331 lines
13 KiB
Text
331 lines
13 KiB
Text
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#---------------------------------------------------------------------------
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#
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# Title : AN/SPN-46 Precision Approach Landing System (PALS)
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#
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# File Type : Implementation File
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#
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# Description : Representative emulation of the functions of the AN/SPN-46 using emesary
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# : Where an AN/SPN-46 is required it is sufficient to instantiate a ANSPN46_System connected to the instantiator model.
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# : Register with an instance of a Transmitter, and provide a Receive method, periodically send out Active messages
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# : expecting ActiveResponse messages which may result in a Communication.
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# : This is implemented as a set of messages that models the operation of the PALS
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#
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# References : http://trace.tennessee.edu/cgi/viewcontent.cgi?article=3297&context=utk_gradthes
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# : http://www.navair.navy.mil/index.cfm?fuseaction=home.displayPlatform&key=E8D18768-14B6-4CF5-BAB5-12B009070CFC
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# : http://www.afceaboston.com/documents/events/cnsatm2010/Briefs/4%20-%20Friday/03-Navy_Landing_Systems_Roadmap-(CDR%20Easler).pdf
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#
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# Author : Richard Harrison (richard@zaretto.com)
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#
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# Creation Date : 29 January 2016
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#
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# Version : 4.8
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#
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# Copyright <20> 2016 Richard Harrison Released under GPL V2
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#
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#---------------------------------------------------------------------------*/
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#Message Reference:
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#---------------------------------------------------------------------------*/
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# Notification 1 ANSPN46ActiveNotification from carrier to aircraft
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# Transmitted via GlobalTransmitter at 1hz
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# - carrier position
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# - beam start
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# - beam angle
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# - channel / frequency information
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# - beam range / power
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#
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# Notification 2 - from aircraft to carrier
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# - aircraft position
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# - radar return size
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# - aircraft altitude, heading, velocity
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# - respose indicating tuned or not
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#
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# Notification 3 - from carrier to aircraft
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# - lateral deviation
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# - vertical deviation
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# - LSO information / messages
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# - system status
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# - lateral
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#
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#Operation:
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#---------------------
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# The ANSPN64 system will send periodically send out a ANSPN46ActiveNotification
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# the rest of the logic within this system related to aircraft will be handled when
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# the ANSPN46ActiveResponseNotification - which itself in turn will send out a ANSPN46CommunicationNotification
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#----------------------
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# NOTE: to avoid garbage collection all of the notifications that are sent out are created during construction
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# and simply modified prior to sending. This works because emesary is synchronous and therefore the state
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# and lifetime are known.
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#
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# Notification(1) from carrier to any aircraft within range.
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#
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var ANSPN46ActiveNotification =
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{
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# Create a new active notification notification. Aircraft will respond to this.
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# param(_anspn46_system): instance of ANSPN46_System which will send the notification
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new: func(_anspn46_system)
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{
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var new_class = emesary.Notification.new("ANSPN46ActiveNotification", _anspn46_system.Ident);
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new_class.ANSPN46_system = _anspn46_system;
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#
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# Set notification properties from the ANSPN46_System.
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new_class.set_from = func(_anspn)
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{
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me.Position = _anspn.GetCarrierPosition();
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me.BeamPosition = _anspn.GetTDZPosition();
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me.BeamAngle = 35;
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me.Channel = _anspn.GetChannel();
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me.BeamRange = 35; ##nm
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me.BeamPower = 999; ## mw ???
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};
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new_class.set_from(_anspn46_system);
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return new_class;
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},
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};
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# Notification(2) - from aircraft to carrier sent in response to Notification(1) above
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#
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var ANSPN46ActiveResponseNotification =
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{
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new: func(_ident)
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{
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var new_class = emesary.Notification.new("ANSPN46ActiveResponseNotification", _ident);
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new_class.Respond = func(_msg)
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{
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new_class.Position = geo.aircraft_position();
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new_class.Heading = getprop("orientation/heading-deg");
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new_class.RadarReturnStrength = 1; # normalised value based on RCS beam power etc.
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new_class.Tuned = 0; # 0 or 1
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new_class.ufps = getprop("velocities/uBody-fps");
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return me;
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}
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return new_class;
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},
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};
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# Notification 3 - from carrier to aircraft as a result of active response notification
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# - only sent if the aircraft is set to the same channel that we are transmitting on
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#
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var ANSPN46CommunicationNotification =
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{
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new: func(_ident, _anspn46_system)
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{
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var new_class = emesary.Notification.new("ANSPN46CommunicationNotification", _ident);
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new_class.Model = _anspn46_system.Model;
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new_class.set_from = func(_ident, _msg, _anspn46_system)
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{
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var carrier_ara_63_position = _anspn46_system.GetCarrierPosition();
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var carrier_heading = _anspn46_system.GetCarrierHeading();
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var carrier_ara_63_heading = 0;
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# relative offset of the course to the tdz
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# according to my measurements the Nimitz class is 8.1362114 degrees (measured 178 vs carrier 200 allowing for local magvar -13.8637886)
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# i.e. this value is from tuning rather than calculation
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if (carrier_heading != nil)
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carrier_ara_63_heading = carrier_heading.getValue() - 8.1362114;
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var range = _msg.Position.distance_to(carrier_ara_63_position);
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var bearing_to = _msg.Position.course_to(carrier_ara_63_position);
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var deviation = bearing_to - carrier_ara_63_heading;
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deviation = deviation *0.1;
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me.ReturnPosition = _msg.Position;
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me.ReturnBearing = getprop("orientation/heading-deg");
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# the AN/SPN 46 has a 20nm range with a 3 degree beam; ref: F14-AAD-1 17.3.2
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if (range < 37000 and abs(deviation) < 3)
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{
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var FD_TAN3DEG = math.tan(3.0 / 57.29577950560105);
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var deck_height=20;
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var gs_height = ((range*FD_TAN3DEG)) + deck_height;
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var gs_deviation = (gs_height - _msg.Position.alt()) / 42.0;
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if (gs_deviation > 1)
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gs_deviation = 1;
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else if (gs_deviation < -1)
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gs_deviation = -1;
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# if not in range message will not be transmitted.
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me.InRange = 1;
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# calculate the deviation from the ideal approach
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me.VerticalAdjustmentCommanded = gs_deviation;
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me.HorizontalAdjustmentCommanded = deviation;
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me.LateralDeviation = deviation;
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me.VerticalDeviation = gs_deviation;
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me.Distance = range;
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me.SignalQualityNorm = 1;
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#
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# work out the rough ETA for the 10 seconds light, and use this
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# to decide whether or not to waveoff
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var eta = range / (_msg.ufps / 3.281);
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if(eta <= 10 and range < 800 and range > 150)
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{
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me.TenSeconds = 1;
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if(math.abs(deviation) > 0.2 or math.abs(gs_deviation) > 0.2)
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{
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me.WaveOff = 1;
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}
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else
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{
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me.WaveOff = 0;
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}
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}
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else
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{
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me.TenSeconds = 0;
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me.WaveOff = 0;
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}
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me.LSOMessage = "";
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me.SystemStatus = "OK"; # Wave off, error, etcc.
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}
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else
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{
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#
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# No response will be sent when not in range; so ensure values are all cleared.
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me.InRange = 0;
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me.VerticalAdjustmentCommanded = 0;
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me.HorizontalAdjustmentCommanded = 0;
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me.SignalQualityNorm =0;
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me.Distance = -10000000000;
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me.TenSeconds = 0;
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me.WaveOff = 0;
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me.InRange = 0;
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me.VerticalDeviation = 0;
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me.LateralDeviation = 0;
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me.LSOMessage = "";
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me.SystemStatus = "";
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}
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};
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return new_class;
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},
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};
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#
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# The main AN/SPN46 system implemented using emesary.
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# Periodically the Update method should be called, which will
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# send out a notification via the global transmitter so that aircraft within range
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# can respond. This is similar to a radar transmit and return.
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# There should be an instance of this class created in the nasal section of the model xml
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# Once an aircraft is within range it will receive guidance that can be displayed.
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# It is the responsibility of the AN/SPN system to decided whether a craft is within range.
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# It is the responsibility of the aircraft receiver to indicate whether it is tuned in or not
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# if it the aircraft is not tuned into the right channel the receiver (e.g. ARA-63) will not receive anything; however
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# the AN/SPN system (being a radar) will still have guidance information that could be relayed over the
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# comms channel or displayed on a radar display on the carrier.
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#
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var ANSPN46_System =
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{
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new: func(_ident,_model)
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{
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print("AN/SNP46 created for "~_ident);
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var new_class = emesary.Recipient.new("ANSPN46_System "~_ident);
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new_class.ara_63_position = geo.Coord.new();
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new_class.Model = _model;
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new_class.communicationNotification = ANSPN46CommunicationNotification.new(new_class.Ident, new_class);
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new_class.Channel = 2;
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new_class.UpdateRate = 10;
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#-------------------------------------------
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# Receive override:
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# Iinterested in receiving ANSPN46ActiveResponseNotification. When we get
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# one of these we can respond with a CommunicationNotification
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new_class.Receive = func(notification)
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{
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if (notification.Type == "ANSPN46ActiveResponseNotification")
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{
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if (notification.Tuned)
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{
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me.communicationNotification.set_from(me.Ident, notification, me);
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if(me.communicationNotification.InRange)
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{
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me.UpdateRate = 0.2;
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emesary.GlobalTransmitter.NotifyAll(me.communicationNotification);
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}
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}
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return emesary.Transmitter.ReceiptStatus_OK;
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}
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return emesary.Transmitter.ReceiptStatus_NotProcessed;
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}
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#
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# Interface methods
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#-----------------------------
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# Required interface to get the current carrier position
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new_class.GetCarrierPosition = func()
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{
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var x = me.Model.getNode("position/global-x").getValue() + 88.7713542;
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var y = me.Model.getNode("position/global-y").getValue() + 18.74631309;
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var z = me.Model.getNode("position/global-z").getValue() + 115.6574875;
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me.ara_63_position.set_xyz(x, y, z);
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return me.ara_63_position;
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};
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#
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# Interface to get the carrier heading
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new_class.GetCarrierHeading = func()
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{
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return me.Model.getNode("orientation/true-heading-deg");
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};
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#
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# offset of the TDZ (wires) from the carrier centre
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new_class.GetTDZPosition = func
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{
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return me.ara_63_position;
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};
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#
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# radar beam angle
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new_class.GetUpdateRate = func
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{
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return me.UpdateRate;
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};
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new_class.BeamAngle = func
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{
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return 30;
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};
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#
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# currently transmitting channel number.
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new_class.GetChannel = func
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{
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return me.Channel;
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};
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new_class.SetChannel = func(v)
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{
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me.Channel = v;
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};
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#
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# main entry point. The object itself will manage the update rate - but it is
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# up to the caller to use this rate
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new_class.Update = func
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{
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# fill in properties of message
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me.msg.set_from(me);
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#
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# manage the update rate; increase each frame until we get to 10 seconds
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# this will be reset if we receive something back from the aircraft.
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if (me.UpdateRate < 10)
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me.UpdateRate = me.UpdateRate+1;
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# print("AN/SPN 46 : update from",me.Ident," rate=",me.UpdateRate);
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return emesary.GlobalTransmitter.NotifyAll(me.msg);
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};
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#
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# create the message that will be used to notify of an active carrier. This needs to be done after the methods
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# have been created as it references them. Implemented like this to reduce garbage collection
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new_class.msg = ANSPN46ActiveNotification.new(new_class);
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emesary.GlobalTransmitter.Register(new_class);
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return new_class;
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},
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}
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