User manual

User Manual PM200
Page 11
English
Squelch Options
The radio supports 3 kinds of Squelch options. A different Squelch option can be applied to each
channel. Sub Audible Tone (SAT) codes are made up from frequencies which are below 300Hz.
These frequencies are lower than the voice audio band. The two most common forms of SAT
codes are CTCSS, Continuous Tone Coded Squelch System, and DCS, Digitally Coded Squelch.
CTCSS / DCS information may be added to speech during transmission. A receiving radio can then
be programmed to behave according to which tones or codes are being sent by a transmitting
radio.
The PM200/250 radios are capable of generating all 38 standard CTCSS tones and can also
generate the 83 standard DCS codes and 83 inverted DCS codes.
CTCSS
38 kinds of TIA/EIA Standard CTCSS tones can be set up. All tones can be set up using the PC
Programmer.
TX Operation: If PTT key is pressed, the radio transmits a programmed CTCSS tone.
RX Operation: If CTCSS tone is detected, the radio status is changed from Busy to Correct Call.
If the CTCSS Tone is not detected, the radio would stay in busy mode or change from Correct
Call to Busy mode.
DCS
The radio supports 83 kinds of TIA/EIA Normal/Inverted DCS codes.
TX Operation: If PTT key is pressed, the radio transmits a pre-programmed DCS Bit pattern.
RX Operation: If DCS Data Stream is detected, the radio status will change from busy mode to
Correct Call. If DCS Data Stream is not detected, the radio will stay in busy mode or be changed
from Correct Call back to busy mode.
Squelch Defeat (Monitor) operation
Basic Radio Operation
Pressing the monitor key will open the squelch and switch on the loudspeaker. Everything on the
channel, including FM noise, will be heard.
It is possible to disable the monitor key via the programmer, to prevent a user openly monitoring
a channel in a closed user group system.
When using CTCSS or DCS controlled squelch, several user groups may use the same RF channel
without overhearing the other groups. It is common practice to allow users to listen to a channel
before placing a call. This allows the user to check they are not going to transmit over a
conversation from another user group.
This allows more efficient use of the RF channels available.