NorthStar 961 Install Manual page 52

SECTION TWO - Installation
Table 4: Troubleshooting radar interference (continued)
Symptom
Radar Device
There's bearing-pulse interference from the radar
(this also applies to depth sounders).
Page 42
Possible Solutions/Reasons
•
The radar's scanning cables may be too closely
bundled with the 961/962's control head-to-processor
coax cable: Run the cables of the radar and the 961/
962 on opposite sides of the vessel.
•
The 961/962 display-to-processor coax cable may be
damaged or improperly terminated. Temporarily
substitute a known-good cable to determine if the
cable is defective.
• The radar scanner cable may be damaged, improperly
terminated, or the system\vessel grounds need
attention.
•
Ensure that the radar display is properly grounded to
an earth ground.
•
There may be a lack of or improper shielding for the
radar's scanning cable. Inspect the radar scanning
cable-to-scanner base grounding for a low impedance
connection (less than .5 ohms (1/2) between the
display end and the scanner base termination is
optimal; if it's higher, consult the radar manufacturers).
Shielding material can be used to attenuate
interference effects. Lead, copper, and Mu metal are
all good choices for flat-sheet shielding (Mu is the most
expensive). There are a number of different sheet,
strap, or mesh copper products that can be purchased
off the shelf. Also, a tinned "expando sleeve" type
copper braided strap can be used for shielding cable
bunches as long as it isn't exposed to saltwater or
corrosive environments. There are several different
sizes of grounding plates available for installation
outside the vessel hull, in water, that provide a good
"seawater-earth" grounding plate.
961/962 INSTALLATION MANUAL Revision A