Glossary

Unsure about some of the technical terms and acronyms? Take a look at this alphabetical listing. If you cant find what you’re looking for or want to learn more, check out our web knowledge base or get in touch and we’ll do our upmost to help!

Radio Technology Glossary

 

Antenna

An antenna (or aerial) is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter applies an oscillating radio frequency electric current to the antenna’s terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified. An antenna can be used for both transmitting and receiving.

Backhaul

In a structured telecommunications network the backhaul portion of the network comprises the intermediate links between the core network (backbone), of the network and the small subnetworks at the edge of the entire network.

Base Station

A base station is a radio receiver/transmitter that serves as the hub of the local wireless network and may also be the gateway between a wired or fibre network and the wireless network.

COFDM (Coded Orthogonal frequency-division multiplexing)

COFDM is a frequency-division multiplexing (FDM) scheme used as a digital multi-carrier modulation method. A large number of closely-spaced orthogonal sub-carriers are used to carry data. The data is divided into several parallel data streams or channels, one for each sub-carrier. Each sub-carrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase-shift keying) at a low symbol rate, maintaining total data rates similar to conventional single-carrier modulation schemes in the same bandwidth.

Decibel

In radio, the decibel (dB) is a logarithmic unit that indicates the ratio of RF power relative to a specified reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities.

DFS (Dynamic Frequency Selection)

In radio resource management of a wireless network, channel allocation schemes are required to allocate bandwidth and communication channels to base stations, access points and terminal equipment. The aim is to achieve maximum system spectral efficiency by means of frequency reuse, but still assure a certain grade of service by avoiding co-channel interference and adjacent channel interference among nearby cells or networks that share the bandwidth. Dynamic Frequency Selection (DFS) is one such approach and may be applied in wireless networks with several adjacent non-centrally controlled access-points. The access-points automatically select a frequency channel with low interference level.

Fresnel Zone

If unobstructed, radio waves will travel in a straight line from the transmitter to the receiver. But if there are obstacles near the path, the radio waves reflecting off those objects may arrive out of phase with the signals that travel directly and reduce the power of the received signal. On the other hand, the reflection can enhance the power of the received signal if the reflection and the direct signals arrive in phase.

In radio communications, a Fresnel zone is one of a number of concentric ellipsoids which define volumes in the radiation pattern created by an antenna.

The cross section of the first (innermost) Fresnel zone is circular. Subsequent Fresnel zones are annular (doughnut-shaped) in cross section, and concentric with the first.

To maximise receiver strength, it is necessary to minimise the effect of the out-of-phase signals by removing obstacles from the radio frequency line of sight (LoS). The strongest signals are on the direct line between transmitter and receiver and always lie in the first Fresnel zone.

GHz

A multiple unit of Hertz (Hz). GigaHertz, 1×109 Hz

GPRS

General Packet Radio Service (GPRS) is a packet oriented mobile data service on the 2G and 3G cellular communication system’s Global System for Mobile communications (GSM). GPRS was originally standardized by European Telecommunications Standards Institute (ETSI). It is now maintained by the 3rd Generation Partnership Project (3GPP).

GSM

GSM (Global System for Mobile Communications), is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation (2G) digital cellular networks. Developed as a replacement for first generation (analogue) networks, the GSM standard originally described a digital, circuit switched network optimised for full duplex voice telephony. The standard was expanded over time to include first circuit switched data transport, then packet data transport via GPRS. Packet data transmission speeds were later increased via EDGE. The GSM standard is succeeded by the third generation (3G) UMTS standard developed by the 3GPP. GSM networks will evolve further as they begin to incorporate fourth generation (4G) and LTE advanced standards.

ISM band

The industrial, scientific and medical (ISM) radio bands are portions of the radio spectrum reserved internationally, originally for the use of radio frequency (RF) for industrial, scientific and medical purposes other than communications. Examples of use include radio-frequency process heating and microwave ovens. The powerful emissions of these devices can create electromagnetic interference and disrupt other radio communication using the same frequency. In general, communications equipment operating in these bands must tolerate any interference generated by other ISM equipment, and users have no regulatory protection from ISM device operation. Despite this, in recent years the fastest-growing uses of these bands have been for short-range, low power communications systems. Cordless phones, Bluetooth devices, and wireless computer networks all use the ISM bands.

Last Mile Access

The “last mile” or “last kilometer” is the final leg of delivering connectivity from a communications provider to a customer. The phrase is often used by the telecommunications industry. The actual distance of this leg may be considerably more than a mile, especially in rural areas. It is typically seen as an expensive challenge because “fanning out” wires and cables is a considerable physical undertaking. Because the last mile of a network to the user is also the first mile from the user to the world in regards to sending data (such as uploading), the term “first mile” is sometimes used.

To solve the problem of providing enhanced services over the last mile, hybrid technology communications networks are used increasingly. One example is Fixed Wireless Access, where a wireless network is used instead of wires to connect a terminal to the wire or fibre network.

Licensed Band

Unlicensed or license-free radio frequencies are those parts of the radio frequency spectrum which can be used without restriction or the need to pay a licence fee as long as the quipment is operating within defined rules.

Any person or organisation may implement a license free network using appropriately certified radio equipoment for private or public purposes.
Some of the most commonly used license free frequencies in the US are at 900 MHz, 2.4 GHz, 5.2/5.3/5.8 GHz, 24 GHz and above 60 GHz.

LoS (Line of Sight)

At higher radio frequencies any obstruction between the transmitting antenna and the receiving antenna will block the signal. Therefore, since the ability to visually see a transmitting antenna roughly corresponds to the ability to receive a radio signal from it, the propagation characteristic of high-frequency radio is called “line-of-sight”.

Low-powered microwave transmitters can be significantly affected by foliage, tree branches and leaves. If a direct visual link cannot be established, it is important to take into account the curvature of the Earth when calculating line-of-sight from maps. The presence of objects not in the direct visual line of sight can also interfere with radio transmission. This is caused by diffraction effects and for the best propagation, an area known as the first Fresnel zone should be kept free of obstructions. Objects within the Fresnel zone can disturb line of sight propagation even if they don’t block the geometric line between antennas. Reflected radiation from the ground may also act to cancel out the direct signal. This effect can be reduced by raising either or both antennas further from the ground.

Mesh Network

Mesh networking is a type of networking where each node must not only receive and transmit its own data, but also serve as a relay for other nodes. A mesh network can be designed using a flooding technique or a routing technique. When using a routing technique, the message propagates along a path, by hopping from node to node until the destination is reached. To ensure all its paths’ availability, a routing network must allow for continuous connections and reconfiguration around broken or blocked paths, using self-healing algorithms. A mesh network whose nodes are all connected to each other is a fully connected network.

NLoS (Near Line of Sight)

A Line of Sight situation where foliage, trees and buildings etc may obstruct the radio signal propogation without detriment to overall link performance.

OFDM (Orthogonal Frequency Division Multiplexing)

Orthogonal frequency-division multiplexing (OFDM), similar to coded OFDM (COFDM) and discrete multi-tone modulation (DMT), is a frequency-division multiplexing (FDM) scheme used as a digital multi-carrier modulation method. A large number of closely spaced orthogonal sub-carriers are used to carry data. The data is divided into several parallel data streams or channels, one for each sub-carrier. Each sub-carrier is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase-shift keying) at a low symbol rate, maintaining total data rates similar to conventional single-carrier modulation schemes in the same bandwidth.

PtP (Point-to-Point)

A point-to-point data link features two communicating devices. The term point-to-point telecommunications generally relates to fixed wireless data communications over IP via radio frequencies in the multi-gigahertz range.

PtMP (Point-to-MultiPoint)

Point-to-multipoint communication is a term that is used in the telecommunications field which refers to communication via a one-to-many connection, providing multiple paths from a single location to multiple locations. Point-to-multipoint is often abbreviated as P2MP, PTMP, or PMP. Typically used in wireless communications using gigahertz radio frequencies, P2MP systems can be designed both as single and bi-directional systems. A central antenna or antenna array broadcasts to, or receives from several remote antennas.

RF (Radio Frequency)

Radio frequency (RF) is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals.

Radio Spectrum

Radio spectrum refers to the part of the electromagnetic spectrum corresponding to radio frequencies – that is, frequencies lower than around 300 GHz (or, equivalently, wavelengths longer than about 1 mm). Different parts of the radio spectrum are used for different radio transmission technologies and applications. Radio spectrum is typically government regulated and, in some cases, is sold or licensed to operators of private radio transmission systems. Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum).

RSSI

In telecommunications, Received Signal Strength Indicator (RSSI) is a measurement of the power present in a received radio signal.
RSSI is a generic radio receiver technology metric, which familiar to users of wireless networking of IEEE 802.11 protocol family.

Satellite

A remote point or radio transmitting device.

Signal Strength

In the context of radio, signal strength refers to the magnitude of the electric field at a reference point that is a significant distance from the transmitting antenna. It may also be referred to as received signal level or field strength. Typically, it is expressed in voltage per length or signal power received by a reference antenna. High-powered transmissions, such as those used in broadcasting, are expressed in dB-millivolts per metre (dBmV/m)or in decibels above a reference level of one milliwatt (dBm).

TPC (Transmit Power Control)

A mechanism used within some networking devices in order to prevent too much unwanted interference between different wireless networks (e.g.the owner’s network and the neighbour’s network).
The network devices supporting this feature are IEEE 802.11h Wireless LAN devices in the 5 GHz band compliant to the IEEE 802.11a. The idea of the mechanism is to automatically reduce the used transmission output power when other networks are within range. Reduced power means

Networking Technology Glossary

10BASE-T

The number refers to the theoretical maximum transmission speed in megabits per second (Mbit/s). The BASE is short for baseband, meaning that there is no frequency-division multiplexing (FDM) or other frequency shifting modulation in use. Each signal has full control of wire, on a single frequency. The T designates twisted pair cable, where the pair of wires for each signal is twisted together to reduce radio frequency interference and crosstalk between pairs.

100BASE-TX

The number refers to the theoretical maximum transmission speed in megabits per second (Mbit/s). The BASE is short for baseband, meaning that there is no frequency-division multiplexing (FDM) or other frequency shifting modulation in use. Each signal has full control of wire, on a single frequency. The T designates twisted pair cable, where the pair of wires for each signal is twisted together to reduce radio frequency interference and crosstalk between pairs.

AES (Advanced Encryption Standard)

A symmetrical data encryption standard with 128, 192 and 256 bit keys. Replaced the earlier DES standard.

Bandwidth

The amount of data that can be transmitted in one second (e.g. 108Mbps or 108Mbits/sec). Also referred to as Line Speed, Data Rate or Transmission Rate.

DES (Data Encryption Standard)

A symmetrical data encryption algorithm using a 56 bit key.

Ethernet

Developed in the early 1970’s as an approach to networking computer equipment. First standardised in 1983 as IEEE 802.3.

Full Duplex (FDX)

A communications link in which transmission and reception of data are possible simultaneously.
All Wavesight links operate in Half Duplex Mode, however a Full Duplex link could easily be established by using radio pairs, one for transmit and one for receive.

Half Duplex (HDX)

A communications link in which transmission and reception of data are possible, but not simultaneously.
All Wavesight links operate using Half Duplex.

IEEE (Institute of Electrical and Electronic Engineers)

A standards development body.

IP (Internet Protocol)

A widely used layer 3 communications protocol.

IP address

A logical network device address assigned by a network manager. Takes the form of 4 bytes expressed in decimal, separated by dots, e.g. 192.168.0.5

LAN (Local Area Network)

A local data network, e.g. Ethernet.

Latency

Time taken between the transmission and reception of data. In IT data networks, increased latency will introduce time delays and slow system throughput. In CCTV camera links, increased latency may result in slow response time to PTZ adjustments and unsatisfactory camera control. Wavesight wireless devices and networks result in systems with the lowest latency of any comparable system available.

MAC (Media Access Control)

MAC address

Fixed hardware address of a network device, assigned by the device manufacturer. Also known as the device physical address. On all Wavesight wireless devices, the MAC address is identified from the last 5 digits of the device serial number.

Mbps

Mega bits per second, Mbit/s.

OUI (Organisational Unique Identifier)

A number allocated by the IEEE and used to identify an organisation and for the basis of generating device MAC addresses (see IEEE OUI Standards.)

As a network device manufacturer, Wavesight has its own registered OUI: 00-03-E8

802.11

The most common family of standards for wireless local area networks ratified by IEEE.

Standard Approved Frequency Range Data Rate Notes
802.11b 1999 2.4GHz 11Mbps License free spectrum
802.11g 2003 2.4GHz 54Mbps License free spectrum
802.11a 1999 5GHz 54Mbps (108Mbps Turbo Mode) License free spectrum, however certain frequencies are reserved in some countries for radar etc
802.11n Draft only 600Mbps

 

WAP

A Wireless Access Point (WAP) is a device that allows wireless devices to connect to a wired network using Wi-Fi or other related standards. The WAP usually connects to a router via a wired network and can relay data between the wireless devices and wired devices on the network

Camera / CCTV / Video Technology

Analogue Camera

An analogue camera produces an analogue voltage signal, usually via a BNC co-axial connector and cable. Analogue cameras can be used as a part of a digital IP network or hybrid system but the analogue camera output would normally be converted to digital IP using an encoder device.

CIF

CIF (Common Intermediate Format) is a format used to standardise the horizontal and vertical resolutions in pixels of video signals.

Frame Rate

The rate at which camera image frames can be transmitted in one second

FPS (Frames Per Second).

IP Camera

Often referred to as a network camera, an IP camera has its own IP address and communicates/outputs digital video typically via an Ethernet connection and can be placed wherever there is a network connection available.

CCTV (Closed Circuit Television)

The use of video cameras, transmitting images for viewing on a controlled suite of viewing screens, usually in a security and surveillance environment.

Codec

Essentially a device that encodes analogue electrical signals (from an analogue CCTV camera, for example) into digital data streams for transmission over a IP network and/or decodes the received digital data back into analogue electrical signals for display (on an analogue viewing monitor, for example).

Compression

Various techniques are used to reduce recorded CCTV image file sizes. Typical formats include MJPEG, MPEG-4 and H.264.

DVR (Digital Video Recorder)

A recording device capable of recording and storing video data to a hard disc, for example.

ONVIF

ONVIF (Open Network Video Interface Forum) is a global and open industry forum with the goal to facilitate the development and use of a global open standard for the interface of physical IP-based security products. Or in other words, to create a standard for how IP products within video surveillance and other physical security areas can communicate with each other. ONVIF is an organisation started in 2008 by Axis Communications, Bosch Security Systems and Sony.
see ONVIF web site

MegaPixel Camera

An IP/networking camera featuring more than one million pixels.

PTZ (Pan-Tilt-Zoom)

Used in reference to a camera that can be panned left and right, tilted up an down or zoomed in and out either manually via a joystick control or automatically via a scanning or sensing system.

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