As indicated by ham users the schematic is low quality in the PDF article released by TAPR. Here sharing a better quality picture, hopefully that helps.
You will find more details for decoding in this article: This is an educational purpose audio stream. You can use this audio stream to experiment with narrow band satellite reception without physical ground station (SDR, LNA and antenna hardware) having fun and learning SDR technologies without experience (and investment) in RF Hardware. Simply open in Read more about INMARSAT STD-C EGC live streaming[…]