HDR sensing and the scientific method:

for HDR sonar or HDR vision and Metavision™

HDR (High Dynamic Range) sensing (also known as "Being Undigital") was invented [link] by Steve Mann in the 1980s as a way of using low-dynamic-range sensors to sense high dynamic range phenomena by combining measurements of the same phenomenon that are captured at multiple sensitivity levels.

Often these different measurements that are taken at multiple sensitivity levels are combined computationally, and in this sense, HDR is known as "Being Undigital", i.e. using digital signal processing to achieve an "undigital" (continuous, non-quantized) result [link].

HDR was originally envisioned as a realtime seeing aid to help people see and understand their world better [ask your TA for a copy of the realtime HDR video article and the cyborg-HDR history chapter if you are interested in learning more].

HDR is related to the previously known and used method called "signal averaging", but instead of measuring the same thing over and over again at the same gain setting, HDR involves measuring the same thing over and over again at different gain settings.

In this lab you will build an HDR sonar system that uses the phenomena of HDR sensing.

HDR sensing

For the basic part of the lab, you will use the setup that you used for the basic part of Lab 2 and Lab 3, with the addition of a simple way to adjust the gain to at least three different gain settings: weak, medium, and strong.

Task:

Arrange both transducers so that they are mounted near each other, but not touching (e.g. maybe about 1 inch apart), and so that they are both facing in the same direction.

Construct a means for moving the apparatus towards and away from a wall or other object, where the apparatus moves along the same path, as shown in the diagram below:

I've shown a toy car that would ride in a track or slot or groove to keep it riding along the same path, but you're free to use your imagination and build any kind of apparatus, e.g. a rail car, or railway guide, or sliding mechanism, or the like, as long as it adheres to the scientific principle of reproducible results.

You may work in pairs on the construction and collection of the data, but each person must do their own data analysis.

Devise a way to collect data for each of the three different exposures, i.e. weak, medium, and strong, for each of a variety of distances from the wall or other subject matter.

Grading

Assembly of the apparatus of Lab 2 and Lab 3 into a sliding system for collecting data. The apparatus of Lab 2 and Lab 3 must be neatly wired, and mounted to the sliding or moving or rolling apparatus, well-done, and well-presented, 4/10.

Collection of data from the apparatus, for each of the three exposures (weak, medium, and strong), as a function of distance from the wall or other object, showing an example of a wave that exhibits clipping and cutoff (i.e. too strong and too weak), with good choice of samping interval (at least satisfy the Nyquist sampling criteron, and preferably well beyond that), and good range (good dynamic range), 4/10

Plotting a graph of the three separate exposures, aligned on top of each other, in a single plot, 2/10.

Bonus mark if you can supply three good quality photographs of wave for each of the three separate sensitivities.

Preparation for Lab 5

For Lab 5, you will combine these exposures into a single exposure of increased dynamic range.