Leo Lam © Signals and Systems EE253 Leo Lam

Leo Lam © Today’s menu Introductions Class logistics and expectations Help available Course material starts!

Leo Lam © Introduction Who is this bozo? – –Anonymous message welcome –Office: 253D Performance guarantee –12-hour response –Reasonable Five questions!

Leo Lam © Introduction TA: Chris Mandic – –Office hours: TBD –MATLAB wiz

Leo Lam © Introduction You!

Goal Introduction to the “language” of “signals” Manipulating the language (the “system”) Using MATLAB to play with it Preparation for DSP etc. System level thinking Engineering “sense” Communicating with each other technically Discipline in practicing engineering Leo Lam ©

Logistics Four lectures One lab per week Lab begins this week (need EE account) Grading –60% consistent work –40% “exams” (1 week-5 midterm/1 Final) –Fair, consistent, not “mean” Textbook: Not required, but recommended Website: wp.ee.washington.edu/ee235sum2011/ Pre-req: Math 136,307,Amath 351, PHY 122 or CSE 142 etc.

Leo Lam © Expectations Active, curious, question Work together No cheating! Lab (six labs) –Read the manual –Communicate clearly –Collaborate

Leo Lam © Help? GoPost – Your learning social media Me and TA (office hours) Each other (and meet new friends!) HKN help for 215, 233, 235 (may not be available in the summer)

Leo Lam © Questions? Before the launch…

Examples of a “signal”? Electrical parameter over time Radio over time and space Sound/Pressure over time Medical parameters over time Images Video Stock prices (discrete time) People in a room daily (discrete variable/time) Leo Lam ©

Definition: Signal A signal is a set of information or data that can be modeled as a function of one or more independent variables. Leo Lam ©

There’s a theme here Continuous time Continuous variable e.g. talking to you Continuous time Discrete Variable e.g. people in the room Discrete time Continuous variable e.g. daily temperature Discrete time Discrete variable e.g. data recorded on CD Leo Lam ©

Taking a signal apart Leo Lam © a0a0 T t (seconds) A+a 0 A sound signal Offset (atmospheric pressure) Frequency Amplitude

Frequency Leo Lam © t (seconds)f (Hz) = time-domainfrequency-domain

t to f Leo Lam © t (seconds) F (Hz)

Combining signals Leo Lam ©

Summary: Signals Signals carry information Signals represented by functions over time or space Signals can be represented in frequency domain Signals can be summed in both time and frequency Leo Lam ©

Systems A system describes a relationship between input and output Examples? Leo Lam © v(t)y(t)g(t)

Definition: System A system modifies signals or extracts information. It can be considered a transformation that operates on a signal. Leo Lam ©

Motivation: Complex systems Leo Lam ©

Filters All kinds, and everywhere Leo Lam ©

Surprising high pass Leo Lam ©

Today What is a signal What is a system Some examples Leo Lam ©