Standardized DVB-T2 RF specifications - DigitalEurope

5- MAXIMUM RECEIVER INPUT LEVEL
The receiver should be able to handle DVB-T2 signals up to a level of -25 dBm while
providing the specified performance. Maximum level for ATV/DTV interfering signals is
-25dBm.
6- C/N PERFORMANCE CALCULATION METHOD FOR AWGN AND 0dB ECHO
The DVB-T2 implementation lines in the A133 Blue Book (ref.1) show two sets of simulations
in tables 44 and 47. The simulations in table 44 represent the absolute best possible
theoretical performance assuming a theoretical receiver that can perform “Genie Aided” demapping
(an infinite number of de-mapping iterations). Table 44 also assumes an infinite
number of LDPC iterations. Clearly neither of these two assumptions is valid for a real
receiver due to finite limits on clock rate and silicon area. In contrast table 47 shows
simulated performance for a receiver using a non-iterative de-mapper and 50 LDPC
iterations (see also section 10.5.5 of ref.1). Table 47 is used to calculate the required AWGN
C/N in this specification. However because table 47 does not include 0dB echo simulations
but table 44 does, both these sets of simulation results are used derive the required C/N
performance in 0dB echo channels as shown below.
6- 1- AWGN C/N calculation
C/N = (C/N)table_47 + A + Pboost+ IL + Dpx, where
(C/N)table_47 = AWGN C/N for post LDPC BER=10 -6 (table 47 of ref.1)
A = additional C/N required to reach post LDPC BER=10 -7 – around 0.1dB
Pboost= correction for pilot boosting (from table 46 of ref.1)
IL = loss due to real channel estimation, imperfect LDPC decoding and other
imperfections not considered part of the back-stop noise. This is derived from ref.1
and includes a small additional allowance for receiver synchronization, fixed point
losses etc. For the E-book specification IL varies with pilot pattern as follows 2.5dB
(PP1-PP2), 2.0dB (PP3-PP4), 1.5dB (PP5-PP7).
Dpx= additional C/N term corresponding to a back-stop noise level at -33 dBc. This
term is derived by first calculating the sum of all terms except Dpx and then checking
how much C/N degradation is caused by the -33 dBc backstop noise level. The term
Dpx is identical to this degradation.
6- 2- 0dB echo C/N calculation
C/N0db = (C/N)table_47 +[END of 0dB echo channel] + A + Pboost+ IL+IL(CR) + Dpx
= (C/N)table_47 +[(C/N)0dB_table_44 – (C/N)AWGN_table_44] + A + Pboost+ IL+IL(CR) + Dpx, where
(C/N)table_47, A, Pboost, IL and Dpx as defined above for the AWGN C/N calculation
END = effective noise degradation (difference between 0dB echo and AWGN C/N)
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