What is Signal

A signal is a function that conveys information about the state or behavior of a physical system or variable. Example:- A speech signal, An ECG, a Stock Price, An Image.

Classification of Signals Based on Nature of Variables

• Continuous Time (CT) Signals:

  → Independent variable (usually time) is continuous.

  → Signal is defined for all time within an interval

  

• Discrete-Time (DT) Signals:

  → Independent Variable is discrete

  → Signal is defined only for the discrete value of time.

  

What is System and Signal Processing

• System → A system may be defined as a physical device that operates on a signal
• Signal Processing → The operation performed on the signal is signal processing.
  • Example → Filter used to reduce the noise and the interference corrupting the information-bearing signal → ****Filter is the system and filtering is the signal processing.

Implementation of DSP

To implement DSP we must be able to perform A/D & D/A conversions.

flowchart LR
  A[Analog Signal] --> B{{Sampling}} --> C[Digital Signal] --> D{{DSP}} --> E[Digital Signal]

flowchart LR
  A[Digital Signal] --> B{{DSP}} --> C[Digital Signal] --> D{{Reconstruction}} --> E[Digital Signal]

Example → Digital recording and playback of music (signal) is sensed by microphones, amplified, converted to digital, processed, and converted back to analog to be played.

Why Do You Need DSP

Many signals in nature are analog, we need additional A/D and D/A components for DSP. Why do we do it?

Because

• Digital Systems can be reprogrammed for other applications / ported to different hardware.
• Reconfiguring Analog System means hardware redesign, testing, verification
• DSP provides better control of accuracy requirements.
• Digital Signal can be easily stored without deterioration.