3
Signal Level
A signal level meter, located on the front panel, indicates the amplitude of each received pulse.
This indicator is used with the manual gain control and a directional hydrophone for tracking and
locating applications. When the indicator is at 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.
Channel Selection
The front panel switch labeled CHANNEL controls the preselected frequencies for the receiver. The
eleven preselected frequencies are listed on a plate either on the front panel or on the inside of the
case lid. These frequencies are also listed in the
VR60 Receiver Specifications
section of the
Appendix. If the receiver has the decoder/display (Option 01), the frequency can also be selected
with the keyboard when the Channel switch is in the external (EXT) position (see
Set Frequency
Command
).
Volume Control
The front panel control marked VOLUME allows the audio output level (volume) to be adjusted.
The volume increases as the knob is turned clockwise. The volume may be turned down (fully
counterclockwise) during data telemetry applications where audio indications are not required. In
tracking applications the audio level can be used instead of, or in conjunction with, the signal level
indicator to determine when signals are strongest (i.e. when the hydrophone points directly at the
transmitter).
Data Output
A BNC connector on the front panel provides a TTL compatible logic signal (high during pulse
detection) of approximately 150 ms duration. A front panel LED provides a visual indication of
each detected pulse.
