Q: What is data networking?
A: A data network transmits information or "data" over a network by either interconnected cables or wirelessly. Two examples of network types are LAN and WAN.
Local area network (LAN):
Consists of at least 2 computers connected by a cable or through an intermediary device such as a hub. Covers a smaller, more 'local' area. For instance, within your home, or in a larger environment such as an office. By connecting these computers together one is able to share information and resources with the computers, such as files, printers and scanners.
Within a LAN there 2 networking schemes, peer to peer and server client:
Peer to peer scheme has computers on this network scheme share resources with each other. Generally this scheme is used when the computers have the same hardware/software configuration.
Server client scheme has computers designated as servers and clients. Clients connect to servers and the server does most of the processing. With this scheme the server is typically more robust then the client.
Wide area network (WAN):
A WAN is used to connect computers or devices together over great distances. Either a single device, or a device on a LAN accesses information through a WAN. A personal computer accessing the internet or a retail network interacting with their head office network, would be uses for WAN. The best example of such would be ISPs (internet service providers). ISPs have networks setup in multiple locations connecting to each other allowing users to access the internet. This function of ISPs enables networks to connect with each other over long distances without the need of a direct connection from one location to another. Another example is a PSTN (Public Switched Telephone Network), unlike ISP's and the Internet however; the PSTN is not available to public access. Like ISPs, PSTNs are set up in multiple locations and route calls from one PSTN to another to its intended locations.
Q: What is a wireless network?
A: A wireless network is a LAN or a WAN without wires between its hosts and servers. The data is transferred as radio frequencies by the use of radio transceivers. These types of networks are useful when the installation of cabling is either too costly or troublesome; it is also beneficial if the host or server requires frequent relocation. The coverage area of a WLAN (wireless LAN) can vary anywhere from hundreds of meters to low kilometers depending on many factors, including but not limited to, antennas and signal strength. As such, a wireless network can have its advantages and disadvantages, depending on use and location.
This diagram gives an example of how a retail environment may use WAN, LAN and wireless connections to communicate. Within the store a network of communication is set up between registers (R)(hardwired and wireless) and managers terminal (M) via LAN. This locations network is then connected to head office (HO) via WAN.
Q: What are some common terms related to data networking and what do they mean?
10Base-T/100Base-T - Cable designations referring to the speed and means of data transmission. The number (10, 100) refers to the speed in Mbps (megabits per second). Base represents "baseband" which means that a single signal is sent over the cable. The last letter (ex. T, TX, FX, etc) indicates the type of cable, twisted pair, fiber optic, etc.
Unshielded Twisted Pair (UTP) - means that the four pairs within the cable are twisted together and contained within the cable jacket. The alternative, "Shielded Twisted Pair", has the four pairs still twisted together with an extra layer of thin metallic shielding that offers more protection from electrical interference. Shielded cable is more costly than unshielded, larger, and often proves more difficult to work with.
Intranet - a set of interconnected networks, using web browsers or specialized software, under the control of a single administrative entity. The intranet is closed to the rest of the world, and allows only specific users.
Networking Interface Cards - NIC for short, is a piece of hardware designed to allow communication over a network.
Hub - A type of equipment used for connecting multiple devices. When a packet arrives at one port, it simply copies the data to all of the Nodes connected to the hub.
Switch - A switch is similar to a hub, but has more advanced abilities for data routing. Switches are capable of inspecting data packets as they are received, determining the source and destination device of that packet, and forwarding it appropriately. This reduces network bandwidth and does not make copies of the packet to all of the Nodes connected.
Repeater - To reduce signal degradation, a repeater receives a signal and re-transmits it at a higher level or power, enabling further traveling distance.
Bridge - A device that connects multiple networks. Originally designed to work in conjunction with hubs to segregate networks.
Router - A router is typically connected to at least 2 networks and directs data packets from one network to another using the best route possible, it does this by reading the header information contained in the data packet, then directing it on its way.
Power Over Ethernet - PoE technology describes a system to transmit electrical power, along with data to devices over ethernet cables.
Q: Why use Power Over Ethernet?
Q: What's the longest distance I can go on my
100base-T or 10base-T network using Cat5 (UTP)?
A: The longest distance allowable for data transmissions on a single twisted pair cable is 100 meters (~328 feet). To go any further you might opt for fiber optic cable or choose a device such as a repeater or a switch to connect two lengths of cable 100 meters or less together.
Q: What do the CAT ratings mean for network cable?
A: The CAT rating tell you the frequency rating of the cable. Additionally it can give you an idea of the typical use for it.
- CAT 3. Typical 10base-T cable. Frequency max: 16mhz (10Mbps)
Typical use: 10base-T networks, 4Mbs token ring networks
- Cat 5: Most common type. Frequency max: 100mhz (100Mbps)
Common use: 100base-T networks / 10base-T networks
- Cat 5e/6: High Speed cable. Frequency ~350+mhz
Typical use: 1000base-T over copper. (Gigabit Ethernet)
Q: Can I use a higher rated cable?
A: Higher rated cables carry data faster and with less loss, so using a cable rated than required is very acceptable. The advantage is that if you want to upgrade your network in the future, it is possible that the existing cable may be sufficient which means no new cable runs are needed.
Q: How does optical fiber differ from CAT cables?
A: Fiber optic cable uses glass or plastic strands to transmit data using light pulses, as opposed to twisted pair cable, which is copper and uses electrical pulses. Fiber optic cable can carry signals further, with less loss, and due to the lack of copper, it is not susceptible to electrical interference. Unfortunately all of these advantages come at a cost; fiber optic cable is more costly to install and terminate than twisted pair cable.
Q: What types of modes are supported with optical fiber?
A: Fiber comes in two modes, multi and single; the difference between the two being in the diameter of the core, and the subsequent difference in amount of light transmission possible. Single mode core diameter is eight to ten micrometers or microns (µ), which supports one type of light transmission as opposed to multimode, with a core diameter of fifty microns (µ) or greater and able to transmit multiple modes of light.
Q: What is a P.A. system?
A: P.A. stands for "public address" which is exactly what it sounds like; it is a system that is able to reinforce a given sound by electronically amplifying a signal to a level that can be distributed to a larger area or group.
Q: What are some of the uses for a P.A. system?
A: Situations that require the use of a P.A. system can vary greatly from a small meeting to a large stadium, and everything in between. Some of the more common uses for a P.A. system we encounter in everyday life might include: schools, churches, shopping malls, office buildings, and public transit.
Q: What are the capabilities of a P.A. system?
A: The capability of a P.A. system is defined by its components. P.A. systems are very modular; based on the number, ability, and quality of the devices you combine; power and versatility can change to suit the needs of a specific application.
Q: What are some of the components of a P.A. system,
and how can I expand it?
A: A smaller system would consist of fewer components, such as: a microphone, mixer/amplifier, and loudspeakers; whereas a larger system may also include more inputs (cd player, receiver), pre-amplifiers (amplifies sound before it reaches the "amplifier"), and signal routers (controls how/where audio signal is amplified). For more complex sound reproduction, such as a concert with live music, the addition of sound mixing boards and signal processors would be necessary. As demands of the system grow, so must the power of the components; the amplifier(s) would need higher output, and speakers would be designed to process specific sound signals.
Q: Why would I need a security system?
A: A security system is a vital tool for protection of personal and business property, it gives you comfort in knowing that your valuables are protected even when you are not present.
Q: What are the capabilities of a security system?
A: Due to the variable size, application, and integration potential of security systems, capabilities are adaptable to your needs. There are the basic devices available to monitor intrusion: PIR (motion detector), door/window contact, and glass break sensor; these devices are designed to notify when there is unauthorized entry or movement. In addition to intrusion monitoring devices, a panel may monitor safety alarms such as smoke/fire alarms, carbon monoxide detectors, etc. If it is desired, a security system can be integrated with other building systems to provide more specific types of protection, for example a heating/cooling system, or CCTV surveillance.
Q: What are some common terms or components of a security system?
A: First we'll start with the "panel", the panel is the main component of the system, or the "brain"; all devices and additional hardware are connected to the main panel, which processes signals and acts accordingly.
The keypad is the part of the system that most people are familiar with. There are different types of keypads available to suit either functionality or cost; unfortunately, as with most technology, the more user friendly, the more expensive. The keypad is the device which is used to arm/disarm the system, tells you which areas covered by PIRs have motion, and which doors/windows that have contacts are open; programming of the system can also be done from the keypad.
PIR is a short form for "passive infra-red", this is a type of motion detector that uses infrared technology to pick up movement by sensing body heat and consumes relatively little energy. Other types of motion detectors available are ultrasonic, microwave, and optical sensor; dual technology motion sensors combine infrared with another technology in order to reduce energy usage and false alarms.
Door/window contacts are used to notify if any doors or windows are opened; they consist of a contact on the frame of the entry, and a magnet on the door or window. When the contact and the magnet are separated it creates an alarm. Contacts can be installed to sit on the surface or flush with the surface they are mounted to.Glass break sensors come in a variety of shapes, sizes, and technologies; there are models that are mounted directly onto the glass or within close proximity. Glass break sensors pick up the sound or shockwave of shattering glass and send an alarm signal to the main panel.
Q: How does a security panel work?
A: Basically, security devices are connected to a panel by a wire, or wirelessly. The panel sends out a signal, which travels through the device, and back to the panel; when a device is "tripped" it interrupts the signal and the panel registers this as an alarm.
Q: Is a security panel hard to use?
A: Basic functions on a security panel are not hard to learn, panels come with user manuals and cheat sheets for quick reference on common usage. If you have your system installed, the installer should have in-depth knowledge of the system and be able to give a general tutorial on use of your system. As mentioned above, there are different types of keypads that may ease use and understanding of your system, but they may be more costly.
Q: What happens when an alarm is tripped?
A: What happens when an alarm is tripped depends on the setup/programming of the panel. Most people arrange to have their systems connected to a monitoring station at an alarm company; in this case, when the system is armed and an alarm goes off, the alarm panel, which is connected to your telephone line, will call the monitoring station that will then follow the procedure which you have arranged with them. If required, an alarm dispatch unit will attend the premises to ensure everything is as it should be, at that time, further action may be taken if an intrusion or break in has occurred.
CCTV System Components
Q: What are some common terms related to CCTV and what do they mean?
Black & White/Colour: CCTV equipment, whether it is a multiplexer or a camera, will generally be one of these two types, although colour equipment is generally more expensive. A black & white camera will often have more definition, especially in low-light situations; however, there are cameras available which are able to switch from colour to black & white mode, depending on available light.
Bullet Cameras: Cylindrical, small self-contained units, usually an affordable consumer-level camera without many options. The lens is often included and not interchangeable, with few mounting options. Outdoor models are often available without a heater, because its small enclosure is kept warm by its own heat.
Box Cameras: Typical design that comes to mind when thinking of a CCTV camera. Sometimes sold without a lens, with standard C/CS mounts for flexibility. A multitude of mounting or enclosure options are available, making this camera quite versatile.
Dome Cameras: With an attractive design, which can vary greatly in size, this type of camera blends into décor easily. Lenses are generally built-in, depending on the model. PTZ cameras are often of this style. Orientation of camera is sometimes difficult to discern, even more so if a smoked dome is in use. As with bullet cameras, outdoor models are available without heater.
Indoor Cameras: These cameras are not designed to brave the elements; their electronics cannot withstand the temperature changes in an outdoor environment. An indoor camera can be used outdoors with the proper enclosure, which includes a heater/blower to regulate the temperature.
Outdoor Cameras: Placing a camera outdoors introduces several challenges. The elements, temperature shifts, and illumination changes can wreak havoc on a camera and the quality of its video. Temperature can be regulated with the use of a heater/blower, though this is not needed with some cameras; if designed properly, their own electronics can keep them warm. Outdoor cameras also have to deal with varying levels of light, from the dark of night to the brightness of sunlight.
Night-Vision Cameras: There are several ways to allow a camera to see at night. Infrared light emitting diodes (LEDs) can illuminate a scene with invisible light; the resulting image can appear rather eerie, but details can still be identified. LEDs only work within a certain range, depending on their strength and number. Day/night cameras display in colour during the day when there is plenty of light, but change to black & white operation at night; these cameras have a very sensitive imaging chip, which can detect minute differences in light. Night-vision can allow a camera to observe a scene with little or no light, this is quantified by a lux value (a measure of light), with 0 lux being complete darkness.
Heater/Blower: Sometimes used with outdoor cameras to regulate temperature. The blower is set to activate when the temperature rises above a certain point; alternatively the heater starts once the temperature drops below a pre-defined mark. A heater/blower allows for camera installations, even in the most extreme environments.
Pan, Tilt, Zoom (PTZ): Pan refers to rotating left and right, tilt is angling up and down, and zoom magnifies the scene; they include a motor in order to orientate the camera, and require control cabling along with the usual power and video cables. PTZ cameras can be set to follow a certain path, or be controlled by an operator; they can also be programmed to respond to external alarms, such as a motion sensor or door contact. Magnification can be of optical or digital type, with optical zoom being preferable; both can be combined for a large total zoom value. PTZ cameras are quite versatile, but also quite expensive.
Lenses: Not all cameras come with a lens, and not all lenses are replaceable, it varies by camera. There are several different types of lenses, including manual iris, auto iris, fixed or varifocal. 'C 'or 'CS' refers to how a lens mounts to the camera; most cameras allow both. CS lenses are more popular and economical, since less optics are required in their construction.
Iris: Refers to amount of light that can enter the camera, measured by its F value. Manual iris lenses must be set, and are suitable for when the lighting conditions do not change. Cameras equipped with an auto iris lens are ideal for varying lighting conditions, such as outdoors; this is called a DC iris, and requires a cable to connect the camera to the lens, allowing it to control the iris. The CCD in the camera can also perform the operations of a DC iris, not requiring a specialized lens.
Focal Length: Measured in millimetres (mm), the larger the focal length, the greater the distance a camera can view, however, its horizontal field of view is reduced; this value can be static ('fixed' or 'monofocal') or changeable (varifocal or zoom). Varifocal lenses are user adjustable over a range, but must be re-focused each time the focal length is changed. Specialized zoom lenses are employed by PTZ cameras, which can change the focal length and refocus automatically.
Audio: Some cameras are capable of capturing audio along with video. Two-way conversation is sometimes possible, which is ideal for door-entry or to act as a help station. Depending on your jurisdiction and application, recording the audio stream could be illegal.
Switchers: As the name implies, a switcher will take input from multiple cameras and allow the output to be switched, either manually or automatically. The number of cameras, and length of time on each camera (dwell time), is adjustable. When this output is recorded, only what is being displayed at that time is recorded. Switchers are the most inexpensive of the video processors, but have their drawbacks; an important event could be missed if the switcher was on a different camera when it occurred.
Quad Processors: Allows four cameras to be displayed or recorded at once. However, the screen is split into four and recorded as such, so that you cannot retrieve the full cameras' resolution once recorded. Unlike a switcher, no important events are missed, but quality is lost.
Multiplexers: The process of taking several cameras and sharing them on the same video cable, when output to a VCR, several cameras can be recorded to the same tape. On a monitor, the screen can be split to allow multiple cameras to be viewed at the same time. Also known as a mux, they are either black & white or colour, available in several sizes, generally 4, 9 or 16 cameras, and offer simplex or duplex operation. Simplex allows for only one operation at once, if only recording, this is a good solution; duplex can perform two functions at the same time, i.e. record to a VCR and allow full control by the operator (change camera or split, etc). Multiplexers are the most advanced of the video processors; they have the capabilities of a switcher and a quad.
Video Cassette Recorder (VCR): Records input to magnetic tape for playback at a later time. Specialized CCTV VCRs usually have a time-lapse function built-in, which allows a standard tape to record for extremely long periods of time. A standard tape can last as long as 960 hours. To allow a standard 6 or 8 hour tape to record for 960 hours, only one frame is recorded about every 8 seconds; this rate is adjustable. CCTV VCRs are designed to be much more robust than the standard consumer variety, as they are expected to record and operate constantly.
Digital Video Recorder (DVR): Records input digitally onto a hard drive. A video processor, such as a multiplexer, is not required as these functions are built-in to the DVR. Maximum recording length is determined by the size of the hard drive; typically several weeks' worth from several cameras can be stored. Recording digitally offers many advantages, such as searching, analyzing, and retrieval of the information. Most DVRs have networking capabilities, allowing for remote viewing over the network.
IP Cameras: A recent technology, video from these cameras is transmitted digitally over computer cabling, rather than being transmitted via analog on coaxial cabling. IP cameras have many advantages over their analog brethren, such as less cabling required, ability to interface with computers, and all the benefits of digital storage.
Video Streaming, Remote Surveillance and Digital Video
New advances are being made with closed-circuit television (CCTV) systems. The transition from traditional analog systems (based on analog cameras and magnetic tape storage/VCRs) to digital has provided numerous benefits including extended storage times, remote access and cabling consolidation.
Traditional CCTV systems use analog based cameras record on a VCR using magnetic tapes as the storage media. Unfortunately the limited life cycle of tapes and the reliance on a large number of moving parts in a VCR make traditional storage systems very prone to physical damage and failure. Tapes have to be changed regularly if archiving is required and a large-scale system can quickly end up consuming large amounts of space. In a traditional CCTV system there are several possible types of cabling required. Video signal and power are always required for basic operations, while additional wiring for audio or control of Pan-Tilt-Zoom (PTZ) cameras is necessary for enhanced functionality. Most of this cabling, with the exception of power, needs to be run back to a central location.
A Digital Video Recorder (DVR) is a great replacement to the traditional VCR. It stores recordings on a hard disk. DVRs offer all of the functionality of a traditional VCR but without the hassles of tapes and complex mechanical components. Most DVRs are designed to re-use existing CCTV cabling and cameras, making them an excellent choice for replacing traditional equipment. DVRs can also offer additional benefits such as a Local Area Network (LAN, i.e. your office) or Wide Area Network (WAN, i.e. the internet) monitoring, control and archiving.A new type of camera has been developed recently. IP-based cameras have a network port directly in the camera. They connect to the computer network using Category 5 or 6 cabling instead of traditional coaxial cable. Power can also be delivered to the camera across this same network cable by utilizing Power over Ethernet (PoE) technology. Audio and PTZ information can also transmitted over the network, meaning that all four traditional CCTV services can now be provided over a single cable.. Compression schemes have improved, allowing many cameras on a network without saturating it. This also allows them to be more readily streamed over the internet and increases recording capacities. Storage is handled by specialized DVRs, or computers, which can be placed anywhere on the network. Every camera is individually addressable and accessible.
Having recordings in a digital format, either with DVRs or IP-based cameras, offers many advantages over analog tape; for example, they can be searched by time, date or event. Playing the recording for a given event or time period is quick and easy as you can seek to a point almost instantly rather than having to fast-forwarding through hours of footage. Archiving is done via DVD or CD recordable media, flash storage, or USB. Images can be magnified to zoom-in on a certain detail.
One of the more cutting edge advantages to digital are video analytics. Facial recognition software allows someone to be identified based on their individual features, even though they may have aged or are wearing a beard. Software can also identify someone based on his or her gait. Counting can be performed, such as the number of people walking into a building or cars passing by on a freeway. A camera placed in a train station could be analyzed for objects left unattended. Even patterns can be recognized: a shot of a parking lot could be analyzed to detect when a person is walking vehicle to vehicle instead of entering one. A large complex may have many cameras, making it virtually impossible (and cost prohibitive) to have human eyes watching and interpreting all of the information in real time. With the aid of computers the information can automatically be prioritized, making it much more relevant and easy to manage.
CCTV technologies have seen many advances in recent years that have helped to make them both more effective and more cost efficient. Cabling, space, and overhead have all been reduced, while the inclusion of computers have allowed for some revolutionary changes in how information is stored and handled.
Q: What is a telephone system?
A: A telephone system essentially creates a telephone communication network within your business, institution, or even home environment. The expandability of a telephone system allows usage in applications of all sizes: providing ease of communications within the localized environment, and increasing efficiency in communications with the outside world. Various types of telephone systems on the market today can offer many different options for current usage and future growth.
The main advantage of a phone system is that it allows for a number of outside lines to be shared among a number of extensions. Many calling features such as forwarding, speed dialing, voicemail, and intercom (calls between extensions) are also common. An automated attendant can route calls to extensions or voicemail boxes without the need of an operator. Phone systems are usually proprietary, only modules, parts, and phones designed for a system will work. The size, capabilities and features of a telephone system vary depending on which type it is.
Q: How can I benefit from a telephone system?
A: With assistance from a qualified installer, and due to the modular nature of a quality telephone system, you can ensure that your communications needs are fulfilled: reducing future costs, and inefficiency within the business environment. By streamlining the process of incoming calls and communications within your office, you allow for happier, more productive employees and customers alike, which increases your bottom line.
Q: What can a telephone system do? What kinds of features are
A: PBX (Private Branch eXchange)- A very large system suitable for campuses or corporations with multiple branches; can handle hundreds or even thousands of extensions. Allows for many advanced call-handling features.
Centrex - A type of hosted PBX which is located at the central office (telephone company). It shares many of the features of a PBX without having to host any of the equipment (other than phones). The equipment must be leased from the phone company and can be quite expensive over the long-term.
Key System - Smaller system, capable of supporting a few extensions to a few hundred. The features have improved to the point that the difference between a PBX and key system have blurred. Only the number of extensions, and some of the more advanced functions, separates the two. They are usually measured by the format of lines x extensions; which means a 3x8 allows three outside lines and eight internal extensions.
VoIP (Voice over Internet Protocol) - Phone calls over a network such as a WAN or internet. Most PBX manufacturers have adapted their systems to support this recent technology. Alternatively, instead of the traditional PBX, a computer server can manage the call routing and features.
Q: What are the common terms for IP based phones?
SIP: "Session Initiation Protocol" - A standard for an interactive session allow for video, voice, instant messaging, online games uses.
PSTN: "Public Switched Telephone Network" - A globally interconnected network of voice communication sometimes referred to as "Plain Old Telephone System" (POTS). This network consists of analog copper lines throughout the world.
PBX: "Private Branch Exchange" - A private telephone system that connects to telephone company lines, allowing many extensions to share few lines, and make use of features such as: direct inward dialing, voicemail, and auto-attendant, just to name a few.
IVR: "Interactive Voice Response" - Voice or touch-tone interaction, can reduce or eliminate live operator direction and assistance.
DID: "Direct Inward Dialing" - Allows each individual extension on a PBX to have a designated seven digit number, even though there are much fewer lines; this allows outside callers to access the desired party directly, bypassing live or automated call routing.
RFC: "Request For Comments" - A collection of documents that contain information regarding Internet advancements, standards, ideas, etc.