Azimuth Extension (Run length, delta theta)
The azimuth increment, often expressed as a number of ACPs, from detection of the leading
edge of a radar plot to detection of the trailing edge of that plot, in a digital plot extractor system Azimuth-0
The angle between North (normally true North) and a radar target, measured from the sensor site.
B
Back Course
Under conventional Instrument Landing Systems (ILS), a B/CRS refers to a type of approach where an aircraft follows a localiser which provides lateral (left or right) guidance along a straight track to the runway when weather conditions prohibit a pilot from relying solely on visual cues. Since a B/CRS approach dose not provide precision or glide slope (vertical) guidance, this type of approach is referred to as "non-precision" approach. This means that the altitude which an aircraft may descend with reference to the ground before having to abort a landing attempt if the runway is not in clear sight, is higher than a 'Front Course' approach or precision ILS where a pilot has more precise guidance to the runway. The difference between a localiser 'Front Course' and a B/CRS is that on a B/CRS the signal from the localiser transmitter is reversed with reference to aircraft position. Hence, unless on-board equipment can compensate accordingly, on-board localiser needle indicators which typically point in the direction of the runway, deviate in the opposite direction - away from the runway.
Back Lobe
A lobe of radiated energy to the rear of an antenna (180° in azimuth with respect to the main lobe).
Band Pass Filter
A filter that allows frequencies between two cut-off frequencies to pass while attenuating
frequencies outside the cut-off frequencies; a band-pass filter can be constructed as the
composition of a low-pass filter and a high-pass filter.

Bandwidth
The range of frequencies included in a radio signal, expressed in Hertz.
Barometric Altitude
Altitude as shown not corrected for instrument error and uncompensated for variation from
standard atmospheric conditions.

Base Rate
The percentage of people in the population taking a selection test who have the ability to succeed in the job (i.e. fall above the criterion threshold value).
Baseline
1- Planning: the baseline is the original plan, plus or minus approved changes. Usually used with a modifier (e.g., cost baseline, schedule baseline, performance measurement baseline). (Ref. Project Management Institute (PMI) - PMBOK guide).
2- Configuration Management: a baseline is a snapshot of the state of a Configuration Item and its components at a point in time. (Ref. Prince).
A line serving as a starting point of analysis showing the current picture.

Tip: to find a specific term, use the Acrobat search : click B on the binocular icon in the window bar menu
Basic Encoding Rules The Basic Encoding Rules use a Type Length Value (TLV) encoding scheme. This means that the encoding of every type consists of three components, always in this exact order: One or more octets indicating the type (called an identifier by the BER); One or more octets indicating the length; One or more octets indicating the value (which BER call the contents). These contents octets may themselves be a value of some type, which is in turn encoded in a TLV format, and so on. Although TLV encoding increases the number of octets transferred, it also increases the flexibility and extensibility of protocols that use it. Basic Training Fundamental knowledge and skills appropriate to the discipline to be pursued in the ATS environment. Basic Training (phase 1 Ab Initio) Training designed to impart fundamental knowledge and skills to enable AIS students to progress to specialised AIS training. Basic Training (Phase 2 Specialist) Specialised AIS training to provide knowledge and skills related to a job category and appropriate to the discipline to be pursued in the AIS environment (ARO, NOF and Publications). Battery A set of tests standardised on the same population, so that norm-referenced scores on the several tests can be compared or used in combination for decision making (CDSEPT, 1996). Baud A unit of data communications signalling speed representing modulations per second. Technically speaking, it is different from bits per second in most modern protocols, but the term is frequently used interchangeably with BPS. Beacon A device that aids in determining position or direction. Beam Steering Unit In the AMSS, the BSU, otherwise known as the Antenna Control Unit (ACU) when used with a mechanically steered antenna, controls the pointing of the airborne antenna. It receives instructions from the SDU on where to point the antenna beam. The instruction are converted into steering commands, either electronic or electro-mechanical, to point the antenna beam toward the desired satellite. Beam Width The angle subtended (either in azimuth or elevation) at the half-power points (3 dB below maximum) of the main beam of an antenna. Bearing Direction on a compass. Behaviour Anchored Rating Scales Focus on the behavioural dimensions (both cognitive and overt) within the cluster representing specific dimensions. Used to measure mastery of Performance. Bias Errors See Systematic Errors Binary Phase Shift Keying The BPSK technique reverses the carrier phase when the digital code transitions from 0 to 1 or from 1 to 0.