GLOSSARY OF TERMS: Industrial Wireless

ABSORPTION:
 Absorption occurs when suspended water molecules in the terrestrial atmosphere extinguish photons. This could cause a decrease in the power density of the RF signal (attenuation). Most UHF signals are highly resistant to this based on good antenna alignment and survey practices.

AUTHENTICATION: The process a station uses to announce its identity to another station. It is the handshake that is either accepted or not accepted.

BAND: Another term for spectrum used to indicate a particular set of frequencies. Wireless networking protocols work in either the 900MHz, 2.4 GHz or the five GHz bands.

CONTINUOUS WAVE: This is an RF signal that maintains full power, i.e., it is not switched off periodically.

GAIN: The amount by which an antenna concentrates signal strength in a wireless network.

LATENCY: The delay between requesting, and actually receiving or accessing data.

MESH NETWORKING: To mesh is to offer multiple paths for data to get from its originating source to its destination point based on its control definition in its packet of data. Most mesh networks are networks that use one of two connection arrangements. Full-mesh topology or partial-mesh topology. In the full-mesh topology, each node is connected directly to each of the others. In the partial-mesh topology, nodes are connected to only some, not all, of the other nodes.

MULTIPATH: The simultaneous reception of two copies of the same signal that arrive via separate paths with different delays. This creates a common error on continuous wave signals that use modulation to send the signal. The nature of FHSS makes it resistant to this echoed signal. In the TV world it could create "ghost" images on the screen.

NODE: Any intelligent device connected to the network. This includes terminal servers, host computers, and any other devices (such as remote terminals, Ethernet, printers) that are directly connected to the network. A node can be thought of as any device that has a hardware address.

PACKET: A series of bits containing data and control information including source and destination node addresses, formatted for transmission from one node to another.

RFI: Abbreviation for Radio Frequency Interference. This is where one may have some form of radio interference on the channel and frequency that they are working on. This could be due to a number of factors, including other radio harmonics, large sidebands, and EMFs.

SIGNAL LOSS: The amount of signal strength that is lost in antenna cable, connectors, and free space. Signal loss is measured in decibels.

TOPOLOGY: The specific layout of a wireless network noting all of its physical layers. Noting different types of layouts like Star, point-to-point and full & partial meshing — just to mention a few.

WAN: Abbreviation for Wide Area Network. A collection of local-area networks connected by a variety of physical means. The Internet is the largest and most well-known wide area network. Wide area network is generally abbreviated to WAN.

ZIGBEE: An alliance committee formed to design low-power, low-cost RF technology to minimize wiring cost in the construction of utility controls.

The terms and definitions for this issue’s Word Search come from a glossary of terms compiled by Honeywell (www.honeywell.com). Honeywell manufactures automation and control solutions for industry, including a line of wireless sensors under its OneWireless brand.