Our Solar PTTs are the answer to long-lasting and lightweight bird tracking. This family of PTTs operates using rechargeable batteries powered by high-efficiency miniature solar cells, and is programmed to regulate battery charging for transmission at any time during the day or night. Solar PTTs are optimal for studying long-distance migrations and mortality.
Solar-powered Rechargeable Battery
Solar power frees our PTTs from the lifetime limitations of primary lithium batteries. Because these PTTs can be continually recharged with solar energy, they have the potential to run for years, making them well suited for long-term studies.
The solar-recharging process is carefully controlled by an internal microprocessor to optimize power distribution and permit nighttime transmissions (as opposed to less sophisticated devices where transmissions occur only when the solar cells are exposed to light).
Argos Doppler Locations
Solar PTTs transmit messages to the Argos satellite constellation. As
a satellite passes overhead and receives those messages, a PTT's
location is estimated using the perceived Doppler shift in signal
frequency of successive transmissions. Triangulating PTTs' positions in
this manner yields locations which are then categorized into "location classes" (LC) based upon their estimated accuracy. Over two-thirds of Argos locations provided by MTI PTTs are in the top three location classes:†
LC3: <250 m radius
LC2: <500 m radius
LC1: <1500 m radius
Please note that Solar PTTs are not equipped with GPS.
Programmable Duty Cycle
Solar PTTs are programmed with a user-defined duty cycle that dictates when the device will turn ON to transmit and OFF to allow for more efficient recharging. The customizability of these transmission intervals allows PTTs to best accommodate the activity of the species being studied and the project objectives. The only exception to this is our new Solar 2g PTT which operates on a continuous duty cycle.
Most models can also have optional XT™ programming which will command a PTT to transmit during the OFF period of its duty cycle when the battery is fully charged. These transmissions do not affect the ON/OFF programming of the duty cycle, but are intended to supplement the ON period transmissions when the PTT is in good lighting conditions.
Ground Track (GT™) Option
Solar PTTs can be programmed with Seasonal and/or Mortality GT™. This feature enables a PTT to also function as a conventional radio transmitter, emitting a UHF frequency at prespecified times that can be heard via a Yagi antenna and receiver. GT™ is helpful for locating birds in real time, pinpointing injured/dead study subjects, and recovering downed transmitters.
Note: Though suitable for most applications, we do not recommend solar-powered PTTs for use on species that are likely to preen feathers over a backpack attachment or inhabit locations/latitudes where sunlight is limited, as these conditions may inhibit proper battery charging.
* While conventional thinking suggests choosing a transmitter weighing <3% of a bird's weight, we are aware that birds routinely carry weights greater, and sometimes less, than 3% of their body weight. Because each species is different, it is crucial that you review the literature on your study species and use proper discretion to determine the appropriate transmitter model for your project.
** Relative battery capacity based on battery size and approximate operating current of Solar PTTs.
*** Relative solar array capability based on solar array size and housing optimization of Solar PTTs.
† Based on 2016 internal test data.