Purpose of Signals

Electronic signals move information much like cars move passengers down the highway. It would be difficult to get to work without transportation, and there would be no transportation with out signals.

Signals allow devices (e.g. sensors or switches) to communicate with control modules (either complicated processors or simple relays) which in turn perform or request (through more signaling) other functions to be carried out.

Signals inform the Climate Control of the outside air temp or tell the brake lights the right time to illuminate.

The use of electronic signals goes far beyond the basic application of electron flow to control components, enabling complex information to be passed from one component to another.

The data (input or output) is conveyed through various forms of changing voltages, resistances, current or frequency modulation.

1. AC Voltage Signals:
   1. Inductive Signals.
   2. Phase Shifted Signals.
   Fig 1: Identifying AC Voltage Signals

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2. DC Voltage Signals:
   1. Analog Signals.
   2. Digital Signals:
      1. Switched (High/Low) Signals.
      2. Modulated Square Wave Signals:
         1. Frequency Controlled Signals.
         2. Pulse Width Controlled Signals.
         3. Duty Cycle Controlled Signals.
   3. Designated Value Signals.
   4. Coded Ground Signals.
   5. Transistor Signals:
      1. Modulated B+/B- Signals.
      2. Momentary B+/B- Signals.
      3. Constant B+/B- Signals.
         Fig 2: Identifying DC Voltage Signals

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