/// <summary>
/// Generates actual data to send to the client.
/// </summary>
/// <remarks>Data is sent according to the behavior of a typical GPS device: $GPGGA,
/// $GPGSA, $GPRMC, $GPGSV sentences are sent every second, and a $GPGSV sentence
/// is sent every five seconds.
/// Developers who want to emulate a specific model of GPS device should override this
/// method and generate the sentences specific to that device.</remarks>
protected override void OnEmulation()
{
// Update real-time position, speed, bearing, etc.
base.OnEmulation();
if (Route.Count == 0)
{
CurrentPosition = EmulatePositionError(CurrentPosition);
}
/* NMEA devices will transmit "bursts" of NMEA sentences, followed by a one-second pause.
* Other sentences (usually $GPGSV) are transmitted once every few seconds. This emulator,
* by default, will transmit the most common NMEA sentences.
*/
// $GPGGA
if (!_gpggaInterval.Equals(TimeSpan.Zero)
// Has enough time elapsed to send the sentence?
&& UtcDateTime.Subtract(_gpggaLastSent) > _gpggaInterval)
{
// Get the tracked satellite count
int trackedCount = Satellites.Count(item => item.SignalToNoiseRatio.Value > 0);
// Yes
_gpggaLastSent = UtcDateTime;
// Queue the sentence to the read buffer
WriteSentenceToClient(new GpggaSentence(UtcDateTime.TimeOfDay, CurrentPosition, _fixQuality, trackedCount,
_horizontalDOP, Altitude.Add(EmulateError(_verticalDOP)), Distance.Empty, TimeSpan.Zero, -1)); //Add an error to the altitude written to the client but don't change the actual value (otherwise it will "walk")
}
// $GPRMC
if (!_gprmcInterval.Equals(TimeSpan.Zero)
// Has enough time elapsed to send the sentence?
&& UtcDateTime.Subtract(_gprmcLastSent) > _gprmcInterval)
{
// Yes
_gprmcLastSent = UtcDateTime;
// Queue the sentence to the read buffer
WriteSentenceToClient(new GprmcSentence(UtcDateTime, _fixStatus == FixStatus.Fix, CurrentPosition, Speed,
Bearing, _magneticVariation));
}
// $GPGLL
if (!_gpgllInterval.Equals(TimeSpan.Zero)
// Has enough time elapsed to send the sentence?
&& UtcDateTime.Subtract(_gpgllLastSent) > _gpgllInterval)
{
// Yes
_gpgllLastSent = UtcDateTime;
// Write a $GPGLL to the client
WriteSentenceToClient(new GpgllSentence(CurrentPosition, UtcDateTime.TimeOfDay, _fixStatus));
}
// $GPGSA
if (!_gpgsaInterval.Equals(TimeSpan.Zero)
// Has enough time elapsed to send the sentence?
&& UtcDateTime.Subtract(_gpgsaLastSent) > _gpgsaInterval)
{
// Yes
_gpgsaLastSent = UtcDateTime;
// Queue the sentence to the read buffer
WriteSentenceToClient(new GpgsaSentence(_fixMode, _fixMethod, Satellites,
_meanDOP, _horizontalDOP, _verticalDOP));
}
// $GPGSV
if (!_gpgsvInterval.Equals(TimeSpan.Zero)
// Has enough time elapsed to send the sentence?
&& UtcDateTime.Subtract(_gpgsvLastSent) > _gpgsvInterval)
{
// Build a list of sentences from our satellites
IList <GpgsvSentence> sentences = GpgsvSentence.FromSatellites(Satellites);
// Yes
_gpgsvLastSent = UtcDateTime;
// Write each sentence to the read buffer
foreach (GpgsvSentence gpgsv in sentences)
{
WriteSentenceToClient(gpgsv);
}
}
// And signal that we have data (or not)
if (ReadBuffer.Count == 0)
{
ReadDataAvailableWaitHandle.Reset();
}
else
{
ReadDataAvailableWaitHandle.Set();
}
}