GPS Latitude Longitude Conversion Guide for Google Maps

Applicable Products Part number Description

ZETA-GEP-LTE4 (EU) Low Power LTE Cat 4 European Modem with GPIO and GNSS

ZETA-G-GPRS Entry Level GPRS Modem with GNSS (GL)

Objective In some applications, the user may require the position of a system shown on Google Maps.

This application note shows how this can be done using a Siretta ZETA modem with GNSS capability.

This document shows how to convert Latitude Longitude to a position in the map.

Solution GPS Location Integration into Google Maps The GNSS engine in the ZETA modem will show the Latitude/Longitude position in Decimal Minutes format (ddmm.mmmm). However, Google Maps requires this information in Decimal Degrees format (dd.ddd). The solution is to convert position from one format to the other to show position on Google Maps.

The AT command AT$GPSACP will return the lat/long position information in the Decimal Minutes format.

GPSACP lat is in the format ddmm.mmmm

GPSACP lon is in the format dddmm.mmmm

Demonstration of Solution Resources used:

ZETA-GEP-LTE4 (EU) - including Cellular and GNSS antennas.

ZETA-xxP Quick Start Guide

Initial Modem Setup Guide App Note

A PC with an installed Terminal Emulator program

ZETA-xxP-LTE1 / ZETA-xxP-LTE4 AT Command Guide

Steps:

Follow the Initial Modem set up guide application note to communicate with the modem using AT commands.

Issue the following AT command AT$GPSP=1 to turn the GNSS engine ON in the modem.

Issue the AT command AT$GPSACP to obtain latitude and longitude

COM3 - Tera Term VT

File Edit Setup Control Window Help

AT

OK

AT$GPSP=1

OK

AT$GPSACP

$GPSACP: 103709.000,5123.1355N,00058.4350W,9.5,96.0,3,303.4,4.5,2.4,050224,03,02

OK

4. Stripping information's from responses of AT$GPSACP.

UTC = 103709.000

Latitude = 5123.1355N

Longitude = 00058.4350W

HDOP = 9.5

Altitude = 96.0

Fix = 3

COG = 303.4

SPKM = 4.5

SPKN = 2.4

Date = 050224

Nsat_GPS = 03

Nsat_GLONASS = 02

Position Information Conversion 5. Obtaining Lat/Long

This position information can easily be converted into Google Maps compatible lat/long readings as shown below:

Strip the dd from the message i.e.

ddmm.mmmm

Which becomes

variable1 = dd

variable2 = mm.mmmm

variable3 = variable2 / 60

Rejoin values to make dd.dddd

dd.dddd = variable1.variable3

i.e. Latitude / Longitude for the Siretta office from NMEA GGA message to lat/long

Lat: ddmm.mmmm: 5123.1355 (N)

Lat: dd mm.mmmm: 51 23.1355

Lat: dd dd.dddd: 51 ( (23.1355 / 60) = 0.38559)

Lat: dd.dddd: 51.38559

Lat: 51.38559 (As this is north it is positive, south is negative)

Long: dddmm.mmmm: 00058.4350 (W)

Long: ddd mm.mmmm: 000 58.4350

Long: ddd dd.dddd: 000 ((58.4350 / 60) =0.9739)

Long: ddd.dddd: 000.9739

Long: -000.9739 (As this is West it is negative, East is positive)

Latitude: 51.38559

Longitude: -000.9739

Display on Maps API Now to get this into Google maps:

Go to http://maps.google.com.

Type the following in to the search box: 51.38559, -000.9739

Then hit Search Maps' and you get the Siretta office!!

For direct access to Google Maps use the URL below:

http://maps.google.com/maps?q=51.38559 -000.9739

Note: AT command AT$GPSACP may return different parameters, depending on your location, date, time, number of available satellites and fix.

Additional Reading Description Author

ZETA Hardware user's manual Siretta

AT command manual Telit

How to use GNSS enabled Siretta modems to obtain Lat and Long positions and Time Siretta

https://www.siretta.com/2023/03/using-a-siretta-gnss-modem-to-test-the-performance-of-a-gps-antenna/

Siretta

https://www.siretta.com/2023/01/using-siretta-modems-to-provide-a-gps-position/ Siretta

https://www.siretta.com/2023/01/initial-modem-setup/ Siretta

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