1007D Altimeter Operators Manual 974-72007001/1.0
Theory of Operation Page 11
Kongsberg Mesotech Ltd.
Port Coquitlam, BC - Canada
If a distinct, valid return is not detected, an over-range value
will be output. For the digital telemetry interface, a zero range
value will be output. For the optional analog interface, a
factory configured over-range voltage will be output (default
= 10.24V).
2.4 Receiver Gain Adjustment
A TVG offset adjustment is available to increase or decrease
the receiver gain by adding or subtracting a DC offset. The
adjustment can be increased to improve the detection of low-
reflectance targets or muddy sea bottoms. Decreasing this
adjustment reduces the sensitivity of detecting spurious mid-
water targets (such as fish), thereby improving tracking of
hard sea bottoms. In standalone 80x modes, the offset is a
constant value over the entire ping. In MS1000 mode, a menu
selection of several TVG types is available as well as a user-
defined TVG configuration which allows custom settings for
spreading loss, absorption and overall gain.
2.5 Auto-GAIN Adjustment
The 1007D’s Auto Gain Adjustment function, available in
standalone 80x modes only, automatically adjusts the
receiver's gain level to compensate for changes in the bottom
return signal strength, and to reduce the sensitivity of
detecting low-strength, mid-water targets. If auto-adjustment
is enabled, the altimeter will attempt to adjust the overall gain
to normalize the bottom return signal level. The gain is
adjusted after every ping by calculating a gain offset that
increases or decreases the receiver gain.
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