Hi Marcus, Thank you so much, it's working like a charm now!
Best, Guy On Wed, Jun 17, 2020 at 5:59 PM Marcus Müller <marcus.muel...@ettus.com> wrote: > Hi Guy, > > you don#t have to stop a flow graph to set the gain value. In fact, you > shouldn't. > > Yes, you'll still have signal passing through your USRP while you're > adjusting the gain, but that's exactly what timed commands are for. > > > I've heard about sending commands to the > > USRP Sink, though I couldn't find any documentation on the subject and > the > > one page I found has been removed (and was never archived). > > Maybe you mean > https://www.gnuradio.org/doc/doxygen/page_uhd.html > ? > > That describes the commands you can send in both via asynchronous > message passing, and via tags. > > > message I keep receiving from the flowgraph: > > > > gr::log :FATAL: tagged_stream_mux0 - Missing a required length tag on > port > > 1 at item #100 > > thread[thread-per-block[10]: <block tagged_stream_mux(14)>]: Missing > length > > tag. > > > > that means you've set your USRP sink to tagged stream block mode, but > then you sent in data that wasn't part of any tagged stream "blob". > > > It seems to happen at random with any tagged block in the flowgraph (the > > point of failure typically changes every time we run it). While we could > > theoretically just catch the error and restart the flowgraph, > > Uuuuh, that sounds like it won't *actually* work. > > I would > > rather find a more permanent solution. We're using two Ettus B200 SDRs > for > > our current tests. > > Yeah, use timed commands to set the gain. Use tags to add them to your > sample stream. Don't use tagged stream blocks unless you actually want to. > > > > > If anyone has any information on proper dataflow control for blocks or > the > > USRP sink message passing API, I'd really appreciate it. > > Best regards, > Marcus > >