Investigating the Transit 5B-5/E-5 Satellite: The oldest satellite still transmitting

Transit 5B-5 is a US Navy navigation satellite that was an early version of the GPS/GNSS system we enjoy today. It was launched in 1964 and has been transmitting continuously for roughly 60 years. Unlike many dead satellites that only emit a carrier tone, this one still broadcasts modulated telemetry on about 136.65 MHz, making it a fascinating target for amateur radio and SDR hobbyists.