Package: nmeasim
nmeasimA Python 3 GNSS/NMEA receiver simulation.A partial rewrite of the Python 2gpssimproject, originally used to generate test data for NMEA consumers.OverviewThe core of the package isnmeasim.simulator, a GNSS simulation library that emits NMEA sentences. The following are supported:Geospatial (GGA, GLL, RMC, VTG, ZDA, HDM, HDT)- simulated using a consistent location/velocity model, time using machine time (not NTP, unless the machine happens to be NTP synchronised).Satellites (GSA, GSV)- faked with random azimuth/elevation.The library supports GP (GPS) and GL (Glonass) sentences. GN (fused GNSS) sentences are not currently supported. Additional GNSS types could be added without too much difficulty by extendingnmeasim.models.GUIAlso included isnmea.gui, a Tk GUI that supports serial output to emulate a serial GPS modem. Currently this only supports GP (GPS) sentences.Features:Static / constant velocity / random walk iterationOptionally set a target location to route toCustom update interval and simulation speedOption to simulate independent RTC (time with no fix)Custom precision can be specified for all measurementsCustom sentence order and presenceSimulate fix/no-fix conditionsSimulate changing satellite visibilityThis can be run from source using the console scriptnmeasim.
The GUI is also delivered as a standalone Windows application by the build pipeline - this can be downloaded and executed independently without any Python dependencies.Installpython-mpipinstallnmeasimSeereleasesfor pre-built Windows GUI binaries.BuildingThis project uses aPEP 617/PEP 621build system, using thesetuptoolsbackend. A stubsetup.pyexists only to enable editable installs.The preferred (and tested) frontend isbuild.Note: If building withpython -m build --no-isolation, the build dependencies will not be installed automatically. Instead, you will need to manually install the packages listed underrequiresin the[build-system]section ofpyproject.toml.ExamplesUse Model Directly to Set Parameters and Get Sentencesfromdatetimeimportdatetime,timedelta,timezonefromnmeasim.modelsimportGpsReceivergps=GpsReceiver(date_time=datetime(2020,1,1,12,34,56,tzinfo=timezone.utc),output=('RMC',))foriinrange(3):gps.date_time+=timedelta(seconds=1)gps.get_output()Output:['$GPRMC,123457.000,A,0000.000,N,00000.000,E,0.0,0.0,010120,,,A*6A']
['$GPRMC,123458.000,A,0000.000,N,00000.000,E,0.0,0.0,010120,,,A*65']
['$GPRMC,123459.000,A,0000.000,N,00000.000,E,0.0,0.0,010120,,,A*64']Simulation - Get Sentences Immediatelyfromdatetimeimportdatetimefrompprintimportpprintfromnmeasim.modelsimportTZ_LOCALfromnmeasim.simulatorimportSimulatorsim=Simulator()withsim.lock:# Can re-order or drop somesim.gps.output=('GGA','GLL','GSA','GSV','RMC','VTG','ZDA')sim.gps.num_sats=14sim.gps.lat=1sim.gps.lon=3sim.gps.altitude=-13sim.gps.geoid_sep=-45.3sim.gps.mag_var=-1.1sim.gps.kph=60.0sim.gps.heading=90.0sim.gps.mag_heading=90.1sim.gps.date_time=datetime.now(TZ_LOCAL)# PC current time, local time zonesim.gps.hdop=3.1sim.gps.vdop=5.0sim.gps.pdop=(sim.gps.hdop**2+sim.gps.vdop**2)**0.5# Precision decimal points for various measurementssim.gps.horizontal_dp=4sim.gps.vertical_dp=1sim.gps.speed_dp=1sim.gps.time_dp=2sim.gps.angle_dp=1# Keep straight course for simulator - don't randomly change the headingsim.heading_variation=0pprint(list(sim.get_output(3)))Output:['$GPGGA,061545.27,0100.0000,N,00300.0000,E,1,14,3.1,-13.0,M,-45.3,M,,*5F',
 '$GPGLL,0100.0000,N,00300.0000,E,061545.27,A,A*6D',
 '$GPGSA,A,3,1,4,7,8,10,13,14,18,21,24,25,26,5.9,3.1,5.0*3A',
 '$GPGSV,4,1,14,01,09,039,31,04,42,278,31,07,11,136,30,08,01,346,34*7B',
 '$GPGSV,4,2,14,10,52,255,35,13,56,061,34,14,12,053,38,18,77,241,38*77',
 '$GPGSV,4,3,14,21,48,056,31,24,09,039,40,25,64,000,36,26,08,131,33*7B',
 '$GPGSV,4,4,14,29,48,213,33,30,33,334,34,,,,,,,,*7B',
 '$GPRMC,061545.27,A,0100.0000,N,00300.0000,E,32.4,90.0,120223,1.1,W,A*2F',
 '$GPVTG,90.0,T,90.1,M,32.4,N,60.0,K,A*21',
 '$GPZDA,061545.27,12,02,2023,13,00*60',
 '$GPGGA,061546.27,0100.0000,N,00300.0090,E,1,14,3.1,-13.0,M,-45.3,M,,*55',
 '$GPGLL,0100.0000,N,00300.0090,E,061546.27,A,A*67',
 '$GPGSA,A,3,1,4,7,8,10,13,14,18,21,24,25,26,5.9,3.1,5.0*3A',
 '$GPGSV,4,1,14,01,08,038,31,04,42,278,30,07,10,136,30,08,01,346,33*7C',
 '$GPGSV,4,2,14,10,52,255,34,13,56,060,34,14,12,052,37,18,76,240,38*79',
 '$GPGSV,4,3,14,21,48,055,30,24,09,039,39,25,63,360,35,26,08,131,32*77',
 '$GPGSV,4,4,14,29,48,213,32,30,33,334,34,,,,,,,,*7A',
 '$GPRMC,061546.27,A,0100.0000,N,00300.0090,E,32.4,90.0,120223,1.1,W,A*25',
 '$GPVTG,90.0,T,90.1,M,32.4,N,60.0,K,A*21',
 '$GPZDA,061546.27,12,02,2023,13,00*63',
 '$GPGGA,061547.27,0100.0000,N,00300.0180,E,1,14,3.1,-13.0,M,-45.3,M,,*54',
 '$GPGLL,0100.0000,N,00300.0180,E,061547.27,A,A*66',
 '$GPGSA,A,3,1,4,7,8,10,13,14,18,21,24,25,26,5.9,3.1,5.0*3A',
 '$GPGSV,4,1,14,01,08,038,30,04,41,277,30,07,10,135,29,08,00,345,33*78',
 '$GPGSV,4,2,14,10,51,254,34,13,55,060,33,14,11,052,37,18,76,240,37*73',
 '$GPGSV,4,3,14,21,47,055,30,24,08,038,39,25,63,359,35,26,07,131,32*7D',
 '$GPGSV,4,4,14,29,47,212,32,30,32,333,33,,,,,,,,*75',
 '$GPRMC,061547.27,A,0100.0000,N,00300.0180,E,32.4,90.0,120223,1.1,W,A*24',
 '$GPVTG,90.0,T,90.1,M,32.4,N,60.0,K,A*21',
 '$GPZDA,061547.27,12,02,2023,13,00*62']Simulation - Output Sentences Synchronouslyimportsysfromnmeasim.simulatorimportSimulatorsim=Simulator()sim.generate(3,output=sys.stdout)Output:$GPGGA,061808.129,0000.000,N,00000.000,E,1,12,1.0,0.0,M,,M,,*4D
$GPGLL,0000.000,N,00000.000,E,061808.129,A,A*54
$GPGSA,A,3,7,9,11,12,13,18,19,21,24,25,26,28,,1.0,*31
$GPGSV,3,1,12,07,81,128,33,09,86,142,37,11,52,087,34,12,09,020,34*79
$GPGSV,3,2,12,13,37,257,32,18,87,260,37,19,56,313,31,21,26,052,33*72
$GPGSV,3,3,12,24,82,000,35,25,69,269,33,26,17,316,30,28,28,329,39*72
$GPRMC,061808.129,A,0000.000,N,00000.000,E,0.0,0.0,120223,,,A*63
$GPVTG,0.0,T,,M,0.0,N,0.0,K,A*0D
$GPZDA,061808.129,12,02,2023,13,00*5B
$GPGGA,061809.129,0000.000,N,00000.000,E,1,12,1.0,0.0,M,,M,,*4C
$GPGLL,0000.000,N,00000.000,E,061809.129,A,A*55
$GPGSA,A,3,7,9,11,12,13,18,19,21,24,25,26,28,,1.0,*31
$GPGSV,3,1,12,07,82,128,33,09,86,142,38,11,52,087,34,12,10,020,35*7C
$GPGSV,3,2,12,13,38,257,33,18,87,260,38,19,57,313,31,21,27,052,33*73
$GPGSV,3,3,12,24,82,001,35,25,69,269,34,26,17,317,31,28,29,329,39*75
$GPRMC,061809.129,A,0000.000,N,00000.000,E,0.0,21.9,120223,,,A*58
$GPVTG,21.9,T,,M,0.0,N,0.0,K,A*37
$GPZDA,061809.129,12,02,2023,13,00*5A
$GPGGA,061810.129,0000.000,N,00000.000,E,1,12,1.0,0.0,M,,M,,*44
$GPGLL,0000.000,N,00000.000,E,061810.129,A,A*5D
$GPGSA,A,3,7,9,11,12,13,18,19,21,24,25,26,28,,1.0,*31
$GPGSV,3,1,12,07,82,129,34,09,87,143,38,11,52,088,34,12,10,021,35*74
$GPGSV,3,2,12,13,38,258,33,18,88,261,38,19,57,313,32,21,27,053,33*70
$GPGSV,3,3,12,24,83,001,35,25,69,270,34,26,18,317,31,28,29,330,39*7B
$GPRMC,061810.129,A,0000.000,N,00000.000,E,0.0,23.4,120223,,,A*5F
$GPVTG,23.4,T,,M,0.0,N,0.0,K,A*38
$GPZDA,061810.129,12,02,2023,13,00*52Simulation - 1PPS to Serial Port (Non-Blocking)fromserialimportSerialfromtimeimportsleepfromnmeasim.simulatorimportSimulatorser=Serial('COM5')ser.write_timeout=0# Do not block simulator on serial writingsim=Simulator()sim.serve(output=ser,blocking=False)sleep(3)sim.kill()Simulation - 1PPS to Serial Port (Blocking)fromserialimportSerialfromtimeimportsleepfromthreadingimportThreadfromnmeasim.simulatorimportSimulatorser=Serial('COM5')ser.write_timeout=0# Do not block simulator on serial writingsim=Simulator()worker=Thread(target=sim.serve,kwargs=dict(output=ser,blocking=True))worker.start()sleep(3)sim.kill()worker.join()LicenseCopyright (c) 2021 Wei Li Jiang

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