9
VLR-100 is powered off.
NOTE:
Because the automatic backtime always sets the minutes to either 58 or 59, the minutes preset operation is skipped
when presetting the time code and using the automatic backtime feature. Preset operation proceeds directly from the
hours preset to the drop/non-drop frame selection.
Time Code Jamsync
Jamsync operation presets the LTC generator to the last good time code number read when the MODE switch is changed from
RDR to GEN LTC. In addition to the time code value, the drop/non-drop frame mode of the jamsync time code is also
transferred to the LTC generator. This permits re-recording good LTC over a poor LTC recording, starting from a point where
the original LTC was good, and also allows adding additional LTC to a tape on which LTC is already recorded but ends at some
arbitrary point.
If the SELECT switch is in its LTC position at the time that the MODE switch is changed to GEN LTC then the generator will
preset to the last good LTC number read. If the LTC reader is currently reading good time code, then the LTC generator starts
running from the jamsync value, producing LTC output that remains in step and continuous with the time code that was being
read. On the other hand, if the LTC reader is not currently reading good time code when the switch to LTC generator takes
place, then the LTC generator presets to the last good time code read, but remains in its STOP mode.
If the SELECT switch is in its VITC position when the MODE switch is changed to GEN LTC then the VLR-100 enters the
VITC-to-LTC translation, which is described in more detail further on in this manual. At this point, a momentary actuation of
the MODE switch to its SET position causes a VITC jamsync operation, leaving the LTC generator running from the last good
VITC time code number.
User Bit Jamsync
The user bits are normally jammed along with the time code when a jamsync operation is performed. However, if they were
previously manually preset, they remain at their preset value. This allows you to preset the LTC generator user bits to a desired
value, for example, to indicate a tape reel number when making a copy of the tape, but still jamsync the time code to the correct
value. If all eight user bit digits are "auto-cleared" as previously described under the section "Presetting the User Bits", then they
now jamsync to incoming VITC or LTC once again.
LTC Recording Levels
Typical levels for recording LTC range from -10dB to +3dB on the recording meter. The lower recording levels introduce less
time code "bleed" (crosstalk) onto an adjacent audio channel when they are used to record time code.
Recording levels are usually fixed when recording on an address track or if the VCR dedicates an audio channel for time code by
way of an audio/time code switch.
When recording LTC on VHS and SVHS VCRs using audio channel-2 for dedicated LTC, it is normal for the program audio
channel-1 recording level meter to peg to the right while channel-2 shows 0-VU. This results from audio channel crosstalk at the
recording head (which started out as a monophonic head and was later split into two heads for stereo) and, although quite severe
because the recording heads are very close to each other, the crosstalk does no permanent harm because it does not get recorded.
However, it does prevent post-recording LTC while making a copy of the tape with program audio in a single operation.
5.3 VITC-to-LTC Translation
When the SELECT switch is in its VITC position and the MODE switch is changed from RDR to GEN LTC, the VLR-100
enters its VITC-to-LTC translation mode of operation. The translated LTC is genlocked to the incoming video (if at play speed)
and tracks the drop/non-drop frame format of the VITC.
This translation mode allows VITC striped tape to be used to operate LTC-based editing systems, synchronize audio transports
or MIDI equipment, operate other LTC equipment such as GPI devices, LTC reader and generators, and time code tape logging
programs, as well as various other pieces of video and audio equipment requiring standard SMPTE LTC to operate.
The LTC output of the VLR-100 in translation mode is always at play speed, thus it can be read by inexpensive play speed
readers and window inserters, such as the HORITA WG-50.