What are the units of measurement in _track.qo

Notehub.io
1

Describing the Units for the JSON fields that have measurements collected by note.add request saved to _track.qo

About Time Stamps

All timestamps are Unix Epoc UTC


{
    "device": "dev:xxxxxxxxxxxxxxx",
    "product": "xxxxxxxxxxx",
    "received": 1609850322.396112, // [seconds] timestamp when data was received by Notehub
    "routed": 1609850326,          // [seconds] timestamp when data was routed to external URL
    "req": "note.add"
    "when": 1609850291,     // [seconds] timestamp when note was added to _track.qo
    "file": "_track.qo",
    "updates": 1,
    "body": {
        "bearing": 355.4197017075076,    // [degrees] compass bearing from true north
        "distance": 97.61843922720755,   // [meters] distance travelled
        "jcount": 4,                     // [count] enumeration of notes in the current journey
        "journey": 1609850177,           // [seconds] timestamp when journey began
        "motion": 3,                     // [count] number of motion events detected
        "seconds": 30,                   // [seconds] period between this GPS location measurement and previous
        "temperature": 14.125,           // [Celsius] temperature of Notecard
        "time": 1609850291,              // [seconds] timestamp when location acquired
        "velocity": 0.0025266186775858668, // [meters/second]
        "voltage": 5.215444224184539     // [Volts]  supply voltage to Notecard modem
    },

    "where_lat": 42.3651325,             // [degrees] GPS acquired latitude
    "where_lon": -71.17483203125,        // [degrees] GPS acquired longitude
    "tower_when": 1609850321,            // [seconds] timestamp when tower connection was established
    "tower_lat": 42.357962500000006,     // [degrees] Approximate tower latitude
    "tower_lon": -71.179046875,          // [degrees] Approximate tower longitude
}

What is Journey and JCount?

A journey is a contiguous sequence of GPS location captures that are determined to be part of the same journey or trip between locations.

In the JSON data, journey field is the timestamp the sequence started. This uniquely identifies the journey sequence for a specific Notecard.

The jcount field is the enumeration of GPS location updates stored in _track.qo for a particular journey. The jcount field starts at 1.

These fields are only available if the tracking mode is enabled, and the GPS tracking period is less than 300 seconds (5 minutes).

4 Likes
2

How is velocity calculated?

Is it the instantaneous velocity of the time the location is captured, or is it the average velocity since the last GPS location?

Thanks,
Karl

3

Hi @Karl_iWell,

When GPS is enabled it supplies data to the Notecard at regular intervals, which updates the “current location” values returned by card.location. When the GPS is in continuous mode the location is being updated super frequently once it is locked onto satellites.

Velocity is computed and placed into _track.qo Notefiles when in a tracking mode. Every time motion starts we begin a “journey” and start logging Notes that contain velocity and bearing, and when motion stops we shut down the gps.

Hope that helps!
Rob