Tait TM8000 Series, Руководство по применению

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60 Programmable I/O Lines TM8000 3DK Hardware Developer’s Kit Application Manual
September 2003 © Tait Electronics Ltd
3.1.17 Force Audio PA On
Application
This input signal is used to activate the audio PA. This action is required to
allow any audio on the RX_BEEP_IN line of the internal options
connector to be heard from the speaker when no other audio unmute
conditions exist.
Configuration
Configure an input line and associate it with this action. Set the active state
(high or low) and the debounce time (0 to 100ms).
Timing
When this input line is activated and the audio PA is off, there will be a delay
of 50ms before audio PA output is unmuted. This delay prevents undesired
transient noise (audible ‘pop’) caused by the audio PA powering up. If the
audio PA is already on or there has been speaker audio within 100ms prior
to activation there is no significant unmute delay.
Description When this input line is activated, the radio unmutes the audio PA. If the
audio PA is already unmuted, no action occurs. If a higher priority mute
condition exists, activation of this line will have no effect.
When this input line is deactivated, the audio PA reverts to its previous state.
If a higher priority unmute condition exists, deactivation of this line will
have no effect.
If the input line is active while the radio is powered up, it must be re-applied
for the action to be carried out.
Related Actions
A related ‘ Force Audio PA Off ’ input signal exists, for which another input
line can be assigned. Separate input lines are needed because deactivation of
each line should release the corresponding action rather than forcing the
audio PA into the opposite state.
The ‘ Mute Audio Output Path ’ input signal activates the Rx audio path
only.
The ‘ Unmute Audio Output Path ’ input signal deactivates the Rx audio
path only.
Figure 3.8 Force Audio PA on/off
RX processing chain mute
audio PA
vol speaker
RX_BEEP_IN
Force Audio PA
on/off
audio tap points
(on AUD_TAP_OUT)
RX_AUD
Rx audio path
beep audio path