Insertion loss

Comparison quantity

Record the before-and-after observable and the authority defining it. The ASA terminology database includes a delivered-power definition based on power reaching the downstream system before and after insertion. [ASA terminology database](https://asastandards.org/working-groups-home/working-groups-portal/asa-standard-term-database/)

1. Which technical field and authoritative definition govern this insertion-loss claim? definition
2. What observable is compared before and after insertion, and at which receiving boundary? measurement

Reported loss convention

Record the numerator, denominator, logarithmic multiplier and sign; require the relevant assumptions before converting power, amplitude or transmission-parameter data.

1. What exact formula produces the reported dB value, and does positive mean reduced transmission? definition
2. If amplitude data or S-parameters are used, what impedance, normalisation and reference assumptions justify the conversion? measurement

Reference equivalence

Describe the baseline connection, bypass or removed-element configuration and any unavoidable difference between reference and inserted measurements.

1. What physically or mathematically replaces the inserted element in the baseline? definition
2. Which source, receiver and path conditions remain equivalent across the two configurations? boundary

Interfaces and fixtures

Record whether connectors, adapters, mounting structures, fixtures and coupling interfaces contribute to the result or have been removed by correction.

1. Where are the reference planes or acoustic observation boundaries, and which interfaces lie between them? boundary
2. Which fixture or interface contributions were removed, and what evidence supports those corrections? provenance

Band and aggregation

Preserve measurement coordinates, resolution and any averaging or weighting used to compress a spectrum into a reported value.

1. At which frequencies, wavelengths or bands was insertion loss measured, and with what resolution? measurement
2. Is the stated value a point, maximum, average or weighted band result, and how was it calculated? definition

Applicable operating envelope

Record domain-relevant conditions such as terminations, optical launch and polarisation, acoustic geometry, signal level and environmental state.

1. Which source, load, launch, mode, polarisation or geometric conditions define this result? measurement
2. Over which signal levels, directions and environmental states has the reported loss been established? boundary

Traceable observations

Preserve original observations, instrument configuration and calibration evidence. Keysight documents S21 and S12 as forward and reverse transmission measurements associated with insertion loss. [Keysight measurement parameters](https://helpfiles.keysight.com/csg/e5055a/S1_Settings/Measurement_Parameters.htm)

1. Which raw readings, traces or files support the reference and inserted-state values? provenance
2. Which calibration, normalisation and processing steps connect those observations to the reported loss? measurement

Result confidence

Assess drift, reconnection variability, background or noise limits and uncertainty shared between the reference and inserted observations.

1. What uncertainty budget covers both configurations, including correlated errors and repeatability? measurement
2. Do dynamic range, background level or drift require reporting a bound or an unresolved result? boundary

Loss attribution

Require additional evidence before attributing insertion loss to dissipation, reflection, leakage or mode redistribution; investigate unexpected signs against the declared baseline.

1. Which additional reflection, absorption or modal measurements support the proposed explanation of the loss? provenance
2. If the result is negative or unexpectedly small, do reference conditions, changed coupling, active gain or measurement uncertainty explain it? action

Permitted use

Record the intended transmission outcome, applicable limit and comparability requirements before ranking alternatives or combining component losses.

1. Does the application require a maximum or minimum insertion loss, across which band and under what uncertainty decision rule? action
2. Are references and operating conditions compatible enough to compare these results or add their dB values in a cascade? boundary

Check these first

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these check these first hold for the sense of Insertion loss this model covers, and on what evidence? provenance

Kinds and varieties

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these kinds and varieties hold for the sense of Insertion loss this model covers, and on what evidence? provenance

Standards and regulation

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these standards and regulation hold for the sense of Insertion loss this model covers, and on what evidence? provenance

Real-world use

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these real-world use hold for the sense of Insertion loss this model covers, and on what evidence? provenance

Typical measurements

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these typical measurements hold for the sense of Insertion loss this model covers, and on what evidence? provenance

Failure modes and hazards

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these failure modes and hazards hold for the sense of Insertion loss this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of Insertion loss this model covers, and on what evidence? provenance