Hi Lukas, hi Marcus the prime, the UHD blocks *can't* know they're in a hier block. That information is not available to them, at all. "Hier Block" is just a flow-graph construction-time concept: It doesn't exist when the UHD block is constructed, and it doesn't exist when the flow graph starts executing.
_BUT_: When you run a GNU Radio flowgraph, you call the start() method of a top_block, which is essentially a hier block containing the whole flow graph. It was told which blocks and connections (vertices and edges) make up the flow graph, by being told to top_block.connect(start,end) blocks. In the case of hier blocks, the connect() thing basically leads to a recursive addition of the subgraph contained in the hier block. However, with your zero in- and output hier block, top_block.connect(something) was *never* called with the hier block, and hence, the hier block didn't become part of a flow graph that is to be executed. It's just a graph that *exists*, not one that *does* something. TL;DR: can't use a hier block without outside connections, since that's not becoming part of the top_block that'll be executed. Best regards, Marcus the second On Wed, 2019-12-04 at 16:44 -0500, Marcus D. Leech wrote: > On 12/04/2019 04:08 PM, Lukas Haase wrote: > > Hi Marcus, > > > > > > > > No, unofrtunately. > > > > 0 gain is still something like -10dBm. Huge and clearly visible on a > > spectrum analyzer. > > Where the exact tone is doesn't matter because my span is 10Mhz (I actually > > meant 915MHz) and I used full span to look at the entire frequency range. > > > > The point is: I filled all numbers in numerically and everything works if > > the URSP Source is in my main block. Then I *copy and paste* everything (to > > avoid any doubts) into a hier-block, put in the hier block and it stops > > working. I showed the exact screenshots. > > Even the leakage from the USRP itself is gone which means that the USRP > > just turns off, crashed badly or similar. > > > > This is either a weird bug or we are not supposed to use the USRP block > > within a hier block. > > > > Thanks, > > Luke > > > > > The USRP source wouldn't really have any "idea" that it's inside a hier > block. This may be a weird Gnu Radio limitation--hier blocks normally > have at least an input, and usually an input and an output. But a GR > expert might want to chime in about whether this case "works". > > > >
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