Palpation
Keying is a temporary switching on or off of an electric current. This can also take place during the higher-level operation of an electrical device. Keying can also be rewritten by switching to a certain time or under certain conditions . In signal processing, keying can also affect more complex electrical or electronic relationships or states.
Keying can be done mechanically, for example with the aid of a button , or electromechanically, such as with a relay , or electronically: With a square-wave generator , the operating voltage is periodically switched on and off; one speaks here of duty cycle .
Difference between switching and keying
Differentiation is made between switching and keying. The terms are also mixed up in common parlance. If a precise scientific understanding is important, then a distinction is necessary. If z. B. If someone turns on the light with a switch, it stays on until the switch is pressed again. With a button, on the other hand, the light is only pressed in and goes out as soon as you let go of the button. Strictly speaking, a relay is a button and not a switch, since it returns to its original position after the control current has been switched off. In contrast, the impulse relay is clearly a switch .
Keying a transmitter
Keying of a transmitter means the transmission of interrupted high-frequency pulses in the rhythm of Morse code . Keying per se is not yet referred to as modulation, but there are keyings in digital modulation that are referred to as modulation, such as phase shift keying .
Individual evidence
- ↑ Werner W. Dieffenbach: "Transmitter for radio sports and remote control", Jakob Schneider Verlag