VEMCO – VR4-UWM Manual
32
1.
The Power Up and Power Down settings may both need to be increased
as the boat drifts
away from the
VR4-UWM. Don’t increase the power levels too quickly or echoes may be created that will create
interference and increase the communication time required.
2.
If the receiver is located in an
acoustically reflective environment
(hard bottom), then avoid using high
power settings as this can cause intense reflected signals (echoes) that could interfere with the direct
communication signals.
3.
If the surface transponder is
close to the VR4-UWM and communication quality
is poor
, then reduce the power levels for both the up and the down communication.
Too much power may cause additional noise in the water and lower the quality of
communication. You many also need to reduce the bit rate to 300 bps or 600 bps.
This should reduce the errors caused in transit and therefore require less
transmission repetition.
4.
Record the power and bit rate settings
for each VR4-UWM location. This will reduce the
communication setup time for your next visit to this location. The acoustic conditions will probably
change due to environmental factors but the physical characteristics of the area should remain constant.
For example, if the area has a hard bottom that is very reflective to acoustic signals and requires a lower
power setting, then start with the same power setting at your next visit since the bottom is probably still
very reflective.
5.
Power scale:
0 dB is the highest power (signal strength) and -21 dB is the lowest power level. Using a
high power level when it is not necessary can saturate the area with acoustic signals and reduce
conditions for communication.
3.4.3
Range Updates
Click the “Update Range” button in Automatic Tuning area to manually request a
range distance between the surface modem unit and the receiver. The button will
remain greyed out until the information has been collected and updated.
Automatic range updates occur at the frequency selected in the Advanced tuning
settings. Click the “Advanced” box next to the Update Range button to view the
advanced settings that can be changed. Open the drop-down list next to the Ranging
Period line and select from the times listed.
Setting the ranging period to “Automatic” will automatically set the ranging update
based on where the Automatic Tuning slider is positioned. On the “Reliable” end, the
range will be updated frequently. On the “Fast” end, it will be updated less frequently.
The “Continuous” setting will send a range command immediately after the last range
distance was received. It can be useful when locating a deployed VR4-UWM receiver, but interferes with
data offloading. All automatic range updates can be disabled by selecting “Disabled” from the list.
Use
caution
if
removing any
Tuning settings
from Automatic.