UNDERSTANDING DIGITAL TV - Ro.Ve.R. Laboratories S.p.A.

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MODULATION PARAMETERS AND LIMIT VALUES Net bit rate (Mbit/s) FEC G.I. Most used in Italy 44 Showing relation between: transport capacity with various Modulations, F.E.C. and Guard Interval
The diagram clearly shows the transport capacity of the DVB-T transmission system, with various modulation layouts (constellations). They range from a capacity of about 7 Mbit / second to a capacity of about 35 Mbits / second, which means being able to transmit from 1 to 4 or 5 programs, some in high definition. As you can see what you get in transmission capacity, you pay in terms of signal robustness and vice versa.. If you want to manage an SFN network, you need to dedicate part of the capacity to the guard interval and FEC, as shown by the length of the histograms. The system chosen is shown, which combines a good ability to correct errors, given the high FEC, and a good Bit Rate capacity; this is accomplished by using 64 QAM modulation, which needs an adequate margin of MER and BER, as we shall see next. 45
Page 1 and 2: UNDERSTANDING DIGITAL TV • Radio
Page 3 and 4: SUMMARY 6 Radio frequency spectrum
Page 5 and 6: The difference between the two sign
Page 7 and 8: The function that allows you to fin
Page 9 and 10: The power of the digital signal is
Page 11 and 12: The modulation is the same type for
Page 13 and 14: We know that signals can be “poll
Page 15 and 16: The DVB-T signal has this behavious
Page 17 and 18: Here you can see a schematic block
Page 19 and 20: When it is said that a DVB-T system
Page 21 and 22: Let us assume that the electromagne
Page 23 and 24: We will illustrate a laborious, but
Page 25 and 26: This chart is useful, even if it do
Page 27 and 28: Another situation where the antenna
Page 29 and 30: The back to front antenna ratio is
Page 31 and 32: The reflections caused by a mismatc
Page 33 and 34: Since the system is immune to refle
Page 35 and 36: Operation is based on being able to
Page 37 and 38: Nearly every instrument has an SFN
Page 39 and 40: Here are a number of rules to impro
Page 41 and 42: This picture shows an example of an
Page 43: As an example, we have superimposed
Page 47 and 48: To obtain minimum reception stabili
Page 49 and 50: These predictions are verified when
Page 51 and 52: The electromagnetic field is measur
Page 53 and 54: Even if the MER is a good indicator
Page 55 and 56: The diagram shows once again the th
Page 57 and 58: This table is calculated for system
Page 59 and 60: Micro-interruptions are not always
Page 61 and 62: So ripple (waves) in the spectrum p
Page 63 and 64: In Figure 3 and 4 you can see the s
Page 65 and 66: Figure 5 shows DVB-T signal ch.8 th
Page 67 and 68: Using this case study you can see h
Page 69 and 70: Directive 2004/108/EC requires that
Page 71 and 72: The diagram shows the real case of
Page 73 and 74: MPEG4 REAL TIME SPECTRUM 6-HOUR BA
Page 75 and 76: mod. HD COMPACT STC THE MOST ADVANC

UNDERSTANDING DIGITAL TV - Ro.Ve.R. Laboratories S.p.A.

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