Calibrated first-order dynamic measurement
For a validated linear first-order sensor model τẏ+y=Kx with τ>0, a step to x_f gives y(t)=Kx_f+[y(0)−Kx_f]e^(−t/τ).
Key knowledge
For a validated linear first-order sensor model τẏ+y=Kx with τ>0, a step to x_f gives y(t)=Kx_f+[y(0)−Kx_f]e^(−t/τ). At angular frequency ω with the e^(iωt) convention, H(iω)=K/(1+iωτ), so amplitude attenuates by |K|/√(1+ω²τ²) and, for K>0, phase lags by arctan(ωτ). Calibration must establish K,τ and their applicable conditions rather than using the static gain at every frequency.
Values and equations
τẏ+y=Kx; H(iω)=K/(1+iωτ); X=(1+iωτ)Y/K
- x,X
- Input signal and sinusoidal phasor; measurand unit
- y,Y
- Output signal and phasor; indication unit
- K
- Calibrated static sensitivity; output unit/input unit
- τ,t
- Positive time constant and time s
- ω
- Angular frequency rad s⁻¹
- H
- Complex response; output unit/input unit
- i
- Imaginary unit
Conditions and scope
- Bounded operating range with a validated linear time-invariant first-order response, stated initial condition and stable positive time constant; static offsets are corrected separately. A real sensor with delays, resonances, hysteresis or changing medium need not satisfy this model.
- For a monochromatic component the inverse is X=(1+iωτ)Y/K where K≠0; this amplifies output noise at high frequency. Propagate joint uncertainty of Re/Im Y,K,τ,ω and model residuals, for example by the vector Jacobian where locally valid. Ideal broadband inversion is not a guaranteed noise-stable reconstruction.
Sources · 3
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- Embedded systems: dynamic transducer specificationsJonathan W. Valvano / University of Texas at AustinTextbook chapter
- Introduction to control: continuous-time transfer functionsMIT 6.310 Introduction to Control (Spring 2023)Course notes
- JCGM 102:2011: extension to multiple output quantitiesJoint Committee for Guides in Metrology / BIPMReference guide · PDF
Evidence and review
Embedded systems: dynamic transducer specifications: §2.2.2: actual first-order temperature-transducer step y=y_f+(y₀−y_f)e^(−t/τ), experimental-environment dependence and sinusoidal magnitude/phase definitions. Introduction to control: continuous-time transfer functions: Continuous-time first-order example dy/dt=−y+1000x and H(s)=1000/(s+1), then step and frequency response; generalize to τẏ+y=Kx by coefficient scaling. Inverse response and noise factor follow algebra; the unrelated printed pole −0.800 for s+0.1 is not used. JCGM 102:2011: extension to multiple output quantities: §6.2.1–§6.2.2: real-vector covariance and complex measurement outputs represented by their real/imaginary components; dynamic response-parameter covariance is an explicitly described application, not a certificate supplied by the source.
2026-10-10 · Independent AI editorial review: Independent root AI editorial review of all29 authored Measurement claims/conditions, displayed equations and37 origin relations. The original26 claims were read against41 primary source sections; all5 requested corrections and the3 affected source bindings were subsequently rechecked. Three actual scalar-nonlinear/vector/dynamic applications were read, independently differentiated or integrated, and checked against the specific additional source material described below. This is reference-content review, not human specialist certification, instrument certification or experimental replication. Full-field sign-off waits for the combined final conceptual matrix. Receipt: measurement-independent-content-review.1.
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