User guide

13.5 Transmitting a Signal
• Press and hold the PTT - button 12 to transmit. The TX symbol is
displayed.
• Hold the unit in a vertical position with the microphone 10cm from the
mouth and speak into the microphone.
• Release the PTT - button 12 when you want to stop transmitting.
13.6 Changing Channels
• Press the - button 7 once, the current channel number flashes on the
display.
• Press the - button or the - button 10 to change the channel.
• Press the PTT - button 12 to confirm and return to stand-by mode.
13.7 CTCSS (Continious Tone Coded Squelch System) /
DCS (Digital Coded Squelch)
License free PMR radio's operating on the 446 MHz frequency band, like the
MTD90 PMR, have 8 available radio channels. If there are many PMR users
in your neighborhood, there is a chance that some of these users are
operating on the same radio channel.
To prevent that you receive signals from other users, sub-channels have
been integrated. Two PMR radio's will only be able to communicate with
each other when they are operating on the same radio channel and when
they have selected exactly the same sub-channel.
There are two kind of sub-channels :
• Continuous Tone Coded Squelch System (CTCSS)
• Digital Coded Squelch (DCS)
When using CTCSS, a low frequency tone (between 67 and 250 Hz) will be
transmitted along with the voice signal. There are 38 available tones to
choose from. You are free to choose one of these 38 available tones. Due to
filtering, these tones will generally not be audible so they will not disturb the
communication.
DCS is similar to CTCSS, but instead of sending a continuous tone of a
selected frequency, a digital data transmission is added to the radio signal.
This Digital Code is transmitted at a really low rate, around 134 bits per
second (the code is 23 bits long). Only the PMR's of the latest generation will
support DCS. There are 83 available DCS codes that can be used. Since
earlier models will only support CTCSS it will be better to use DCS to
To check the channel activity use the monitor function
(See chapter “13.8 Monitor”).
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MTD90
LICENCE FREE 2-WAY RADIOS
If no button is pressed within 5 seconds during setting, the unit will
return to standby.