
Pathfinder DVL Guide
April
2018
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Page 41
R
V
I
r
leak
=
Where
r
V
is the voltage across the resistor and
battery
V
= 12V in our example.
11. The impedance noted should be 32M
Ω
at 32V.
Do not short the housing to any grounded surface (such as an ESD mat) or water tank while
conducting this part of the test. Otherwise you create a ground short, and leakage current
will rise above the acceptable limit, indicating a false failure.
Electro-Magnetic Interference (EMI)
The main sources of EMI are induced voltages from signal and power lines that are located in proximity to
the effected component or signal. These problems are avoided or minimized by the proper routing of
wires, proper shielding of wires and proper location of individual systems components. EMI is also caused
by unwanted differences in potential on signal or ground electronic lines as is discussed below.
EMI Coupling Through Cables
A remote head DVL is susceptible to interference along the length of the cable connecting the DVL to the
receiver located in the electronics chassis. Interference signals injected into or adjacent to the remote
head cables may be increased in voltage more than 100,000 times due to the gains of the internal amplifi-
ers. It is critical that to route all DVL cables such that they are not in proximity to interfering signal
sources, such as clocks, CPU’s, DC-DC converters, engine controls, and hydroelectric power units, power
lines, acoustic devices and their power electronic. In the case of radiated EMI to the cables, then the EMI
can be rapidly reduced as the power reduction goes by square of the separation distance between the
source and the DVL cables. It is recommended that detailed bench trials be conducted on all cabling con-
figurations before implementing this configuration into the operational platform. For more information,