Ryan Malloy
493c21c511
Implement the transmit/generate side as streaming GNU Radio blocks, complementing the existing receive chain. Each block maps to a physical instrument on CuriousMarc's Keysight bench: pcm_frame_source - PCM bit stream generator (sync_block + FrameSourceEngine) nrz_encoder - bits to NRZ waveform (+1/-1) with upsampling bpsk_subcarrier_mod - NRZ x cos(1.024 MHz) BPSK modulator fm_voice_subcarrier_mod - 1.25 MHz FM test tone source pm_mod - phase modulator: exp(j * deviation * input) usb_signal_source - convenience wrapper wiring all blocks together Includes GRC YAML definitions for all blocks under [Apollo USB] category, 49 new tests (271 total, all passing), and a loopback test that validates the full TX->RX round trip including frame recovery with 30 dB AWGN.
59 lines
1.7 KiB
YAML
59 lines
1.7 KiB
YAML
id: apollo_fm_voice_subcarrier_mod
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label: Apollo FM Voice Subcarrier Mod
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category: '[Apollo USB]'
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flags: [python]
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parameters:
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- id: sample_rate
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label: Sample Rate (Hz)
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dtype: real
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default: '5120000'
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- id: subcarrier_freq
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label: Subcarrier Frequency (Hz)
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dtype: real
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default: '1250000'
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- id: fm_deviation
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label: FM Deviation (Hz)
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dtype: real
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default: '29000'
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- id: tone_freq
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label: Test Tone Frequency (Hz)
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dtype: real
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default: '1000'
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outputs:
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- label: out
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domain: stream
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dtype: float
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templates:
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imports: from apollo.fm_voice_subcarrier_mod import fm_voice_subcarrier_mod
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make: >-
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apollo.fm_voice_subcarrier_mod.fm_voice_subcarrier_mod(
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sample_rate=${sample_rate},
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subcarrier_freq=${subcarrier_freq},
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fm_deviation=${fm_deviation},
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tone_freq=${tone_freq})
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documentation: |-
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Apollo FM Voice Subcarrier Modulator
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Source block that generates a 1.25 MHz FM subcarrier with a sinusoidal test
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tone. Transmit-side counterpart to the voice subcarrier demodulator.
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The signal chain is: test tone -> FM modulator -> upconvert to 1.25 MHz
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-> real-valued output. With default parameters this produces a signal
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matching the Apollo USB downlink voice subcarrier (+/-29 kHz deviation).
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On the real spacecraft, voice audio (300-3000 Hz) drives an FM VCO at
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113 kHz, which is mixed with the 512 kHz master clock and doubled to
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produce the 1.25 MHz FM subcarrier.
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Parameters:
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sample_rate: Output sample rate in Hz (default 5.12 MHz)
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subcarrier_freq: FM subcarrier center frequency in Hz (default 1.25 MHz)
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fm_deviation: FM deviation in Hz (default +/-29 kHz)
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tone_freq: Internal test tone frequency in Hz (default 1 kHz)
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file_format: 1
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