[Discuss-gnuradio] queries on ofdm implementation

[Sheshanandan KN]

Hi all,
I am using the trunk repository with revision no. 11025. I am
presently experimenting on ofdm. The given code is working fine on the
USRP setup. Here we specify the center frequency at which the ofdm
signal is going to be transmitted. I have a few questions on this:
1) Is this the center frequency of the sub-carrier of a particular
channel? If so, what is the bandwidth used?
2) If not, how the sub-carrier is differentiated from the channel? How
many sub-carriers are supported?
3) Is it possible to switch to a different frequency at runtime?
4) The modulation parameter is the modulation technique defined for a
particular sub-carrier, right? If so, can we also define a different
modulation technique to be used at runtime once we switch to a
different frequency?
5) The preamble defined for the packets - are they standardized? I
mean to say, any ofdm packet will be having the same preamble?
6) Why the interpolation/decimation values need to be specified for
this experiment alone? This is not the case for other examples given
in 'gnuradio-examples' folder.

Please help me figure out the answers for these. It will help in
proper understanding of ofdm implemented on gnuradio.

Shesh