S-VHS
Super VHS:
is a type of video format in which
the illuminance and chrominance signals
are sent separately resulting in improved
picture quality. Salvo
switching:
is a feature in matrix switchers.
On command from the matrix switcher or
an alarm event. a group of cameras can
be switched simultaneously onto a group
of monitors.
SECAM
Sequential Coluleur A'Memorie:
a color television system used
in France and a few other countries.
Sensitivity
of a camera:
is the minimum light level required
at the CCD chip which will generate a
usable video picture. It is measured in
lux.
Sequential
switcher:
is a type of switcher that allows
multiple cameras to be displayed or recorded
one at a time.
Shield:
is a copper braid which covers
the dielectric and centre core of a coaxial
cable. It protects the video signal from
EMI.
Signal
loss:
is a reduction in signal strength
expressed in decibels.
Signal
to noise ratio:
It is the ratio between the signal
voltage and the noise voltage generated
by an electronic circuit. It is measured
in decibels (dB).
Simplex:
is a system which can handle
only one channel of video, audio or data
signal.
Single
mode cable:
is an expensive type of fibre
optic cable with a narrow glass core which
allows only a single path for signal transmission.
Silicon
wafer:
is a semiconductor material on
which the CCD chips are etched.
Snow:
is a fault in the picture, appearing
as small dots on the monitor and is caused
by heavy noise in the video signal.
Sodium
vapour lamp:
is a type of artificial light
source which is very efficient and uses
sodium vapour to produce a yellow-orange
light.
Spectral
response:
is the sensitivity of a device
to different light frequencies.
Standard
angle lens:
is a type of lens which provides
a view having the same proportions as
seen by the human eye. It has a magnification
ratio of 1.
Step
down transformer:
is a transformer used in power
supplies to step down or lower the main
line voltage. The ratio between the number
of turns of the primary coil to the secondary
coil determines the step down voltage.
Stranded
cable:
is a type of cable in which a
number of wires enclosed in an outer jacket
are used to transmit the electrical signal.
Sunshield:
is a movable accessory placed
on top of outdoor housings to prevent
direct light falling on the camera.
Sync
generator:
is a device which generates sync
pulses which are then used to synchronise
cameras.
Synchronisation:
is a process which ensures that
the formation of frames in a multi camera
system start at the same time. There are
different ways to achieve camera synchronisation. |
