Millivolts and millivolts per volt describe different quantities. In a UG35 sensor-integration proposal, identify whether the acquisition chain reports bridge output voltage, a ratio to excitation, or a converted engineering value. Request a traceable example that preserves the units and scaling responsibility. Do not assume the aircraft includes a bridge interface or a particular measurement module merely because the proposed sensor uses this terminology.

Begin with the exported column

A buyer receives two sensor proposals. One describes an output in millivolts; the other presents millivolts per volt. Copying both figures into a single voltage column creates a comparison that the documents do not support. Before discussing resolution, range or price, ask each supplier to name the quantity at the point where the purchaser will receive the data. That point may be different from the sensor's electrical output.

This article is a ground-level procurement review, not an instruction to connect or energize hardware. Its purpose is to help an integrator specify evidence and responsibility. Wiring, excitation, calibration and installation must follow the applicable equipment documentation and qualified review. A correct explanation of units does not establish electrical compatibility, aircraft integration approval or fitness for a particular measurement task.

The documented distinction

NI's Bridge Sensor Scaling manual, updated July 30, 2026 and checked October 27, describes bridge measurements as a ratio of measured output to excitation. It distinguishes hardware ratiometric division from voltage measurement and describes offset and gain terms in its scaling expression. Conversion into physical units depends on the bridge configuration or relevant sensor scaling.

The documentation supports the distinction between stages in a measurement chain. It is not evidence that UG35 contains NI hardware, supports a particular bridge sensor, or provides a given calibrated result. Keep the documentation's general explanation separate from the proposed bill of materials. Ask the supplier to identify the actual equipment and the documents that establish its specific capabilities and limitations.

A hypothetical ratio, not a product specification

For a deliberately simplified arithmetic example, suppose a bridge output is 6 millivolts and the associated excitation is 3 volts. The ratio is 2 millivolts per volt. If another illustrative condition produces 12 millivolts with 6 volts excitation, the same arithmetic ratio results. These numbers are invented solely to explain the units; they are not settings, operating limits, calibration results or specifications for any offered product.

The example leaves many real measurement questions unanswered. It does not say whether the excitation was measured at the relevant point, whether an offset was removed, or whether a physical-unit conversion is valid. Its procurement value is narrower: a reviewer can see why comparing the two output voltages without their denominators could answer the wrong question. The actual proposal must provide its own evidence.

Draw the evidence chain in four boxes

Ask the supplier to show four stages: the sensor's declared output quantity, the acquisition quantity, any normalization or correction, and the delivered engineering value. For each stage, request units, the responsible component or software step, and the supporting document. A compact diagram is enough if it is precise. A marketing label such as complete measurement solution is not a substitute for identifying where the conversion occurs.

Keep configured and observed quantities distinct. A nominal excitation setting and an actual reference used for scaling are not interchangeable descriptions of evidence. The supplier should explain which one the proposed implementation uses and under what documented conditions. The buyer should not fill that gap by assuming every device follows the same approach as an example in another manufacturer's manual.

Agree what the handover must preserve

Decide whether the purchaser needs only final engineering values or also intermediate evidence for review. Retaining intermediate fields can improve traceability, but it can also increase storage, documentation and support obligations. Do not ask for every possible field without explaining its intended use. Identify the disputed decisions the receiver may need to revisit and request enough information to investigate those decisions responsibly.

A data dictionary should state the units, scale, missing-value convention and meaning of each requested field. If a supplier exports a ratio as volts per volt while the receiving template expects millivolts per volt, the conversion needs an explicit owner. Review the actual file in the receiving workflow. A correct label in a presentation does not prove that the export uses the same convention.

Review one row from end to end

Our practical field lesson is to trace one exported row before debating a long specification table. Ask the integrator to explain the source quantity, reference, conversion and final units using the proposed documentation. The reviewer should be able to distinguish what was measured from what was calculated, configured or assumed. Record any missing step as an open question rather than repairing it with an undocumented spreadsheet formula.

This is an editorial acceptance exercise, not a claimed customer result or calibration method. Use a controlled, supplier-approved example and require an expected explanation. The receiving team should not improvise electrical experiments on an aircraft to answer a documentation question. Where a real measurement demonstration is necessary, its equipment, limits, competence requirements and responsibility need to be agreed separately.

Avoid hidden double scaling

Imagine a fictional handover in which the acquisition software has already produced a normalized ratio, but a receiving worksheet treats that field as raw voltage and applies another normalization. The file may still contain plausible-looking numbers. Our recommendation is to make every transformation visible and assign one owner to the final receiving calculation. A clean chain of responsibility is easier to audit than several undocumented corrections layered together.

The opposite purchasing risk is assuming a conversion has occurred when the supplier only promised an unscaled output. Resolve that distinction in the scope of supply. State which party provides the conversion, maintains the coefficients, approves revisions and explains exceptions. If the processing service is excluded from the price, record it as an explicit exclusion rather than letting the receiver discover the omission during commissioning.

Time and identity remain separate checks

A correct ratio does not tell the buyer which observation it belongs with. When several streams are combined, the UIV2200 timestamp-matching guide asks for the direction, tolerance and source-row identity behind each match. Keep that evidence separate from the units review. Neither a neat table nor a consistent unit label establishes that the right records were paired.

Physical delivery also needs a traceable identity chain. The UG82 packing-list and invoice review describes connecting commercial lines with received packages. The same procurement habit is useful here: the module named in an engineering explanation must be reconciled with the actual proposed and delivered item. A substitute component should reopen the affected review instead of inheriting approval from a similar name.

Put the actual UG35 configuration in writing

The approved UG35 product page provides the model identity for a payload discussion. It does not establish the presence of the hypothetical sensor, acquisition unit, excitation source or analysis software discussed here. Request an identified proposed configuration and a clear boundary between supplied equipment, integration work and customer responsibilities. For unconfirmed specifications, contact us for configuration details.

US and Irish integrators can use these questions in their purchasing process without treating the same evidence as approval for every installation. Define the measurement objective, environment and receiving system before asking the supplier to recommend an interface. Leave unsupported compatibility claims unresolved. The right next step may be a documentation review or a separately scoped feasibility study rather than an immediate equipment commitment.

Three useful questions at quotation review

Does a ratio remove every measurement error?

No such conclusion follows from the unit. Ask which effects the proposed implementation addresses and which remain in the measurement uncertainty and suitability assessment. Do not turn a general technique into a guarantee about an unspecified system.

Can a numeric range be compared before the units are resolved?

Only after the quantity and interpretation are clear. Keep unlike quantities in separate columns until a responsible reviewer has established a valid comparison and documented any conversion needed.

What should the supplier demonstrate first?

Start with a traceable documented example, including the exported field. It should expose the denominator and scaling owner without asking the buyer to infer them from an abbreviated label. Preserve the reviewed document revision and reviewer identity beside the final purchasing decision.

Request a quantity-aware proposal

Use the VTOL and fixed-wing collection to frame the aircraft discussion, then send your sensor documents and receiving data requirements through the UNITED UAV inquiry page. Ask for a UG35 configuration review that identifies what each number means and who is responsible for converting it. That is a more useful starting point than comparing unexplained values under a shared voltage heading.