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Signal
Communicated information: a piece of informationcommunicated by an action
Means of communication: an action, gesture or sign as a mean of communication
Incitement: something that incited somebody to action
Electronics transmitted information: information transmitted by means of modulated current or an electromagnetic wave and received by telephone, telegraph, radio or radar
Spectra
Signal spectra (plural of spectrum) describe thefrequency content of the signal
Spectrum is a condition or value that is not limited to aspecific set of values but can vary infinitely within a continuum
Evolved from old english “Spectre” meaning ghostor apparition but the modern meaning now comesfrom it’s use within science`
First scientific use of word spectrum is within the field of optics.it is used to describe the rainbow of colors in visible light whenseparated using prism (prismatic diffraction)
Analog signal
Any variable signal continuous in both time and amplitude. Any information can be conveyed by an analog signal, often such a signal is measured response to changes in physical phenomena, such as sound, light , temperature, position or pressure, and is achieved using a transducer.
This signal uses some property of medium to convey the information. Electrically, the properties commonly used are Voltage followed closely by frequency, current and charge
Digital Signal
Is a digital representation of discrete-time signal which is often derived from analog signal. An analog signal is a datum that changes over time
Discrete-time signal is a sampled version of an analog signal: the value of the datum is noted at fixed intervals rather than continuously. If individual time values of the discrete-time signal, instead of being measured precisely (which would require an infinite number of digits) and are approximated to a certain precision – which therefore, only requires a specific number of digits - then the resultant data stream is Digital Signal
Digital Signal
Quantization – the process of approximating the precise value within a fixed number of digits
Signal Processing
Refers to extracting information from a signal, conditioning a signal for subsequent use,
signal transformation or altering a signal structure
Analog signal Processing
Any signal processing conducted on analog signals by analog means. Specifically the mathematical algorithm that processes the the signal is implemented with analog electronics in which the mathematical values are represented as a continuous physical quantity, an analog, usually as voltage, electric current or electric charge around some components in the electronic devices. A small error or noise affecting such physical quantities will result in a corresponding error in the signals represented by such physical quantities
Digital Signal Processing (DSP)
Is the study of signals in a digital representation and the processing methods of signals.
Four major subfields of DSP are:a. Audio signal
processingb. Control
engineeringc. Digital image
processingd. Speech
processing
Transmitter
It is the device that generates high frequency power, which, by means of a suitable antenna, is radiated or transmitted through space, or through conductors or through obstructive media, such as walls and glass
It may be modulated with information, (noise, voice, pictures). This modulation or information may be received and demodulated in a receiver, where the combination of transmitter and receiver is known as radio system.
Radio Receiver
Is understood to mean any device which is intended to receive a radio signal and extract the information or intelligence (modulating signal) from the rf signal (carrier signal)
Tuned Radio Frequency (TRF)
Composed of several tuned-radio frequency amplifiers followed by circuits to detect and amplify the audio signal
Characteristic of Good Receiver
Selectivity – ability of the receiver to receive the desired signal and reject all others
Sensitivity – ability of the receiver to amplify weak signals
Fidelity – it is the ability of the receiver to faithfully reproduce the information
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