**5.3.1 Effect of the small component**

The harmonic components are smaller in practical non-sinusoidal signals. The uncertainty estimation at full range in Table 5.2.1 cannot be directly applied to smaller amplitudes. A general method for non-linear amplitudes can be employed, where the ratio of (*Vk* /*V*1 ) is replaced by [0.8(*Vk*/*V*1)+0.2], in which a minimum value of 0.2 (or 20%) is maintained even if *Vk* = 0. The ratio 0.8:0.2 (or 80%:20%) is taken from the experimental results. Eq. (4.1.4) then becomes

$$
\mu(\Delta V\_k/V\_1) = \begin{bmatrix} 0.8(V\_k/V\_{1\parallel}) \ \text{+0.2} \end{bmatrix} \times \mu(\Delta V\_k/V\_k) \,. \tag{5.3.1}
$$
