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 be added for cable. For outdoor applications, one to 7 pounds each should
be added for wind and snow loading. The mount has to carry the total
weight.
b) Wall and ceiling mounts are recommended for indoor use; wall and
pedestal mounts for outdoor use. In PTZ applications, the clearance
required by the entire mounted unit is a large mount size determinant.
c) Many manufacturers make similar quality mounts; not all mounts
fit all camera brands; prices vary between manufacturers; comparison
shopping is advised before final specification.
6.2.4.5 Video Recorders. Also known as video tape recorders or "VTRs,"
these devices are used for event recording as discussed in paragraph titled
"Event Recording." (Video disc and solid state video recordings are
relatively new technologies which are not presently in general use for CCTV
security applications and consequently will not be discussed in this design
manual.) Real time recording of alarm zone scenes is generally reserved for
alarm situations. Most VTRs operate in a time lapse mode for access portal
and other activity monitoring and in a real time mode for sensor alarm
queued situations. In this manner, over 100 hours of elapsed time can be
selectively compressed onto one 2-hour tape. Three different kinds of VTRs
are generally available: 1/2-inch reel-to-reel; 1/2-inch cassette; and
3/4-inch cassette. Generally, the reel-to-reel models have been available
longer than cassette models and are specifically available for security
applications. The prime disadvantage of reel-to-reel models is that tape
handling is required for threading prior to recording. Attendant damage and
missed recordings have resulted in the cassette models being the general
models of choice for DoD and Navy applications. The 3/4-inch tape generally
provides a higher quality picture with present technology. The system
designer should consider that, like an operator, a VTR can also go into an
overload condition when too many cameras are in an "alarm" state.
Generally, for large systems (over 40 cameras) where alarm activity is high,
a second VTR is recommended. A recommended option for a VTR is a time/date
generator which superimposes that data on the tape picture. This is
required for introduction of the recording as court evidence and is useful
for command review of events. Sensor zone labelling is also possible if
desired, but is not required for evidence purposes. Such generators are
often used for alarm station monitor orientation. A less expensive
alternative is to have an unobtrusive sign in each camera FOV with the
sensor zone designation. The system designer should consider the VTR as an
option when pictorial event recording is a necessity. For most
applications, the record provided by the hard copy record of a printer will
suffice for security management purposes. For larger systems, a VTR is
often a cost-effective supplement for management purposes.
6.2.4.6 Switching Equipment and System Integration. Video switchers enable
the cost-effective use of multiple cameras with a few monitors. The
ergonomic (human factors) benefits are also well documented. Generally, for
any CCTV system with over a few cameras, the cost of a video switcher is a
clear advantage over the costs associated with dedicated monitors and an
operator overload. When two or more cameras are used in a system, a
switching device may be employed. For two camera systems, for example, a
manual or passive
13.02-96
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