Software Manual

152 ALFOplus 24GHz (North America) - Release 01.05.0x - MN.00395.E - 004
• Rx Quality Alarm BER <10
-6
In order to understand why quality alarms are present, RxPwr performance window must be used (in NMS,
WEBLCT, SCT).
Fig.116
11.14 RADIO LINK QUALITY PROBLEMS
11.14.1 Radio link affected by fading
This problem is revealed by low Rx level (how much lower depends on the severity of tropospheric phe-
nomena), and consequent low quality in RX signal, in both directions of the link.
Rain, multipath fading, rain drop depolarization and diffraction cause Reduced capacity notification alarm,
Rx Power low, Rx Quality warning, Rx Quality alarm, Telemetry fail. These alarms are fleeting because of
the fluctuating attenuation:
• F > 10 GHz the fading is given by rain (for F > 30GHz rain is a serious problem)
• F < 10 GHz the fading is given by ducting and multipath.
When propagation problems occur the link performance will be restored as the weather gets back to normal
and if problems persist (Rx level remain different from normal) the reason must be searched in wrong an-
tenna disalignment (…probably caused by strong wind or snow/ice).
Local status ->
.
Rx levels are low... and before? From RxPwr table we see that in the last 15min record
Rx level is <-80dBm but in previous records Rx level was higher.
From the situation the reason of quality problem is the rain (...f>10GHz).
If the two alarms are present during a high Rx levels period (Rx level>-50dBm) the
quality fall should be caused by interference. Investigate about.
If the problem suggests a rain or other weather related fading condition and it
matches the prevailing weather conditions, do not performed any further
action until the situation gets better.
Usage of RxPwr window is important because troubleshooting can be performed also
after the problem disappearing ... comparing the starting time of the alarms with older
Rx power measurements relevant the alarm period.