The telecommand can be done in real time or not depending on the circumstances (in space, delay may be of days), as was the case of Marsokhod.
[1] For a Telecommand (TC) to be effective, it must be compiled into a pre-arranged format (which may follow a standard structure), modulated onto a carrier wave which is then transmitted with adequate power to the remote system.
Based on the change in electrical resistance, the integrated circuit distinguishes which button was pushed and sends a corresponding binary code to the light-emitting diode (LED) usually located at the front of the remote.
[3] The strength of the transmitting LED can vary and determines the required positioning accuracy of the remote in relevance to the receiver.
Inventor Robert Adler is known for inventing the remote control which did not require batteries and used ultrasonic technology.