50
2.048Mb
p
s Wireless Modem
SALES: 0118 965 5100
Long haul/Short haul
This parameter determines the sensitivity of the receiver circuits in the line interface to the
end equipment. If the distance between modem and the end equipment is up to 500 meters, it
should be set to 0 (short haul). If the distance is more than 500 meters, it should be set to 1
(long haul) to compensate for losses by increasing the sensitivity of the receiver circuits by
approximately 30 dB.
CRC4 Usage
When there is a need for an enhanced error monitoring capability, bit 1 of each frame is used
for a Cyclic Redundancy Check 4 (CRC4) procedure. Bit 1 of each frame is used for CRC4
bits and other related information such as a CRC4 alignment sequence to verify identification
of the CRC4 bits. These bits are the result of a certain calculation performed on all the bits of
the applicable sub-multiframe (8 frames). CRC4 bits may be used by the receiving equipment
to determine proper reception of all bits sent to it. If the end equipment does not use CRC4,
these bits may be used for other purposes, and the CRC4 Usage parameter should be set to 0
(CRC4 not used). If the end equipment uses CRC4, or if it is not known whether the end
equipment uses CRC4, this parameter should be set to 1 (Auto detect CRC4).
Echo Canceller disabling method
Set these parameters in accordance with the echo cancellation disabling method used by the
end equipment (see also appendix C).
• Straight 2100Hz tone (0): The most popular method based on transmitting a straight
2100Hz tone.
• Phase reversed 2100Hz tone (1): A 2100Hz tone with phase reversals for improved
differentiation from voice signals.
• 2100Hz VPA tone (2): A tone in the range 2000-2100Hz.
Fractional E1 Alarm Buffer
LOS (Loss Of Signal) Also referred to as all zeros signal, indicates that no signal is received
from the data equipment.
AIS (Alarm Indication Signal) No signal is received by the connected end equipment.
Remote Frame Alarm Indication from the connected end equipment that it is not able to
synchronize with the modem.
Frame-slip Indicates lack of compatibility between the clocks of the modem and the end
equipment.