nmea

nmea - Imports GPS NMEA-formatted data files.

class upoints.nmea.Fix(time, latitude, longitude, quality, satellites, dilution, altitude, geoid_delta, dgps_delta=None, dgps_station=None, mode=None)[source]

Bases: upoints.point.Point

Class for representing a GPS NMEA-formatted system fix.

New in version 0.8.0.

Initialise a new Fix object.

Parameters:
  • time (datetime.time) – Time the fix was taken
  • latitude (float) – Fix’s latitude
  • longitude (float) – Fix’s longitude
  • quality (int) – Mode under which the fix was taken
  • satellites (int) – Number of tracked satellites
  • dilution (float) – Horizontal dilution at reported position
  • altitude (float) – Altitude above MSL
  • geoid_delta (float) – Height of geoid’s MSL above WGS84 ellipsoid
  • dgps_delta (float) – Number of seconds since last DGPS sync
  • dgps_station (int) – Identifier of the last synced DGPS station
  • mode (str) – Type of reading
static parse_elements(elements)[source]

Parse essential fix’s data elements.

Parameters:elements (list) – Data values for fix
Returns:Fix object representing data
Return type:Fix
quality_string()[source]

Return a string version of the quality information.

Returns::
str: Quality information as string
class upoints.nmea.Locations(gpsdata_file=None)[source]

Bases: upoints.point.Points

Class for representing a group of GPS location objects.

New in version 0.8.0.

Initialise a new Locations object.

import_locations(gpsdata_file, checksum=True)[source]

Import GPS NMEA-formatted data files.

import_locations() returns a list of Fix objects representing the fix sentences found in the GPS data.

It expects data files in NMEA 0183 format, as specified in the official documentation, which is ASCII text such as:

$GPGSV,6,6,21,32,65,170,35*48
$GPGGA,142058,5308.6414,N,00300.9257,W,1,04,5.6,1374.6,M,34.5,M,,*6B
$GPRMC,142058,A,5308.6414,N,00300.9257,W,109394.7,202.9,191107,5,E,A*2C
$GPGSV,6,1,21,02,76,044,43,03,84,156,49,06,89,116,51,08,60,184,30*7C
$GPGSV,6,2,21,09,87,321,50,10,77,243,44,11,85,016,49,12,89,100,52*7A
$GPGSV,6,3,21,13,70,319,39,14,90,094,52,16,85,130,49,17,88,136,51*7E
$GPGSV,6,4,21,18,57,052,27,24,65,007,34,25,62,142,32,26,88,031,51*73
$GPGSV,6,5,21,27,64,343,33,28,45,231,16,30,84,198,49,31,90,015,52*7C
$GPGSV,6,6,21,32,65,170,34*49
$GPWPL,5200.9000,N,00013.2600,W,HOME*5E
$GPGGA,142100,5200.9000,N,00316.6600,W,1,04,5.6,1000.0,M,34.5,M,,*68
$GPRMC,142100,A,5200.9000,N,00316.6600,W,123142.7,188.1,191107,5,E,A*21

The reader only imports the GGA, or GPS fix, sentences currently but future versions will probably support tracks and waypoints. Other than that the data is out of scope for upoints.

The above file when processed by import_locations() will return the following list object:

[Fix(datetime.time(14, 20, 58), 53.1440233333, -3.01542833333, 1,
     4, 5.6, 1374.6, 34.5, None, None),
 Position(datetime.time(14, 20, 58), True, 53.1440233333,
          -3.01542833333, 109394.7, 202.9,
          datetime.date(2007, 11, 19), 5.0, 'A'),
 Waypoint(52.015, -0.221, 'Home'),
 Fix(datetime.time(14, 21), 52.015, -3.27766666667, 1, 4, 5.6,
     1000.0, 34.5, None, None),
 Position(datetime.time(14, 21), True, 52.015, -3.27766666667,
          123142.7, 188.1, datetime.date(2007, 11, 19), 5.0, 'A')]

Note

The standard is quite specific in that sentences must be less than 82 bytes, while it would be nice to add yet another validity check it isn’t all that uncommon for devices to break this requirement in their “extensions” to the standard.

Todo

Add optional check for message length, on by default

Parameters:
  • gpsdata_file (iter) – NMEA data to read
  • checksum (bool) – Whether checksums should be tested
Returns:

Series of locations taken from the data

Return type:

list

class upoints.nmea.LoranPosition(latitude, longitude, time, status, mode=None)[source]

Bases: upoints.point.Point

Class for representing a GPS NMEA-formatted Loran-C position.

Initialise a new LoranPosition object.

Parameters:
  • latitude (float) – Fix’s latitude
  • longitude (float) – Fix’s longitude
  • time (datetime.time) – Time the fix was taken
  • status (bool) – Whether the data is active
  • mode (str) – Type of reading
mode_string()[source]

Return a string version of the reading mode information.

Returns:Quality information as string
Return type:str
static parse_elements(elements)[source]

Parse position data elements.

Parameters:elements (list) – Data values for fix
Returns:Fix object representing data
Return type:Fix
upoints.nmea.MODE_INDICATOR = {'A': 'Autonomous', 'E': 'Estimated', 'D': 'Differential', 'M': 'Manual', 'N': 'Invalid', 'S': 'Simulated'}

NMEA’s mapping of code to reading type

class upoints.nmea.Position(time, status, latitude, longitude, speed, track, date, variation, mode=None)[source]

Bases: upoints.point.Point

Class for representing a GPS NMEA-formatted position.

New in version 0.8.0.

Initialise a new Position object.

Parameters:
  • time (datetime.time) – Time the fix was taken
  • status (bool) – Whether the data is active
  • latitude (float) – Fix’s latitude
  • longitude (float) – Fix’s longitude
  • speed (float) – Ground speed
  • track (float) – Track angle
  • date (datetime.date) – Date when position was taken
  • variation (float) – Magnetic variation
  • mode (str) – Type of reading
mode_string()[source]

Return a string version of the reading mode information.

Returns:Quality information as string
Return type:str
static parse_elements(elements)[source]

Parse position data elements.

Parameters:elements (list) – Data values for position
Returns:Position object representing data
Return type:Position
class upoints.nmea.Waypoint(latitude, longitude, name)[source]

Bases: upoints.point.Point

Class for representing a NMEA-formatted waypoint.

New in version 0.8.0.

Initialise a new Waypoint object.

Parameters:
  • latitude (float) – Waypoint’s latitude
  • longitude (float) – Waypoint’s longitude
  • name (str) – Comment for waypoint
static parse_elements(elements)[source]

Parse waypoint data elements.

Parameters:elements (list) – Data values for fix
Returns:Object representing data
Return type:nmea.Waypoint
upoints.nmea.calc_checksum(sentence)[source]

Calculate a NMEA 0183 checksum for the given sentence.

NMEA checksums are a simple XOR of all the characters in the sentence between the leading “$” symbol, and the “*” checksum separator.

Parameters:sentence (str) – NMEA 0183 formatted sentence
upoints.nmea.nmea_latitude(latitude)[source]

Generate a NMEA-formatted latitude pair.

Parameters:latitude (float) – Latitude to convert
Returns:NMEA-formatted latitude values
Return type:tuple
upoints.nmea.nmea_longitude(longitude)[source]

Generate a NMEA-formatted longitude pair.

Parameters:longitude (float) – Longitude to convert
Returns:NMEA-formatted longitude values
Return type:tuple
upoints.nmea.parse_latitude(latitude, hemisphere)[source]

Parse a NMEA-formatted latitude pair.

Parameters:
  • latitude (str) – Latitude in DDMM.MMMM
  • hemisphere (str) – North or South
Returns:

Decimal representation of latitude

Return type:

float

upoints.nmea.parse_longitude(longitude, hemisphere)[source]

Parse a NMEA-formatted longitude pair.

Parameters:
  • longitude (str) – Longitude in DDDMM.MMMM
  • hemisphere (str) – East or West
Returns:

Decimal representation of longitude

Return type:

float