TM 11-5830-263-10
1.10.5. Loudspeaker (LS)
The LS receives only analog audio and enables crewmembers, without headsets,
to monitor intercom and/or radio traffic. It is normally connected to the MCS but
may be connected to any crewstation (FFCS or MOS) in place of a headset. The
LS, when utilizing a mounting bracket, is secured with a large wing nut. This
allows quick removal from the bracket and unrestricted placement anywhere
inside or outside the vehicle (within reach of the cord). The LS provides
intelligible audio up to 50 feet from the vehicle.
Figure 1-7. Loudspeaker (LS)
1.10.6. Headsets (CVC, PICVC, CAPS, ACAPS, and CCH)
These headsets employ similar features, such as Active Noise Reduction (ANR)
and/or Passive Noise Reduction (PNR) to achieve noise reduction and enhance
audibility. ANR is accomplished (when turned on) by electronic generation of
noise canceling acoustic waves within each earcup. PNR is accomplished by soft
conformal ear seals that are snug against the head and attenuate or reduce
outside noise. All headsets are connected to the VIS system via a standard audio
connector and quick-disconnect bailout connector to enable rapid disconnection
from the system.
The Combat Vehicle Crewman's (CVC) headset consists of a Headset,
Microphone installed in a liner. The liner comes in various sizes and contains
fire-resistant fabric and bump-protection foam. It adjusts to fit individual heads by
means of front and rear straps, with an adjustable chin strap to insure a tight fit
for proper ANR operation. The electronic portion of the headset has two rigid,
contoured, noise-attenuating earcups that fit into the liner and has a noise
canceling microphone mounted on an adjustable boom off the right earcup. The
left earcup has a three-position PTT switch mounted on the outside that is spring
loaded to the center (disabled) position, with a momentary forward PTT position
and a fixed rear live intercom position. In addition to PNR each earcup contains
an independent ANR system controlled by an ANR/PNR switch mounted on the
right earcup. The ANR system, which is activated when the switch is in the rear
position, reduces background noise within each earcup. The PICVC headset has
a provision for local communication when the headset is disconnected from the
VIS to permit extra-vehicular communication. This provision is known as Talk
Through Circuit (TTC), and when switched on, signals from microphones on front
of the earcups are fed by battery powered electronics to speakers in the
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