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RF Glossary
ACP, Adjacent Channel Power
AES, Advanced Encryption Standard, a symmetric block cipher for encrypting and protecting of information. The algorithm must be used with key sizes of 128 bits, 192 bits, or 256 bits depending on the application security requirement.
ARIB, The Association of Radio Industries and Businesses, commonly known as ARIB, is a standardization organization in Japan. ARIB is designated as the center of promotion of the efficient use of the radio spectrum and designated frequency change support agency.
ASIC, Application Specific Integrated Circuit. A semicustom design technique that is less expensive than full custom design and allows a very quick design cycle time. A chip designed for use in only one type of electronic equipment and not as a general-purpose component.
BER, Bit Error Rate. A measure of the quality of transmission. BER is the percentage of bits with errors divided by the total number of bits that have been transmitted, received or processed over a given time period. The lower the rate, the better the signal.
BNC, Bayonet-Neill-Concelman. Connector for connecting coaxial cables. It is used to connect IEEE 802.3 cables. Connector often used for video signals & radio microphone antennas.
CAN, Controller Area Network. A serial multi-drop bus originally developed by Bosch for automotive applications. In ALMA it is used to connect the ABM to most hardware devices located at the antenna. It will also be used with the correlator and in other places.
CER, Character Error Rate.
Cofetel, Comisión Federal de Telecomunicaciones, the Mexican equivalent of the US FCC
CSA, Canadian Standards Association -- the government agency in Canada that certifies electrical devices.
CSMA-CA, In computer networking, Carrier Sense Multiple Access With Collision Avoidance (CSMA/CA) is a network control protocol in which: *a carrier sensing scheme is used,*a data station that intends to transmit sends a jam signal*after waiting a sufficient time for all stations to receive the jam signal, the data station transmits a frame*while transmitting, if the data station detects a jam signal from another station, it stops transmitting for a random time and then tries again.
dBm, Unit of measure of the power level of a signal expressed in decibels above 1 milliwatt.
DeviceNet, a higher layer protocol for CAN, used for automation. Standardized by ODVA.
DIP, Dual In-Line Package. A type of chip housed in a rectangular casing with two rows of connecting pins on either side. The DIP is characterized by two rows of external connecting terminals or pins, which are inserted into the holes of the printed circuit board.
EIA-232 (RS232), RS232 is an electrical signaling specification published by the Electronic Industries Association (EIA). Although not identified in the specification, the 25-pin (DB25) connector, with specific pin assignments, is commonly accepted as "the RS232 connector or the serial connector." A common physical interface standard for the interconnection of devices. The standard allows for a single device to be connected at baud rates up to 9600 bps, at distances up to 15 meters.
EIA-485 (RS485), EIA-485 (formerly RS-485 or RS485) is an OSI Model physical layer electrical specification of a two-wire, half-duplex, multipoint serial connection. The standard specifies a differential form of signalling. The difference between the wires' voltages is what conveys the data. One polarity of voltage indicates a logic 1 level, the reverse polarity indicates logic. A balanced signal mode utilizes a pair of wires where a voltage difference is used to transmit/receive binary information. A balanced voltage signal level travels faster and much longer distances than an unbalanced type. Used extensively for telemetry control systems.
EMC, Electro Magnetic Compatibility. The requirement for both electromagnetic emissions and susceptibility of a piece of equipment to comply with a governing set of standards.
EPROM, Electronically Programmable Read-Only Memory. Memory chip that can be programmed or reprogrammed (with software) by writing information on it at a higher than normal voltage.
ETR, ETSI technical report.
ETSI, The European Telecommunications Standardisation Institute, which is the European standardisation body for telecommunications.
FCC, Federal Communications Commission - The FCC has the authority to regulate all interstate communications originating in the United States.
FieldBus, A control and instrumentation system architecture in which each device has its own intelligence and communicates via a data highway. Fieldbus refers to a standard for fieldbus control systems developed and administered by the Fieldbus Foundation. It is officially known as Foundation Fieldbus. It was originally intended as a replacement for the 4-20 ma standard, but many delays in its development have prevented its large scale use, and has allowed other technologies such as Modbus, Profibus, and industrial ethernet to gain large installed bases.
Flash memory, Flash memory stores permanent information on some palm-sized computers. Unlike RAM (random-access memory), flash memory can continue to store information in the absence of a power source. Palm devices often make use of flash memory to store the operating system and core applications. Unlike ROM (read-only memory), you can write to flash memory, making it possible to update the operating system and applications via software. Flash memory is more expensive than ROM
FM, Frequency Modulation. A method of transmitting information on radio waves by encoding the information as change in frequency or number of cycles per second.
FSK, Audio Frequency Shifting Keying. A method of using frequency modulation to send digital information. Comon method to transmit packet data. Bits 0 and 1 are differentiated by changes in the frequency of a signal.
GMSK, Gaussian Minimum Shift Keying. A form of frequency shift keying that shapes pulses to minimize spectral leakage.
I/O, I/O (input/output). The process of transferring data to and from a computer-controlled system using communication channels, operator interface devices, data acquisition devices, or control interfaces. It describes any operation, program, or device that transfers data to or from a computer. Typical I/O devices are printers, hard disks, keyboards, and mouses. In fact, some devices are basically input-only devices (keyboards and mouses); others are primarily output-only devices (printers); and others provide both input and output of data (hard disks, diskettes, writable CD-ROMs).
IC, Integrated Circuit. An integrated circuit (IC), sometimes called a chip or microchip, is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, and transistors are fabricated. An IC can function as an amplifier, oscillator, timer, counter, computer memory, or microprocessor. A particular IC is categorized as either linear (analog) or digital, depending on its intended application.
IEEE, Institute of Electrical and Electronics Engineers, pronounced "I-triple-E." Founded in 1963, IEEE is an organization composed of engineers, scientists, and students. IEEE is best known for developing standards for the computer and electronics industry.
IEEE 802.11, Specifies the standards used between a wireless client and a base station or between two wireless clients. IEEE 802.11a -- an add on to 802.11 that applies to wireless LANs and provides up to 54 Mbps in the 5GHz band. IEEE 802.11b (also referred to as 802.11 High Rate or Wi-Fi) -- an add on to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (all includes 5.5, 2 and 1 Mbps) in the 2.4 GHz band. 802.11g -- applies to wireless LANs and provides 20+ Mbps in the 2.4 GHz band.
IF, Intermediary Frequency. Frequency to chich a selected incoming signal is converted by heterodyne with the local oscillator signal to which the remaining circuits of the receiver can be preciselz tuned regardless of the frequency of the desired incoming signal.
ISM band, Industrial, Scientific, Medical Band. A global, public, high frequency, license free radio band. 433MHz, 868MHz, 915MHz, 2.4GHz.
Jitter, is a measure of the variability over time of the latency across a network. A very low amount of jitter is important for real-time applications using voice and video. Jitter is the deviation in or displacement of some aspect of the pulses in a high-frequency digital signal . As the name suggests, jitter can be thought of as shaky pulses. The deviation can be in terms of amplitude, phase timing, or the width of the signal pulse. Another definition is that it is "the period frequency displacement of the signal from its ideal location." Among the causes of jitter are electromagnetic interference (EMI) and crosstalk with other signals.
Latency, the minimum time required to move data from one point to another. Once latency is present, it cannot be optimized. The cause has to be removed (as in using an internal device rather than an external one to remove the latency caused by the serial port). To maximize throughput, use the highest bandwidth available. In a network, latency, a synonym for delay, is an expression of how much time it takes for a packet of data to get from one designated point to another. The term is often used to mean any delay or waiting that increases real or perceived response time beyond the response time desired.
LNA, Low Noice Amplifier. Used to amplify very low signals captured by an antenna without contributing significant SNR degradation.
LonWorks, a networking platform specifically created to address the unique performance, reliability, installation, and maintenance needs of control applications. The platform is built on a low bandwidth protocol created by Echelon Corporation for networking devices over media such as twisted pair, powerlines, fiber optics, and RF. It is popular for the automation of various functions within buildings such as lighting and HVAC; see Intelligent building. Local Operating Networks is another fieldbus, used by about 2,000 companies. The chips are made by Toshiba and Motorola for the German Echelon. They are then sold onto to various manufacturers.
LSI, Large-scale integration. Chips which are densely packed with components; typically with lead counts of 80 or more
MAC, In a WLAN network card, the MAC is radio controller protocol. It corresponds to the ISO Network Model's level 2 Data Link layer. The IEEE 802.11 standard specifies the MAC protocol for medium sharing, packets formats and addressing, and error detection
Mesh networking, a way to route data, voice and instructions between nodes. It allows for continuous connections and reconfiguration around blocked paths by "hopping" from node to node until a connection can be established.
ModBus, a communication protocol, designed by Modicon for use with its programmable logic controllers (PLC)s. It is almost a de facto standard communications protocol in industry since it represents the most commonly available means of connecting almost any industrial electronic devices, which permits great savings in wiring costs. A lot of the reason for the extensive use of Modbus instead of other communications buses is the fact that it is openly published.
MOS, Metal Oxide Semiconductor - a type of semiconductor device fabricated with a conducting layer and a semiconductor layer separated by an insulating layer. MOS semiconductors are unipolar devices that use either holes or electrons for conduction, but not both at once, ie they are not bipolar devices.
Node, any device connected to network. PCs, servers, and printers are all nodes on the network.
NRZ, Non Return to Zero. A binary encoding scheme in which 1 and 0 are represented by opposite and alternating high and low voltages and where there is no return to a zero voltage between encoded bits.
OEM, Original Equipment Manufacturer. The maker of equipment marketed by another vendor, usually under the name of the reseller. The OEM may make only certain components or complete devices, which can then be configured with software and/or hardware by the reseller.
Packet, a unit of data formatted for transmission on a network. Data is broken up into packets for sending over a packet switching network. Each packet has a header containing its source and destination, a block of data content, and an error-checking code. All the data packets related to a message may not take the same route to get to their destination; they are reassembled once they have arrived.
PHY, Physical Layer. The physical layer provides the electrical and mechanical interface required for transmission and reception of data packets transferred across the serial bus. The physical layer implements services for decoding and encoding, repeater and arbitration control. NEC's PHY is the hardware implementation of the described interface. 1394.a ports are specified for transmission of 4.5 m, whereas 1394.b ports are capable of long hauls depending on the media used. A term used to designate Layer one of the OSI model for communications protocols. The physical layer consists of Physical Media Dependent, Transceiver, and overhead processing chips. The bottom layer of the ATM protocol reference model, it is subdivided into two sublayers: Transmission Convergence (TC) and Physical Medium (PM). It provides ATM cell transmission over the physical interfaces that interconnect the ATM devices.
PLC, Programmable Logic Controller. A microprocessor-based industrial control system. It communicates with other process control components through data links. It is used in process control for simple switching tasks, PID control, complex data manipulation, arithmetic operations, timing and process and machine control.
PLL, Phase Lock Loop. An electronic circuit that consists of a phase detector, low pass filter and and oscillator. It controls an oscillator so that it maintains a constant phase angle on the frequency of an imput signal.
ProfiBus, Process Field Bus is the most popular type of fieldbus with worldwide more than 10 million nodes (2004) in use.
PROM, Programmable Read-Only Memory. A memory chip whose contents cannot be changed after it has been programmed. Once programmed with permanent data, it becomes a Read-Only Memory.
QoS, Quality of Service. On the Internet and in other networks, Quality of Service is the idea that transmission rates, error rates, and other characteristics can be measured, improved, and, to some extent, guaranteed in advance. This typically involves the specification of latency, jitter, loss, availability etc.
RF, Radio Frequency.
RFID, Radio Frequency Identification.
FFD, Full Functional Device.A device that determines the next network point to which a data packet should be forwarded enroute toward its destination. The router is connected to at least two networks and determines which way to send each data packet based on its current understanding of the state of the networks it is connected to. Routers create or maintain a table of the available routes and use this information to determine the best route for a given data packet.
RSSI, Received Signal Strength Indicator. Typically an analog 0 to 5 VDC signal from a receiver module that is representative to the strength of a signal being received. This signal is often correlated to a dBm level, in code, for the system to measure and determine the signal strength.
Rx, Reception.
SIP, in Single In-line Packaging, groups of RAM chips are soldered on a small board either by the DIP process or surface mounting SMD process. The board itself has a single row of pin-leads (like a comb) extending from its bottom edge, which plug into a special socket on a system- or system-expansion board.
SMT / SMD, Surface mount technology (SMT) is a method for constructing electronic circuits in which the components are mounted directly onto the surface of printed circuit boards (PCBs). Electronic devices so made are called surface-mount devices or SMDs. In the industry it has largely replaced the previous construction method of fitting components with wire leads into holes in the circuit board (also called through-hole technology)
SoC, System On Chip. A complete system in a single ASIC
SRD, Short Range Device.
Stack, A reserved area of memory used to keep track of a program's internal operations, including functions, return addresses, passed parameters,etc. A stack is usually maintained as a "last in, first out" (LIFO) data structure, so that the last item added to the structure is the first item used.
TNC, A threaded type of BNC coaxial connector.
Topology, network topology. The geometric physical or electrical configuration describing a local communication network; the shape or arrangement of a system. The most common topologies are the bus, ring, star, cluster tree and mesh.
TTL, Transistor-Transistor Logic. More commonly, the name of a class of integrated circuits operating at discrete levels of 0 and +5 volts. Typically, 0 to +0.8 volts is defined as logic level 0, +2.3 to +5 volts as logic level 1 (these definitions may be reversed). Compared to MOS logic, TTL is generally faster, although it uses more power and offers less packaging density. TTL signals are usually limited to two states, low and high, and are thus much more limited than analogue signals.
Tx, Transmission.
UWB, Ultra Wide Band
VCO, Voltage Controlled Oscillator. An oscillator whose frequency can be changed by altering the amount of voltage sent to its control input.
VCTCXO, Voltage Controlled and Temperature Compensated Chrystal Oscillator.
WPAN, Wireless Personal Area Network; personal area means up to 10 meter radius. Example: Bluetooth, IEEE 802.15
X-10, an industry standard for communication among devices used for home automation. It primarily uses power line wiring for signalling and control, where the signals involve short radio frequency bursts representing digital information. A radio-based transport is also defined.
