
April
2018
Pathfinder DVL Guide
Page 106
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Range
nnnnn = 1 to Maximum Altitude dm (0 = automatic)
Default
#BF0
The default setting for this command is recommended for most applications.
Description
When set to a non-zero value, the Pathfinder transmits a fixed pulse based on a given bot-
tom range. This is useful for applications with fixed range bottoms. The command re-
duces the amount of time the Pathfinder uses to search for the bottom if lost.
#BH – Gain Switch Threshold
Purpose
Sets the RSSI thresholds for switching the receiver gain for a bottom track ping.
Format
#BH nnn, nnn (lo;hi)
Range
nnn = 0 to 255 counts
Default
#BH 105,180
The default setting for this command is recommended for most applications.
Description
Receiver gain control for bottom track always uses low gain when the altitude over the sea
bottom is less than the Gain Switch Altitude (set by the #BI command). When the altitude
is above the Gain Switch Altitude:
•
Switch to high gain when RSSI is below the low threshold set by the #BH command.
•
Switch to low gain when RSSI is above the high threshold set by the #BH command.
Using two thresholds provides hysteresis, so that the gain does not need to switch on every ping when the
RSSI is at some in-between level.
#BI - Gain Switch Altitude
Purpose
Selects the maximum vertical distance from the transducer to the bottom at which the
Pathfinder operates at low gain.
Format
#BInnn
The BI commands work with or without the # sign. For example, using BI or #BI are both valid
commands.
Range
nnn = 0 to 3 meters
Default
#BI005
The default setting for this command is recommended for most applications.
Description
When the vertical range to the bottom is less than #BI, the unit operates in low gain.
When the vertical range is greater than #BI, internal logic determines which gain (low or
high) is optimal. In high backscatter areas, it may be necessary to raise this setting in or-
der to detect bottom throughout the range of the system.