Tilter plugin

2011 Dec. 5: FIXME!!

Although learning happens independently at different elevation angles, we are applying the same
blip filtering criteria at all angles, which is silly because a given target will be hit by more pulses in a sweep when it
is on the beam axis at a higher elevation vs. at a lower elevation, which will change these blip characteristics:

• number of samples
• area
• angular span

The changes are predictable, and we should be automatically modifying the filtering criteria to match the elevation angle at which the
blips were observed.  Thanks to Beth Thurber for pointing this out.

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radR can control the tiltable parabolic dish made by Dave Wilson of Electro Marine Canada, by use of the tilter plugin.
Here are animations showing the tilter operating in a rapid volume scan (animation speed is ~ realtime) and a passing storm captured by radR (animation speed is ~ 20 times realtime):

(hit the Esc key to stop the animations; reload this page to restart them)

This plugin is controlled by its radR menu:

This plugin allows volume scanning by setting low, high, and step angles, along with the duration (in seconds) to spend at
each elevation angle, as set on the controls menu:

Clutter is learned at each individual elevation angle (rounded to the nearest degree). 

The plugin communicates with a server whose job is to send commands out the serial port to the tilter control box, while maintaining a precise model of the tilter controller's internal state.  This is necessary because the initial tilter controller is "write only", and no read-back of the dish elevation angle or internal tilter state is possible.  However, because the tilter hardware uses a microcontroller with open source code, we were
able to modify its firmware, and run the modified version on a simulator to obtain all the timing constants required to accurately maintain
a model of the dish's current position.  Here is a short example of radR interacting with the tilter via the server: