Our study analyzes the limitations of Bluetooth-based trace acquisition initiatives carried out until now in terms of granularity and reliability. We then go on to propose an optimal configuration for the acquisition of proximity traces and movement information using a fine-tuned Bluetooth system based on custom HW. With this system and based on such a configuration, we have carried out an intensive human trace acquisition experiment resulting in a proximity and mobility database of more than 5 million traces with a minimum granularity of 5 s.last modified : 2012-06-12release date : 2012-06-12date/time of measurement start : 2010-11-24date/time of measurement end : 2010-11-24collection environment : The Pilot Project was carried out at Tecnalia's headquarters with a human sample of 56 people for 6 weeks.network configuration : We assigned a PDPD (Bluetooth customized Device) to every person in the Pilot Project with careful instructions about the procedure and the goals of the Pilot Project. 30 Beacons were distributed in strategic zones all over the building (departments, corridors, cafeteria, meeting rooms, etc).data collection methodology : The system comprises the following components: - Personal Devices of Proximity Detection (PDPD). - Beacons, used as static references. - Central server used as repository for all the traces. - Gateways, usually PCs or similar, to transfer the information of the PDPD to the central server. - Synchronization system to have all the traces synchronized. The core of the system is the PDPD. It consists of a Bluegiga Bluetooth module and some other peripheral modules for the detection of proximities and other relevant information such as the state of the PDPD. The peripherals are controlled by the microcontroller of the Bluetooth module itself. The traces are stored in 2 non-volatile I2C FRAM memories of 1Mbit each, with almost infinite read-write cycles (this is important to solve the memory depletion problems of other papers). The PDPDs download the traces periodically to the gateways, which send them to the central server. Every PDPD is powered by two 1.2 V AAA NiMh rechargeable batteries. The PDPD has a power system that recharges the batteries through a USB connector. The PDPD is equipped with an accelerometer for detecting its state with the aim of distinguishing when the person is wearing the PDPD or has left it aside and of detecting the person's movement. The connectivity trace...