User's Manual

Exalt Installation and Management Guide
EX-i Series GigE (FDD) Digital Microwave Radios
202675-008 101
2016-06-01
Exalt Customer Care, the process to rectify the system is much more expedient due to the in-depth
knowledge related to the implementation and the RF environment.
Improper RF Cable Termination
Improper RF Cable termination is a common problem. In many cases, this is a problem that occurs
during installation and is not a problem that suddenly appears. However, if cables are moved or flexed,
especially near the termination points, and radio errors, changes in RSL or other performance issues
occur, this is a sign of this issue.
Another method to test for this condition is to decrease the output power of the radio system (at each
end, one end at a time). Poor RF cable termination may be reflecting too much RF energy back into the
radio system, and reducing output power reduces the reflected energy at a faster rate than the
transmitted energy towards the far end. Be careful not to reduce the output power to the point where
the radio’s threshold is reached. Typically, a reduction of just 3 to 6dB is enough to determine if this is
the issue. If the reduction of output power clears the error condition, this is the likely cause.
Use a reflectometer or meter that can read VSWR at the operating frequency to identify poor
terminations as well as poor antenna feeds.
Multipath Propagation
Multipath propagation is a term that encompasses changes to the RF path, such as reflections and/or
refraction, causing partial or complete destruction of the radio signal, and thus excessive bit errors and/
or system outages.
Rapid changes in temperature, inversion layers, humidity, air pressure, water evaporation, as well as
standing water or moisture on objects along the path are all examples of changes that can cause
multipath propagation. New building construction near either end of the path or along the path can
cause new reflection characteristics.
If your system has been operating without issue and is suddenly experiencing issues that are
symptomatic of a certain time of day or related to change in climatic events or some of the external
factors listed above, this is likely the cause. Consult a professional RF path engineer in these cases.
Often, minor repositioning of the antennas at either or both ends can reduce or eliminate these
problems.
RF Interference
RF interference is usually indicative of another radio system nearby either end of your radio system or
aimed towards one or both ends of your radio system – usually at or near the same frequency and
usually with a similar signal level. This is less common for licensed systems, but still can occur.
Other forms of RF interference also exist, such as electronic equipment placed close to the radio
chassis or transmitters that couple onto the cabling or grounding system of the radio. Microwave ovens
and wireless communication devices used near the equipment or cabling are examples of electronic
equipment interference.
RF interference, like most other causes of problems, is indicated by significant bit errors and/or system
outages.
One means to determine presence of interference is the use of a
Spectrum Analyzer that covers the
same range as the radio system. A professional RF engineer can use a spectrum analyzer to locate
Note: The Praxsym VSWR meter is an excellent tool for this purpose.