Examples of Signal

A/D and D/A Conversions转换

Time Domain  vs.  Frequency Domain

What DSP Does

Signals

      Voltage,   Current,   Air Pressure,   Temperature,

       Sound,  Image,  Movie,...    

Whale Song  (鲸鱼叫声)

(Courtesy Michael Noonan, Ph.D., Canisius College)

Nozzle Stream (射流) (Images copyright Vision Research, Inc., Wayne, N.J., USA; created using Personal AVI Editor)

Breaking Bulb (Copyright Vision Research, Inc., Wayne, N.J., USA)

A/D

Sampling采样,  Holding保持, Quantification量化,  Coding编码

          ...    001   101   110   100   110   001   011   ...

D/A

Decoding解码,   Holding,   Smoothing平滑

Wave波    Vs.   Spectrum谱

Filtering滤波

  Enhancement增强, Restoration还原, Reconstruction重构

     Estimation估计 & Prediction预测, Synthesis合成 ...

        Low Pass,     Band Pass,     High Pass,      Band Stop

   Low pass filter, cut-off  at 456 Hz,  applied to the CEG chord

   Low pass filter, cut-off  at 361 Hz,  applied to the CEG chord

   Low pass filter, cut-off  at 296 Hz,  applied to the CEG chord

2D Low Pass Filter  Blurs模糊 an Image.

2D High Pass Filter  Emphasizes突出 Edges.

                      Equivalent Analog System

            PreFilter: Anti-aliasing filtering

            PostFilter: Smooth out the staircase waveform

Advantages

       Developed Using Software on Computer

       Working Extremely Stable

       Easily Modified in practice

       Low Cost and Portable

Disadvantages

       Lower Speed and Lower Frequency

Signal Analysis:

      Measurement of signal properties

      Spectrum(frequency/phase) analysis

      Target detection, verification, recognition

Signal Filtering

      Signal-in-signal-out, filter

      Removal of noise/interference

      Separation of frequency bands