Vemco VR100 - Adjusting Gain and Signal Strength

VEMCO – VR100 Manual 28 May 2018 31
4.2.3 Using Signal Strength and Gain when tracking
When tracking a tag using the VR100 and a directional hydrophone (the VH110 for example), the signal
strength will increase as the hydrophone approaches the tag. The gain must be set to manual (“M” appears in
the Monitor screen – see section 4.2.1) during this procedure.
When the signal strength bar graph is near full scale, the manual gain should be reduced so meter variations
will indicate transmitter direction as the hydrophone is turned. If the signal level indicator is at the bottom of
the scale, the gain should be increased to detect meter variations. If the gain is too high, the signal can be
saturated and difficult to detect.
4.2.4 Select Channel to Monitor
There are eight channels that can be simultaneously monitored, but only channel can be viewed at a time in
the VR100 Main screen. To select the channel to be viewed in the screen, press the number on the keypad
corresponding to the channel number to be monitored (section 2.3 explains how to setup channels).
4.2.5 Log GPS Coordinates
A GPS reading is automatically stored in the VR100’s memory with each detection if the GPS receiver is
“locked”. Manual GPS readings can be taken while in the Monitor screen (see section 4.2.1) and stored to
memory by pressing the LOG GPS button on the front panel of the receiver. A message will briefly appear
on the VR100’s display to verify that the location has been stored. If the GPS receiver does not have a
position fix when manually logging GPS readings, the VR100 will report “ERROR! No GPS fix.”
The signal strength reading is a relative measure of the voltage level present at the receiver input (0dB
= minimum measureable voltage, 105dB = full scale voltage). It is strictly a relative measure of signal
strength and cannot be used to measure the output power of a transmitter in terms of dB re 1uPa @ 1m.
This GPS reading is the location of the VR100, not necessarily the
location of the hydrophone that is detecting the pings or the tag.