Signals from Space!

Here is a recent thing I have been playing around with.  NOAA has a series of weather satellites that broadcast images as they orbit.  We have all seen them as the jumpy cloud maps in the weather segment of the news.  You can tune them in if you go off the top of the FM radio range to ~137 MHz.  They orbit the earth every 101 minutes or so in a near polar orbit, but not in a fixed circle, so their orbital loops slowly pass around the planet.  Currently NOAA-15 is passing close to Hawai'i each day, so I have been tracking it online and trying to catch the signal for the past few days. 

NOAA-15 was launched almost 14 years ago in 1998 (link).  It is showing its age, parts of the satellite are not fully operational (link). 

I tracked it using this website.

On the first day it was to come overhead early in the morning, just before sunrise, so I got up to listen for the signal but the batteries in my radio receiver were dead...

On the second day, it was due to rise above the horizon at 5:38 AM.  This time I was fully charged and ready to go.  I caught the signal at 5:41 (there are mountains toward the north which likely blocked the early part of the signal).  Beep, beep, beep, ...  It lasted for almost 10 minutes before dropping below the horizon again.

This morning, the third day, it was due to rise at 5:13 AM.  The night before I bought an audio cable and adapter to connect the radio to my laptop and record the signal.  Here it is coming in from the north.

I used Audacity to record the APT format signal and WXtoIMG to decode it. 
The best part of the recording was when it was directly overhead at 5:20 AM. 



This was before sunrise, so you don't expect to be able to see any features in the actual image.  And, this was done with the bare minimum of equipment, with a lot of noise and static.  But, you can just make out, in the center of the image, the telemetry bar of the broadcast.  There are many steps I can take to work toward improving the reception.  Below is an image of 4 minutes of reception including the part in the video above.