4RF Aprisa XE User Manual page 75

Modem Mute Mode
The Aprisa XE radio always mutes its interface ports when the modem loses lock.
The Modem Mute feature mutes its interface ports when the modem Reed Solomon forward error
correction capability can no longer correct errors.
This can occur when the signal strength of the RF link reduces to within about 2 dB of the theoretical
sensitivity of the radio or when the radio is operating well above the sensitivity threshold but is in an
environment subject to impulse noise interference on the RF path.
When the mute activates;
On the analog cards, Q4EM, DFXS and DFXO, the audio path mutes and the signalling states go
idle.
On the digital cards, QV24 and HSS, it causes an all ones data pattern to be driven on the RXD
output line and handshake lines such as RTS / CTS to their off states while on the QJET card it
forces the ports to an AIS state.
The Modem Mute feature effectively reduces the radio receiver sensitivity by 2 to 3 dB from its published
values but will prevent errors from corrupting the tributary audio circuits.
Modem Mute Time
The Modem Mute Time determines the time the mute will persist after the last uncorrectable block is
received. This can be set from 0 to 10 seconds in 0.1 second steps.
Note: The Modem Mute feature is only available if the radio modem is Rev D or later. If the radio has a
Rev A, Rev B or Rev C modem, the modem mute functionality is not displayed in SuperVisor.
Aprisa XE User Manual
Configuring the Terminal | 73