Editing Pilot signal (section)

=== Cable ===
In cable service plant infrastructures, two or more pilot frequencies are used to allow network amplifiers to automatically adjust their gain over temperature swings. This is done by the amplifiers having special circuitry that track the frequencies in order to maintain a consistent gain. Without this capability, network amplifiers may drive the signal too strongly or weakly, thus requiring constant adjustment. Pilot frequencies can be generated by an agile modulator, taking the space of analog NTSC channels, or by dedicated equipment.  Sometimes it is necessary to employ several independent pilot frequencies. Most [[radio relay]] systems use radio or continuity pilots of their own but transmit also the pilot frequencies belonging to the [[Carrier wave|carrier frequency]] multiplex system.