| Term |
Definition |
| L Band |
A portion of the electromagnetic radiation spectrum used in certain satellite and microwave systems. The frequency used is approx 1 GHz. |
| LAN |
Local Area Network - A non-public data network in which serial transmission is used without store and forward techniques for direct data communication among data stations located on the user's premises |
| Land Line |
A slang term to describe any "wire" connection between any two terrestrial points. |
| LANE |
Local Area Network Emulation - LANE is a method for emulating Ethernet behavior over ATM AAL5. It takes over the behavior of the MAC layer in Ethernet networks. |
| LASCR |
Light Activated Silicon Controlled Rectifier. |
| LASER |
Light Amplification by Stimulated Emission. A device which emits light at a single frequency with all radiation "in phase". The emitted light may also be referred to as "coherent" light |
| Latency |
The time or delay in a network. This accounts for PDV and must be accomadated in the jitter buffers. |
| LBA |
Linear Block Array. |
| L-carrier System |
A transmission service for voice telephone using a variety of media and occupying a bandwidth from 68 KHz to over 8 million Hz. |
| LD |
Line Driver - A signal converter which conditions a digital signal to ensure reliable transmission over an extended distance. |
| LDMOS |
Lateral Double diffused Metal Oxide Semiconductor. |
| LDO |
Low Dropout. |
| LE |
Local Exchange. |
| Leased Line |
A circuit (virtual or physical) leased from a common carrier for the EXCLUSIVE use of a specific user. Since the circuit may be virtual performance may vary from day to day. This service should be compared with a private line (higher cost) where the facilities employed will be the same at ALL times. |
| LED |
Light Emitting Diode - A solid state device which radiates light at a single frequency. |
| LEP |
Light Emitting Polymer. |
| LF |
Low Frequency. |
| LFO |
Low Frequency Oscillator. |
| Lightwave Communication |
A term used to identify light as an information carrier. Often used instead of the word "optical" to eliminate confusion with other "picture" transmission systems such as facsimile. |
| Line |
A physical path that provides direct communication between devices. Normally, but not always, a piece(s) of wire. |
| Line Code |
A code chosen to suit the transmission medium and giving the equivalence to a set of digits generated in a terminal, or other processing equipment, and the pulses chosen to represent that set of dig-its for the line transmission. |
| Line Control |
The process in data communications of determining which device is the transmitter and which is the receiver. Line control is handled by the data link control protocol. |
| Line Discipline |
The sequence of operations to produce actual transmission and reception of data. The set of rules defining the sequence is normally referred to as the communications or data link control protocol. |
| Line Hit |
A slang phrase used to describe a short term failure of a communications channel's physical medium. |
| Line of Sight Transmission |
Transmission which is limited to straight lines. i.e., Microwave, Laser. |
| Line Termination |
In ISDN, the termination required on the network side of the user-interface, which matches NT1 at the subscriber side. |
| Line Turnaround |
In a half duplex transmission system the time between when one block of data has been sent and received and the next block can be transmitted. The delay is caused by the fact that the transmit line must be reconfigured to be the receive line and a response from the receiver processed and the line then reconfigured for transmit before a second block can be sent. |
| Linear Quantization |
Quantization in which all the intervals are equal, i.e., linear A/D converter. |
| Linearity |
Linearity is a basic measurement of how well an ADC or DAC is performing. Linearity is typically measured by making the ADC or DAC attempt to generate a linearly increasing signal. The actual output is compared to the ideal of the output. The difference is a measure of the linearity. The smaller the number, the better. Linearity is typically specified as a range or percentage of LSBs (Least Significant Bits). |
| Link Light |
An optional status LED on an Ethernet transceiver that indicates the status of the link integrity test. If this light is lit on the transceivers at both ends of the link, it indicates that the link has passed the integrity test. |
| Link Pulse |
A communication mechanism used in Ethernet link segments to indicate link status and, in auto-negotiation equipped devices, to communicate information about abilities and negotiate communication methods. The original 10Base-T used Normal Link Pulses (NLP) which indicate link status only. Ethernet nodes equipped with auto-negotiation exchange information using a Fast Link Pulse (FLP) mechanism which is compatible with NLP. |
| Link Redundancy |
The ratio of the actual number of links between nodes in a network and the minimum number which would be required to ensure that any node could transmit to any and every other node. This ratio will be a measure of alternate routing availability. |
| Link Segment |
In Ethernet, a point to point segment that connects two and only two transceivers at its endpoints. |
| LISN |
Line Interference Stabilisation Network. |
| LMI |
Local Management Interface - Frame Relay network management mechanism that uses DLCIs 0 and 1023 to pass management messages over the user-to-network interface (UNI). |
| LNA |
Low Noise Amplifier. |
| LO |
Local Oscillator. |
| Load Balancing |
The process whereby multiple services units are used equally. For example if two communications lines are available between two points each carries half of the traffic load. |
| Load Capacity |
In PCM, the level expressed in dBm0, of a sinusoidal signal the positive and negative peaks of which coincide with the positive and negative virtual decision values of the encoder. |
| Load Coil |
A device used to improve communication characteristics of a transmission line. |
| Loaded Line |
A telephone line to which has been added induction coils to reduce distortion. Used to improve the transmission speed of the line. |
| Loading |
The addition of inductance to a line in order to minimize amplitude distortion. Used commonly on public telephone lines to improve voice quality, it can make the lines impassable to high speed data, and baseband modems. |
| Local Access Transport Area (LATA) |
The geographical areas defining local telephone service. Any call within a LATA is handled by the local telephone company, but calls between LATAs must be handled by long-distance companies, even if the same local telephone company provides service in both LATAs. |
| Local Loop |
In common carrier voice network (telephone company) terms the portion of the network between the customer premise and the first switching point (the local office). |
| Loop resistance |
The total resistance of a wire from one point to another and back. |
| Loop Start |
The most common way of initiating a telephone based communication session. Removal of the hand set from it's cradle closes a circuit loop and allows a current to flow which is detected by the PBX or local exchange. |
| Loopback |
A method of testing systems where transmitted signals are returned by the receiver (or other intermediate device) to the transmitter so that they can be compared with the original data. |
| Loose Tube |
A protective tubular encapsulant, often filled with a gel, used to contain one or multiple cabled fiber. |
| LORAN |
Long Range Navigation. |
| Lossless Compression |
Data compression technique that reduces the number of bits used to represent data in a file, thereby reducing its size while retaining all the original information. This makes it suitable for computer code and text files. Lossless compression typically achieves space savings of 30%. |
| Lossy Compression |
Data compression technique that dramatically reduces the size of a file by eliminating superfluous data. The lost information is either unnoticeable to the user, or can be recovered during decompression by extrapolation of the existing data. JPEG and MPEG are lossy methods that can reduce the size of graphics, audio, and video files by over 90%. |
| Lowpass Filter |
A circuit that passes frequencies below a specific frequency (the cutoff frequency). Frequencies above the cutoff frequency are reduced in amplitude to eliminate them. |
| LP |
Low Pass. |
| LPC |
Linear Predictive Coding. |
| LW |
Long Wave. |
