FR
EN
FIELD TEST DEVICE - LoRaWAN US 902-928 - Mode d'emploi V1.0.0
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4. DECODING THE PAYLOAD
The payload is divided into 2 frames to be compliant with regulation. The first byte (status byte) will enable you to identify the presence of
information contained in the payload.
These 2 frames are systematically transmitted in periodic mode or in event mode (button pressed or triggering of the accelerometer). Specif-
ically, during accelerometer triggering (following a vibration detected by the FTD), the MAC LinkCheckRequest command is issued and the
LinkCheckAnswer command is received back (symbolized by the ANS on the DL line of the display).
4.1. Frame 1 description
Information will always be shown in the order indicated in the following table.
Byte N°
1
2 to 5
6 to 9
10
Description
Status
GPS Latitude
GPS Longitude
GPS Quality
Example
30
45 15 96 90 00 55 34 50
27
Example of a payload received: 30451596900055345027
This example will be used in order to explain how the payload is decoded.
if no GPS coordinate is available, only the Status byte (byte n°1) is sent.
if no GPS coordinate is available and transmission was generated from periodic transmission mode (no bouton pressed, no accelerometer), only
the first byte (status byte) is sent and its value will be 0x00.
4.1.1 Status
For frame 1, using the previous example, the value of status byte is 0x30 i.e. 0011 0000 in binary so in the table:
Hex
Binary
Comments
30
0
Not used
0
Transmission triggered by the accelerometer
1
Transmission triggered by pressing pushbutton 1
1
Presence of GPS information
0
Not used
0
Not used
0
Not used
0
Not used
0: Data missing from the payload
1: Data present in the payload
4.1.2 Latitude
Hex Frame N°
Byte N°
Bit N°
Comments
Value
45
1
2
7..4
BCD coding of the entire degree section (tenth of a degree)
4
5°15,9690
3..0
BCD coding of the entire degree section (whole degrees)
4
5
°15,9690
15
3
7..4
BCD coding of the entire minute section (tenth of a minute)
45°
1
5,9690
3..0
BCD coding of the entire minute section (whole minutes)
45°1
5
,9690
96
4
7..4
BCD coding of the decimal section (tenth)
45°15,
9
690
3..0
BCD coding of the decimal section (one hundredth)
45°15,9
6
90
90
5
7..4
BCD coding of the decimal section (one thousandth)
45°15,96
9
0
3...1
Not used
0
Hemispheric coding
0 : North
1 : South
Note:
the value expressed in the payload will be in degrees, minutes and fractions of a second. A conversion to degrees, minutes and seconds
must be carried out in order to make a comparison with the coordinates displayed on the device’s LCD screen.
