For the first time today I tried receiving the RTTY transmitted by GAGA-1 and decoding it using DL-FLDIGI. It worked (first time!).
To illustrate the whole set up here's a little video. The radio I'm using is a Yaesu FT-790R II which I bought second-hand on eBay. This is an old radio, but it's sturdy and can do SSB at 70cm. Although it's a portable, I managed to buy one that had never been outside and it looks like it's been treated with great care. Thanks, eBay!
The flight computer is in a loop transmitting $GAGA-1 Test Transmission using 7-bit ASCII, with two stop bits, no parity at 50 baud.
Apologies for the shaky hand and blurry video. The combination of me + the iPhone's poor camera isn't great. Just listen to that lovely RTTY sound though.