Narrowband
Encyclopedia
In radio, narrowband describes a channel in which the bandwidth of the message does not significantly exceed the channel's coherence bandwidth
. It is a common misconception that narrowband refers to a channel which occupies only a "small" amount of space on the radio spectrum
.
The opposite of narrowband is wideband
.
In the study of wireless 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. This is usually used as an idealizing assumption; 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.
(FCC) Order issued in December 2004 requiring all CFR 47 Part 90 VHF (150-174 MHz) and UHF (421-512 MHz) PLMR (Private Land Mobile Radio) licensees operating legacy wideband (25 kHz bandwidth) voice or data/SCADA systems to migrate to narrowband (12.5 kHz bandwidth or equivalent) systems by January 1, 2013.
Coherence bandwidth
Coherence bandwidth is a statistical measurement of the range of frequencies over which the channel can be considered "flat", or in other words the approximate maximum bandwidth or frequency interval over which two frequencies of a signal are likely to experience comparable or correlated amplitude...
. It is a common misconception that narrowband refers to a channel which occupies only a "small" amount of space on the radio spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
.
The opposite of narrowband is wideband
Wideband
In communications, wideband is a relative term used to describe a wide range of frequencies in a spectrum. A system is typically described as wideband if the message bandwidth significantly exceeds the channel's coherence bandwidth....
.
In the study of wireless channels
Channel (communications)
In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...
, narrowband implies that the channel under consideration is sufficiently narrow that its frequency response
Frequency response
Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system. It is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input...
can be considered flat. The message bandwidth will therefore be less than the coherence bandwidth
Coherence bandwidth
Coherence bandwidth is a statistical measurement of the range of frequencies over which the channel can be considered "flat", or in other words the approximate maximum bandwidth or frequency interval over which two frequencies of a signal are likely to experience comparable or correlated amplitude...
of the channel. This is usually used as an idealizing assumption; 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
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
spectrum to describe sounds which occupy a narrow range of frequencies.
In telephony
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
, narrowband is usually considered to cover frequencies 300–3400 Hz.
Two-way radio narrowband
Two-Way Radio Narrowbanding refers to a U.S. Federal Communications CommissionFederal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(FCC) Order issued in December 2004 requiring all CFR 47 Part 90 VHF (150-174 MHz) and UHF (421-512 MHz) PLMR (Private Land Mobile Radio) licensees operating legacy wideband (25 kHz bandwidth) voice or data/SCADA systems to migrate to narrowband (12.5 kHz bandwidth or equivalent) systems by January 1, 2013.
See also
- Land Mobile Radio ServiceLand Mobile Radio ServiceThe Land Mobile Radio Service is regulated in the United States by the Federal Communication Commission in CFR 47 Part 90 for non-federal government wireless use between land-based mobile and fixed stations...
- Rural InternetRural InternetRural Internet is the access to the Internet from rural areas , which are settled places outside towns and cities. Inhabitants live in villages, hamlets, on farms and in other isolated houses...
- BroadbandBroadbandThe term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...
- WidebandWidebandIn communications, wideband is a relative term used to describe a wide range of frequencies in a spectrum. A system is typically described as wideband if the message bandwidth significantly exceeds the channel's coherence bandwidth....
- Ultra-widebandUltra-widebandUltra-wideband is a radio technology that can be used at very low energy levels for short-range high-bandwidth communications by using a large portion of the radio spectrum. UWB has traditional applications in non-cooperative radar imaging...