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14.4 Calibrating the radar
You must calibrate the newly installed radar by adjusting the trigger delay and the heading calibration.
To evaluate medium and short range returns, you are recommended to perform the calibration at sea in a normal operating environment and under fair weather conditions. There should be an area of at least 3 nautical miles forward of the vessel, containing known targets including the coastline. A wave height of about one to two feet (half a meter) to create some sea clutter, is ideal. Do not perform the calibration in an enclosed or busy area such as a boatyard.
Attempts to tune and calibrate under less than recommended conditions may lead to substandard performance. A sea trial that allows the selection and use of all the ranges is highly desirable.
14.4.1 Prepare for calibration
Prepare for calibration as follows:
1. Press RADAR to display the radar screen on the 6000i or 6100i.
2. The unit may ask if you want to turn on the scanner. If it does, turn it on. You should see range rings displayed on the screen or the scanner warm-up countdown followed by a message saying "Radar is OFF". If nothing appears, the radar control box is not powered up or not properly interfaced to the navigator. Check the power wiring, interface wiring, and navigator communications configuration.
3. Press Page 2, Page 3, Page 4, then Restore... .
4. Press Restore factory settings. (A new Northstar 6000i or 6100i is shipped with standard factory settings that are appropriate for basic operation.)
5. Press Return.
14.4.2 Tune the radar
The Northstar radar uses a fully automatic tuning procedure that continuously checks for optimum adjustment during operation. Northstar recommends using auto tuning mode for normal operation.
For special situations requiring manual tuning, see the section on "Manual Tuning Mode".
Tune the radar so that the radar receiver frequency matches the transmitter frequency.
For normal operation of a Northstar radar, you're recommended to set the tuning mode to Auto.
To tune the unit manually see the section "Manual tuning procedure for the 6000i or 6100i system".
To check the tuning mode or change it to Auto:
1. Press RADAR to display the radar screen on the 6000i or 6100i.
2. Press Page 2, Page 3, Page 4, then Install... and then Tune... .
3. If necessary, press Tune mode repeatedly until it displays Auto.
14.4.3 Set the STC Curve
The STC (Sensitivity Time Control) attempts to compensate for the high strength of nearby echoes compared with the very much weaker echoes from distant objects. It lowers the receiver gain when the pulse is transmitted, and raises the gain as echoes return from longer distances. Ideally, the result is that all echoes are displayed with strengths proportional to the reflectivity of the objects. A graph showing the receiver gain plotted against time is called the STC curve. You can select different curve shapes, if required for special applications.
The height of the scanner affects the STC curve shape needed for the sea control to effectively reduce sea clutter. The STC curve shape corresponds to the scanner's height (in meters) above the waterline; for example, if the scanner is 20 ft (6 m) above the waterline, select STC curve 6.
Curve 4 is the default, and represents a scanner 13 ft (4 m) above the waterline.
To select a different curve:
1. Press RADAR to display the radar screen on the 6000i or 6100i.
Northstar 25 kW Radar Installation Manual 41
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Table of contents
- 17 How to find the optimum height for the scanner
- 18 How to find the maximum detection range
- 19 How to reduce false echoes and shadow zones
- 19 Install an open array scanner on a trestle
- 20 25 kW radar dimensions
- 21 Install the 25 kW scanner unit
- 21 When to install the open array
- 22 Install the radar processor
- 23 Wiring guidelines
- 23 Connect the interconnection cable (NS003105/NS003106) to the 25 kW scanner
- 26 25 kW radar processor connectors
- 27 Run the interconnection cable (NS003105/NS003106) to the radar processor
- 28 Earth the 25 kW scanner
- 29 Install the 25 kW open array
- 30 Connect the 25 kW radar processor to a 6000i or 6100i display
- 31 Connect the radar communications cable (NS003107) to the junction box
- 33 Configure the remote power control for a 6000i or 6100i (common power source)
- 34 Configure the remote power control for a 6000i or 6100i (different power sources)
- 35 Connect the 25 kW radar processor to an 8000i display
- 36 Configure the remote power control for an 8000i
- 36 Connect an 8000i network cable (NS00481X)
- 36 Connect the optional NMEA compass for an 8000i
- 36 Configure the optional NMEA compass
- 37 Connect the power cable
- 37 Connect the ground wire
- 38 Radar system checklist
- 39 Turn the radar on and off
- 39 Before you turn on the radar for the first time
- 39 Turn the radar on
- 39 Turn the radar off
- 40 Configure the navigator communications
- 40 Heading sensor requirements
- 40 Disable the heading sensor input
- 41 Calibrating the radar
- 41 Prepare for calibration
- 41 Tune the radar
- 41 Set the STC Curve
- 42 Set the trigger delay
- 42 Set the heading calibration (heading sensor installed)
- 43 Set the heading calibration (heading sensor not installed)
- 43 Adjust the appearance settings
- 44 Restore all the factory settings
- 44 Restore the factory appearance settings
- 45 General maintenance
- 45 Scanner maintenance
- 45 Other maintenance items
- 46 Technical support, service and repairs
- 46 Radar is not operating correctly
- 47 If the scanner fails to turn
- 47 How to reduce noise and interference
- 48 Make sure the power is present and correctly wired
- 48 Confirm the equipment installed
- 48 Are Range Rings displayed?