This answer may not help but I will offer it up. You can sleep (pause) the flow graph python script, change parameters such as frequency then run the flow graph again. Note, in my set up I dumped the first few samples after the change to clear the old data.
If someone else has a solution go with that.
Good luck
Kindly help out，is there any timer in GNU Radio?
I have six B205mini， I want to use all of them to achieve spectrum sensing periodically，for example，the first usrp is used for sensing 1G-2G frequency band，the second usrp is used for sensing 2G-3G frequency band….…my task is to sense 1G-6G at the same time. But because of the limitation of hardware，for every single usrp，it only can sense 56M bandwidth at most for every moment，so I have to use a timer to control the usrp ，this moment it should sense 1G-1.056G ，and next moment，it will move to 1.056G-1.112G，but I didn't find a relevant block in GNU Radio.