Knowledge
Measurement, explained properly
Written for the engineer writing the specification. Straight answers to the questions that decide a sensor choice. No product pitch until the question is answered.
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Where do you want to start?
Three ways in, depending on whether you have a problem to solve, a technology to understand or a document to find.
19 problemsSolve a measurement problem
Start from what has to be measured and what is getting in the way. Each solution compares the approaches honestly, then sets out what to specify.
See the problems
24 questionsUnderstand the technology
How the measurement works, how it compares with the alternative, and how to specify it, each answered on its own page.
Browse the questions
Guides and documentsRead and download
Long-form guides, notes from real installations, case studies and range brochures to take away.
Find something to readSolve a measurement problem
Common problems and how to solve them
Start from the measurement problem rather than the product. Each solution compares the approaches honestly, including where another technology is the better choice, then sets out what to specify.
Wind and weather
Wind measurement without moving parts
Wind measurement without moving parts. How ultrasonic anemometers compare with cup and vane sensors, where each fits, and the Gill WindSonic, WindObserver, WindUltra and WindMaster ranges.
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Wind and weather
Wind on moving platforms
Wind measurement on moving platforms: vessels, USVs, buoys, vehicles and UAVs. Apparent and true wind, sensor placement and compact ultrasonic sensors such as WindUltra.
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Wind and weather
Wind measurement in icing conditions
Wind measurement in icing conditions. Heated ultrasonic wind sensors, WindObserver, WindSonic M and WindUltra, and the power, siting and specification decisions behind them.
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Wind and weather
Wind alarms and operating limits
Wind alarms and operating limits for cranes, construction sites, events and exposed operations. Ultrasonic wind sensors, gust measurement and wind displays feeding site alarm systems.
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Wind and weather
Turbulence and flux measurement
Turbulence and flux measurement with 3-axis ultrasonic anemometers. Research range R3 and HS at 50 or 100 Hz for eddy covariance, and WindMaster for general 3-axis wind.
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Wind and weather
Site weather monitoring
Automatic weather stations for site weather monitoring. Compact MaxiMet or separable MetConnect for wind, temperature, humidity, pressure, rain and solar.
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Wind and weather
Rainfall measurement without moving parts
Rainfall measurement without moving parts. TruMet PW100 is an optical rain gauge that replicates a tipping-bucket pulse output, 0 to 200 mm/hr at 5% accuracy.
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Wind and weather
Heat stress monitoring
Heat stress monitoring for outdoor and industrial work. MaxiMet GMX552 calculates WBGT (in accordance with ISO 7243:2017) and Thermal Work Limit onboard, continuously, at the work site.
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Wind and weather
Air quality monitoring
Wind and weather data for air quality monitoring. Pollutant readings need wind speed, direction and weather to explain where pollution came from and where it will go.
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Level, position and machine condition
Fuel, oil and coolant level sensing
Fuel, oil and coolant level sensing for vehicles, machines and motorsport. Capacitive level sensors with no moving parts, sealed electronics and analogue, RS232 or CAN outputs.
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Level, position and machine condition
Level sensing in difficult liquids
Level sensing in difficult liquids: foaming, viscous, contaminated or corrosive. Capacitive level sensors with no moving parts, including LevelSlick for challenging conductive liquids.
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Level, position and machine condition
Non-contact position sensing
Non-contact position sensing for linear and rotary movement. Blade inductive position sensors measure across a gap to a passive activator, IP67, sealed for temporary immersion (1 m for 30 min), with configurable range.
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Level, position and machine condition
Oil condition and wear debris monitoring
Condition monitoring that starts in the oil. WearDetect captures ferrous wear debris in real time, reporting fine and coarse debris, water presence and oil temperature.
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Level, position and machine condition
Gas engine ignition and air/fuel control
Gas engine ignition and air/fuel ratio control. GS8, GS12 and GT6 ignition modules and the AF120 closed-loop air/fuel ratio controller, IP67, with CAN communication.
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Integration, power and evidence
Sensor integration and outputs
Getting sensor data into your system. Gill sensors output Modbus RTU, SDI-12, NMEA 0183, RS232, RS422, RS485, CAN and analogue, depending on model.
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Integration, power and evidence
Marine and NMEA integration
Marine sensor integration for vessels and offshore. Wind, weather and tank level sensors with NMEA 0183, RS422 and Modbus outputs, Lloyd's Register approved WindObserver models and marine MaxiMet.
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Integration, power and evidence
Low-power remote monitoring
Low-power remote monitoring for solar, battery and telemetry sites. Ultrasonic wind sensors and weather stations with no moving parts and low supply current.
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Integration, power and evidence
OEM and custom sensors
OEM sensor integration and custom sensor development. Wind, level and position sensors embedded in customers' products, and engineering for requirements beyond the catalogue.
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Integration, power and evidence
Calibration and measurement traceability
Measurement traceability for Gill and non-Gill instruments. Labcal, a UKAS-accredited laboratory (Lab 0625, ISO/IEC 17025:2017), calibrates six measurement parameters.
Read the solutionUnderstand the technology
The questions that decide a sensor choice
24 questions, each answered on its own page: what the technology does, how it compares with the alternative, how to specify it, and how to prove the measurement afterwards.
What is an ultrasonic anemometer?
An ultrasonic anemometer measures wind speed and direction using sound pulses between fixed transducers, with no moving parts. How it works and where it is used.
Read the answerHow ultrasonic worksHow does an ultrasonic wind sensor work?
Ultrasonic wind sensors time sound pulses travelling between fixed transducers. The measurement principle, why it needs no calibration drift, and what affects it.
Read the answerHow ultrasonic worksWhat is the difference between true wind and apparent wind?
Apparent wind is what a moving platform measures. True wind is the atmospheric wind after platform motion is removed. Why the difference matters and what it needs.
Read the answerComparing technologiesUltrasonic anemometer vs cup anemometer
How ultrasonic and cup-and-vane anemometers differ in measurement principle, maintenance, response and whole-life cost, and when each still makes sense.
Read the answerComparing technologiesUltrasonic anemometer vs mechanical wind sensor
Mechanical wind sensors wear. Ultrasonic sensors have no moving parts. The wear mechanisms, what each costs over a deployment, and how to choose.
Read the answerComparing technologiesWhat is the difference between a weather station and a wind sensor?
A wind sensor measures wind. A weather station measures several parameters in one instrument. Which one an application needs, and where the two overlap.
Read the answerComparing technologiesOptical rain gauge vs tipping bucket rain gauge
Tipping buckets block, stick and under-read in heavy rain. Optical gauges have no moving parts. The comparison, the limits of each, and how to retrofit.
Read the answerSpecifyingWhat does full-range accuracy mean?
Six Gill wind products state accuracy across the full operating range rather than at a single reference speed, tested at accredited facilities and published in every datasheet. What that changes when you write a specification.
Read the answerSpecifyingHow accurate does a wind sensor need to be?
Accuracy is only half the question. Repeatability, long-term stability and the reference speed matter as much. How to write a wind specification that means something.
Read the answerSpecifyingWhat is the best wind sensor for harsh environments?
Salt, ice, vibration, dust and submersion each demand something different. How to match a wind sensor to what the site actually does to it.
Read the answerSpecifyingHow long should a professional wind sensor last?
Service life depends on technology, environment and maintenance. What wears, what does not, and how to work out the real cost of a deployment.
Read the answerSpecifyingWhat should I consider when choosing a weather station?
Parameters, siting, outputs and maintenance decide a weather station choice. A practical route from what you need to measure to a specific model.
Read the answerBy applicationWhat weather sensors are used at airports?
Airports measure wind, temperature, humidity, pressure, precipitation, runway state and visibility. What each is for, and why formal acceptance decides the wind sensor.
Read the answerBy applicationWhat weather sensors are used offshore?
Offshore platforms, wind farms, vessels and buoys measure wind, temperature, humidity, pressure and rainfall. What the environment demands and what certification decides.
Read the answerCalibrationHow are wind sensors calibrated?
Wind sensors are calibrated against traceable reference standards in a wind tunnel. What calibration proves, what UKAS accreditation adds, and what it does not do.
Read the answerCalibrationHow often should a weather station be calibrated?
Calibration intervals depend on application, environment and quality requirements. How to set an interval you can defend, and which sensors drift and which do not.
Read the answerLiquid levelHow does capacitive level sensing work?
Capacitive level sensors measure liquid level through the change in capacitance as liquid displaces air between two electrodes. The principle, the calibration and the limits.
Read the answerLiquid levelCapacitive vs float level sensors
Float sensors are cheap, mature and mechanical. Capacitive sensors are solid-state and continuous. What each does well, and where the whole-life cost lands.
Read the answerLiquid levelFuel level sensing for UAVs
Combustion-powered UAVs need fuel level accurate to the last drop, at the lowest possible weight. Why automotive sensors fail at it and what to specify instead.
Read the answerLiquid levelBlackwater and wastewater tank level sensing
Floats and ultrasonics struggle in sludge and blackwater. A smooth, hole-free coated probe does not foul, so the reading stays honest without regular cleaning.
Read the answerPositionHow does inductive position sensing work?
Inductive position sensors measure a metallic activator with a series of coils, in a three-step generate, respond and compare cycle. The principle and what it buys you.
Read the answerPositionInductive vs Hall effect position sensors
Both are non-contact. Hall effect needs a magnet and drifts with temperature. Inductive needs only a ferrous target. Four differences that decide the choice.
Read the answerMachineryWhat causes bearing failure in gearboxes?
Overload, misalignment, contamination and heat account for most of them. What each one does, the signature it leaves in the oil, and how early it can be caught.
Read the answerMachineryHow does a four-stroke engine work?
The four strokes, why one cycle takes two crankshaft revolutions, what ignition advance is, and why the timing reference comes from the camshaft.
Read the answerRead and download
Long-form material to take away
Long-form guide
Marine sensing: knowledge and FAQs
Thirty questions on choosing, siting, integrating and calibrating marine sensors, answered in one place.
Read the guide
Have an application to discuss?
Speak to our team
Tell us what you need to measure, where and under what conditions. We’ll help you work out the appropriate approach.