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SATA (Serial Advanced Technology Attachment)

Is a computer bus primarily designed for transfer of data between a computer and mass storage devices such as hard disk drives and optical drives.  Serial ATA adapters and devices communicate over a high-speed serial cable.

Saturation

An attribute of perceived color, or the percentage of hue in a color.  Saturated colors are called vivid, strong, or deep.  Desaturated colors are called dull, weak, or washed out.

Screen Resolution

The setting that determines the amount of information that appears on your screen, measured in pixels. Low resolution, such as 640 x 480, makes items on the screen appear large, although the screen area is small. High resolution, such as 1024 x 768, makes the overall screen area large, although individual items appear small.

Security

Security is the condition of being protected against danger or loss. In the general sense, security is a concept similar to safety.

Sensitivity

Expression of the nature of a photographic emulsion's response to light.  It can be concerned with degree of sensitivity as expressed by film speed or response to light of various colours (spectral sensitivity).

Sharpness

A term used to describe the ability of a lens to render fine detail clearly; dependent on the contrast and resolution of a lens and varies with the f/stop; in general, a lens is sharpest at the middle apertures.  Also technically it can be explained as clarity of the photographic image in terms of focus and contrast. Largely subjective but can be measured to some extent by assessing adjacency effects, i.e. the abruptness of the change in density between adjoining areas of different tone value.

Shield

A tape, serve or braid (usually copper, aluminium or other conductive material) placed around or between electric circuits or cables or their components, to prevent signal leakage or interference.

Shielded Armored

Types of shield: Aluminium, Aluminium/Steel and Copper.  Cables with shielded armored is that requires some sort of shield.

Shielded Twisted Pair, STP

Twisted pair cables are available unshielded (UTP) or shielded (STP), with UTP being the most common.  STP is used in noisy environments where the shield around each of the wire pairs, plus an overall shield, protects against excessive electromagnetic interference. A variation of STP, known as ScTP for "screened twisted pair" or FTP for "foil twisted pair," uses only the overall shield and provides more protection than UTP, but not as much as STP.

Shutter

Blades, a curtain, plate, or some other movable cover in a camera that controls the time during which light reaches the film.

Shutter Speed

Many security cameras can capture images at various shutter speeds ranging from 2 seconds to 1/10,000 second.  When capturing images at normal shutter speeds (ex. 1/60 sec.), moving objects can be captured clearly without picture blur.  On the contrary, when capturing images at slow shutter speeds (ex. 1 sec.), the camera’s CCD accumulates more light so that the image captured is brighter; however, for moving objects, the accumulation period can be too long, resulting in picture blur.  By using a slow shutter speed, it is possible to skew the minimum illumination value in a specification so that the lux rating is much lower than that taken at a normal shutter speed.  However, because the resulting image is blurred, it is not useful in most surveillance monitoring applications.

Signal

It is any visible or audible indication which can convey information.  Also, the information conveyed through a communication system.

Signal to Noise Ratio, S/N

An S/N ratio can be given for the luminance signal, chrominance signal and audio signal.  The S/N ratio is the ratio of noise to actual total signal, and it shows the ratio of a signal power to the noise power corrupting the signal.  It is expressed in decibels (dB), and the bigger the value is, the crisper and clearer the picture and sound will be during playback.  An S/N ratio is calculated with the logarithm of the normal signal and the noise RMS value.

Silicone

It is a material made from silicon and oxygen.  It can be in thermosetting elastomer or liquid form.  The thermosetting elastomer form is noted for high heat resistance.  This is a very soft thermoset insulation.  It has excellent electrical properties plus ozone resistance, low moisture absorption, weather resistance, and radiation resistance.  It typically has low mechanical strength and poor scuff resistance.

Simple Mail Transfer Protocol, SMTP

SMTP is used for sending and receiving e-mail. However, as it is “simple,” it is limited in its ability to queue messages at the receiving end, and is usually used with one of two other protocols, POP3 or IMAP. These other protocols allow the user to save messages in a server mailbox and download them periodically from the server.  SMTP authentication is an extension of SMTP, whereby the client is required to log into the mail server before or during the sending of email. It can be used to allow legitimate users to send email while denying the service to unauthorized users, such as spammers.

Simple Network Management Protocol, SNMP

SNMP forms part of the Internet Protocol suite, as defined by the Internet Engineering Task Force. The protocol can support monitoring of network-attached devices for any conditions that warrant administrative attention.

Single-mode Fiber

This is an optical fiber wave guide in which only one mode will propagate.  The fiber has a very small core diameter of approximately 8 micro meters.  It permits signal transmission at extremely high bandwidths and is generally used with laser diodes.

Slow Synchronization

It means a flash technique for using the flash at a slow shutter speed.  Flash shooting in dim light or at night at a fast shutter speed often results in a flash-illuminated subject against a dark background.  Using a slower shutter speed with the flash brings out the background details in the picture. Use of a slow shutter speed with Rear-Curtain Sync is particularly effective for illustrating the movement of a stream of light. The F5's Slow Sync mode extends the automatically controlled shutter speed range (in Programmed Auto and Aperture-Priority Auto) down to 30 sec.

Stranded and Solid
Both UTP and STP come in stranded and solid wire varieties. The stranded wire is the most common and is also very flexible for bending around corners. Solid wire cable has less attenuation and can span longer distances, but is less flexible than stranded wire and cannot be repeatedly bent.

Surge

It refers to a temporary and relatively large increase in the voltage or current in an electric circuit or cable, also called transient.

SVHS

Super Video Home system.  Clearer than the conventional method for video, VHS because it separates chrominance and luminance signal transmission lines to provide better picture quality.

Synchronisation
Concerted action of shutter opening and closing of electrical contacts to fire an electronic flash at the correct moment to make most effficient use of the light output.