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Subaudible Tone (CTCSS) Features
Subaudible tones, also known as CTCSS (Continuous Tone-Coded
Squelch System) are low-frequency tones that are mixed with a
transmission. They are used by many repeaters to limit interfer-
ence from other nearby radio transmitters. When a repeater uses a
subaudible tone, it does not react to any transmission that does
not include that tone.
Your HTX-242 includes all 38 standard subaudible tones. You can
set your HTX-242 to include any of these tones with your trans-
missions. You can also set your HTX-242 to limit reception to only
those transmissions that include the selected tone.
Repeater Operation
Operation through a repeater, where you transmit on one fre-
quency and receive on another, is called
duplex
operation. Opera-
tion direct to another station where you transmit and receive on
the same frequency is called
simplex
operation.
A repeater is a station that receives signals on one frequency (the
input
frequency) and then retransmits them on a different fre-
quency (the
output
frequency). Repeater antennas are typically at
the tops of tall buildings or on antenna towers, so a relatively low-
power signal can reach the repeater. The repeater retransmits the
signal at a higher power. This gives users of low-power transceivers
the ability to communicate over a much greater range.
To use a repeater, you must know the repeater’s input and output
frequencies. Repeaters are usually identified by their output fre-
quency. Thus, a repeater that has an output frequency of 146.94 is
referred to as the 146.94 repeater. To determine the input fre-
quency you must know the frequency
offset
(600 kHz for most of
the 2-meter band) and the
offset direction
(+ if you add 600 kHz to
the output, or – if you subtract 600 kHz from the output).
Your HTX-242 is programmed with the default 600 kHz frequency
offset and direction for the 2-meter band. See “Frequency Offset
Defaults” on Page 25. When you tune to a frequency that is nor-
mally assigned for repeater use, the HTX-242 automatically selects
the correct input frequency if you turned on the AS option.
Memory Channels
Your HTX-242 has 41 memory channels (40 standard memory
channels and one calling-frequency memory channel). Each mem-
ory channel can hold a transmit and receive frequency, subaudible
transmit and receive tones, the transmit power level, and whether
subaudible tone transmit and squelch are on or off. The HTX-242
can even scan a selected range and automatically store active fre-
quencies in unused memory locations.
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