DD ISO/TS 13473-4:2008

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Basic outline of methodologies of spatial frequency
   analysis
5 Sampling of surface profiles
   5.1 Sampling of road sections
   5.2 Measurement of laboratory samples
6 General principles and requirements
   6.1 Requirements concerning profilometers
   6.2 Conversion of spatial frequencies to temporal frequencies
   6.3 Drop-outs
   6.4 Anti-aliasing filtering
   6.5 Digital sampling
7 Spectral analysis in constant-percentage bandwidth bands
   (octave- or one-third-octave bands) by analogue filtering
   (Method 1)
8 Spectral analysis in constant-percentage bandwidth bands
   (octave- or one-third-octave bands) by digital filtering
   (Method 2)
9 Spectral analysis in narrow constant bandwidth bands by means
   of Discrete (Fast) Fourier Transform methods (Method 3)
   9.1 Overview of methodology
   9.2 Slope and offset suppression
   9.3 Windowing
   9.4 Discrete Fourier Transform and Power Spectral Density
   9.5 Wavelength resolution
10 Transformation of constant bandwidth spectral data to
   constant-percentage bandwidth spectral data
11 Uncertainty of analysis results
12 Reporting of analysis results
Annex A (normative) Uncertainty of spectral analysis results
Annex B (informative) Aliasing
Annex C (informative) Estimation of the deviation in energy
        within a frequency band caused by variations in speed
Annex D (informative) Compensation for speed variations during
        processing of the measured data
Annex E (informative) Explanation of the relation between the
        wavelength resolution and the spatial frequency resolution
Annex F (informative) Spectral analysis and profile asymmetry
Bibliography

Specifies the methods that are available to perform a spectral analysis of pavement surface profile signals.

This Technical Specification describes the methods that are available to perform a spectral analysis of pavement surface profile signals. It specifies three possible methods for spatial frequency analysis (or texture wavelength analysis) of two-dimensional surface profiles that describe the pavement roughness amplitude as a function of the distance along a straight or curved trajectory over the pavement. The result of the frequency analysis will be a spatial frequency (or texture wavelength) spectrum in constant-percentage bandwidth bands of octave or one-third-octave bandwidth. This Technical Specification offers three alternative methods to obtain these spectra: analogue constant-percentage bandwidth filtering; digital constant-percentage bandwidth filtering; constant narrow bandwidth frequency analysis by means of Discrete Fourier Transform, followed by a transformation of the narrow-band spectrum to an octave- or one-third-octave-band spectrum. The objective of this Technical Specification is to standardize the spectral characterization of pavement surface profiles. This objective is pursued by providing a detailed description of the analysis methods and related requirements for those who are involved in pavement characterization, but are not familiar with general principles of frequency analysis of random signals. These methods and requirements are generally applicable to all types of random signals, but are elaborated in this Technical Specification in a specific description aimed at their use for pavement surface profile signals. NOTE The user of this Technical Specification should be aware that spectral analysis as specified in this document cannot express all characteristics of the surface profile under study. In particular, the effects of asymmetry of the profile, e.g. the difference of certain functional qualities for “positive” and “negative” profiles cannot be expressed by the power spectral density, as it disregards any asymmetry of the signal. (See AnnexF.)