Operating instructions

LOCAL OPERATION
3-77
CTCSS
The CTCSS tones system uses a continuous tone at a precise frequency, transmitted below the
audio pass band, to unsquelch the receiver.
Fig. 3-24 RF CTCSS encoder screen and menu
Pressing the [CTCSS] key on the TONES selection screen will display the screen shown in
Fig 3-24, RF CTCSS encoder screen and menu.
The CTCSS function of the Service Monitor will generate a single AF tone, selected from those
listed on the display.
Output level
The required output level of the tone signal can be set using the data entry keys, after highlighting
the legend
Tone Level: by pressing the [Tone Level] key.
The units used to specify the output level will relate to the selected output routing and, when RF
output is selected, the modulation method. The modulation type is automatically set, to be
appropriate to the level terminator key used (FM for Hz, kHz or MHz; AM for %).
The valid output range for each output option is shown in the following table.
Output type Output range Default
RF AM 0 - 99% 30%
RF FM 0 - 75 kHz 1.5 kHz
Audio
100 µV - 4 V
100 mV
Tone selection
The required tone is selected from the table in the lower part of the display. Press the
[Select Tone] key to highlight the legend
Tone No:. Use the data keys to enter the number of the
required tone, then press the [ENTER] key.
Tone frequency shift
The frequency of the selected tone can be shifted by up to ±10%. Press the [Freq Shift] key to
highlight the legend
Frequency Shift:. Use the data keys to enter the value of frequency shift
required. Only whole numbers within the above range are valid. Complete the entry with the [%]
key.