NMEA GPS Emulator

The NMEA-GPS Emulator is a simple script that emulates a GPS receiver (simulates unit's movement). Data generated by the script are sent to clients in NMEA 0183 format. This script can be useful for testing applications or systems that require some unit's GPS position data.

The NMEA-GPS Emulator script can be used in one of the following operating modes:

• NMEA TCP Stream (sends TCP packets to the specified client),
• NMEA UDP Stream (sends UDP packets to the specified client),
• NMEA TCP Server (the server waits for client connections, then sends TCP packets to the connected clients - max 10 connections)
• NMEA Serial (transmit serial data on specified RS port).

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Features

• The script allows the user to enter the following data:
  • unit's position;
  • unit's speed;
  • unit's course;
  • operating mode selection (NMEA Serial, NMEA TCP Server, NMEA TCP or UDP Stream);
  • IP address & port pair or serial port name.
• After the NMEA data transmission has started, the script allows the user to interactively change the speed and course of the unit.
• Generated NMEA sentences are resent to the selected clients periodically (every second). Each time a data with NMEA sentences is sent, the position of the unit is updated based on its speed and course.

List of NMEA sentences generated by NMEA-GPS Emulator script:

GPGGA - Global Positioning System Fix Data
GPGLL - Position data: position fix, time of position fix, and status
GPRMC - Recommended minimum specific GPS/Transit data
GPGSA - GPS DOP and active satellites
GPGSV - GPS Satellites in view
GPHDT - True Heading
GPVTG - Track made good and ground speed
GPZDA - Date & Time

Output example:

$GPGGA,173124.00,5430.000,N,01921.029,E,1,09,0.92,15.2,M,32.5,M,,*6C
$GPGSA,A,3,22,11,27,01,03,02,10,21,19,,,,1.56,0.92,1.25*02
$GPGSV,4,1,15,26,25,138,53,16,25,091,67,01,51,238,77,02,45,085,41*79
$GPGSV,4,2,15,03,38,312,01,30,68,187,37,11,22,049,44,09,67,076,71*77
$GPGSV,4,3,15,10,14,177,12,19,86,235,37,21,84,343,95,22,77,040,66*79
$GPGSV,4,4,15,08,50,177,60,06,81,336,46,27,63,209,83*4C
$GPGLL,5430.000,N,01921.029,E,173124.000,A,A*59
$GPRMC,173124.000,A,5430.000,N,01921.029,E,10.500,90.0,051121,,,A*65
$GPHDT,90.0,T*0C
$GPVTG,90.0,T,,M,10.5,N,19.4,K*51
$GPZDA,173124.000,05,11,2021,0,0*50

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Getting Started

Below instructions will get you a copy of the project up and running on your local machine.

Requirements

Python third party packages:

• pyproj
• pyserial
• psutil

In order to use NMEA Serial mode correctly, it is necessary to use dedicated serial null modem cable.

On Linux systems you will probably need to change the permissions for the device matching your serial port before running the script.

# Example command for /dev/ttyUSB0 device
sudo chmod a+rw /dev/ttyUSB0

Installation with venv

The script can be build and run locally with virtualenv tool. Run following commands in order to create virtual environment and install the required packages.

$ virtualenv venv
$ source venv/bin/activate
(venv) $ pip install -r requirements.txt

Running the script

You can start the script using the following command:

(venv) $ python main.py

After starting the script correctly, the following prompt should appear in the OS console:

..####...#####....####...........######..##...##..##..##..##.......####...######...####...#####..
.##......##..##..##..............##......###.###..##..##..##......##..##....##....##..##..##..##.
.##.###..#####....####...........####....##.#.##..##..##..##......######....##....##..##..#####..
.##..##..##..........##..........##......##...##..##..##..##......##..##....##....##..##..##..##.
..####...##.......####...........######..##...##...####...######..##..##....##.....####...##..##.
.................................................................................................
        
### Choose emulator option: ###
1 - NMEA Serial
2 - NMEA TCP Server
3 - NMEA TCP or UDP Stream
4 - Quit
>>>