为什么使用 python 的 GPS 输出为零或 Nan？

我在 GPS 输出方面遇到问题。当我输入：

$ cat /dev/ttyUSB0

我有 NMEA 句子出来（这就是我想要的）

$GPGGA,134131.000,4548.0018,N,01557.1026,E,1,06,1.5,123.8,M,42.4,M,,0000*56

$GPGSA,A,3,12,15,24,17,22,18,,,,,,,2.3,1.5,1.8*30

$GPGSV,3,1,12,24,76,320,29,12,49,254,44,15,42,195,17,17,38,057,15*7A

$GPGSV,3,2,12,25,15,249,,09,12,112,,26,11,162,,18,09,267,19*75

$GPGSV,3,3,12,22,08,297,23,14,08,323,,04,06,114,,28,03,061,*78

$GPRMC,134131.000,A,4548.0018,N,01557.1026,E,1.71,291.64,210513,,,A*67

但是，当我尝试使用 python 查看输出时（这是基本代码）：

import gps
session=gps.gps('localhost','2947')
session.stream()
print session

我懂了：

Time:      (nan)
Lat/Lon:  0.000000 0.000000
Altitude: ?
Speed:    ?
Track:    ?
Status:   STATUS_NO_FIX
Mode:     MODE_NO_FIX
Quality:  0 p=0.00 h=0.00 v=0.00 t=0.00 g=0.00
Y: 0 satellites in view:

我尝试了别人的代码，但它总是显示 NaN 或 0：

    #! /usr/bin/python

# Written by Dan Mandle http://dan.mandle.me September 2012

# License: GPL 2.0

import os

from gps import *

from time import *

import time

import threading

gpsd = None #seting the global variable

os.system('clear') #clear the terminal (optional)

class GpsPoller(threading.Thread):

 def __init__(self):

    threading.Thread.__init__(self)

    global gpsd #bring it in scope

    gpsd = gps(mode=WATCH_ENABLE) #starting the stream of info

     self.current_value = None

    self.running = True #setting the thread running to true

 def run(self):

    global gpsd

    while gpsp.running:

     gpsd.next() #this will continue to loop and grab EACH set of gpsd info to$

if __name__ == '__main__':

 gpsp = GpsPoller() # create the thread

 try:

    gpsp.start() # start it up

    while True:

     #It may take a second or two to get good data

     #print gpsd.fix.latitude,', ',gpsd.fix.longitude,'  Time: ',gpsd.utc

     os.system('clear')

     print

     print ' GPS reading'

    print '----------------------------------------'

     print 'latitude    ' , gpsd.fix.latitude
    print 'longitude   ' , gpsd.fix.longitude

     print 'time utc    ' , gpsd.utc,' + ', gpsd.fix.time

     print 'altitude (m)' , gpsd.fix.altitude

     print 'eps         ' , gpsd.fix.eps

     print 'epx         ' , gpsd.fix.epx

     print 'epv         ' , gpsd.fix.epv

     print 'ept         ' , gpsd.fix.ept

     print 'speed (m/s) ' , gpsd.fix.speed

    print 'climb       ' , gpsd.fix.climb

     print 'track       ' , gpsd.fix.track

     print 'mode        ' , gpsd.fix.mode

     print

     print 'sats        ' , gpsd.satellites

     time.sleep(5) #set to whatever

Output:

 GPS reading
----------------------------------------
latitude     0.0
longitude    0.0
time utc       +  nan
altitude (m) nan
eps          nan
epx          nan
epv          nan
ept          nan
speed (m/s)  nan
climb        nan
track        nan
mode         1

sats         []

那么有人知道为什么这全是零并且未知吗？

请帮忙，我正在尝试修复它一周。

Thanks

我也有类似的问题python-gps封装在树莓派。切换到gps3为我做了这个伎俩：

from time import sleep
from gps3.agps3threaded import AGPS3mechanism

agps_thread = AGPS3mechanism()
agps_thread.stream_data()
agps_thread.run_thread()

while True:
    print('{},{}'.format(agps_thread.data_stream.lat, agps_thread.data_stream.lon))
    sleep(2)

话虽如此，第一项始终是n/a,n/a由于某种原因，但后续值显示正确的数据，而之前的情况并非如此。