User's Guide

Advanced Features
English
43
MDC Over-the-Air Rekeying (OTAR) Page
This feature allows to view or define MDC Over-the-Air
Rekeying (OTAR) features.It is applied only when operating in
secure encrypted mode and only for conventional
communications. In additional to Rekey Requests, OTAR
transmissions include Delayed Acknowledgements, and Power-
up Acknowledgements.
Some of the options selected may also need to be set up at the
Key Management Controller (KMC) site to work properly.
Note: This feature must be preprogrammed by a qualified
radio technician. Check with your dealer or system
administrator for more information.
Hear Clear
There are two components of Hear Clear.
1 Companding:
Reduces the channel noise, e.g. OTA transmission, that is
predominantly present in UHF2 and 900 MHz channel with
the following features.
• Compressor – reduces the background noise flow and the
speech signal at transmitting radio.
• Expander – expands the speech while the noise flow
remains the same at receiving radio.
2 Random FM Noise Canceller (Flutter Fighter):
Reduces the unwanted effects of random FM noise pulses
caused by channel fading under high Signal-to-Noise (S/N)
conditions such as in a moving in a transportation. The fading
effects, heard as audio pops and clicks, are cancelled without
affecting the desired audio signal.
The Random FM Noise Canceller operates only in receive
mode.
Note: This feature must be preprogrammed by a qualified
radio technician. Check with your dealer or system
administrator for more information.
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APX_7000_TopD.book Page 43 Wednesday, November 2, 2011 5:31 PM