INDOORS is a research project which studies indoor localization based on ambient radio signals broadcasted by FM, TV and cellular stations (also called "infrastructure-free localization").
Data acquisition platform for a long-term study
Data acquisition platform (DAQ) is a tool designed to facilitate creation of indoor signal fingerprinting datasets. Its source code is available under the open MIT license.
The DAQ consists of three main components: an SDR receiver; the DAQ core, which controls the workflow of the system; and the user interface.
In order to ensure system modularity and compatibility with different hardware configurations, the user interface is implemented as a dynamic web page which communicates with the DAQ core via HTTP and WebSocket protocols. This also allows separation of the tasks between different devices, for example running the resource-intensive SDR streaming on a heavy powerful laptop and controlling the process from a lightweight tablet.
In order to accommodate SDR receivers with different programming interfaces, SDR control is delegated to a dedicated hardware-specific command-line utility, which can be adapted for different receivers. Once the user requests acquisition of an RF data sample, the DAQ launches the SDR control utility, providing it with a list of tuning parameters, sampling duration, and a directory for storing the acquired data. Overall, the system is rather flexible and SDR receiver can even be replaced with other location-sensing hardware, such as magnetic or light sensors.
The user interface of the DAQ features two key parts: a control panel and a floorplan with predefined test points:
At the start of the experimental session, the operator selects radio bands of interest and the testbed where the session takes place, and specifies the environment's social dynamics — that is, whether the session takes place in an empty building (e.g. offices on weekends), populated building (e.g. offices during work days), or in a dense crowd (e.g. student canteen during lunch). Current weather conditions are acquired from a web service and include such parameters as temperature, humidity, precipitation intensity, pressure, cloud density, wind speed and direction and even ozone levels.
In the course of the experimental session, the operator visits the predefined test locations, selects the current location on the floorplan, and starts RF sample acquisition. Depending on the selected radio bands of interest, sampling takes from 15 s to 2 minutes per point. The user can monitor the sampling progress via log messages from the DAQ core.