Sunday, January 30, 2011

Winner of the 2011 IAP Radar Course SAR imaging contest

Tony Hyun Kim, Nevada Sanchez, and Paresh Malalur have won the SAR imaging contest for the 2011 MIT IAP radar course.

Their winning SAR image is of the outdoor statue by Alexander Calder, La Grande Voile (The Big Sail), 1965, Painted steel, 480 in. high (shown above). This is one of the most beautiful SAR images i have seen! (also, it is not bad for a radar built out of coffee cans and that plugs into your laptop audio input)

As you can see, this group built their own linear rail to acquire the image. They have acquired numerous other SAR images including some of the Stata center and other MIT landmark buildings.

Check out their site for more fascinating imagery from around the MIT campus.

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.

Monday, January 24, 2011

Gustavo's Page: Cleaner Ranging and Multiple Targets

This is awesome, Gustavo has written a nice GUI to plot the range to target in real-time with clutter cancellation for the MIT IAP 2011 coffee can radar system.

There is a great demo of his GUI and radar set here:

Gustavo's Page: Cleaner Ranging and Multiple Targets: "I got my friend Rachel to be an additional target. You should be able to make out the both of us in the range vs. time plot. We cross paths ..."

Sunday, January 23, 2011

A method of improving 2 pulse cancellation on the MIT IAP 2011 radar system

Tony Hyun Kim, Nevada Sanchez, and Paresh Malalur have figured out a method of reducing the clutter from 2-pulse cancelation necessary to find range-to-target of moving targets using the MIT IAP 2011 Radar system.

Rather than subtracting the last pulse from the latest in the time domain (directly off the mixer in the FMCW radar system) they instead subtract the magnitude of the IFFT of the last pulse from the latest.

This reduces the apparent clutter dramatically (see top figure compared to bottom) because the sample bandwidth of the audio input to a laptop is not sufficient to line up the trigger pulses perfectly from pulse to pulse. This group has figured this out by running simulations of radar data and dithering the sample clock slightly (see 2nd figure above).

To improve your coffee can radar performance when acquiring range-time plots try this method.

Friday, January 21, 2011

More exciting results from the MIT IAP 2011 Radar Course. 2nd year MIT student Gustavo has built the radar shown above, where results of some doppler vs. time plots of traffic is also shown above with an informative diagram showing the geometry of measuring the doppler shift of a moving vehicle. Some great analysis, explanation, and a Python based gui is shown on his blog here.

Thursday, January 20, 2011

The First SAR image acquired using the audio input port on a laptop

Today i acquired what i think is the first SAR image using the audio input on a laptop to digitize raw de-chirped radar data and transmit synchronization pulses.

This was done as part of preparation for Monday's lecture on SAR imaging for the MIT IAP course, 'Build a Small Radar System Capable of Sensing Range, Doppler and Synthetic Aperture Radar Imaging.'

A photo of the radar used to acquire this SAR image is shown. This radar is made out of coffee cans, a block of wood, a few mini-circuits parts, solderless breadboard, runs on 8 AA batteries, and uses your laptop's audio input port for digitization. Data is recorded as a .wav file then processed in MATLAB.

Complete details on this will be posted to the MIT Opencourseware site later this winter.

Monday, January 17, 2011

MIT IAP 2011, LL Radar Course results thus far

I am pleased to report that we are having a great time teaching the MIT IAP 2011 radar course.

Today i received the results of time vs. doppler experiments from one of the 8 student groups building the radar kit. This group consists of Tony Kim, Nevada Sanchez, Paresh Malalur (photos from their site As you can see the results are fantastic.

please visit their website for more details and photos.

I am very proud of our students and happy that there is so much enthusiasm for the study of applied electromagnetics.


Saturday, January 15, 2011

new project: a retro Jefferson Golden Hour Mystery Clock

Picked up this Jefferson Golden Hour Mystery Clock (above) at an antique shop for $10. Its date of MFGR is 1956. It does not work so i am going to attempt to repair it. I think it would look great next to my old zenith K725 radio at the office (shown below).

Will keep everyone posted on the clock restoration.