id: apollo_bpsk_subcarrier_mod
label: Apollo BPSK Subcarrier Mod
category: '[Apollo USB]'
flags: [python]

parameters:
- id: subcarrier_freq
  label: Subcarrier Frequency (Hz)
  dtype: real
  default: '1024000'
- id: sample_rate
  label: Sample Rate (Hz)
  dtype: real
  default: '5120000'

inputs:
- label: in
  domain: stream
  dtype: float

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

templates:
  imports: from apollo.bpsk_subcarrier_mod import bpsk_subcarrier_mod
  make: apollo.bpsk_subcarrier_mod.bpsk_subcarrier_mod(subcarrier_freq=${subcarrier_freq}, sample_rate=${sample_rate})

documentation: |-
  Apollo BPSK Subcarrier Modulator

  Multiplies an NRZ baseband waveform (+1/-1) by a 1.024 MHz cosine to produce
  a BPSK-modulated subcarrier: output(t) = nrz(t) * cos(2*pi*f_sc*t).

  The cosine phase flips 180 degrees at each NRZ sign change, implementing
  bi-phase shift keying. This is the transmit-side counterpart to the
  Apollo BPSK Subcarrier Demod block.

  On the real spacecraft, the PCM encoder drives the BPSK subcarrier modulator
  before summing with the voice subcarrier for PM transmission.

  Parameters:
    subcarrier_freq: BPSK subcarrier frequency in Hz (default 1.024 MHz)
    sample_rate: Sample rate in Hz (default 5.12 MHz)

file_format: 1