Digital Signal Processing Reference
In-Depth Information
21.3.1 Additive White Gaussian Noise (AWGN)
White noise (AWGN, Additive White Gaussian Noise) leads to cloud-
shaped constellation points. The larger the constellation point, the greater
the noise effect. The signal/noise parameter S/N can be determined by ana-
lyzing the distribution function (normal Gaussian distribution) in the deci-
sion field. The RMS value of the noise component corresponds to the stan-
dard deviation. Noise effects affect every DVB-T subcarrier and can also
be found on every subcarrier. The effects and measuring methods are
completely identical with the DVB-C methods.
Fig. 21.7.
Effect of phase jitter
21.3.2 Phase Jitter
Phase jitter leads to a striated distortion in the constellation diagram. It is
caused by the oscillators in the modulator and also affects every carrier
and can also be found on every carrier.
Here, too, the measuring methods and effects are completely identical.
with those in DVB-C.
21.3.3 Interference Sources
Interference sources affect individual carriers or carrier ranges. They can
be noise-like and the constellation points become noise clouds, but they
can also be sinusoidal when the constellation points appear as circles.
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