Ingress cancellation is a method for removing
narrowband
Narrowband signals are signals that occupy a narrow range of frequencies or that have a small fractional bandwidth. In the audio spectrum, ''narrowband sounds'' are sounds that occupy a narrow range of frequencies. In telephony, narrowband is ...
noise
Noise is sound, chiefly unwanted, unintentional, or harmful sound considered unpleasant, loud, or disruptive to mental or hearing faculties. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrat ...
from an
electromagnetic signal using a
digital filter
In signal processing, a digital filter is a system that performs mathematical operations on a Sampling (signal processing), sampled, discrete-time signal to reduce or enhance certain aspects of that signal. This is in contrast to the other ma ...
. This type of filter is used on
hybrid fiber-coaxial
Hybrid fiber-coaxial (HFC) is a broadband telecommunications network that combines optical fiber and coaxial cable. It has been commonly employed globally by cable television operators since the early 1990s.
In a hybrid fiber-coaxial cable syst ...
broadband
In telecommunications, broadband or high speed is the wide-bandwidth (signal processing), bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Inter ...
networks.
If a
carrier appears in the middle of the upstream
data signal, ingress cancellation can remove the interfering carrier without causing
packet loss
Packet loss occurs when one or more packets of data travelling across a computer network fail to reach their destination. Packet loss is either caused by errors in data transmission, typically across wireless networks, or network congestion.Ku ...
.
Ingress cancellation also removes one or more carriers that are higher in
amplitude
The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...
than the data signal. Ingress cancellation eventually will break if the in-channel ingress gets too high.
References
See also
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Distortion
In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal ...
*
Electromagnetic interference
*
Ingress filtering
In computer networking, ingress filtering is a technique used to ensure that incoming packets are actually from the networks from which they claim to originate. This can be used as a countermeasure against various spoofing attacks where the att ...
*
Noise reduction
Noise reduction is the process of removing noise from a signal. Noise reduction techniques exist for audio and images. Noise reduction algorithms may distort the signal to some degree. Noise rejection is the ability of a circuit to isolate an u ...
{{Tech-stub
Digital electronics