Hi Sagnik, right now, you can't build loops out of stream connections. That has causality reasons – if you had such a loop, and the "merging" block at the start of the loop would need input on both channels, GNU Radio couldn't guarantee your flow graph could ever start¹.
If you can live with a loosely–coupled feedback loop, message passing would be an appropriate method: You can pass messages from any block to any block without any restrictions - but also, without backpressure. See chapter four or five of http://tutorials.gnuradio.org . (If you haven't already, read the tutorial from the start – I think it's rather nice!) Best regards, Marcus ¹ In fact, that restriction has historical reasons, and we know we could remove it in some cases, but we didn't, so far. I used to have an experimental branch where we didn't have that restriction, but then a lot of our not-directly-stream-connection-related stuff breaks; basically, a lot of algorithm in GNU Radio's internal data handling depend on the Flow Graph being cycle-free. On 22.02.2017 12:51, Sagnik Basu wrote: > I am using a GRC flowgraph for testing the energy detection algorithm > for cognitive radio.I want to update my threshold for probability > detection by estimating the SNR of the channel. > > However, for this, I need a feedback loop, which I want to know how to > implement. > > Regards, > Sagnik Basu > B. Tech | 2013-2017 > Dept. of Electronics and Communication > NIT Rourkela > M: 8337942928 > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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