setup_dgps.py

在linux系统下开发的GPS接收程序,具有良好的图形操作界面.

#!/usr/env python
#------------------------------------------------------------------------------
# dgps_setup.py : estimate the position of a DGPS reference station
#
#	- programmed by Boyoon Jung ([e-mail])
#------------------------------------------------------------------------------
import uspp.uspp
import sys
import time


# GPS class
class NovatelGPS:
    """
    Novatel GPS device driver.
    """
    
    def __init__(self, device, baudrate):
	"""
	initialize communication.
	"""
	# open a serial port
	self.serial = uspp.SerialPort(device, None, baudrate)

	# send a command
	self.serial.write('log com1 bestposa ontime 1\r\n')

    def __del__(self):
	"""
	finalize communication.
	"""
	self.serial.write('log com1 bestposa once\r\n')

    def update(self):
	"""
	parse a single sentence.
	"""
	# read out a garbage
	while 1:
	    sentence = self.serial.read(1);
	    if sentence == '#':
		break;

	# read a sentence
	sentence = ''
	while 1:
	    sentence += self.serial.read(1);
	    if sentence[-1] == '\r':
		sentence = sentence[:-10]	# no checksum info
		break;

	# parse the sentence
	tokens = sentence.split(';')[1].split(',')
	self.status = tokens[0]
	self.latitude = tokens[2]
	self.longitude = tokens[3]
	self.altitude = tokens[4]
	self.std_lat = tokens[7]
	self.std_lon = tokens[8]
	self.std_alt = tokens[9]

    def fix(self):
	"""
	fix the position of the reference station.
	"""
	# change the interface mode of com2
	self.serial.write('interfacemode com2 none rtcm\r\n')

	# fix the position
	self.serial.write('fix position ' + self.latitude +
				      ' ' + self.longitude +
				      ' ' + self.altitude + '\r\n')

	# make it generate RTCM messages
	self.serial.write('dgpsrxid auto\r\n')
	self.serial.write('log com2 rtcm1 ontime 2\r\n')
	self.serial.write('log com2 rtcm3 ontime 5\r\n')
	self.serial.write('log com2 rtcm9 ontime 2\r\n')



# main function
if __name__ == '__main__':

    # load default settings
    device = '/dev/ttyS0'
    baudrate = 9600

    # process the command line arguments
    if len(sys.argv) > 2: device = sys.argv[1]
    if len(sys.argv) > 3: baudrate = int(sys.argv[2])

    # initialize communication
    gps = NovatelGPS(device, baudrate)

    # wait until the GPS receiver is initialized
    try:
	sys.stderr.write('Initializing GPS receiver ')
	while 1:
	    sys.stderr.write('.')
	    gps.update()
	    if gps.status == 'SOL_COMPUTED':
		sys.stderr.write(' Done.\n\n');
		break;
    except:
	print "Fail to initialize GPS receiver."
	sys.exit(0)

    # print the information
    try:
	while 1:
	    gps.update()
	    print 'Pose = (' + gps.latitude + ',' \
			     + gps.longitude + ',' \
			     + gps.altitude \
		+ ') STD = (' + gps.std_lat + ',' \
			      + gps.std_lon + ',' \
			      + gps.std_alt + ')'
    except:
	gps.fix()
	print
	print 'Position is fixed to'
	print '    Latitude  : ' + gps.latitude
	print '    Longitude : ' + gps.longitude
	print '    Altitude  : ' + gps.altitude
	print