Hello, this is my reply:
The edge carriers at the upper and lower channel edge are set to zero, they are inactive and carry no modulation at all, their amplitudes are zero. The continual pilots are located on the real axis, the I (in-phase) axis, either at 0 degrees or at 180 degrees and have a defined amplitude. The continual pilots are boosted by 3 dB compared with the average signal power and are used in the receiver as phase reference and for automatic frequency control (AFC), for locking the receive frequency to the transmit frequency.
There are two basic reasons for the existence of unused zero-information carriers:
• Preventing adjacent channel crosstalk by facilitating the filtering of the shoulders of the COFDM spectrum.
• Adapting the bit capacity per symbol to the input data structure.
Because IFFT is used, however, it is necessary to select a power of two as the number of carriers which, after subtracting all data and pilot carriers, still leaves carriers, namely the zero-information carriers.
I dont know if your number of zero-carriers is correct. But take account of this: The various types of carriers used in DVB-T are briefly summarized as follows. Of the 2048 carriers in the 2K mode, only 1705 carriers are used and all others are set to zero. Within these 1705 carriers there are 1512 payload carriers which can be QPSK, 16QAM or 64QAM modulated, 142 scattered pilots, 45 continual pilots and 17 TPS carriers.
Perhaps scattered pilots and TPS carriers aren't necessary for your project. Only fixed continual pilots.
I also attach a figure of the physical layer frame for the DVB-S2, in which you'll see that the pilot block is periodically put into the FEC (Forward Error Correction) frame.
Regards.