If you would like to suggest new
glossary terms, please contact us.
Fast Fourier Transform is a computationally efficient mathematical technique that converts digital information from the time domain to the frequency domain for rapid spectral analysis. FFTs generally use a "time weighting" function to compensate for data records with a non-integer number of samples; some popular weighting functions are Hanning Window and 4-term Blackman-Harris.
Given the nature of process control, any faults which disrupt production or cause measurement errors and yield failures are a big issue. Fault protection describes any circuitry which prevents faults from occurring. This can be in the form of over-voltage protection circuitry, error detection and correction circuitry, thermal overload detection and correction circuitry and the like.
Field instruments sense, process, monitor, diagnose, record and communicate physical control variables such as temperature, pressure, flow, and level. They form a closed loop feedback system with the industrial controllers. Field instruments are often referred to as "smart transmitters" because they not only perform a sensing function, they also process the sensor signal and transmit the result to the industrial controller.
Fieldbus is a digital-based system network for industrial real-time distributed control used to connect controllers to network elements such as motors, actuators, valves and sensors. The amount of cable required is much lower in fieldbus systems than in 4 mA to 20 mA systems. This is because many devices share the same set of cables in a multi-dropped fashion rather than requiring a dedicated set of cables per device as in the case of 4mA to 20 mA systems. Being a digital system, several parameters can be communicated per device in a fieldbus network whereas only one parameter can be transmitted on a 4mA to 20 mA connection. There is a wide variety of competing fieldbus standards; some of the most common ones are: Profibus, Modbus, Interbus and CAN.
FIFO refers to a First-In, First-Out memory stack. Data points are processed in the same order in which they are stored. Having a FIFO built in to a sensor provides a data storage buffer that can be used to reduce the resources required by the host processor.
Free-fall is the state of motion with no acceleration other than acceleration due to gravity.
Carrier frequency shifting in discrete increments in a pattern dictated by a code sequence. The transmitter jumps from frequency-to-frequency within some predetermined set: the order of frequency hops is determined by a code sequence, which, in turn, is detected and followed by the receiver.
A modulation scheme that shifts between two frequencies to represent a "1" or "0" state of data transmission.
The maximum frequency measured at unity gain for which the rated output voltage can be obtained for a sinusoidal signal at rated load without distortion due to slew rate limiting.
Full-scale error is a measure of the output error when full-scale code is loaded to the DAC register.Full-scale error is expressed in LSBs.
Full Scale Power is expressed in dBm. It is computed using the following equation:
Functional isolation is separating two circuits that have different grounds, which might interfere with each other if directly connected.
The purpose of functional safety is to converge to zero the probability of unacceptable risk to the person and damage to the health of people or the environment. A system or sub-system is declared functionally safe once every specified safety function is carried out and the level of performance required of each safety function is met. Functional Safety can only be awarded when independently certified to one of the recognized functional safety standards, e.g. IEC 61508, by a certification agency.