Wednesday, January 26, 2011

MIT IAP '11 radar course SAR example, imaging with coffee cans, wood, and the audio input from your laptop

The MIT IAP '11 course radar is designed from coffee cans, block of wood, 6 mini-cirucits parts, 3 op-amps, 8 AA batteries and a few other parts. The analog output of this radar is fed into the R and L audio input channels of your laptop computer, where you record a .wav file of the radar data. This is fed into various matlab scripts that process the digitized radar data to provide doppler time, range time, and SAR images.

To acquire a SAR image, a toggle switch is placed in-line with the L channel. The L channel is connected to the synchronization pulse from the linear ramp generator. Turn off the L channel to move the radar to a new position along a straight measuring tape. Turn on the L channel when you are in position. Re-position the radar every 2" to acquire a SAR data set.

An example SAR image is shown above. Not bad for for a coffee can laptop radar, where the tree-line and all prominent metal scatterers is shown (image acquired this past weekend in 2 ft of snow, so there was actually additional snow clutter not shown in the google earth image). Currently the students in the course are attempting their own SAR images with their radars. Will post results as i get them.