SIGNAL PROCESSING
A signal carries information and the objective of signal processing is to extract the information carried by the signal, i.e.,Signal processing is concerned with the mathematical representation of the signal and the algorithm micro operation carried out to extract the information present
Characterization of Signals
• One-dimensional (1-D) signal:
– Function of a single independent variable,e.g., speech signal, s(t)
• Two-dimensional (2-D) signal:
– Two independent variables, e.g., image s(x,y)
• Multidimensional signal:
– Black and white video signal is a 3-D signal, two spatial variables and time, i.e., v(x,y,t)
– Color video signal has three channels of 3-D signals (RGB), i.e., u(x,y,t)=[r(x,y,t) g(x,y,t) b(x,y,t)]
TYPES OF SIGNALS:
(a) Analog signal:Continuous in both time and amplitude
(b) Digital signal:Discrete in both time and amplitude
(c) Sampled-data signal:Discrete-time and continuous amplitude signal
(d) Quantized boxcar signal: Continuous-time and discrete amplitude signal
Discrete-time signal
A discrete signal or discrete-time signal is a time series consisting of a sequence of quantities.
Unlike a continuous-time signal, a discrete-time signal is not a function of a continuous argument; however, it may have been obtained by sampling from a continuous-time signal. When a discrete-time signal is obtained by sampling a sequence at uniformly spaced times, it has an associated sampling rate.
Acquisition
Discrete-time signals may have several origins, but can usually be classified into one of two groups:
- By acquiring values of an analog signal at constant or variable rate. This process is called sampling.
- By observing an inherently discrete-time process, such as the weekly peak value of a particular economic indicator.
Sampling (signal processing)
Signal sampling representation. The continuous signal is represented with a green colored line while the discrete samples are indicated by the blue vertical lines.
In signal processing, sampling is the reduction of a continuous-time signal to a discrete-time signal. A common example is the conversion of a sound wave (a continuous signal) to a sequence of samples (a discrete-time signal).
A sample is a value or set of values at a point in time and/or space.
A sampler is a subsystem or operation that extracts samples from a continuous signal.
A theoretical ideal sampler produces samples equivalent to the instantaneous value of the continuous signal at the desired points.
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