CQT Talk by Grégory Langue, Liège Space Centre,University of Liège, Belgium
Title: Prototyping of a high-speed, time-of-flight, distance measuring device for formation flying satellites. Date/Time: 24-Jul, 04:00PM Venue: CQT Level 3 Seminar Room, S15-03-15
Abstract: There are a multitude of ways of measuring distance, however not all are suitable for space. This study is focused on distance measurement using time of flight (TOF) and more specifically on the development of a space-compatible receiver device that operates at distances, around 1km, where the recovered energy is very low.
A MPPC (Multi-Pixel Photon Counter) was investigated and developed into a prototype receiver.
Crosstalk and afterpulse phenomena related to the MPPC were observed, and the limits of the system were established. The results highlighted the importance of a neat design and the limitations related to internal noise (produced by the circuit and the sensor) and external noise (stray light).
The conclusion of this work is the realisation of a supervisory circuit for the functional MPPC. Although the card correctly conditions the pulses of current emitted by the sensor, improvements can be made.
One of the developments envisaged is the acquisition of the pulses by FPGA and the processing (as well as the communication) would be left to the microcontroller. The use of FPGA would also implement
digital filters and / or algorithms to bring out, more easily, the useful impulses embedded in the noise.
Abstract: No device built according to the rules of quantum field theory can measure proper time along its path. Highly accelerated quantum clocks experience the Unruh effect, which inevitably influences their time rate. This contradicts the concept of an ideal clock, whose rate should only depend on the instantaneous velocity and not acceleration.