NovaTel Differential GPS Tutorial

This tutorial assumes the reader:
(1) Has a basic knowledge of Visual C++
(2) Has some familiarity with GPS concepts

The rest of the tutorial is presented as follows:

• Step 1: Introduction
• Step 2: System Wiring
• Step 3: GPS Configuration
• Step 4: C++ Datalogging
• Final Words

Drexel Mini Grand Challenge Vehicle with NovaTel GPS

Step 1: Introduction

Step 2: System Wiring

Step 3: GPS Configuration

com com2 9600 n 8 1 n
saveconfig

log com2 rtcaobs ontime 2
log com2 rtcaref ontime 10
log com2 rtcadata1 ontime 5
interfacemode com2 none rtca
saveconfig

fix position LAT LON ALT
saveconfig

com com2 9600 n 8 1 n
interfacemode com2 rtca none
saveconfig

Step 4: C++ Datalogging

	int GPSport = 9;
	unsigned char *GPSBuffer = new unsigned char[400];
	int i;
	
	// Time to run
	int seconds = 250;
	
	CSerial GPS_Serial;
	if(GPS_Serial.Open( GPSport, 57600)){

		int count = 0;
		
		for(int j = 0; j < seconds; j++){
			for(i=0; i < 400; i++){
				GPSBuffer[i] = 0;	
			}
			
			// Get GPS Data
			static char command[14];
			command[0] = '\r';
			command[1] = 'L';
			command[2] = 'O';
			command[3] = 'G';
			command[4] = ' ';
			command[5] = 'B';
			command[6] = 'E';
			command[7] = 'S';
			command[8] = 'T';
			command[9] = 'P';
			command[10] = 'O';
			command[11] = 'S';
			command[12] = 'A';
			command[13] = '\r';

			unsigned char lat_gps[15], long_gps[15];
			int lat_size = 0;
			int long_size = 0;
			int data_waiting = 0;

			GPS_Serial.SendData( command, 14 );
			while(GPS_Serial.ReadDataWaiting() < 219);
			data_waiting = GPS_Serial.ReadDataWaiting();
			GPS_Serial.ReadData( GPSBuffer, data_waiting);

			printf("Got GPS data...\n");

			for(i=4; i < data_waiting; i++){
				if( (GPSBuffer[i-4] == 'O') && (GPSBuffer[i-3] == 'A') && (GPSBuffer[i-2] == 'T') && (GPSBuffer[i-1] == ',') ){
					printf("Single found\n");
					int k = 0;
					while(GPSBuffer[i+k] != ','){
						lat_gps[k] = GPSBuffer[i+k];
						k++;
					}
					lat_size = k;
					i += k+1;
					k = 0;
					while(GPSBuffer[i+k] != ','){
						long_gps[k] = GPSBuffer[i+k];
						k++;
					}
					long_size = k;
				}
			}


			// Begin Text File Output
			FILE *textOutput = fopen("SICK_Data.csv", "a");
		
			// Output GPS data
			for(i=0; i < lat_size; i++){
				fprintf(textOutput,"%c", lat_gps[i]);
			}
			fprintf(textOutput,",");
			for(i=0; i < long_size; i++){
				fprintf(textOutput,"%c", long_gps[i]);
			}
			fprintf(textOutput,"\n");
			
			fclose(textOutput);
			//End Text File Output 
		}
			
		delete [] GPSBuffer;

		return 1;
	}else{
		printf("Com port failed to open\n");
		return 0;
	}

Final Words

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