift

and press

SELECT

2) Use the

and

DOWN

keys to select one of the

following settings:

If this setting is anything other than

off

on one

or more DTRS unit, the

PULL UP/DN

indicator

[10] of the RC-898 will light when the appropriate
machine is selected, as will the indicator on the
DTRS unit(s).

8.2.4 Error bypass

When a DTRS unit is chasing timecode from an
external source, the source timecode may drop out
for a few frames or be otherwise discontinuous. To
allow for this, a “flywheel” facility is provided,
which allows the DTRS unit to continue for a set
period until timecode is received again. The fly-
wheel period may be set for either 10 frames or 30
frames, in the following way:

1) From menu group 4, move the cursor to

ErrByPass

and press

SELECT

2) Use the

and

DOWN

keys to select between

and

frames for the “flywheel” period.

8.2.5 Rechase mode

The DA-98 provides another facility which is

used when chasing to timecode.

O u t p u t

T C

S o u r c e

M a c h i n e

T a p e

( T C

T r a c k )

TAPE (TC
Track)

Outputs the timecode as recorded on
the dedicated timecode track.

TAPE
(ABS)

Outputs the timecode as synthesized
from the ABS subcode, with all off-
sets, etc. as set up in 8.1.2, “Synthe-
sizing timecode from ABS times”.

External
(reGen)

Timecode received at the timecode
input is regenerated and output.

External
(reshape)

Timecode received at the timecode
input is filtered and retransmitted.

O u t p u t

T C

T i m i n g

D i g i t a l

A n a l o g

M a c h i n e

F s

S h i f t

M o d e

M a c h i n e

o f f

off

Pull Down 30NDF

Pull Up 29.97NDF

Pull Up29.97DF

Pull Down 30DF

NOTE

If you want to use the Fs Shift function, make sure that the
reference clock is set to Video

Int

(see 7.2.6,

“Clock selection”). If the reference clock is Word

although the setting can be made,

the Fs Shift func-

tion will not be enabled.

E r r o r

B y p a s s

M a c h i n e

1 0

F r a m e