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Intro

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Processing:

• Beam 0 polA and polB were used for the processing.
• The 2.5 Mhz bandwidth was reduced to 300 Khz by averaging 8 samples and then decimating.
• Dynamic spectra were made using +/- 10 kHz bw for the 50 seconds.
• The total power over the central 20 Khz was computed and plotted vs time.
• Combs were found that repeated every 12 seconds. These are radar rotation periods.  1 second spectral averages were taken around 3 different combs.
• A model of the combs created by the airport faa radar over plotted on the measured combs.

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The images/plots:

    You can see the comb in the image. The image is scaled  to have maximum intensity at 8 *sigma. On the left edge of the image are horizontal lines showing where the combs are at. These lines are repeated every 12 seconds.

Plots of total power and average spectra (.ps) (.pdf):

• Page 1 Total pwr vs time: The central 20 kHz of the spectra were averaged and then plotted vs time.  Black is polA and red is polB. The dotted colored lines correspond to the horizontal dashed lines in the image. They are repeated every 12 seconds. The bottom shows the time for the first pulse of each of the 3.
• Page 2: 1 second average spectra around the combs. Black is polA, red is polB. The plots show +/- 10 Khz about DC. The 3 frames are for the 3 different sets of combs found. The bottom plot (birdies starting at 1.89 seconds do not look like a comb). The other two do.
• Page 3:  The same plot as page 2 but now limited to +/-  2 kHz about DC.
• You can now make out the individual comb elements.
• The green dashed vertical lines are the frequency combs created by the FAA radar using a model. See the faa radar specs for the input used to make the model.  You can also see the idl routine that generates the data (mkfaarot).
• The frequency comb in the top two plots corresponds to the faa radar comb. The bottom plot does not.

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Summary:

• The pulses/comb seen in the seti data corresponds to the faa radar.
• There are two 12 second sequences offset in phase by 6.34 seconds (or 190 degrees of rotational phase). This may be the back lobe of the radar that we are seeing. It also could be a reflection from an airplane that was landed. If it was an airplane, then one of the 12 second sets should go away.
• The 3rd 12 second sequence did not have an obvious comb.