In telecommunications, attack-time delay is the time needed for a receiver or transmitter to respond to an incoming signal.
[1] If a squelch circuit is operating, the receiver attack-time delay includes the time for the receiver to break squelch.
For a transmitter, the attack-time delay is defined as the interval from the instant the transmitter is keyed-on to the instant the transmitted radio-frequency signal amplitude has increased to a specified level, usually 90% of its key-on steady-state value.
[1] The transmitter attack-time delay excludes the time required for automatic antenna tuning.
This article incorporates public domain material from Federal Standard 1037C.