User Guide for GPS sensor

The GPS sensor only works outdoors.

IMPORTANT: Do not power up your GPS sensors until they are registered into the backend.

Register you sensors to backend

For Lora; register the sensors to Lora backend / stack. You can find App-Key and App-EUI from cloud.vicotee.com/#/lora

For NarrowBand; register the sensors by login to cloud.vicotee.com and use Device Manager to register your GPS NarrowBand devices. You can read more about Vicotee's Cloud App and how to install them here.

Power up the sensors

You must be outdoor clear view of the sky when you power up the sensors, this will ensure the sensors can acquire ephemeris data from satellites currently in view. To power up the sensors, follow the instructions as described in the User Guide for devices with LoRa or NarrowBand IoT.

What is Ephemeris data

Precise orbital information for the transmitting satellite, information about their location, current and predicted, timing and "health". The GPS sensors can take up to 12.5 minutes to acquire all ephemeris data from satellites currently in view. To ensure the data can be downloaded, you must be outdoor when starting up the senors.

It is not possible to obtain a lock on the satellites if the sensor failed to download ephemeris data when you turn on the sensor.

NMEA GPS Positioning to Decimal Degrees

The GPS returns payload with latitude and longitude in GNGGA.  The format is DDMM.MMMMM.

Here is an example of a payload from sensor:

FA012A000901120002015145B9AE9151447DC148510104454E8356435400830000000E840303040086011C65648500000042CE

Using online Decode VicPack from cloud.vicotee.com, you will get

    Latitude: 5941.82080078125
    Longitude: 1015.02001953125
    Compass Direction: N (ASCII 78)
    Compass Direction: E (ASCII 69)
    

    You can convert them into Decimal Degrees DD.MMMMM as follow:

    Latitude : 5941.82080078125 becomes 59 degrees and 41.82080078125 seconds = 59 + 41.82080078125 / 60 = 59.69701334635
    Longitude : 1015.02001953125 becomes 10 degrees and 15.02001953125 seconds = 10 + 15.02001953125 / 60 = 10.25033365885
    

    Pseudocode:

    DD = int( float(Latitude) / 100 )
    MM = float(Latitude) - (DD * 100)
    
    LatitudeDec = DD + (MM / 60)

    Don't forget North/South indicator, i.e. "S" or "N". If the indicator is "S" you need to negate your LatitudeDec value.

    The processing for the longitude will be similar. This time the compass indicator can "E" or "W". If it's "W", you need to negative your longitude value.

    Service and Maintenance

    The batteries are the only user serviceable parts of the device. Depends on sample rate, temperature and signal strength such as range to the LoRaWAN gateway or NarrowBand base stations, the batteries should last 4 to 5 years for LoRA and 2 to 3 for Narrowband. Note: battery self-discharge is typical 1-2% per year.

    Click here to read more about replacing of the batteries.

    Precautions

    • Read all instructions in this manual.
    • Keep instrument dry.
    • Never let water or other liquids into the sensor.
    • Do not drop the device or subject it to continuous vibration.
    • Do not store in high levels of dust.
    • Do not clean the instrument with cleaning chemicals or solvents. Clean it with a damp cloth.
    • Do not operate near heavy aerosols (spray) usage or where oxygen Is being administered.