14
SUBAUDIBLE TONE (CTCSS) FEATURES
Subaudible tones, also known as CTCSS (Continuous Tone-Coded
Squelch System) are low-frequency tones that are mixed with a transmis-
sion. They are used by many repeaters to limit interference 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-212 includes all 38 standard subaudible tones. You can set your
HTX-212 to include any of these tones with your transmissions. You can
also set the your HTX-212 to limit reception to only those transmissions
that include the selected tone.
REPEATER OPERATION
Operation through a repeater, where you transmit on one frequency and
receive on another, is called duplex operation. Operation direct to another
station where you transmit and receive on the same frequency is called
simplex operation.
A repeater is a station that receives a signal on one frequency (the input
frequency) and then retransmits that signal on a different frequency (the
output frequency). Repeater antennas are typically located 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 frequen-
cies. Repeaters are usually identified by their output frequency. Thus, a
repeater that has an output frequency of 146.94 is referred to as the
146.94 repeater. To determine the input frequency you must know the fre-
quency offset (600 kHz for the 2-meter band) and the offset direction (+ if
you add 600 kHz to the output or – if you subtract 600 kHz from the out-
put).
Your HTX-212 is programmed with the default 600 kHz frequency offset
and direction for the 2-meter band. When you tune to a frequency that is
normally assigned for repeater use, the HTX-212 automatically selects the
correct input frequency. See “Frequency Offset Defaults” on Page 26.
MEMORY CHANNELS
Your HTX-212 has 31 memory channels (30 standard memory channels
and one calling-frequency memory channel). Each memory 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. You cannot store non-amateur frequencies in mem-
ory.
19-1125.fm Page 14 Tuesday, August 3, 1999 9:47 AM
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