Validation & warnings¶

The library checks a budget at two points: when you construct a component, and when you compute the budget.

Constructor validation¶

Component constructors reject values that would produce a crash or nonsense by raising ValueError immediately:

linkbudget.FreeSpacePathLoss("p", "", distance=0.0, frequency=5e9)
# ValueError: distance must be positive (got 0.0)

linkbudget.Mixer("m", "", mode="mix")
# ValueError: mode must be one of ('downconvert', 'upconvert') (got 'mix')

linkbudget.SubBandTune(signal_lower_freq=5e6, signal_upper_freq=2e6)
# ValueError: signal band is empty: signal_upper_freq (2000000.0) must be
#             greater than signal_lower_freq (5000000.0)

What is checked: positive distances / frequencies / bandwidths / bit depths / antenna diameters / integration times; physical temperatures above zero; aperture efficiency in (0, 1]; elevation angle in (0, 90]; role is None / "tx" / "rx"; mixer.mode is a known value; SubBandTune band edges are non-negative and ordered; ArrayFactor.num_elements >= 1.

Where a band mismatch is physically meaningful rather than an error — a SubBandTune whose output band does not overlap the signal band — the signal is clamped to zero (fully filtered out) instead of going negative.

Budget checks¶

After compute(), the budget is scanned for configurations that are syntactically fine but physically dubious. Get the findings explicitly:

for message in budget.check():
    print(message)

check() returns a list of strings (empty means nothing looked wrong). The same messages are emitted as LinkBudgetWarning from compute() (and therefore from publish() and summary()) unless the container is built with warn=False:

budget = linkbudget.LinkContainer(warn=False)   # silence the warnings

What is flagged:

Check	Why it matters
Final signal power is zero	no `SignalSource`, or the signal is fully attenuated
A stage produced negative signal or noise power	always a bug or bad input
More than one `ThermalNoise` (or more than one `AntennaNoiseTemperature`) stage	that noise floor is being double-counted
A negative `total_loss_db` / `conversion_loss_db`	a "loss" that is really a gain — usually a sign error
A path stage's `frequency` differs from the container's `carrier_frequency`	a mismatched frequency (checks stop at the first `Mixer`, which legitimately moves the carrier)

The scan is a helper, not a guarantee — check_budget(data_list) in linkbudget.checks is a plain function you can call on any computed data_list.