This document provides an introduction to signals for a presentation. It begins with welcoming the audience and introducing the presenters. It then defines what a signal is and describes the main types as analog and digital. It provides examples and classifications of different analog and digital signals. It discusses continuous and discrete time signals. It also includes block diagrams of analog and digital signal processing and defines signal to noise ratio. It concludes by comparing the advantages of analog versus digital signals.

1. Welcome
TO OUR PRESENTATION

2. Submitted to:
Fahmida Hossain Tithi
Assistant Professor
Department of EEE
Daffodil International University
Nahida Sultana 143-33-2135
Uzzal Hossain 143-33-2287
Parag Rahman 143-33-2269 Sadequr Rahaman
143-33-2268
Tariqul Islam 143-33-2283

3. What is Signal ?
A signal is an electrical or electromagnetic current that is
used for carrying data from one device or network to another.

4. Main signal are two types :
1) Analog signal
2) Digital Signal

5. Analog Signal
An analog signal is a continuous wave denoted by a sine
wave and may vary in signal amplitude or frequency .

6. Examples of Analog Signals :
■ Human Voice – best example
■ Ear recognises sounds 20KHz or less
■ AM Radio – 535KHz to 1605KHz
■ FM Radio – 88MHz to 108MHz

7. Types of analog signal
■ DC Signal
■ Time Domain Signal
■ Frequency Domain Signal

8. DC Signal
DC are also used when referring to voltages and
electrical signals which are not currents

9. Time domain signal :
■ In the time domain, the signal or function's value is known for all
real numbers, for the case of continuous time or discrete time.

10. Digital signals
■ Represented by Square Wave
■ All data represented by binary values
■ Single Binary Digit – Bit
■ Transmission of contiguous group of bits is a bit stream
■ Not all decimal values can be represented by binary

11. Types of Digital signal
■ ON-OFF signal
■ Pulse Train signal

12. ON-OFF signal
On-off keying (OOK) denotes the simplest form of amplitude-shift
keying (ASK) modulation that represents digital data at the
presence or absence of a carrier wave .

13. Pulse Train signal
Pulse train is a kind of non-sinusoidal waveform that is similar to a square
wave, but does not have the symmetrical shape associated with a perfect
square wave.

14. Classification of Signals
There are several classes of signals :
 Continuous time and discrete time signals
 Real and Complex signals
 Periodic and aperiodic signals
 Even and Odd Signals
 Energy and power signal

15. Continuous time and discrete time
signals
■ Continuous signals : signal that is specified for a continuum (ALL) values time t
can be described mathematically by continuous
■ function of time as :
■ x(t) = A sin (0 t + )
■ Discrete time signals : signal that is specified only at discrete values of t

17. Analog signal processing
The analog signal processing is basically, filtering of the signal . It can be denoted
by the following diagram

18. Digital signal processing-Block
diagram
The digital signal processor consists of anti-aliasing filter, analog to
digital converter (ADC), a digital filter represented by the transfer
function H(z), a digital to analog converter and a reconstruction filter.

19. Signal to Noise
■ The signal to noise ratio is given by
■ The signal to noise in dB is expressed by
■
PowerNoise
PowerSignal
N
S













N
S
N
S
dB 10log10
dBmdBmdB NS
N
S






for S and N measured in mW

20. Analog vs. Digital
Analog Advantages
■ Best suited for audio and video
■ Consume less bandwidth
■ Available world wide
■ Less susceptible to noise
Digital Advantages
■ Best for computer data
■ Can be easily compressed
■ Can be encrypted
■ Equipment is more common and less expensive
■ Can provide better clarity

21. Thanks
TO All