[Discuss-gnuradio] a few queries related to ofdm implementation

[sheshanandan k narayanan]

Hi,
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.
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