PCBWay 3rd PCB Design Contest

Direct Time of Flight Rangefinder


I'm electronics engineering student at Bialystok University of Technology. Since I start studying I always want to do something more. At bachelor studies I was participating in sumo robots competitions (in Europe, Japan and the USA). There was not only battle between robots, but also between ideas and technology. Many teams (including my team) was using super black or mirrors covers to make robot invisible to other robots. This push me to dig dipper into proximity sensors world. I decided to do own sensor as my master graduation project.

Main goal in my project is design, prototype and test rangefinder. I choice direct time of flight measuring method. Idea is very simple: send optical signal and counting time until it return. Problem is that light travel 299792458 m/s. That mean it will pass 1 meter distance both ways in less then 7ns. This is beginning of advanced engineering in this project. Optical signal have to be enough strong to come back from low reflective targets and be enough weak to be safe for eyes. This means that pulses have to have high amplitude and very short duration time. To transmit and receive that pulse high not only bandwidth components are required, but also carefully designed circuits board. While pushing several amperes thru laser diode in sub-nanoseconds pulsed parasitic trances inductance are major limitation. While receiving short pulses main limitation is parasitic capacitance. Another important problem is were to set trigger lever. To low trigger level will result in fake detects and to high in distance measure inaccuracies.

Now move to technical details.

My project will have a modular construction that allow to make tests with different light sources and receivers. This idea will allow to move device tests from lab to real world. Main board will contain microcontroller with external SDRAM memory, precision time to digital converters, LCD with touchpanel and DC/DC converters. Transmitters will contain local DC/DC converters, short pulse generator, laser driver, laser diode and comparator as start pulse trigger. Receiver will contain photodiode bias supply, photodiode, transimpedance amplifier and comparator as stop pulse trigger.

Unfortunately I can's share more details like schematics, layouts, bill of materials and other before graduation (expected in October 2019). If you plane do something like this or you already did it and have some tips or just want to talk about this project don't hesitate to write to me at n.thernstrom(at)student.pb.edu.pl

Dear PCBWay, I hope that you can support this project. Project budged from University is very limited and not cover even 1/10 costs of component. Most components I got as samples from companies like Omega Optical, Hamamatsu,OnSemi, Analog Devices, iC-Haus, Osram and mamy many more. I will put thanks to all companies that support my project in my thesis and in project publications (after graduation).

Best regards,


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Jul 18,2019
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