User's Manual

ISO 9001:2000 Cert. N°4500/1
Version 1.1 SDT_ARK6_User_Manual_ENG_vATSC Page 71 of 206
5.9.1.1 Adaptive Filter
The Adaptive Filter provides the ARK6 with an effective adaptive linear compensation.
The developed system is responsible for pre-emptively compensating a DVB-T/T2 signal in order to make
unimportant the contribution of the system transmission section. The signal passes through the
transmission section and re-enters the system as to determine the distortion and the compensating
adaptive filter.
The system is composed of two main blocks: a Power Calculation block and a 128-tap Complex FIR. The
modulated signal, with IQ format and sampled at c frequency, enters both blocks:
Power Calculation block is responsible for estimating the mean power level that will be restored at both
transmitting and receiving sides;
128-tap Complex FIR is responsible for linearly pre-correcting the modulated signal. Filter coefficients
are obtained by estimating the channel between the signal before the transmission section and the
signal reentering the system, after the channel distortion and the A/D conversion.
Figure 31. Adaptive Filter