Wiktionary
a. Describing communication systems with a smaller bandwidth than wideband.
Wikipedia
In radio, narrowband describes a channel in which the bandwidth of the message does not significantly exceed the channel's coherence bandwidth.
In the study of wired channels, narrowband implies that the channel under consideration is sufficiently narrow that its frequency response can be considered flat. The message bandwidth will therefore be less than the coherence bandwidth of the channel. That is, no channel has perfectly flat fading, but the analysis of many aspects of wireless systems is greatly simplified if flat fading can be assumed.
Narrowband can also be used with the audio spectrum to describe sounds which occupy a narrow range of frequencies.
In telephony, narrowband is usually considered to cover frequencies 300–3400 Hz.
Usage examples of "narrowband".
Fed by the towed array, the narrowband processors listened for specific frequencies known to be emitted by most Russian submarine classes, from such as their turbine-generator resonance, a 300-cycle-per-sec- and sound.
Sonar, narrowband contact Sierra One, bearing either three five zero or one seven zero, is a submerged contact, Russian nuclear type four, probable AKULA class, making three zero turns on one eight bladed screw.
He concentrated on the two possible bearings to the narrowband contact.
There were no sonar detects on the OMEGA on broadband, and none on any of the guessed narrowband frequency gates they were searching in.
The ambiguity must be resolved by turning the ship and seeing which new two directions the tonal seems to be coming from, or correlating a narrowband towed array bearing to a broadband bearing.
For this reason, biologies are usually investigated with narrowband sonar to prove they do not hide an enemy submarine.
INTEGRATE The accumulation of data of the BAT-EARS narrowband sonar processors.
SOUND SIGNATURE The collection of characteristic sounds, both broadband and narrowband tonals, that uniquely identify a class of ship, and sometimes, the exact ship itself.
TONAL SEARCH GATE A filter set up on a narrowband passive sonar that only listens to a small range of sound frequencies in anticipation of finding a particular tonal.
It watched the narrowband and broadband sonar arrays that reached out to the infinite reaches of the sea to hear the noises of man-made machinery.
He exhaled and glanced at the sonar display on the command console, flipping screens from the broadband to the narrowband processors to the acoustic daylight imaging.
But then, the ten minutes would be worth it to allow the narrowband processors to check out the sea for a contact.
Zhou shook his head, knowing that the narrowband sonar processors were a gift and a curse in one package.
With narrowband taking too long to be useful, a gallop and-walk could only use the broadband sonar, and in truth, a few minutes of reduced ambient and own-ship noise would be a beneficial thing for the broadband sonar.
Zhou selected his left screen to the broadband display, the central screen to the narrowband frequency buckets, even though five minutes was not enough to integrate narrowband on one sector, they might get lucky.