Proper way to implement flowgraph programming

[Lukas Haase]

Hello,

I have a conceptual question which has not reasonably well answered by studying 
the tutorials. I work with GRC for some time now but I find it impossible to 
implement simple things that require basic control logic. Clearly these things 
are trivial to implement with a prcedual language (MATLAB). While I am not a 
friend of LabView, it still supports these things with Loop elements, push 
buttons etc.

Examples:

1.) Frequency hopping with USRP: I want to receive a signal, do some processing 
and extract the phase angle from the I/Q samples. This should happen at 
multiple (say, 10) different carrier frequencies. The resulting 10 phase angles 
should be combined to form another signal (possibly packetized) for further 
processing. What is the proper way to implement this "loop"?

2.) Calibrations: Things like phase rotation etc should be obtained, stored in 
a variable and re-used when my GRC program runs in non-calibration mode. In my 
example above, I would like to obtain the phases from the ten carriers at 
startup. When the program runs in normal mode, these phases should be 
subtracted (to calibrate constant phase shift due to RX/TX/cables etc)

What is the proper way to achieve this?

Thanks,
Luke