/// <inheritdoc />
protected bool Equals(SatelliteVisibilityPeriod other)
{
return(Satellite.Equals(other.Satellite) &&
Start.Equals(other.Start) &&
End.Equals(other.End) &&
MaxElevation.Equals(other.MaxElevation) &&
MaxElevationTime.Equals(other.MaxElevationTime) &&
ReferencePosition.Equals(other.ReferencePosition));
}
/// <summary>
/// Creates a list of all of the predicted observations within the specified time period for this GroundStation.
/// </summary>
/// <param name="satellite">The satellite to observe</param>
/// <param name="start">The time to start observing</param>
/// <param name="end">The time to end observing</param>
/// <param name="deltaTime">The time step for the prediction simulation</param>
/// <param name="minElevation">The minimum elevation. Default is Angle.Zero.</param>
/// <param name="clipToStartTime">Whether to clip the start time of the first satellite visibility period to start, if applicable. Default is true</param>
/// <param name="clipToEndTime">Whether to clip the end time of the last satellite visibility period to end, if applicable. Default is false</param>
/// <param name="resolution">The number of second decimal places to calculate for the start and end times. Cannot be greater than 7 (i.e. greater than tick resolution). Default is 3.</param>
/// <returns>A list of observations where an AOS is seen at or after the start parameter</returns>
/// <exception cref="ArgumentException">Thrown if start is greater than or equal to end, deltaTime is non-positive, resolution is not in range 0-7, or minElevation is greater than 90°</exception>
public List <SatelliteVisibilityPeriod> Observe(
Satellite satellite,
DateTime start, DateTime end,
TimeSpan deltaTime,
Angle minElevation = default(Angle), // default is Angle.Zero
bool clipToStartTime = true, // default is true as it is assumed typical use case will be for future propagation, not searching into the past
bool clipToEndTime = false, // default is false as it is assumed typical use case will be to capture entire future pass
int resolution = 3)
{
// check input constraints
if (deltaTime.TotalSeconds <= 0)
{
throw new ArgumentException("deltaTime must be positive", "deltaTime");
}
start = start.ToStrictUtc();
end = end.ToStrictUtc();
if (start >= end)
{
throw new ArgumentException("start time must be less than end time", "start");
}
if (deltaTime <= TimeSpan.Zero)
{
throw new ArgumentException("deltaTime must be greater than zero", "deltaTime");
}
if (resolution < 0)
{
throw new ArgumentException("resolution must be non-negative", "resolution");
}
if (resolution > 7)
{
throw new ArgumentException("resolution must be no more than 7 decimal places (no more than tick resolution)", "resolution");
}
if (minElevation != null && minElevation.Degrees > 90)
{
throw new ArgumentException("minElevation cannot be greater than 90°", "minElevation");
}
start = start.Round(deltaTime);
var clippedEnd = clipToEndTime ? (DateTime?)end : null;
var obs = new List <SatelliteVisibilityPeriod>();
DateTime aosTime;
var t = start;
do
{
// find the AOS Time of the next pass
aosTime = FindNextBelowToAboveCrossingPoint(satellite, t, end, deltaTime, minElevation, resolution);
if (aosTime > end)
{
break;
} // if aosTime is greater than end, we're done
t = aosTime + deltaTime;
// find the LOS time and max elevation for the next pass
DateTime losTime;
DateTime maxElTime;
if (clippedEnd.HasValue && t > clippedEnd.Value)
{
losTime = clippedEnd.Value;
maxElTime = clippedEnd.Value;
}
else
{
var tu = FindNextAboveToBelowCrossingPoint(satellite, t, deltaTime, minElevation, resolution, clippedEnd);
losTime = tu.CrossingPointTime;
maxElTime = tu.MaxElevationTime;
}
var before = maxElTime - deltaTime;
if (clipToStartTime) // ensure before is clipped for max elevation search
{
before = start > before ? start : before;
}
var after = maxElTime + deltaTime;
if (clipToEndTime) // ensure after is clipped for max elevation search
{
after = end < after ? end : after;
}
// add the visibility period for the pass
var refinedMaxElResult = FindMaxElevation(satellite, before, maxElTime, after, resolution);
var maxEl = refinedMaxElResult.Item1;
maxElTime = refinedMaxElResult.Item2;
obs.Add(new SatelliteVisibilityPeriod(satellite, aosTime, losTime, maxEl, maxElTime, Location));
t = losTime + deltaTime;
} while (t <= end);
// if clipToStartTime is false and the start time has been clipped, walk back in time until previous AOS crossing point has been found
if (!clipToStartTime && obs.Count > 0 && obs[0].Start == start)
{
var first = obs[0];
var tu = FindNextAboveToBelowCrossingPoint(satellite, first.Start, deltaTime.Negate(), minElevation, resolution);
var maxElTime = first.MaxElevation > tu.MaxElevation ? first.MaxElevationTime : tu.MaxElevationTime;
var refinedMaxElResult = FindMaxElevation(satellite, maxElTime - deltaTime, maxElTime,
maxElTime + deltaTime, resolution);
var maxEl = refinedMaxElResult.Item1;
maxElTime = refinedMaxElResult.Item2;
obs[0] = new SatelliteVisibilityPeriod(satellite, tu.CrossingPointTime, first.End, maxEl, maxElTime, first.ReferencePosition);
}
return(obs);
}
/// <inheritdoc />
protected bool Equals(SatelliteVisibilityPeriod other)
{
return(Satellite.Equals(other.Satellite) && Start.Equals(other.Start) && End.Equals(other.End) &&
MaxElevation.Equals(other.MaxElevation) && StartAzimuth.Equals(other.StartAzimuth) &&
EndAzimuth.Equals(other.EndAzimuth));
}
