[Discuss-gnuradio] Timing/preamble trigger output from the OFDM receiver

[tianji]

Hi there,

I am logging the output 1 of the ofdm_sync block (i.e., the timing 
triggers after the timing synchronization) and the output 1 of the 
ofdm_frame_aq block (i.e., the preamble triggers after both fine and 
coarse frequency synchronization). I saw varied gaps between adjacent 
values in these two streams.

For example, using the default OFDM sender/receiver parameters (pkt 
size=90 bytes),  in one run, I got gaps in the former stream like these: 
3200    3199    3200    3200    3200    3199    3200    3199    3202   
 3198    3201    3197    3200    3202    3200............ The gaps in 
the latter stream like these: 1000    1000    1000    1000    1000    
1000    1000    1000    1200    1000    1000    1000    1000    1200    
1000    1200......

I wonder why the gaps are not the same.

Note that I modified the latter stream so that it contains zeros and 
ones for each 'occupied bin' rather than each 'OFDM symbol'.

Thanks
Tianji