The frequency domain of a voice signal is normally continuous because voice is a
nonperiodic signal.
discrete because the signal of an alarm is periodic.
A Z-transform is a mathematical transform which converts a discrete time-domain signal into a complex frequency-domain representation.
The analog signal is converted to discrete signal. Even after the conversion, the frequency of the actual signal still remains the same. If the frequency of the discrete signal is different from the analog signal, the reconstructed signal would be different again. This is not what we expect. So base spectrum for similar signals have same frequencies, whether they are discrete or analog. Why do the repetitions occur? The original analog signal is multiplied with a dirac pattern. The base frequency is then shifted to the places, where diracs are available. So long the diracs keep repeating, the base frequency do repeats. Hope you are convinced with my answer
to shift the frequency of information signal ,at the frequency domain to a higher frequency ...so the information can be transmitted to the receiver.
we often confuse our-self with continuous time and analog signals. An analog signal is a signal which can take any amplitude in continuous range that is signal amplitude can take infinite values on the other hand a digital signal is one whose amplitude can take only finite numbers of values THE TERM CONTINUOUS SIGNAL AND DISCRETE SIGNAL CLASSIFY THE SIGNALS ALONG THE TIME (i.e. horizontal axis) where as THE TERM ANALOG AND DIGITAL SIGNAL CLASSIFY THE SIGNAL ALONG THE AMPLITUDE (i.e vertical axis)
To answer this properly more context is needed but frequency is in most contexts continuous.
In signal processing, sampling is the reduction of a continuous signal to a discrete signal. A common example is the conversion of a sound wave (a continuous signal) to a sequence of samples (a discrete-time signal).
discrete because the signal of an alarm is periodic.
A Z-transform is a mathematical transform which converts a discrete time-domain signal into a complex frequency-domain representation.
The linear discrete time interval is used in the interpretation of continuous time and discrete valued: Quantized signal.
A continuous signal is one that is measured over a time axis and has a value defined at every instance. The real world is continuous (ie. analog). A discrete signal is one that is defined at integers, and thus is undefined in between samples (digital is an example of a discrete signal, but discrete does not have to imply digital). Instead of a time axis, a discrete signal is gathered over a sampling axis. Discrete signals are usually denoted by x[k] or x[n], a continuous signal is x(t) for example. Laplace transforms are used for continuous analysis, Z-transforms are used for discrete analysis. Fourier transforms can be used for either.
The analog signal is converted to discrete signal. Even after the conversion, the frequency of the actual signal still remains the same. If the frequency of the discrete signal is different from the analog signal, the reconstructed signal would be different again. This is not what we expect. So base spectrum for similar signals have same frequencies, whether they are discrete or analog. Why do the repetitions occur? The original analog signal is multiplied with a dirac pattern. The base frequency is then shifted to the places, where diracs are available. So long the diracs keep repeating, the base frequency do repeats. Hope you are convinced with my answer
Sampling rate or sampling frequency defines the number of samples per second (or per other unit) taken from a continuous signal to make a discrete or digital signal.
analog (continuous) and discrete (discontinuous)
An analog signal is a continuous signal that contains time-varying quantities. Unlike a digital signal, which has a discrete value at each sampling point, an analog signal has constant fluctuations. netonplus.com
advantage is that if we represent a composite signal in frequency domain........then we clearly see that how much signals are involved in composite signal and their separate peak values
THE TERM CONTINUOUS SIGNAL AND DISCRETE SIGNAL CLASSIFY THE SIGNALS ALONG THE TIME (i.e. horizontal axis) where as THE TERM ANALOG AND DIGITAL SIGNAL CLASSIFY THE SIGNAL ALONG THE AMPLITUDE (i.e vertical axis) we often confuse our-self with continuous time and analog signals. An analog signal is a signal which can take any amplitude in continuous range that is signal amplitude can take infinite values on the other hand a digital signal is one whose amplitude can take only finite numbers of values