- Detection
In general, detection is the extraction of information from any clear or clouded ambient or otherwise accessible stream of information without neither support from the sender nor synchronization to the sender.
In the history of
radio communications, "detectors" where the first operable type ofsemiconductor diodes to extract modulated signal from theircarrier . Still today, in multi-channel systems, detecting is the selective extraction of an AM signal from its carrierfrequency .In communications, detection is the extraction of intelligence from a carrier signal in a stream of electro-magnetic energy. Note that this may be either an "overt" signal, as in a conventional
radio broadcast, a "noise" signal as in heavily interfered ambient signals or a "covert" signal, as insteganography .In opto-electronic or other radiation systems, the detection means the generation of an electrical signal in response to a received optical input. For example, the optical signal received from an optical fiber is converted to an electrical signal in a
detector , often by aphotodiode .In
steganography , attempts to detect encoded intelligence from suspected carrier material is referred to assteganalysis . Steganalysis has an interesting difference from most other types of detection, in that it can often only produce theprobability of the existence of payload material encoded in the carrier; this is in contrast to the detection of signals which are simplyencrypted , as theciphertext can often be detected with certainty, even if it cannot be decoded.In the
military , detection means the special discipline ofreconnaissance with the aim to recognize the presence of an object in a location or ambience.Finally, the
art of detection , also known as "following clues", is the work of anydetective [http://ca.geocities.com/t369@rogers.com/index.html] .ee also
*
Signal detection theory
Wikimedia Foundation. 2010.