PCIe-TC User Guide Page 8 April 2012
INSTALLATION
(continued)
LTC INPUT CONNECTION (J1):
Refer to the board outline on page 6. J1 is the LTC input connector. In
most cases (if you look carefully) you can see the text “LTC IN” stamped
onto the bracket next to this connector. The LTC input connector is adja-
cent to the green status LED. The LTC input connector can be either an
RCA jack (standard equipment), a Mini-XLR(m), or an isolated BNC(f).
You can skip the rest of this section if your board does not have an LTC
reader installed.
The LTC input is high impedance (20kohms typical). This differential
input will reject at least 34dB of 50Hz or 60Hz hum. The input is de-
signed to handle signals which have no more than +1V of DC offset, and
which have an amplitude of 100mVpp to 20Vpp. The maximum readable
tape speed is 80x play speed. The minimum readable tape speed is tape
machine dependent.
If you are using either an RCA plug or a BNC connector for the LTC input,
be sure that the connector shield (outer conductor) does not contact the
PCIe-TC board bracket, the computer chassis, or any other connector
shields. This is a differential audio input, and you normally do not want
to ground the shield at the receiving end. You may choose to wrap black
electrical tape around the connector body several times to make sure that
such a short does not occur.
If you are using a Mini-XLR connector, refer to the EXTERNAL MINI-
XLR CONNECTOR WIRING section of this manual (see page 11) for ex-
ternal connector wiring details. In this case you do not have to worry
about accidentally grounding the connector shell.
Because LTC is a specialized type of audio signal, it may be present on
any audio track. Some VTR’s have a separate track dedicated to LTC, in
which case you should connect the PCIe-TC board’s LTC input to the VTR’s
LTC output connector. If LTC is present on a normal audio track, keep in
mind that audio channels are often muted (turned off) when the tape is
operating at anything other than play speed, thus making your LTC track
temporarily unreadable.
PCIe-TC User Guide Page 9 April 2012
INSTALLATION
(continued)
LTC OUTPUT CONNECTION (J2):
Refer to the board outline on page 6. J2 is the LTC output connector. It is
located in between the LTC input connector (J1) and the video input con-
nector (J3). The LTC output connector can be either an RCA jack (stan-
dard equipment), a Mini-XLR(m), or a BNC(f). You can skip the rest of
this section if your board does not have an LTC generator installed.
The LTC output is low impedance (100ohms typical). This is a single
ended (unbalanced) output, even if you use a Mini-XLR connector. The
output amplitude is about 1.5Vpp (approximately 0dBm), and nominally
has zero DC offset. The LTC output waveform meets all EBU and SMPTE
specifications. The rise and fall times of the output waveform are auto-
matically adjusted depending on whether EBU or SMPTE LTC is being
generated. For the case of FILM (24fps) LTC, the rise and fall times are
the same as for the 25fps EBU case. The LTC output level is zero when-
ever the LTC generator’s output is off.
The LTC output shield is connected directly to frame ground (the bracket),
so you don’t have to worry (as in the LTC input case) about the connector
shield becoming accidentally grounded (because it is already grounded).
If you are using a Mini-XLR connector, refer to the EXTERNAL MINI-
XLR CONNECTOR WIRING section of this manual (see page 11) for ex-
ternal connector wiring details.
Because LTC is a specialized type of audio signal, it can be recorded onto
any audio track. Some VTR’s have a separate track dedicated to LTC, in
which case you should connect the PCIe-TC board’s LTC output to the
VTR’s LTC input connector. You can also record LTC onto a normal audio
track, but keep in mind that there may be some crosstalk from the LTC
track to other audio tracks (like between the left and right audio chan-
nels), and that audio channels are often muted (turned off) when the tape
is operating at anything other than play speed, thus making your LTC
track temporarily unreadable.
