[Discuss-gnuradio] Channel Model Block; 'epsilon'

[Uzair Baig]

I am confused about the channel model block:

It needs the following parameters:

Creates a channel model that includes:
          - AWGN noise power in terms of noise voltage

          - A frequency offest in the channel in ratio
          - A timing offset ratio to model clock difference (epsilon)
          - Multipath taps

The 'epsilon' in particular is confusing. I have referred, it represents the inverse of the fractional interpolation ration. Now, firstly I need to know, 

whether this parameter will cause delay between the Tx and Rx path ? I have tried working my way with the frac_interp_ff block and recognize, that
it doesn't return the same number of samples to me? For a value of 1, the number of samples input are more than the number of samples output! 

Doesnt the interpolation mean an increase in the number of samples?

Secondly, I have connected this channel model to polyphase filter banks for clock recovery. I don't get a correct output if I increase epsilon? And 

another thing, can you please share as to what does each parameter filter bank imply? ( I have read the documentation, but, cannot make much sense of it).

Regards, 

UB