Error Due To Floating Representation; Es/N0 Estimators In Dvb-S2 And Sccc Environment; Warning; Standard Es/N0 Estimation - Safran CORTEX Series User Manual

3.3.10.9.2

Error Due to Floating Representation

The floating representation may generate an error in Ts  Ts2
case of 0.1 s programming), which could have generated an error on Doppler estimation of
 
 Ts 

.
t f 2 23
2
But this floating representation is converted into double, owing to rounding processing, so that this error
is not added to the previous one (provided that the programmed sampling period does not have more
than 5 digits in its fractional part).
3.3.11

Es/N0 estimators in DVB-S2 and SCCC environment

3.3.11.1

Warning

The HDR unit has been designed for optimal demodulation and decoding of IF signals. As such, it also
provides some estimates of typical useful parameters such as Es/N0, IF Level and so on. However
these estimates are not intended to compete with dedicated constellation analysers in terms of
accuracy and precision.
3.3.11.2

Standard Es/N0 estimation

Let's consider a QPSK modulation.
The standard method for Es/N0 estimation is to compute on the constellation the following values:

Mean Radius of the constellation. The square of this value leads to Es

Variance of the I/Q vector. This leads to N0.
This simple method can be applied in a similar way to multilevel modulations such as 16APSK and
32APSK.
This method is simple, but is biased at low SNRs (or Es/N0), when I/Q points easily cross the decision
regions, especially in high density modulation where those regions are very small. Below is a typical
example of this effect in different modulation schemes.
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HDR-4G+ USER'S MANUAL

Figure 34: Typical Es/N0 estimation over the constellation

It cannot be duplicated or distributed without expressed written consent.
Ref. DTU 100782
Is.Rev
Date:
-23
(for example, 0.1 + 1.4910
Safran Data Systems
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June 1, 2021
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