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linkbudget.margin

margin

margin.py

Link-margin / closure analysis.

LinkMargin 

LinkMargin(name: str = 'Link margin', description: str = '', required_ebno_db: float | None = None, required_esno_db: float | None = None, required_cn_db: float | None = None, required_snr_db: float | None = None, noise_bandwidth: float | None = None, data_rate: float | None = None, symbol_rate: float | None = None, implementation_loss_db: float = 0.0, coding_gain_db: float = 0.0)

Bases: Component

Terminal analysis stage: compares the achieved link quality against a required threshold and reports the margin.

Signal and noise pass through unchanged; the stage is annotated with achieved_snr_db, achieved_ebno_db / achieved_esno_db, required_db, margin_db and closes.

Provide the requirement as exactly one of required_ebno_db, required_esno_db, required_cn_db or required_snr_db. When the requirement is Eb/N0 or Es/N0, noise_bandwidth and data_rate (or symbol_rate) are needed to convert the achieved C/N.

coding_gain_db is added to the achieved metric and implementation_loss_db is subtracted from it before the margin is taken.

Source code in linkbudget/margin.py 
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def __init__(self, name: str = "Link margin", description: str = "",
             required_ebno_db: float | None = None,
             required_esno_db: float | None = None,
             required_cn_db: float | None = None,
             required_snr_db: float | None = None,
             noise_bandwidth: float | None = None, data_rate: float | None = None,
             symbol_rate: float | None = None, implementation_loss_db: float = 0.0,
             coding_gain_db: float = 0.0) -> None:
    requirements = {
        "required_ebno_db": required_ebno_db,
        "required_esno_db": required_esno_db,
        "required_cn_db": required_cn_db,
        "required_snr_db": required_snr_db,
    }
    given = [key for key, value in requirements.items() if value is not None]
    if len(given) != 1:
        raise ValueError(
            "give exactly one of " + ", ".join(requirements) + f" (got {given})")

    self.name = name
    self.description = description
    self.required_ebno_db = required_ebno_db
    self.required_esno_db = required_esno_db
    self.required_cn_db = required_cn_db
    self.required_snr_db = required_snr_db
    self.noise_bandwidth = noise_bandwidth
    self.data_rate = data_rate
    self.symbol_rate = symbol_rate
    self.implementation_loss_db = implementation_loss_db
    self.coding_gain_db = coding_gain_db

is_margin class-attribute instance-attribute 

is_margin = True

name instance-attribute 

name = name

description instance-attribute 

description = description

required_ebno_db instance-attribute 

required_ebno_db = required_ebno_db

required_esno_db instance-attribute 

required_esno_db = required_esno_db

required_cn_db instance-attribute 

required_cn_db = required_cn_db

required_snr_db instance-attribute 

required_snr_db = required_snr_db

noise_bandwidth instance-attribute 

noise_bandwidth = noise_bandwidth

data_rate instance-attribute 

data_rate = data_rate

symbol_rate instance-attribute 

symbol_rate = symbol_rate

implementation_loss_db instance-attribute 

implementation_loss_db = implementation_loss_db

coding_gain_db instance-attribute 

coding_gain_db = coding_gain_db

propagate_signal 

propagate_signal(signal_power: float, noise_power: float) -> StageData

Pass the power through unchanged; annotate the stage with the achieved metric, the requirement and the resulting margin.

Source code in linkbudget/margin.py 
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def propagate_signal(self, signal_power: float, noise_power: float) -> StageData:
    """Pass the power through unchanged; annotate the stage with the
    achieved metric, the requirement and the resulting margin."""
    if noise_power > 0.0:
        achieved_snr = signal_power / noise_power
    else:
        achieved_snr = float("inf")
    achieved_snr_db = convert.linear_to_db(achieved_snr)

    cn0 = None
    if self.noise_bandwidth:
        cn0 = fom.cn0_from_snr(achieved_snr_db, self.noise_bandwidth)
    achieved_ebno_db = fom.ebno_db(cn0, self.data_rate) if (
        cn0 is not None and self.data_rate) else None
    achieved_esno_db = fom.esno_db(cn0, self.symbol_rate) if (
        cn0 is not None and self.symbol_rate) else None

    metric, achieved_db, required_db = self._achieved_and_required(
        achieved_snr_db, cn0)

    margin_db = None
    if achieved_db is not None:
        margin_db = (achieved_db - required_db
                     + self.coding_gain_db - self.implementation_loss_db)

    return {"name": self.name,
            "description": self.description,
            "signal_power_in": signal_power,
            "noise_power_in": noise_power,
            "signal_power_out": signal_power,
            "noise_power_out": noise_power,
            "metric": metric,
            "achieved_snr_db": achieved_snr_db,
            "achieved_ebno_db": achieved_ebno_db,
            "achieved_esno_db": achieved_esno_db,
            "achieved_db": achieved_db,
            "required_db": required_db,
            "coding_gain_db": self.coding_gain_db,
            "implementation_loss_db": self.implementation_loss_db,
            "margin_db": margin_db,
            "closes": bool(margin_db is not None and margin_db >= 0.0)}