Motorola ASTRO Digital Spectra, Instruction Manual

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6881086C22-B 87
Appendix A - Cross Patch Configuration
Audio Degradation Issues
The Consolette Cross Patch Interface is a base band audio interface that can be used to interconnect the following:
• Analog to Analog systems
• Digital to Analog systems
• Analog to Digital systems
• Digital to Digital systems
Analog to analog patch systems should experience no audio degradation since there are no vocoders in the system.
The audio will not be degraded in the digital to analog or analog to digital patches since the voice audio is only
vocoded once. The digital to digital patches will experience degraded audio. The repeated voice will not be as
intelligible as the original digital audio. The voice audio that passes through the patch is vocoded twice, and therefore
isn’t quite as sharp as the original. The small artifacts of the first vocoding are amplified and added to by the second
vocoding. The net result is voice that isn’t as intelligible as the high quality first vocoding. The voice has some audio
aberrations, but mainly it’s harder to understand what is being said. The degree of intelligibility loss varies with the
type of vocoder. Field experience has shown that VSELP is affected more than IMBE, but both are degraded from
the original message.
When using the Cross Patch, you may exceed the
duty cycle rating of the Consolette. If this condition
is expected, the customer may want to reduce the
RF power output of the Consolette.
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C a u t i o n