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3D Time-of-flight distance measurement with custom - Universität ...

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OPTICAL TOF RANGE MEASUREMENT 39<br />

input signal<br />

short-time<br />

integration<br />

ideal sampling<br />

DFT-amplitude spectrum<br />

<strong>of</strong> naturally sampled signal<br />

Amplitude spectrum Phase spectrum<br />

S()<br />

f<br />

0.5<br />

⎛<br />

⎜<br />

f<br />

sinc 2π<br />

⋅<br />

⎝ 4f0<br />

()<br />

f<br />

S int<br />

0 f0<br />

0 f 3<br />

0.5<br />

⎛ 1⎞<br />

⎜ ⎟<br />

⎝ π ⎠<br />

0 f0<br />

0 f 3<br />

S ()<br />

int, samp f<br />

0<br />

⎞<br />

⎟<br />

⎠<br />

⎛ 1 ⎞<br />

⎜ ⎟<br />

⎝ 3π<br />

⎠<br />

0<br />

f<br />

()<br />

f<br />

F samp<br />

1<br />

f<br />

0.5<br />

1<br />

f0 0 f 2 0 f 4 0 f 6<br />

0<br />

aliasing<br />

ϕ()<br />

f<br />

ϕ0<br />

3ϕ0<br />

ϕ0<br />

f0<br />

3 f0<br />

4f0 0 f 8 0 f 12 f<br />

f<br />

()<br />

ϕint<br />

f<br />

π<br />

π − 3ϕ0<br />

f 3<br />

f0 0<br />

3ϕ0<br />

− π<br />

− π<br />

4f0 0 f 8 0 f 12 f<br />

Figure 2.12 Aliasing for s( t)<br />

= cos(<br />

ω0t<br />

− ϕ0<br />

) + cos(<br />

3ω0t<br />

− 3ϕ0<br />

) sampled <strong>with</strong> only<br />

four sampling points. Influence on amplitude and phase spectrum.<br />

f<br />

f

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