User's Manual

Exalt Installation and Management Guide
ExtendAir G2 24GHz Digital Microwave Radios
40 209866-002
2015-09-09
• Set the Antenna Gain (dB) parameter to compute the Calculated EIRP (dBm).
• The read-only Calculated EIRP (dBm) field displays the EIRP based on Radio Transmit Power
and Antenna Gain (for regulatory compliance purposes).
• Set the Bandwidth (MHz) parameter to the value determined in the design/engineering stage. The
Bandwidth parameter must also match at both ends of the link. In conjunction with the Mode
parameter, the Bandwidth parameter directly relates to the capacity supported.
• Adaptive Coded Modulation (ACM) allows the radio to reduce throughput as link conditions fall
below what can be supported during normal operation. The advantage is that instead of the link
being down or highly errored, the link remains up for longer periods, but with reduced throughput.
• ACM Mode parameter enables or disables ACM. Some regulatory environments may not allow
ACM or may require special licensing. Check your local regulations before enabling this feature.
• ACM Policy parameter selects the modulation to run and how fast to switch between settings.
– Aggressive settings switch the radio from modulation to modulation at the moment that the
signal-to-noise ratio allows. This can result in rapidly changing throughput characteristics, but
always provides the highest throughput, even if the currently selected setting is not error-free.
– Conservative applies hysteresis (that is, the time-based dependence of a system’s output on
current and past inputs) to the switching decision, waiting longer to make a change in the
‘upward’ direction. Switching to a lower modulation is instantaneous, but the radio ‘waits’ to
switch back to a higher modulation state until the signal-to-noise ratio is above the threshold
for that setting. The result is slightly slower changes between modulations and less overall
switching (which could be less disruptive to some network operations).
• ACM Base Modulation parameter sets the minimum modulation for the radio to select. There are
cases where regulatory limits may apply that govern the minimum modulation that can be used,
which is sometimes based on licensing. Check your local regulations before deciding this
parameter setting.
Note: If you enter an invalid combination of Radio Transmit Power and Antenna Gain, a
regulatory-specific warning appears (ETSI warning shown below) and the out-of-specs field
is highlighted.
Click OK to change the values per regulatory requirements.
Note: Changing Bandwidth will temporarily interrupt traffic. The Bandwidth parameter
must match at each end. Adjust the far-end radio first, and then the near-end radio.
Changing Bandwidth changes the radio’s threshold. A wider bandwidth has worse threshold
performance and improved interference immunity, therefore if changing to a narrower
bandwidth, there is an opportunity that the link may be lost and unrecoverable through GUI
control. Check the available fade margin to determine if the impact to threshold and increased
bandwidth is acceptable to maintain the link and the desired performance. If the link is lost
due to increasing the Bandwidth parameter, travel to the radio location(s) may be required to
reset the value.