public MPacketReceived ReceivePacket()
{
MPacketReceived packetIn = new MPacketReceived();
m_physLayer.Receive(packetIn);
return(packetIn);
}
// send, wait for response and return received packet:
public MPacketReceived Transact(MPacket packet)
{
string str = packet.ToString();
MPacketReceived packetIn = new MPacketReceived();
m_physLayer.Transact(str, packetIn);
return(packetIn);
}
public void Transact(string packetBodyOut, MPacketReceived packetIn)
{
//log("Transact --------------------------- started");
packetIn.isGood = false;
int tries = 0;
while (!packetIn.isGood && tries++ <= 3)
{
if (tries > 1)
{
logError("Transact - try " + tries);
}
this.Send(packetBodyOut);
this.Receive(packetIn);
}
//log("Transact --------------------------- finished");
}
public void Receive(MPacketReceived packetIn)
{
packetIn.isGood = false;
int tries = 0;
while (!packetIn.isGood && tries++ <= 3)
{
//log("Receive() - waiting... try " + tries);
packetIn.m_string = base.Receive();
//log("received: " + packetIn.m_string);
if (packetIn.m_string.StartsWith("$PMGNCSM"))
{
log("received astray CSM: " + packetIn.m_string);
tries--;
continue;
}
if (m_handshake)
{
string cs = NmeaPacket.checksumReceived(packetIn.m_string);
MPacketCsm packet = new MPacketCsm(cs);
string str = packet.ToString() + NmeaPacket.checksum(packet.ToString());
log("sending handshake response: " + str);
base.Send(str);
}
if (!NmeaPacket.checksumVerify(packetIn.m_string))
{
packetIn.isGood = false;
if (m_handshake)
{
logError("bad checksum, waiting for resent packet");
}
else
{
logError("bad checksum, returning bad packet");
break; // just report the received package, isGood = false
}
}
else
{
packetIn.isGood = packetIn.basicParse(packetIn.m_string);
// packet is good and parsed, so the fields array is filled
}
}
logPacket("received " + (packetIn.isGood?"good":"bad") + " packet=" + packetIn);
}
public void StartRealTime(GpsRealTimeHandler realtimeCallback)
{
int total = 0;
int maxErrors = 5;
int errors = maxErrors;
bool finished = false;
m_stopRealTime = false;
while (!finished && !m_stopRealTime)
{
GpsRealTimeData pvtData = new GpsRealTimeData(); // will be returned empty if no data
MPacketReceived received = null;
try
{
received = m_linkLayer.ReceivePacket();
if (!received.isGood)
{
m_linkLayer.logError("StartRealTime: bad packet received, count=" + total);
pvtData.comment = "bad data packet from GPS";
realtimeCallback(pvtData);
continue;
}
}
catch (Exception e)
{
m_linkLayer.logError("StartRealTime: " + e.Message + " count=" + total);
//if(received != null)
{
try
{
m_linkLayer.ReOpen();
}
catch (Exception ee)
{
m_linkLayer.logError("while ReOpen(): " + ee.Message);
}
}
pvtData.comment = e.Message.StartsWith("Timeout") ?
"GPS not responding - check cable" : ("error: " + e.Message);
realtimeCallback(pvtData);
continue;
}
//m_linkLayer.log("" + total + " === " + received);
m_linkLayer.log("StartRealTime: good packet received, count=" + total + " " + received);
if (received.header.EndsWith("GGA")) // NMEA GGA expected for location
{
m_linkLayer.log("StartRealTime: " + received.header + " packet received, count=" + total + " content=" + received);
try
{
MPacket pvt = received.fromString();
/*
* $GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47
*
* Where:
* GGA Global Positioning System Fix Data
* 0 123519 Fix taken at 12:35:19 UTC
* 1 4807.038,N Latitude 48 deg 07.038' N
* 3 01131.000,E Longitude 11 deg 31.000' E
* 5 1 Fix quality: 0 = invalid
* 1 = GPS fix
* 2 = DGPS fix
* 6 = estimated (2.3 feature)
* 6 08 Number of satellites being tracked
* 7 0.9 Horizontal dilution of position
* 8 545.4,M Altitude, Meters, above mean sea level
* 10 46.9,M Height of geoid (mean sea level) above WGS84
* ellipsoid
* 12 (empty field) time in seconds since last DGPS update
* 13 (empty field) DGPS station ID number
* 47 the checksum data, always begins with *
*/
double Lat = pvt.parseLat(1);
double Lng = pvt.parseLng(1);
double Elev = pvt.parseElev(8); // alt above mean sea level
pvtData.location = new GeoCoord(Lng, Lat, Elev);
//m_linkLayer.log("coord=" + pvtData.location);
// time component:
pvtData.time = pvt.parseNmeaTime(0, Project.localToZulu(DateTime.Now)); // UTC
// errors and velocity:
pvtData.posError = 0;
pvtData.posErrorH = 0;
pvtData.posErrorV = 0;
pvtData.fix = 0; // failed integrity check
switch ((string)pvt.fields[5])
{
case "0": // invalid
pvtData.fix = 1; // invalid
break;
case "1": // GPS fix
pvtData.fix = 2; // two dimensional
break;
case "2": // DGPS fix
pvtData.fix = 4; // two dimensional differential
break;
case "6": // estimated
pvtData.fix = 6; // estimated
break;
}
pvtData.velocityEast = 0;
pvtData.velocityNorth = 0;
pvtData.velocityUp = 0;
pvtData.comment = "received " + received.header;
//realtimeCallback(pvtData);
total++;
errors = maxErrors;
}
catch (Exception ee)
{
m_linkLayer.logError("StartRealTime: " + ee.Message);
}
}
else if (received.header.EndsWith("RMC")) // NMEA RMC may come
{
m_linkLayer.log("StartRealTime: " + received.header + " packet received, count=" + total + " content=" + received);
try
{
MPacket pvt = received.fromString();
// $GPRMC,052458.73,V,3334.6441,N,11739.6622,W,00.0,000.0,290103,13,E*4F
/*
* see http://www.gpsinformation.org/dale/nmea.htm for NMEA reference
*
* RMC - NMEA has its own version of essential gps pvt (position, velocity, time) data.
* It is called RMC, The Recommended Minimum, which might look like:
*
* $GPRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A
* $GPRMC,050821.000,A,3334.5551,N,11739.7705,W,0.00,,251006,,,A*67
*
* Where:
* RMC Recommended Minimum sentence C
* 0 123519 Fix taken at 12:35:19 UTC
* 1 A Status A=active or V=Void.
* 2 4807.038,N Latitude 48 deg 07.038' N
* 4 01131.000,E Longitude 11 deg 31.000' E
* 6 022.4 Speed over the ground in knots
* 7 084.4 Track angle in degrees True
* 8 230394 Date - 23rd of March 1994
* 9 003.1,W Magnetic Variation
* 6A The checksum data, always begins with *
*
* Note that, as of the 2.3 release of NMEA, there is a new field in the RMC sentence
* at the end just prior to the checksum. The value of the entry is
* A=autonomous, D=differential, E=estimated, N=Data not valid.
*/
bool status = "A".Equals(pvt.fields[1]);
if (status)
{
double Lat = pvt.parseLat(2);
double Lng = pvt.parseLng(2);
double Elev = 0.0d;
pvtData.location = new GeoCoord(Lng, Lat, Elev);
//m_linkLayer.log("coord=" + pvtData.location);
// time component (only time part):
pvtData.time = pvt.parseNmeaDateTime(0, 8); // UTC
if (!"".Equals(pvt.fields[6]))
{
double knots = Convert.ToDouble(pvt.fields[6]);
pvtData.velocity = knots * Distance.METERS_PER_NAUTICAL_MILE / 3600.0d;
// calculate velocity vector based on track angle:
if (!"".Equals(pvt.fields[7]))
{
double trackAngleRad = Convert.ToDouble(pvt.fields[7]) * Math.PI / 180.0d;
pvtData.velocityNorth = pvtData.velocity * Math.Cos(trackAngleRad);
pvtData.velocityEast = pvtData.velocity * Math.Sin(trackAngleRad);
}
}
pvtData.fix = 2; // assume two-dimensional
pvtData.comment = "received " + received.header;
realtimeCallback(pvtData);
}
total++;
errors = maxErrors;
}
catch (Exception ee)
{
m_linkLayer.logError("StartRealTime: " + ee.Message);
}
}
else if (received.header.EndsWith("GLL")) // NMEA GLL may come
{
m_linkLayer.log("StartRealTime: GLL packet received, count=" + total + " content=" + received);
try
{
MPacket pvt = received.fromString();
// $GPGLL,3334.6464,N,11739.6583,W,052707.129,A*29
/*
* see http://www.gpsinformation.org/dale/nmea.htm for NMEA reference
*
* GLL - Geographic Latitude and Longitude is a holdover from Loran data and some old units
* may not send the time and data valid information if they are emulating Loran data.
* If a gps is emulating Loran data they may use the LC Loran prefix instead of GP.
*
* $GPGLL,4916.45,N,12311.12,W,225444,A,*31
*
* Where:
* GLL Geographic position, Latitude and Longitude
* 0 4916.46,N Latitude 49 deg. 16.45 min. North
* 2 12311.12,W Longitude 123 deg. 11.12 min. West
* 4 225444 Fix taken at 22:54:44 UTC
* 5 A Data valid or V (void)
* 31 checksum data
*
*/
bool status = "A".Equals(pvt.fields[5]);
if (status)
{
double Lat = pvt.parseLat(0);
double Lng = pvt.parseLng(0);
double Elev = 0.0d;
pvtData.location = new GeoCoord(Lng, Lat, Elev);
//m_linkLayer.log("coord=" + pvtData.location);
// time component (only time part):
pvtData.time = pvt.parseNmeaTime(4, Project.localToZulu(DateTime.Now)); // UTC
pvtData.fix = 2; // assume two-dimensional
pvtData.comment = "received " + received.header;
//realtimeCallback(pvtData);
}
total++;
errors = maxErrors;
}
catch (Exception ee)
{
m_linkLayer.logError("StartRealTime: " + ee.Message);
}
}
else if (received.header.EndsWith("GSV")) // NMEA GSV may come for satellite reception status
{
m_linkLayer.log("StartRealTime: GSV packet received, count=" + total + " content=" + received);
/*
* see http://www.gpsinformation.org/dale/nmea.htm for NMEA reference
*
* $GPGSV,3,1,08,14,69,204,,15,57,105,36,18,45,047,36,03,42,263,36*71
* $GPGSV,2,1,08,01,40,083,46,02,17,308,41,12,07,344,39,14,22,228,45*75
*
* Where:
* GSV Satellites in view
* 0 2 Number of sentences for full data
* 1 1 sentence 1 of 2
* 2 08 Number of satellites in view
* for up to 4 satellites per sentence {
* 3 01 Satellite PRN number
* 4 40 Elevation, degrees
* 5 083 Azimuth, degrees
* 6 46 Signal strength - higher is better
* }
* 75 the checksum data, always begins with *
*/
//MPacket pvt = received.fromString();
//pvtData.comment = "received";
//realtimeCallback(pvtData);
total++;
errors = maxErrors;
}
else if (received.header.EndsWith("VTG")) // NMEA GSA may come
{
m_linkLayer.log("StartRealTime: GPVTG packet received, count=" + total + " content=" + received);
// $GPVTG,309.62,T,,M,0.13,N,0.2,K*6E
/*
* VTG - Course Over Ground and Ground Speed
*
* Name Example Units Description
* Message ID $GPVTG VTG protocol header
* Course 309.62 degrees Measured heading
* Reference T True
* Course degrees Measured heading
* Reference M Magnetic
* Speed 0.13 knots Measured horizontal speed
* Units N Knots
* Speed 0.2 Km/hr Measured horizontal speed
* Units K Kilometers per hour
*/
}
else if (received.header.EndsWith("GSA")) // NMEA GSA may come
{
m_linkLayer.log("StartRealTime: GPGSA packet received, count=" + total + " content=" + received);
// $GPGSA,A,2,15,18,14,31,,,,,,,,,05.6,05.6,*17
/*
* see http://www.gpsinformation.org/dale/nmea.htm for NMEA reference
*
* GSA - GPS DOP and active satellites. This sentence provides details on the nature of the
* fix. It includes the numbers of the satellites being used in the current solution and
* the DOP. DOP (dilution of precision) is an indication of the effect of satellite geometry
* on the accuracy of the fix. It is a unitless number where smaller is better. For 3D fixes
* using 4 satellites a 1.0 would be considered to be a perfect number. For overdetermined
* solutions it is possible to see numbers below 1.0. There are differences in the way the
* PRN's are presented which can effect the ability of some programs to display this data.
* For example, in the example shown below there are 5 satellites in the solution and
* the null fields are scattered indicating that the almanac would show satellites in
* the null positions that are not being used as part of this solution. Other receivers
* might output all of the satellites used at the beginning of the sentence with the
* null field all stacked up at the end. This difference accounts for some satellite
* display programs not always being able to display the satellites being tracked.
*
* $GPGSA,A,3,04,05,,09,12,,,24,,,,,2.5,1.3,2.1*39
*
* Where:
* GSA Satellite status
* A Auto selection of 2D or 3D fix (M = manual)
* 3 3D fix - other values include: 1 = no fix
* 2 = 2D fix
* 04,05... PRNs of satellites used for fix (space for 12)
* 2.5 PDOP (dilution of precision)
* 1.3 Horizontal dilution of precision (HDOP)
* 2.1 Vertical dilution of precision (VDOP)
* 39 the checksum data, always begins with *
*
*/
}
else
{
m_linkLayer.log("StartRealTime: good other (unrecognized) packet received, count=" + total + " content=" + received);
}
} // end while()
m_linkLayer.log("StartRealTime: finished receiving fixes count=" + total);
}
public MPacketReceived ReceivePacket()
{
MPacketReceived packetIn = new MPacketReceived();
m_physLayer.Receive(packetIn);
return packetIn;
}
// send, wait for response and return received packet:
public MPacketReceived Transact(MPacket packet)
{
string str = packet.ToString();
MPacketReceived packetIn = new MPacketReceived();
m_physLayer.Transact(str, packetIn);
return packetIn;
}
public void Transact(string packetBodyOut, MPacketReceived packetIn)
{
//log("Transact --------------------------- started");
packetIn.isGood = false;
int tries = 0;
while(!packetIn.isGood && tries++ <= 3)
{
if(tries > 1)
{
logError("Transact - try " + tries);
}
this.Send(packetBodyOut);
this.Receive(packetIn);
}
//log("Transact --------------------------- finished");
}
public void Receive(MPacketReceived packetIn)
{
packetIn.isGood = false;
int tries = 0;
while(!packetIn.isGood && tries++ <= 3)
{
//log("Receive() - waiting... try " + tries);
packetIn.m_string = base.Receive();
//log("received: " + packetIn.m_string);
if(packetIn.m_string.StartsWith("$PMGNCSM"))
{
log("received astray CSM: " + packetIn.m_string);
tries--;
continue;
}
if(m_handshake)
{
string cs = NmeaPacket.checksumReceived(packetIn.m_string);
MPacketCsm packet = new MPacketCsm(cs);
string str = packet.ToString() + NmeaPacket.checksum(packet.ToString());
log("sending handshake response: " + str);
base.Send(str);
}
if (!NmeaPacket.checksumVerify(packetIn.m_string))
{
packetIn.isGood = false;
if(m_handshake)
{
logError("bad checksum, waiting for resent packet");
}
else
{
logError("bad checksum, returning bad packet");
break; // just report the received package, isGood = false
}
}
else
{
packetIn.isGood = packetIn.basicParse(packetIn.m_string);
// packet is good and parsed, so the fields array is filled
}
}
logPacket("received " + (packetIn.isGood?"good":"bad") + " packet=" + packetIn);
}