Hi SunnySkyguy,
Many thanks for your helpful information. I am measuring the group delay between the TX and RX inputs and it is fixed to 40 ( filter span in symbols*oversampling factor) regardless the use of preamble.
Am I measuring the delay in the right position? I would appreciate if you could give some more information about this issue, for example: How does the preamble length changes the delay of the system? I could not find any information about it on the literature.
Many thanks,
Rodolfo