CTCSS
- continuous
tone coded squelch. This is a subaudiable
tone that allows the radio or
scanner’s squelch to be opened.
These tones range from 67 Hz to 255 Hz.
The tone is filtered out
on certain equipment and is not heard; to
less expensive scanners it can be heard
as a light buzzing noise.
A specific tone can be selected so only
users or certain repeaters can be heard.
This is useful if there
is another user on the same frequency but
not a user you wish to hear. In radio
monitoring a CTCSS tone
serves as way of identifying the user of
a frequency with two or more separate
users. Example: Rescue Squads
for county A and county B use the same
frequency, with the exception of the
CTCSS tone frequency.
You can identify if it is county A or
county B by the CTCSS tone. DCS –digital coded squelch. An
encoded 3 digit digital signal is
transmitted to allow the squelch to be
broken.
This digital burst can be heard sometimes
at the end of the transmission. The
squelch tail at the end of transmissions
is completely eliminated when using this
type of squelch. DCS offers more
combinations than CTCSS.
See http://mmi-comm.tripod.com/dcs.html for technical details on DCS.
DTMF – dual tone
multi-frequency. Two combined audible
tones that are used to access
different functions on radio networks.
Radios also have A, B, C, and D.
Example:
Telephone Keypad.
Click here for a list of the
actual CTCSS frequencies
as well as DTMF and DCS
designator codes. |
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