A trip is a stretch of driving between two parkings. Polygon works out trips from the messages a device sends. For each message it decides whether the unit is moving. It then joins the moving stretches into trips and the still stretches into parkings. The device's Trip Detector tab holds the settings for every step. When a customer asks why a trip is missing, split in two or too long, the answer is in these rules.
The trips list on the map, the unit card and every trip, parking and mileage report all read the same stored trips. The app works them out as messages arrive and keeps them, so a report does not recount raw messages. When you change the device's sensors or its trip settings, the app works out the recent trips again. See Trip Detector tab for how far back that goes.
The trip start and trip end events you see while a unit drives come from a second, faster check. That check runs on each message as it arrives. It uses the same saved settings, but decides some things differently (see Defaults and differences).
Movement Detection says which evidence decides that the unit is moving:
| Option | The unit is moving when |
|---|---|
| Odometer | The odometer sensor's reading grew since the last message, and the speed is at least Min. Moving Speed (Km/h). |
| Relative Odometer | The relative odometer sensor reports a distance above zero, and the speed is at least the minimum. |
| Ignition | The ignition is on, and the speed is at least the minimum. |
| GPS Coordinates | The position changed since the last message, the fix is good enough, and the step is not a jump. |
| Speed | The speed is at least the minimum and comes from a good fix or a speed sensor. |
| Off | Never. The unit has no trips; all of its time counts as parked. |
| Auto | The app picks one of the sources above from the device's sensors. |
With Auto, the trips list and reports take the first source the device has a sensor for. The order is odometer, relative odometer, ignition, and otherwise GPS positions. If the chosen sensor sends nothing in the device's first 200 messages, the app moves on to the next one in that order.
A speed sensor, such as one on the CAN bus, wins over the GPS speed. The Tracking screen does the same. When a speed sensor shows on the unit card, it replaces the GPS speed on the card, in the list and in the status. A speed sensor reading of -1 means "no reading", not slow.
Allow GPS Correction heads a group of four settings that decide whether a position counts. While it is on, the app applies them:
While Allow GPS Correction is off, these four fields are unavailable on the tab and the app does not apply them. Positions they would filter out still show on the Messages screen. When the device has an absolute odometer sensor, distance comes from the odometer instead of the positions, so jumps do not matter for distance.
Positions from cell towers or Wi-Fi never move a unit or add distance. The exception is a device whose Position filter tab counts them in trips.
When the unit stops moving, the app starts timing. Once it has stood still for Min. Parking time (Seconds), the stop becomes a parking and the trip before it ends. A shorter stop, at a traffic light or a quick delivery, stays a stop inside the trip.
A trip starts with the first movement after a parking. With Ignition as the source, turning the ignition on also starts a new trip. A trip ends when a parking begins.
The app also splits a trip in these cases:
The app drops a trip shorter than Min. Trip Time (Seconds), or, while Allow GPS Correction is on, shorter than Min. Trip Distance (Meters). Its time joins the parking around it, so a car moved across a yard does not appear as a trip.
A trip's top speed ignores readings above 200 km/h, and GPS speeds from a poor fix or a jump. This keeps one bad reading from showing up as the trip's maximum. There is no setting for this on the tab.
Until someone saves the Trip Detector tab, the device has no trip settings of its own. The tab then shows its own starting values, but the trips list, reports and live events use built-in defaults, and three of them differ:
| Setting | The tab shows | Trips list and reports use | Live trip events use |
|---|---|---|---|
| Max . Distance Between Messages (Meters) | 1000 | 2000 | 2000 |
| Min. Trip Distance (Meters) | 200 | 50 | 100 |
| Max. Interval In Messages | 1500 | 300 | 1500 |
Select Save Changes on the tab once, even without changing anything, and all three use the values you see. A device created from a model that comes with a GPS sensor starts with the tab's values already saved. The gap shows up on devices whose GPS sensor someone added later, and on devices imported without trip settings.
Two differences stay after saving: