First set of sensors arrived yesterday from Amazon. 20 minutes of soldering later they are hooked up to the arduino. I had time over the weekend to write the code to drive them all and return the values in a defined format

sample: [04]:[67]:[45]:[90]\r\n

I also rewrote the vb.net application to handle the data as each line and optimized the code further. I am now working with bitmaps instead of the original hacked together draw a panel and then fill with smaller panels. Should have the benefit of easily marking things on the waterfall and easier to save to a data file. Bandwidth is also a concern with getting fast sample rates rendered on the screen. Using the graphics library will be faster than the original panel solution and has the benefit of being able to stream data into the view.

To reduce testing errors the sensors are mounted linearly on an aluminum square tube, wire lengths are kept to a minimum. Each unit (PCB) is spaced 5cm apart for a very uniform look. Each unit is mounted in parallel with the aluminum tube, which results in a more uniform test. Each sensor is isolated from the aluminum tube with electrical tape which should help reduce any additional resonance from the nearby sensors being transmitted through the backing.

The test unit looks a little unrefined but the test data looks good. With an effective 4 pixel sweep over about 30cm and no additional attempts to compile multiple sweeps or higher sampling or beam shaping, I can discern my desk, coffee cup, and monitor base at about 60 cm distance.

I'm checking with the local college lab if they have a laser vibrometer for more precise testing that will be required once phased beamshaping is implemented.

Additional sr04 sensors from ebay are still on the way. I will need to build some hardware logic to address the 14 sensor array from the uno. I'm concerned the uno may be too slow or rather the combination of uno and sr04 sensors will be to slow to be practical, however as an extended proof of concept I think it will work sufficiently.

These are the transducers I am considering to build into the active array: http://www.ebay.ca/itm/1pc-Ultrasonic-Sensors-Integrated-Transceiver-Waterproof-Diameter-16MM-/191136732745?pt=LH_DefaultDomain_0&hash=item2c80a31649

I am liking their size, availability and that they are pre-waterproofed; less thrilled at the price. They will be embedded in a non resonating material for ease of mounting and consistency. I am currently considering silicon as it has the benefit of being able to remove the transducers from it easily and it should absorb additional vibration from the transducers reducing co-location interference and letting us scan at a faster rate.

Thanks for reading!