Best regards, Marcus
On 22/04/2020 19.40, Lukas Haase wrote:
Hi, Before going to hardware (and since my HW access is limited in Corona times) I want to build my "TRX1" with a behavioral model of "TRX2" (TRX2 will eventually be a simple hardware TRX on PCB, TRX1 a more signal processing heavy gnuradio application). I thought UDP Source/Sink over localhost is the way to go but this works very unreliably here. For TRX1 I use (simple demo): Signal Source (fs=5MHz, f=1MHz) --> Throttle (5MHz) --> UDP Sink (127.0.0.1:1235) | \-----> | | QT GUI Time Sink UDP Source (127.0.0.1:1234) ------------> | For TRX2 I use (simple demo): UDP Source (127.0.0.1:1235) --> Throttle (5MHz) --> MultiplyConst (2) --> UDP Sink (127.0.0.1:1234) I start TRX2 first and then TRX1. Initially this simple demo worked well with default values (payload_size=1500-20, sendnullpkt=false) but frequently I got the following error messages (from both TRX1 and TRX2): Too much data; dropping packet. This surprised me a lot because it's localhost which should be insanely fast. I run USRP with 200 MSps (10Gbe) on the same machine without a single packet drop! Well, I checked the MTU of lo is not 1500 but 65536. Still baffled how this can happen with a ridiculously low sampe_rate=5M, I set payload_size=65516. Now the error is largely gone. However, here and there I get a new nasty error message: ERROR: send error: send_to: Message too long This only seems to happen for TRX2. After this error I have to restart both flowgraphs. Unfortunately this only happens with more complicated stuff implemented within TRX1/TRX2 and not reproducibly. Has anyone done something like this before and has a recommendation for a reliable setup? Is UDP Source/Sink over localhost even the best way to go? Best, Lukas
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