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The prototype logs each bluetooth signal that gets detected in a local database. In parallel, a local scheduler periodically is in charge to synchronize the data gathered by the probe with the data stored in the central system. Each (fixed) roadside station is part of a virtual private network (VPN) which in turn delivers the data to the central system through a wifi or 3g internet connection.
  • Rasperry-pi

    The Raspberry-Pi is a small and powerful credit card sized computer. It costs around US$ 25 (Model A) and US$ 35 (Model B) and is powered by an ARM processor (700 MHz). It consists of 256MB RAM (Model A, Model B rev2) and 512 RAM (Model B rev1). Our prototype uses the model B rev 1 due to the presence of two USB ports, one connected to the bluetooth while the other is supposed to be used by the 3g/wifi device through which we plan to transfer the data gathered.
  • Bluetooth dongle

    The bluetooth dongle is the key part of the project, it actively listens for new devices. The bluetooth protocol has 3 different major classes (1, 2, 3) the class 1 has the largest communication range, this has the positive result of being able to query cars far away from the fixed position where it is located, however it consumes much more energy compared to the other classes. On the contrary, the other classes have a smaller communication range but consume less energy. Moreover the communication range depends on several factors such as the antenna, the propagation condition and the material coverage just to name a few. To sum up, the choice of a device might be strongly dependent on the station position and the number of roadways involved.
  • Battery

    The prototype is powered by a 12V-9.0Ah which gives up to 2 days of life time.
  • DC-DC converter

    To speed up the experiments in the initial phase of development of the prototype we have decided to use, we used the common car cigarette lighter adapter which has an usb port. The adapter converts the 12V of the battery to the 5V needed by the raspberry-pi.
  • The box

    The box is weather resistant, according to the IP (International Protection Marking) standard. The box is IP56.
  • Bluelog

    Bluelog is a Bluetooth scanner designed to discover nearby devices as quickly as possible. It seamlessly loops by inquiring and logging as many devices as possible. Initially developed by Tom Nardi, the reference code for this project is here.
  • Vtraffic

    In the earlier phases the application has been developed for just plotting graphs on a webpage as a proof of concept for the initial tests. Right now, it allows users to submit, query and plot the results of the data analysis being carried out. In the following phases much of the effort will be spent on implementing the data delivery infrastructure to store real-time data coming from the different stations installed on the road network.
  • The Raspberry-Pi, for its 3V3 rail uses a linear regulator. This kind of component dissipates approximately one third of the energy as heat. In our case this is a waste that reduces the battery life. To solve this problem we tried to replace the linear regulator with a more efficient switch mode power. This solution should lead to a reduction in the power consumption of aproximately 25%.
    In order to provide more details about the hack that sould be done on the board in order to reach this results we created a dedicated section: Power consumption: reduce the waste of the Raspberry-Pi.
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