@type t() :: %Sidereon.GNSS.QC.SystemObservation{
  completeness_ratio: float() | nil,
  epochs_with_observations: non_neg_integer(),
  expected_observations: non_neg_integer(),
  gap_count: non_neg_integer(),
  satellites_seen: non_neg_integer(),
  system: String.t(),
  total_gap_s: float(),
  value_observations: non_neg_integer()
}