INTEROPERABILITY NOW
5-1
5
System Troubleshooting
5.1
System Troubleshooting
This section provides some hints to optimization of ARA-1 setup based on system operation
symptoms.
These symptoms include:
•
Missed first syllables
•
Missed syllables in mid-conversation
•
Ping pong (cross-connected radios key and unkey repeatedly after the end of an intended
transmission)
•
False keying (inappropriate keying due to noise)
5.2
Missed First Syllables: Radio Side
If the users on the radio-system end of an ARA-1 conversation regularly miss the initial syllables
of messages from the network, it is likely that the TX audio delay setting of the ARA-1 must be
increased. There are two probable causes:
•
A trunked radio system
•
Network VOX or VMR function is not optimized in a system that is not trunked
A trunked radio system is the most common and most obvious example of this condition because
of the time it takes a trunked radio to acquire an open channel. See Section 5.6 for a full
explanation.
If the radio system is not trunked, the missed syllables could be caused by a Network VOX or
VMR function that is not optimized. In this case, it may still be that the TX audio delay should
be increased in order to give the function enough time to detect the existence of valid audio.
Alternatively, it could be that the Network VOX or VMR threshold needs to be made more
sensitive. Adjustments may be required to both settings. If the sensitivity is set too high, it is
likely that the radio listener will also hear dropouts in the middle of a message, rather than only
at the beginning. See Section 5.3. Attempt to rectify first by optimizing the threshold setting.
NOTE:
The
Radio TX Audio Delay
must never be set below 200 milliseconds
when VOX or VMR are used to gate the audio coming in from the network side.
Clipping of the first syllables of any spoken message is very likely to occur with
lower delay settings.