Hi

Looking at the ofdm receiver at ofdm_rx grc, I see that schmidl and cox

synchronisation algorithm uses sync1 and sync2 which are two ofdm

training

symbols that help in frequency offset correction and also timing

estimate

to detect the start of the packet.

Then there is channel estimator block in grc that again uses preamble

ofdm

symbol to detect coarse frequency offset. In the entire implementation

I

haven’t seen the use of pilot symbols in each ofdm symbol for either

channel estimation or synchronisation. So does that mean that if you are

using a packet structure with a preamble there is no need of pilots for

any

receiver processing.

I get this doubt because benchmark_rx.py which uses ofdm gives you a

terminal option saying occupied tones which can be set by user at

terminal.

So if you can set or increase occupied tones to any number less than fft

length, then that means you can be flexible with increasing or

decreasing

pilot symbols to a value that you want. Am I right?