User's Manual

Chapter Six Troubleshooting
man_905_2.1.doc Page 51
range of influences, including atmospheric conditions, changing landscape, degradation of aerials or
co-axial cable, low battery voltage etc. Fade margin is an indication of how far a radio path can
deteriorate before communication becomes unreliable.
When using the Signal feature, a meter is displayed with a mark indicating the current received radio
signal level. To check the radio path between two units, select the signal option at the local unit. The
remote unit may then be set up for tone reversals (refer 1 above) and the signal level read from the
meter.
A simpler method when remote units are not easily accessible is to cause a transmission from the
local unit to the remote unit (by setting a digital input which maps to the remote unit, for example).
The meter will latch the received signal from the remote unit for half a second, allowing the received
level to be read.
Under normal radio conditions, a reading of 0 indicates a very marginal communication path. For
reliable communications, the signal reading should be 3 or above.
>k Minimum signal level for reliable comms
Signal
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In areas experiencing radio interference or high background noise, reliable communications may not
be achievable even with this signal level. To determine if interference is occurring the signal option
may be selected without any other 105 units active. In a normal radio environment, no reading
should be displayed. If a reading is displayed, then the received signal strength from the remote
should be at least three counts higher than the background noise for reliable communication.
>k Displayed signal level of
Signal background noise/interference
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>k Minimum signal level for reliable comms
Signal
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When using directional aerials (i.e. YAGI aerials) this feature may be used to peak the received
signal level. Set-up the remote unit to transmit tone reversals as described above, and observe the
signal indication while adjusting the orientation of the aerial. A peak in signal level indicates optimum
orientation of the aerial.