avoiding loop in frequency coupling

Hello,

I want to implement a frequency coupler using GNU radio. Coupling is a
bi-directional repeater. Whatever is heard on frequency A is repeated on
the frequency B one and vice-versa. There are three states of possible:
no signal (squelched) on both frequencies, repeating A on B and
repeating B on A. Whatever comes first (ie. opens squelch), wins until
it's signal is gone.

GNU radio with standard blocks prohibits this setup, as it (quite
correctly) detects loop in the data flow. In other words: I need GNU
radio to decide it's behaviour based on previous state, not only current
data.

As I understand GNU Radio logic, even if I write a custom
"state-controller" block, it will fail loop detection: it's output would
still have some path to the input.


Is there any way to circumvent this? Like changing a variable from
inside a block?


--
73!
Wojtek SP9WPN