modular-radar/02_text_description.md

Radar Text Descriptions for the Left Hand Text Field (Or on separate monitor)

The following four radar descriptions shall be applied to the left hand text description field:

1. Chain Home radar The UK developed the chain home radar in the 1940's. This was one of the earliest radar, developed in response of threats of air attacks from the Germans.

   The scope is similar to that of an oscilloscope. One the horizontal axis of the scope is the range. The vertical axis is the amplitude of the returned echo from aircraft.

   The bearing of the incoming echo signal is detrmined by feeding the signals from two identical dipole antennas, mounted at right angles to each other into a radiogoniometer. The operator menually turns a search coil until the signal strengh on the oscilloscope reaches a null poing (minimum signal). The direction (bearing) is read from a calibrated dial.

   In our exhibit, the chain home radar is located in Ventnor, on Isle of Wight.

2. Marine a-scope The UK, after developing microwave radar, which with it's shorter wavelengths, became able to pick up echos from small targets such as the parascope and the connong tower from enemy submarines.

   The system consists of a steerable microwave dish connected to an oscilloscope display. The horizontal axis is the range; the vertical axis is the strength of the return; and the bearing (direction) is determined by manually rotating the microwave antenna using a servo control at the console that drive servo motor attached to the microwave dish antenns.

   These radars were used on the Brittish Corvetts boats that were used in anti submarine warefare.

   In our exhibit, this radar is on a boat moored at the dock of the Community Boating Center in Bellingham Bay.

3. Marine Traffic Control Radar

   The marine traffic control radar is a plan position indicator (PPI) type radar, where the display consists of a circular sweep beam. The range is determined by how far the blip is from the center of the scope. The bearing is determined by the direction of the beam in its rotation. The beam rotates clockwise staring from north. The strength of the echo is determined by the brightness of the blip on the scope.

   All modern radars use this type of display.

4. Police Boat Radar

   The police boat radar is a plan position indicator (PPI) type radar, where the display consists of a circular sweep beam. The range is determined by how far the blip is from the center of the scope. The bearing is determined by the direction of the beam in its rotation. The beam rotates clockwise starting from the heading of the boat. A small line indicated which direction is north. the strength of the echo is determined by the brightness of the bliip on the scope.