Posted 23 May 2017
As you may recall from previous posts, I have been collaborating with my long-time friend and mentor John Jenkins on the idea to use square-wave modulation of the charging station IR beam to suppress ‘flooding’ from ambient IR sources such as overhead incandescent lighting and/or sunlight.
More than likely, If it is possible to implement a software processing algorithms to recover steering information from potentially corrupted data, it will have to be housed on a dedicated processor. So, I decided to set up a separate test setup using two processors – one to generate a square-wave modulation waveform, and another to receive that waveform through an IR link. The link can then be modified in a controlled way to simulate link losses and/or ‘flooding’. The initial hardware setup is shown below.
Then I ran my little test program on the receiver processor that simply acquires 100 samples at roughly 20 samples/cycle and then prints out the results. The following two images are Excel plots of the results for 12cm & 78cm separation.
As can be seen from these two plots, the 12 & 78cm separation values provide a reasonably good simulation of the ‘very good’ and ‘reasonably crappy’ signal conditions.
Next I verified that I can successfully ‘flood’ the receiver with my portable battery-operated IR signal generator. I monitored the transmitted and received waveforms, without and then with flooding. In both cases, the bottom trace is the 5V square-wave transmitted signal, shown at 2V/div, and the top trace is the received signal shown at 1V/div. The ground for both traces is the same line on the scope screen.
As can be seen in the scope photos, I can indeed produce almost 2V of ‘flooding’ using the IR signal generator, so I should be able to determine whether or not a particular recovery algorithm is successful at suppressing flooding effects.
Stay tuned
Frank
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