48 TMAA02-02 DTMF Microphone TM8000 Mobile Radio Accessories Manual
March 2004 © Tait Electronics Limited
4.1.2 Installing the Microphone Clip
Install the microphone clip in the most convenient location for the radio
user. It must be within easy reach of the user, but in such a position that the
microphone PTT key cannot be inadvertently activated or jammed on.
Connect the microphone clip to the negative supply if hookswitch
operation is required.
4.2 Adjustment
Remove the DTMF microphone back cover and set the DTMF tone level
to approximately 80% deviation (±4kHz for wide bandwidth radios and
±2kHz for narrow bandwidth radios).
4.3 Radio Programming
The following table shows the settings required for CH_GPIO1 in the
Programmable I/O form of the TM8000 Programming Application. This
setting means that when a key is pressed on the microphone, the DTMF
tones are fed into the radio’s speaker at a reduced volume, giving the radio
user confidence that the tones are being transmitted. Refer to the online
help of the programming application for more information.
4.4 Interface Specification
The following table and diagram summarizes the signals used for the DTMF
microphone on the radio’s microphone connector and shows the interface
between the DTMF microphone and the radio.
Table 4.1 DTMF microphone settings in the Programmable I/O form, Digital tab
Pin Direction Label Action Active Debounce Signal State Mirrored To
CH_GPIO1 Input None Send Mic Audio
To Spkr
High None None None
Table 4.2 DTMF microphone connector - pins and signals
Pin Signal Colour Description
1 ——not connected
2 13V8_SW red power supply (switched)
3 — yellow not connected
4 MIC_PTT black PTT and hookswitch
5 MIC_AUD white audio from the microphone
6 AGND blue analogue ground
7 ——not connected
8 MIC_GPIO1 green mute out
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