Date Code 20181001 SEL-3031 Instruction Manual
Performance Monitoring, Testing, and Troubleshooting
Monitoring Radio Performance
5.3
To get a good availability reading, issue a RAD C command from Access Level 2. This
will reset all of the availability numbers. Let the radio link run for a couple of days or
longer. The longer period of time, the more accurate the numbers. After a few days
have passed issue the RAD command and view the availability numbers. If the overall
availability number is less than desired then look at the availability numbers per zone.
If all of the zones are down in availability then more adjustment is needed on the
antennas. If a few of the zones are down by a large percentage and the rest are
acceptable then go back to the radio settings and change the SKIP zone setting. Enter
the zones, as many as six, that you want to skip with the lowest availability. Issue a
RAD C command and let the radio run for a couple of days.
NOTE: If the radio availability is above 85%, there is, at
best, a marginal gain for skipping that zone.
You may need to repeat these steps before the availability reaches the desired level.
Note: There are 16 zones available in the SEL-3031 where a radio link only uses a
maximum of 10 zones. Skipping zones will turn on zones not previously used and may
give worse performance. The default SKIP setting of NONE will make the SEL-30310
SKIP zones 11–16, or force the Brazilian SEL-30311 to skip zone 16. If the availability
between the zones only varies by a few percent then changing the SKIP setting will not
help. The SKIP setting is for avoiding areas with high levels of noise, not to overcome
multipath propagations.
If the overall availability of most of the zones is bad (below 85%) and positioning the
antenna did not help then the radio link has a large amount of interference or there is an
obstruction to the Fresnel zone that is causing reflection issues. The interference can be
caused by a number of items. A path study is critical to determine how good the line-
of-sight is and how high the antennas need to be. If the path study results do not match
your actual results you will need to make sure all of the parameters used to make the
path study were correct. If the results still do not match then there is an unaccounted
obstruction in the path (either buildings or trees) that is causing the decrease in
availability. View Section 2: Installation for more information on properly installing
the antenna. If the availability numbers are less than desired then the problem is within
the location, interference, or multipath radio issues. If the antenna tower is not located
high enough and proper steps are not done to detect noise floors or obstructions to the
Fresnel zone then the availability numbers may not reach those used in the path study.
Monitoring MIRRORED BITS Performance
When using one, two, or three ports of the SEL-3031 for MIRRORED BITS
communications it is important to monitor the availability of the channel. The
SEL-3031 provides channel availability information and the M
IRRORED BITS devices
each contain communications data for each M
IRRORED BITS channel. This section
describes how these work and how to optimize the MIRRORED BITS channel to achieve
a high level of availability.
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