FAQ’s

The device weighs, with a size of 24 mm (height) x 29 mm (width) x 64 mm (length), 32 grams.

The charging station weighs 40 g and has a diameter of 68 mm and a height of 25 mm.

GRETA is dust and waterproof according to the protection standard IP67.

In addition, GRETA is ultrasonically welded to protect it against external influences. This process makes GRETA particularly robust.

An overview of the different protection standards can be found here:

Schutzart (Wikipedia)

No, you do not need another SIM card. GRETA already has an integrated SIM card. To use this SIM card, it is necessary to book a service package. This covers the costs incurred and always ensures that your GRETA always has enough data to communicate.

There is no LED signal during locating.

If you happen to charge GRETA and the LED does not light up when you place GRETA on the charger, you can check the following:

• Does the charging station have enough power?
• Is the USB cable possibly damaged?
• Does the LED also not work if you use another USB cable?
• Is the adapter for the power outlet possibly defective?

To save energy, GRETA is not always active. The tracker switches between an active and a sleep mode.

If the tracker is resting and its position does not change, the tracker will enter a sleep mode. In sleep mode, GRETA does not transmit any signals. Only when the tracker is moved again does it switch back to active mode.

Depending on how long GRETA has been in sleep mode, it may take a while for the first position to be found. Why this is so you can read in the following article:

Why does it sometimes take longer for GRETA to find a position?

A slightly longer phase to get a first position may occur if GRETA has not been moved for a long time. In this case, the tracker was in a sleep mode. Now it is possible that when returning to active mode other GPS satellites are visible than before. This means that GRETA first has to reorient itself and interpret data to determine a position.

Imagine sleeping and waking up in a different place. Now you probably need to reorient yourself to know where you are. This is similar to when GRETA wakes up from hibernation and finds new GPS satellites.

How long the battery of a GRETA holds depends on the usage and the environment. The discharge speed can thus always vary a little.

If GRETA is actively used, there are always new positions. The transmission of this data always consumes energy a little bit of energy. Of course this can be controlled to a certain extent over the selectable interval.

However, if GRETA is in an area where it is difficult to get a GPS position or network connection, the power consumption is slightly higher. This slight increase comes about because it takes longer to transfer data. You may also have noticed this with your mobile phone: If there is only a slow network connection, the battery runs out faster.

The free apps for your smartphone can be found in the App Store for iOS devices and in the Play Store for Android devices under the keyword Prothelis, or via the following links:

App Store
https://itunes.apple.com/us/app/prothelis/id1077727750?mt=8

Play Store
https://play.google.com/store/apps/details?id=com.prothelis.tracker

After the first installation, the app asks you to access the location of your smartphone. This happens for two reasons:

1. By accessing the app, you can see your position relative to the position of your GRETA.
2. To determine the distance between you and your GRETA, the app needs to know your current location.

If you have denied access first and want to enable it later, you will not be able to do it directly from the Prothelis app. In this case, go to the settings menu of your smartphone and allow the permission in the details of the Prothelis application.

If you do not receive mobile app updates, there are several reasons:

1. Your version is already up to date? Excellent! Then there is nothing else to consider.
2. You have not activated the automatic updates. In this case, you have to check for a newer version yourself, or set the automatic update on your smartphone.
3. Due to technical advances, and the ongoing evolution of mobile apps, older devices may be excluded from new updates if they no longer meet the minimum requirements.
4. In some cases, the origin of the smartphone you are currently using may also play a role in your ability to use the mobile app. This is then independent of the minimum technical requirements.

Once a geofence has been created, you can choose in what form and when you want to be notified.

In principle, it is always possible to react to whether the geofence enters or leaves. For this purpose, you can now set whether the notification should be done via push message, telephone call or both ways.

To receive push messages, you need an active network connection, either via WiFi, or mobile data.

In order to be informed by telephone call, please check your telephone number that you have specified when setting up your account at https://my-prothelis.de/account.

It should be noted that the tracker requires at least one more location, from the current location, to determine where it is in relation to the geofence. This means that no notification will be sent if the geofence is drawn at the current position of the tracker and the following position is outside the geofence.

A geofence is a word of art from geographic and fence and describes a virtually built fence that encloses a particular area.

Depending on the setting, GRETA can respond to both entering and leaving a geofence.

Currently, two forms are supported for geofences:

• Circle
• Polygon

Circle

For a circular geofence, set the center, and then specify the radius. The circle can have a radius of 50 meters to 5000 meters.

Polygon

For a polygon or polygon, the shape of the geofence is up to you. You set the points on the map and determine what the geofence looks like. To create an area, at least three points are needed.

To better understand how geofences are evaluated and how to interpret the messages, we recommend that you also read the following article:

What should I watch out for when creating a geofence?

When creating a geofence, it should be noted that the GRETA does not always have an optimal view of the existing GPS satellites, e.g. inside a building.

In this case, the position is estimated as best as possible, taking into account the existing data. Since it may well happen that the displayed position deviates by several meters.

To avoid false alarms being triggered later, the area covered by the geofence should be large enough.

If a tracker has a small interval, the system waits up to three confirmation positions to make sure that the tracker is really out of geo-fence.

Further information can also be found in the section Positioning.

For GRETA to determine a position several systems are used.

GRETA uses GPS, GSM and GLONASS systems for position determination.

Further information about the systems can be found under the following links:

• GPS (Wikipedia)*
• GSM (Wikipedia)*
• GLONASS (Wikipedia)*

* The links open in a new window.

Under optimal conditions, GRETA achieves a positioning accuracy of up to three meters.

Now, under some circumstances, the optimal conditions are not there. What can influence the position determination, you can read in the following article:

What influences the position determination?

A slightly longer phase to get a first position may occur if GRETA has not been moved for a long time. In this case, the tracker was in a sleep mode. Now it is possible that when returning to active mode other GPS satellites are visible than before. This means that GRETA first has to reorient itself and interpret data to determine a position.

Imagine sleeping and waking up in a different place. Now you probably need to reorient yourself to know where you are. This is similar to when GRETA wakes up from hibernation and finds new GPS satellites.

You can set in the app (in the browser or on the smartphone) in which intervals the position should be updated.

Will the position be sent at the specified interval? – Not necessarily.

To send the position, GRETA needs a working network connection. Depending on the circumstances, GRETA may be able to record a new position but not send it because the tracker is currently unable to establish a network connection, e.g. because of a radio hole.

Positions that can not be sent within the set interval are cached and sent the next time the network connection is successful.

As with all GPS systems, GRETA also believes tracking works better the more GPS satellites are available. Since GPS satellites are not geostationary, accessibility can fluctuate even in the open air. In general, visibility is already limited as soon as a GPS tracker is hidden – either by being in a bag or by the tracker being in a building. Depending on the location, the shield is different, and sometimes has more, sometimes less influence on the position determination.

And what does that mean exactly for the position?

As the number of visible GPS satellites decreases, the accuracy of positioning is reduced. Due to the fact that insufficient data is available for an exact position, the position is estimated as accurately as possible. As a result, successive positions may look like the tracker is jumping. However, this jumping usually only occurs when the tracker is not moving, as in that case no significant change in position can be detected.

Lithium polymer batteries generally have a limited number of charge cycles. The full charge (1-100%) is always crucial – no matter how they are divided.
Our GRETA GPS tracker is charged via induction charging. This has the advantage of not having to use annoying cables. This makes our GRETA particularly resistant to environmental influences.
Despite the latest technology, this type of charge generates more waste heat than with wired charging. This is completely normal and harmless.

Continuous heating and charging may shorten the life of the LiPo battery. Therefore we recommend removing the device from the charging cradle after full charge.