« What is Wireless Communications? | Home | Wireless Fencing Scoring System »
Signals & Signal Processing
By kaklong | February 14, 2008
Believe it or not, there are signals everywhere in our life. We might have not realized it. Deep down in the roots of human history, signals have been used significantly over the years for communications. Speech is one of the normal everyday signals. One of the most common long-distanced communication during the historic era is smoke signal which is often used by native Americans.
As the time goes by into the modernization era, more and more signals have been discovered which includes musics, pictures and videos.
1. Speech
Speech is a 1-dimensional signal which means that it is a function of single variable. It is a perfect example of air pressure as a function of time in space.
2. Music
Music is also an example of air pressure as a function of time at a point in space.
Black and white picture is a representation of light intensity as a function of two spatial coordinates. Black and white picture is an example of two dimensional signal since it is a function of two variables.
4. Video
A video is a sequence of images, called frames, and is a function of 3 variables: 2 spatial coordinates and time. Thus, video is a 3 dimensional signal.
Signals carries information and can be generated either naturally or synthetically. Signal processing is thus used to extract this information from the signal. Signal processing is usually concerned with mathematical representation of the signals and also the algorithmic operation that is carried out on it to extract the information present in the signal.
There are two types of signal - analog signal and digital signal. An analog signal is a continuous time signal with continuous amplitude. Analog signals usually occur naturally such as speech.
A digital signal in another hand, is a discrete-time signal with discrete-valued amplitudes represented by a finite number of digits. As an example, a music signal stored on a CD is a discrete time signal.
Signals can also be categorized to either be real-value or complex-valued depending on the values. Signals can also be generated by a single source (scalar) or multiple sources (vector).
Sources:
1) Digital Signal Processing: A computer-based Approach (Sanjit K Mitra) McGrawHill
Topics: Digital Signal Processing |
One Response to “Signals & Signal Processing”
Comments
April 17th, 2008 at 3:40 pm
I would have argued that black and white image was a function of 3 variables, x, y and intensity/chroma/luminence/whatever gives the image discernable differences in the dots (otherwise all you get is a grey/black/white uniform blank wall). In order to see if I was right I clicked the links, but they do not lead to the information directly and I am not buying the book to find out.
I am not bothered if the Engineers say it is 2 not 3 dimensional, I am just writing to suggest you add target=”_blank” to the URL so as to stop the link removing your site, if someone deletes the window in annoyance at not being taken to the information they might expect, at least they will be brought back to your site for another read of something else, increasing the chances they might see an Adsense Ad that they like and click on it.