83 lines
2.8 KiB
C++
83 lines
2.8 KiB
C++
// altimeter.cxx - an altimeter tied to the static port.
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// Written by David Megginson, started 2002.
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// Modified by John Denker in 2007 to use a two layer atmosphere
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// model in src/Environment/atmosphere.?xx
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//
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// This file is in the Public Domain and comes with no warranty.
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// Example invocation, in the instrumentation.xml file:
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// <altimeter>
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// <name>encoder</name>
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// <number>0</number>
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// <static-pressure>/systems/static/pressure-inhg</static-pressure>
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// <quantum>10</quantum>
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// <tau>0</tau>
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// </altimeter>
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// Note non-default name, quantum, and tau values.
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <simgear/math/interpolater.hxx>
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#include <simgear/math/SGMath.hxx>
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#include <Main/fg_props.hxx>
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#include <Main/util.hxx>
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#include <Environment/atmosphere.hxx>
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#include "altimeter.hxx"
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Altimeter::Altimeter ( SGPropertyNode *node, double quantum )
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: _name(node->getStringValue("name", "altimeter")),
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_num(node->getIntValue("number", 0)),
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_static_pressure(node->getStringValue("static-pressure", "/systems/static/pressure-inhg")),
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_tau(node->getDoubleValue("tau", 0.1)),
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_quantum(node->getDoubleValue("quantum", quantum))
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{}
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Altimeter::~Altimeter ()
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{}
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void
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Altimeter::init ()
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{
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string branch;
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branch = "/instrumentation/" + _name;
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SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
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raw_PA = 0.0;
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_kollsman = 0.0;
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_pressure_node = fgGetNode(_static_pressure.c_str(), true);
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_serviceable_node = node->getChild("serviceable", 0, true);
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_setting_node = node->getChild("setting-inhg", 0, true);
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_press_alt_node = node->getChild("pressure-alt-ft", 0, true);
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_mode_c_node = node->getChild("mode-c-alt-ft", 0, true);
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_altitude_node = node->getChild("indicated-altitude-ft", 0, true);
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if (_setting_node->getDoubleValue() == 0)
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_setting_node->setDoubleValue(29.921260);
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}
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void
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Altimeter::update (double dt)
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{
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if (_serviceable_node->getBoolValue()) {
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double trat = _tau > 0 ? dt/_tau : 100;
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double pressure = _pressure_node->getDoubleValue();
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double setting = _setting_node->getDoubleValue();
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double press_alt = _press_alt_node->getDoubleValue();
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// The mechanism settles slowly toward new pressure altitude:
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raw_PA = fgGetLowPass(raw_PA, _altimeter.press_alt_ft(pressure), trat);
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_mode_c_node->setDoubleValue(100 * SGMiscd::round(raw_PA/100));
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_kollsman = fgGetLowPass(_kollsman, _altimeter.kollsman_ft(setting), trat);
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if (_quantum)
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press_alt = _quantum * SGMiscd::round(raw_PA/_quantum);
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else
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press_alt = raw_PA;
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_press_alt_node->setDoubleValue(press_alt);
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_altitude_node->setDoubleValue(press_alt - _kollsman);
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}
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}
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// end of altimeter.cxx
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