In
telecommunications
Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...
, attack-time delay is the time needed for a
receiver or
transmitter
In electronics and telecommunications, a radio transmitter or just transmitter (often abbreviated as XMTR or TX in technical documents) is an electronic device which produces radio waves with an antenna (radio), antenna with the purpose of sig ...
to respond to an incoming signal.
For a receiver, the attack-time delay is defined as the
time interval
Time is the continuous progression of existence that occurs in an apparently irreversible succession from the past, through the present, and into the future. It is a component quantity of various measurements used to sequence events, to compa ...
from the instant a
step radio-frequency signal
Radio waves (formerly called Hertzian waves) are a type of electromagnetic radiation with the lowest frequencies and the longest wavelengths in the electromagnetic spectrum, typically with frequencies below 300 gigahertz (GHz) and wavelengths g ...
, at a level equal to the receiver's threshold of
sensitivity, is applied to the receiver input, to the instant when the receiver's output
amplitude
The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...
reaches 90% of its
steady-state value.
[Federal Standard 1037C] If a
squelch circuit
In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver in the absence of a strong input signal. Essentially, squelch is a specialized type of noise gate designed to suppress weak s ...
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.
[ The transmitter attack-time delay excludes the time required for automatic antenna tuning.
]
See also
*Transmit-after-receive time delay
In telecommunications, transmit-after-receive time delay is the time interval from removal of RF energy at the local receiver input until the local transmitter is automatically keyed on and the transmitted RF signal amplitude has increased to 90% ...
* Receive-after-transmit time delay
References
{{FS1037C MS188
Telecommunications engineering
Radio technology