I may have received a radiosonde this morning. Even though the winds were not favorable, I decided to give it a try. I had a carrier on 1676 MHz starting at around 1205z. Then at around 1215z or so, I started to see modulation on it. I ran my app, and got 5 packets with a bad CRC (unfortunately I didn't enable the option to display bad CRC packets). Then after fiddling around trying to get an app running to record the audio, I went back to the waterfall, and the signal was completely gone. So I am not sure what I had.
When the balloon bursts, how quickly does it fall? I'm wondering if I caught the signal when the balloon was at the maximum height? From the CUSF map it looks like it was south of DC.
For those interested, I was using my discone antenna feeding a Radio Shack Satellite pre-amp (950-2050 MHz) and an RTL dongle, running Gqrx under Mac OS X.
I'll need to be better prepared for next time.