introduction:From 2004, the following requirements for access by CTCSS became mandatory for all new repeater applications (including changes) 1750Hz tone burst access, to the previous standard, is still permitted in addition to CTCSS.
access:The repeater must not be carrier accessed directly from "cold" and adequate immunity must be provided against access by speech or noise.
Initial access shall, as a minimum, be by a carrier modulated with a CTCSS tone of the frequency stated on the Notice of Variation.
The CTCSS detector for this purpose, should respond to only that tone, when it is present for less than 1 second at a deviation of 10% or less of the appropriate maximum i.e. +/-500Hz for 25kHz units and +/-250Hz for 12.5kHz units.
In addition, but optionally, access may be by a tone "burst" of 1750Hz plus or minus 25Hz at a deviation of 50% or less. The acceptance time of the tone between 200 and 400ms.
The repeater once accessed, must radiate the same CTCSS tone at nominal level of 10% of maximum. I.e. +/-500Hz for 25kHz units and +/-250Hz for 12.5kHz units.
re-access:Once the repeater has been accessed, subsequent control of talk-through should normally be by carrier alone, unless CTCSS-only access has been requested by the Keeper.