Crossword clues for selectivity
selectivity
Wiktionary
n. 1 The quality of being selective; usually the extent to which something is selective. 2 The ability of a radio receiver to separate a desired signal frequency from others.
WordNet
n. the property of being selective
Wikipedia
Selectivity is a measure of the performance of a radio receiver to respond only to the radio signal it is tuned to (such as a radio station) and reject other signals nearby in frequency, such as another broadcast on an adjacent channel.
Selectivity is usually measured as a ratio in decibels (dBs), comparing the signal strength received against that of a similar signal on another frequency. If the signal is at the adjacent channel of the selected signal, this measurement is also known as adjacent-channel rejection ratio (ACRR).
Selectivity also provides some immunity to blanketing interference.
LC circuits are often used as filters; the Q ("Quality" factor) determines the bandwidth of each LC tuned circuit in the radio. The L/C ratio, in turn, determines their Q and so their selectivity, because the rest of the circuit - the aerial or amplifier feeding the tuned circuit for example - will contain present resistance. For a series resonant circuit, the higher the inductance and the lower the capacitance, the narrower the filter bandwidth (meaning the reactance of the inductance, L, and the capacitance, C, at resonant frequency will be relatively high compared with the series source/load resistances). For a parallel resonant circuit the opposite applies; small inductances reduce the damping of external circuitry.
There are practical limits to the increase in selectivity with changing L/C ratio:
- tuning capacitors of large values can be difficult to construct
- stray capacitance, and capacitance within the transistors or valves of associated circuitry, may become significant (and vary with time)
- the series resistance internal to the wire in the coil, may be significant (for parallel tuned circuits especially)
- large inductances imply physically large (and expensive coils) and/or thinner wire (hence worse internal resistance).
Therefore other methods may be used to increase selectivity, such as Q multiplier circuits and regenerative receivers. Superheterodyne receivers allow use one or more fixed intermediate frequency tuned circuits for selectivity. Fixed tuning eliminates the requirement that multiple tuning stages accurately match while being adjusted.
Selectivity may refer to:
Usage examples of "selectivity".
Brevity, selectivity, precision, and imaginative appeal are key terms in description.
Take any descriptive passage in your novel and try to improve it in terms of brevity, selectivity, precision, and imaginative appeal.
He made some final adjustments in the selectivity of the Boreth's electromagnetic receivers, then began working out his strategy for applying what he had learned to his next attempt to raise the Defiant.
And there was a lot of getting in and out of boats, in and out of pools, and, in a daze of booze and indifference, getting in and out of beds, even though I had long since discovered that it is a habit which degrades the receptivity to sensation, coarsens selectivity, implies obligation, and turns off most useful introspection.
The viral envelope proteins selectively subdued the mother's immune response to her fetus without weakening the mother's defenses against external pathogens, an exquisite dance of selectivity.