id: apollo_fm_voice_subcarrier_mod
label: Apollo FM Voice Subcarrier Mod
category: '[Apollo USB]'
flags: [python]

parameters:
- id: sample_rate
  label: Sample Rate (Hz)
  dtype: real
  default: '5120000'
- id: subcarrier_freq
  label: Subcarrier Frequency (Hz)
  dtype: real
  default: '1250000'
- id: fm_deviation
  label: FM Deviation (Hz)
  dtype: real
  default: '29000'
- id: tone_freq
  label: Test Tone Frequency (Hz)
  dtype: real
  default: '1000'
- id: audio_input
  label: Audio Source
  dtype: bool
  default: 'False'
  options: ['True', 'False']
  option_labels: ['External Input', 'Internal Test Tone']

inputs:
- label: audio
  domain: stream
  dtype: float
  optional: true
  hide: ${ 'all' if not audio_input else 'none' }

outputs:
- label: out
  domain: stream
  dtype: float

templates:
  imports: from apollo.fm_voice_subcarrier_mod import fm_voice_subcarrier_mod
  make: >-
    apollo.fm_voice_subcarrier_mod.fm_voice_subcarrier_mod(
      sample_rate=${sample_rate},
      subcarrier_freq=${subcarrier_freq},
      fm_deviation=${fm_deviation},
      tone_freq=${tone_freq},
      audio_input=${audio_input})

documentation: |-
  Apollo FM Voice Subcarrier Modulator

  Generates a 1.25 MHz FM subcarrier for the voice channel. Can operate in
  two modes:

  Internal mode (default): Uses a built-in sine test tone as the audio source.
  This is useful for testing and signal validation.

  External mode (audio_input=True): Accepts an external float audio stream as
  input. Use this to modulate actual Apollo mission voice recordings or live
  audio onto the 1.25 MHz FM subcarrier with +/-29 kHz deviation.

  On the real spacecraft, voice audio (300-3000 Hz) drives an FM VCO at
  113 kHz, which is mixed with the 512 kHz master clock and doubled to
  produce the 1.25 MHz FM subcarrier.

  Parameters:
    sample_rate: Output sample rate in Hz (default 5.12 MHz)
    subcarrier_freq: FM subcarrier center frequency in Hz (default 1.25 MHz)
    fm_deviation: FM deviation in Hz (default +/-29 kHz)
    tone_freq: Internal test tone frequency in Hz (default 1 kHz, ignored when audio_input=True)
    audio_input: When True, accept external audio via float input port

file_format: 1