Thrifty

Thrifty is proof-of-concept SDR software for TDOA positioning using inexpensive SDR hardware such as the RTL-SDR.

Requirements

• Python <http://www.python.org/>_ 2.7 or later
• Numpy <http://www.numpy.org/>_
• [Optional] matplotlib <http://matplotlib.org/>_

Installation

To install thrifty::

$ sudo apt-get install python-pip
$ sudo pip install .

or::

$ sudo python setup.py install

In addition to installing thrifty into the system's Python environment, this will also download and install the Python module requirements from PyPI <http://pypi.python.org/>_.

To install thrifty in developer mode, which creates a symbolic link from the source location to the user's install location::

$ make dev

Thrifty requires fastcard to capture data. Refer to fastcard/README.md <fastcard/README.md>_ for installation instructions. Furthermore, refer to fastdet/README.md <fastdet/README.md>_ for more information regarding fastdet, a fast replacement for thrifty detect.

Refer to rpi/installation.md <rpi/installation.md>_ for instructions on configuring an Raspberry Pi 3 for use as an inexpensive TDOA receiver.

Usage

A command-line interface (CLI) is available through the thrifty command. Run thrifty help for a summary of the modules that are available through the CLI.

Typical CLI workflow::

$ cd example/
$ vim detector.cfg   # edit config

$ # On RX0:
$ thrifty capture rx0.card
$ thrifty detect rx0.card -o rx0.toad

$ # On RX1:
$ thrifty capture rx1.card
$ thrifty detect rx0.card -o rx1.toad

$ # On server:
$ thrifty identify rx0.toad rx1.toad
$ thrifty match
$ thrifty tdoa
$ thrifty pos

Alternatively, use the Makefile::

cd example/
vim detector.cfg   # edit config
thrifty capture cards/rxX.card
make

Detection on slow hardware: see fastcard <fastcard/README.md>_ and fastdet <fastdet/README.md>_.

Cookbook:

• Live detection without capturing (for monitoring)::

  thrifty capture - 2>/dev/null | thrifty detect - -o /dev/null
  

• Parallel capture-and-detection::

  thrifty capture rx.card
  tail -f rx.card | thrifty detect -
  

For advanced use cases, use the thrifty API from Python or IPython, e.g.:

.. code-block:: python

"""Plot histogram of SoA offsets for all detections from TX #0."""

import matplotlib.pyplot as plt

from thrifty import toads_data

toads = toads_data.load_toads(open('rx.toads', 'r'))
data = toads_data.toads_array(toads, with_ids=True)
tx0_data = data[data['txid'] == 0]
plt.hist(tx0_data['offset'], bins=20)
plt.show()

Publications

Thrifty forms part of the dissertation at https://hdl.handle.net/10394/25449. Please cite this dissertation when using Thrifty in your work:

.. code-block:: bibtex

@mastersthesis{kruger2016inexpensive,
  title={An inexpensive hyperbolic positioning system for tracking wildlife using off-the-shelf hardware},
  author={Kr{\"u}ger, Schalk Willem},
  year={2016},
  school={North-West University (South Africa), Potchefstroom Campus}
}

Refer to https://swk.za.net/publications for contact information.