Assembles the complete Apollo USB downlink signal from individual blocks:
PCM frames on 1.024 MHz BPSK + crew voice on 1.25 MHz FM, both PM-modulated
onto a single complex carrier. Receives and splits into decoded PCM frames
and recovered voice audio.
Clean: 399/402 frames, 8s voice. At 25 dB SNR: 395/402 frames.
