Radio-enabled tracking tags have dramatically enhanced our knowledge of wildlife behavior over the last 3 decades, and new types of tags are being developed which capture and transmit dramatically more information about their behavior. Advances in microelectronics have also reduced the size and increased the lifetime of tags, increasing the number of species that can be tagged. Unfortunately these various tags use a wide variety of frequencies, coding schemes, and communication protocols, requiring an entirely new base station for each new tag. This makes new deployments more expensive, disallows sharing of monitoring stations between overlapping studies, and requires that that biologists in the field carry a base station for every tag type in use.
The goal of this project is to develop a general-purpose radio transceiver for behavioral ecologists and others that can be easily configured to communicate with any existing wildlife tracking tag, as well as with foreseeable future designs. Our approach is based on software defined radios, where most of the parameters of the radio are configured in software, allowing a single piece of hardware to cover multiple types of tags. In this project we will develop working prototypes able to cover at least 3 different existing avian tags, and show them working in the field. We will also develop a mode where signals can be captured, but not decoded, to allow tag signals from different researchers to be captured by the same physical basestation, and then distributed to the various researchers to be decoded. Finally, we will ensure that the resulting outputs are in a format that allows smooth upload of captured signals to databases such as MOVEBANK.
To ensure that our 'universal base stations' are available to other researchers, we will post on the internet all board designs, parts lists and software we develop, as well as documentation of all designs and software. Our goal is that UBS designs be accessible not only to researchers, but also to amateur birders and other 'citizen scientists', allowing them to contribute to research, as well as enhancing their birding experience (or example, by allowing them, after detecting a tagged bird, to look up 'their bird' in a database and learn more about it's particular behavior and movement. To further this goal, we will attempt to develop a smart-phone interface to our UBS, to allow birders in the field to capture and upload data from tags they encounter via their phones.
While this work will provide a valuable tool for biologists, both professional and amateur, it will also provide valuable educational experience for engineering students. Parts of this project will be incorporated into class projects, and much of the design work required will be completed by undergraduate and Masters of Engineering students completing as design projects required for graduation. Because this project requires teamwork, has specific concrete goals and specifications, and clear end-customers (field biologist who are collaborating on this project), this project will provide invaluable experience in preparing students planning on working in industry.
For more details, see: http://molnargroup.ece.cornell.edu/research.html
Although birds are part of our everyday life, there is still much we don’t know about them, and this lack of knowledge is in part a technological problem. Birds move long distances in their annual life cycles, and to track the movements of birds from nesting through migration and back to the breeding grounds again, multiple generations of radio-frequency (RF) tracking tags have been developed. Historically, each tag has been co-developed with a receiver to track the tag, and in this project, a collaboration between electrical engineers and ornithologists, we applied and developed techniques from modern software-defined radio technology to improve receiver design while co-developing new classes of tags to take advantage of this new flexibility. To cover the multiple bands used in wildlife tracking, we designed, and refined an RF receiver daughter board, which contained all of the required functions for reception and frequency control, and simple select-ability for band-switching. The board is simple, compact, and fully functional. In order to transfer the resulting signals into the digital domain, we developed two versions of interface to the software domain. The first of these enabled simple scanning, detection and capture of active signals along with the capability for rapid spectral analysis for detection and capture of tag signals. This system worked as intended. It also became clear that once this basic function was complete, it would almost certainly make more sense to hand the problems of demodulation and storage off to a PC or laptop, where software updates are easier. In the second generation interface we targeted broader-band, higher resolution capture, across multiple receiver chains and we moved to more advanced electronics that will enable critical capabilities such as direction finding, and multi-band capture of simultaneously arriving signals. We developed both USB and Ethernet connections for this interface. Finally, to develop software defined, bi-directional communications, we also put effort into developing a transmitter daughter-board. This work is ongoing, but looks to provide the needed power and frequency range. This work on receiver design adds fundamental new features to the potential tool set on wildlife receiver designs, and we are evaluating how and if it makes sense to meld these advances with the software defined radios that have been developed independently and deployed by ornithologists on the past few years. We also worked on the development of tags to be used with the universal base station described above. The tag developed in part with funding from this grant was the DTT (Digital Turnstile Tag), a tag that records and time-stamps light levels around twilights and stores these data for solar geolocation for up to a year. Compared to previous solar geolocation loggers whose data can only be recovered from recaptured birds, the DTT provides much better usability. The birds wearing them need be captured only once, as the data can all be recovered via an RF data upload many months after deployment. The fully functional prototype developed by our team weighs 3-5 g depending on battery size and potting. We are working on two further modifications of the DTT tag: one miniaturized through a reduction in part number and the addition of solar energy harvesting (and a consequent reduction in battery mass); and the other ruggedized for application to marine birds. Our team has been working in parallel (with separate funding) on a GPT (Generic Programmable Tag), a battery-less, solar-powered radio transmitter that sends a digital ID signal, once every second that it is in full sun. This tag weighs only about 0.4 g, and its exceptionally long life opens up all kinds of applications in the tracking of small animals. We mention this second tag because it, and many new digital tags like it, raise new challenges for base-station receivers: the digitally encoded id signals are very short, only transmitted about once per second, and many tags are on the exact same frequency, increasing the chance that multiple tags will transmit at the same time, "stepping on each other" and voiding both of their transmissions. The short signals also make it difficult to use the normal signal processing algorithms to localize the source of the signal. Therefore, we have been developing real-time algorithms to blindly separate incoming signals and find their direction and identification code based on single pings from each tag. All our developments are made in a collaborative working partnership with engineering students at Cornell; these totaled 24 undergrads and 9 graduate students in this project. By working on systems to be used by biologists in the field, these students gain distinctive real-world experience, drawing on multiple sub-disciplines and combining them, exposing themselves to many of the same problems and scenarios posed by modern electronic systems in industry.
