New to Anitra tags ?

What you shoud know about how Anitra solar-charged GPS-GSM devices work and how to handle them efficiently

In the solar-charged GPS-GSM tags, the actual energy balance is a struggle between solar panel energy charging and energy usage on the other side (GPS taking and data sending using GSM). Battery level is one of the essential metrics for tag management.

The users with admin rights to devices can see their devices in the Device section of the Anitra platform. The device list and device profile also show the battery percentage. More on the platform user quick guide.

The solar charging itself is active anytime the battery is not fully charged (overcharge protection) and there is sufficient sunlight available. With good sunlight, the device can recharge an empty battery within hours. We advise you to observe the battery evolution in charts. More on solar charging here.

The energy consumption on the other is mainly due to GPS taking and GSM data submission. Between the measurements and sending session the device is brought to sleep so actually only the duty cycles i.e. intervals of GPS measurements and sending intervals influence the energy usage. Check below more about GPS taking and GSM data transmission.

Device configuration can be accessed using cog wheel icons. This functionality allows modifying device behavior (including GPS and GSM duty cycles). A detailed configuration guide is here.

New device configuration is applied during the next successful communication session. Normally it is during the next planned session however with Anitra tags you can speed up the process by enforcing extra communication sessions manually using a magnet. More on managing Anitra tag with magnet is here.

Just received new tags ?

What should you do after receiving new tags

Make sure you see the new tags in the device section of the Anitra platform. More on the platform user quick guide is here.

Adjust tag configuration according to your plans. A detailed configuration guide here.

Test the tag functionality after the transport

Use a magnet to:

  • check the battery state of the device (the approaching magnet should give you a blue/red LED indication)
  • wakeup the tags from the storage mode
  • enforce extra comm session to test GSM communication in your area.

Place the tags in the sun to recharge them. Observe the evolution of the battery in the graph.

Place the tags outside with good sky visibility for some hours and subsequently check if the new location was detected correctly.

Note the GPS module drains the battery substantially whenever satellite visibility is blocked (indoors). Consider this while storing devices. For long-term storage devices inside you can bring them to the storage mode.

Plan some charging time before deployment. It is not recommended to deploy tags with an empty battery.

Anitra platform help

Where do I find all the info and hints on Anitra platform usage

The most up-to-date guide to Anitra platform usage is embedded within the platform itself as “help”.

You can access it from the main application menu using the “question mark” icon or wherever in the application from right-click context menu as “help”.

The Quick guide can be also accessed directly using this link:

Make sure you browse the guide at least briefly for a smooth start with the platform.

Advanced guides related to particular application areas can be accessed from the Quick guide.

Solar charging

What should I know about the solar charging

The solar charging mechanism is an automatic process that is activated with sufficient sunlight available any time the battery is not charged fully.

Overcharge protection in place ensures the battery is not damaged or deteriorated by charging too much.

The actual speed of battery charging depends mainly on the intensity and energy of the sunlight and on the battery capacity on the other side (smaller batteries recharge quicker than large batteries). The speed of battery recharge also depends on what the device actually does (duty cycle in combination with satellite availability etc)

With good sunlight and good satellite visibility, the tag can recharge an empty battery of standard size within several hours.

Note our solar cells can also charge efficiently when placed e.g. behind the car window. You can also substitute sunlight with artificial light using a cold LED bulb when testing or preparing the tags for deployment. Also, note that solar charging efficiency is negatively influenced by high temperatures and overheating (so charging the devices in direct summer sunlight can result in poorer charging surprisingly).

We also advise checking the battery evolution in charts and adjusting duty cycles accordingly. A stable or better positive energy balance should be aimed for. A metric of solar percent is also useful in this context. Only values starting at 80-85% of solar are sufficient for efficient and visible charging.

Using magnet

How can Anitra tags be managed using magnet

Compared to other tags Anitra devices have a unique behavior implemented which makes the manipulation and maintenance very comfortable.

Since production Anitra devices are always ON (i.e. either active when measuring /sending or in a sleep mode between the schedules. No need to activate them anyhow.

A magnet can be used to check the device’s state and to enforce extra session (GPS taking + communication). The Device first tries to acquire GPS position followed by connecting to the GSM network sending data. This video shows the magnet control: Anitra tag magnet control

For storing devices long term we have a “storage mode” feature. This mode switches devices from normal mode to deep sleep but at the same time, it allows devices to report their battery status and position in predefined 24-hours intervals (intervals from 24 hours to 30 days can be defined). The tag can wake up from this mode either by receiving the configuration or manually using a magnet (same magnet sequence as for enforcing communication session).

GPS fixing

What problems related to GPS fixing shoud you consider

GPS fixing is by far the most energy-demanding task performed by the tag. This process involves the activation of the GNSS module in the predefined duty cycles. The module is active and using energy since it is started till it gets GPS fix successfully or till the fixing attempt is terminated due to timeout. TTF metric defines the time used to get the GPS fix. In good conditions, the TTF is several seconds and the energy usage is reasonable. In worsened or bad conditions (e.g. indoors), the GNSS module can run and use energy very long time. In such conditions, energy use rises dramatically.

The ability, speed, and ultimately also quality of GPS fixing are influenced primarily by satellite visibility. Note the satellites available in a certain place are not constant in time as the navigation satellites are moving along their orbits. Any time the device attempts to get fix the current new satellite constellation (list and positions of all the satellites) needs to be understood by the module first. Anitra tags use multiple navigation systems (GPS, GLONASS, GALILEO) to maximize the chances and speed of GPS fixing. Besides constellations other factors such as the presence of obstacles around the device (e.g. tree canopy, signal-reflecting building walls, etc.) matter and complicate acquiring a GPS fix.

Between the measurements, the device (i.e. also the GNSS module) is switched to sleep. Each new schedule involves wakeup and a fresh GNSS start locating the satellites. To make this process faster and optimized GNSS modules first attempt to use the last known satellite constellation. Therefore the performance of the module is also additionally influenced by the previous history of fixes (a long time since the last successful fix can significantly complicate the next fixing attempt as new data about the satellites available need to be fetched from scratch first).

Similarly, when the geographical position of the device changes a lot since the last successful fix the device can struggle to find a new location for some time even with good sky visibility. This often happens when transporting devices long distances or after having them long time indoors without satellite visibility.

Before deployment make sure the devices have been outside with good sky visibility (full horizon visibility) long enough to stabilize.

You can also speed up the acclimatization process by enforcing extra GPS fixing/comm sessions using the magnet when in place with good sky visibility.

GSM data transfer

What you should understand about GSM data transfer.

Anitra GPS-GSM tags use GSM (mobile network) for delivering data from the device to the server.  We use 2G (older tags) and 4G/2G technology (a new generation of tags).

Connecting to the GSM network and sending data is very demanding in terms of energy consumption. To optimize energy the data are submitted in scheduled intervals controlled by configuration. For instance, the default configuration plans two communication slots per day. With a good energy balance and a lot of collected data, you are likely to run comm sessions more frequently.

Note you can enforce extra (unplanned) comm sessions using a magnet.

General facts using mobile networks:

    • GSM signal is transmitted by BTS towers run by mobile operators.
    • To be able to submit the data the tag needs to be within the signal radius of any nearby tower at the scheduled data session time (and also during whole the time when data are being sent).
    • You can check the coverage for your study area eg. here:
    • The quality of the GSM connection can be estimated from RSSI and BER communication metrics. You can review those per session in the comm history in the Anitra platform. RSSI values range from 0 to 32. Values from 20 to 32 indicate a very good GSM signal while values below 10 indicate a poor signal. BER values additionally tell about transmission errors (possibly caused by some interference)
    • In a bad signal, there is significantly more energy needed for transferring the same amount of data compared to a good signal situation. In a bad signal, the connection can also get closed before all the data (or even any data) is transferred.
    • To avoid useless waste of energy Anitra tags are configured to give up relatively easily in bad signal saving energy for future sessions with hopefully better GSM signal

Some implications and practical tips for bad signal situations:

    • The signal tends to be better higher above the ground. You can try to schedule your communication slots to hours when the animal is expected to fly or whenever it is likely to be closer to BTS.
    • To improve your chances of receiving data more regularly you can add more communication schedules.
    • Defining a floating interval that shifts the session every day to a different time (e.g. 13-hour interval) is also a good way to prevent repeated unsuccessful communication attempts from a distant roost site.

Communication concentrates the energy use to a very short time (peak usage). Poorly charged batteries (battery percentage below 10%) sometimes do not provide enough power to connect or transfer all the data stored in memory. The result can be similar to sending data in poor signal i.e. failed session with incomplete or no data row transferred.