Applications of Signals and SystemsApplication AreasControl ApplicationsCommunication ApplicationsModulationSlide 6Digital ModulationSignal Processing ApplicationsMultimedia ApplicationsJPEG ExampleBiological Signal AnalysisExampleBiometricsAudio Signal ProcessingFiltering ExampleApplications of Signals and SystemsFall 2002Application Areas•Control•Communications•Signal ProcessingControl Applications•Industrial control and automation (Control the velocity or position of an object)•Examples: Controlling the position of a valve or shaft of a motor•Important Tools: –Time-domain solution of differential equations–Transfer function (Laplace Transform)–StabilityCommunication Applications•Transmission of information (signal) over a channel•The channel may be free space, coaxial cable, fiber optic cable•A key component of transmission: Modulation (Analog and Digital Communication)Modulation•Analog Modulation: Transmitting audio signals.•Advantage: Higher frequency range good propagationXX ( t )L o c a l O s c i l l a t o rA x ( t ) c o s ( w t )Modulation•Frequency Modulation (FM), modulate the angle of the carrier. •Advantage: More robust to interferenceDigital Modulation•Used in CDs, digital cellular service, digital phone lines and computer modems.•Advantages: –Can be encrypted–Electronic routing of data is easier–Digital storage faster–Multimedia capabilitySignal Processing Applications•Signal processing=Application of algorithms to modify signals in a way to make them more useful.•Goals:–Efficient and reliable transmission, storage and display of information–Information extraction and enhancement•Examples: –Speech and audio processing–Multimedia processing (image and video)–Underwater acoustic–Biological signal analysisMultimedia Applications•Compression: Fast, efficient, reliable transmission and storage of data•Applied on audio, image and video data for transmission over the Internet, storage•Examples: CDs, DVDs, MP3, MPEG4, JPEG•Mathematical Tools: Fourier Transform, Quantization, ModulationJPEG Example 43K 13K 3.5K•JPEG uses Discrete-Cosine Transform (similar to Fourier Transform)Biological Signal Analysis•Examples:–Brain signals (EEG)–Cardiac signals (ECG)–Medical images (x-ray, PET, MRI)•Goals: –Detect abnormal activity (heart attack, seizure)–Help physicians with diagnosis•Tools: Filtering, Fourier TransformExample•Brain waves are usually contaminated by noise and hard to interpretBiometrics•Identifying a person using physiological characteristics•Examples:–Fingerprint Identification–Face Recognition–Voice RecognitionAudio Signal Processing•Active noise cancellation:Adaptive filtering–Headphones used in cockpits•Digital Audio Effects–Add special music effects such as delay, echo, reverb•Audio signal separation–Separate speech from interference–Wind sound from music in carsFiltering