Re: [Discuss-gnuradio] Multiple-Transmitter OFDM

[Michael Dickens]

Hi Ramazan - The "tP" means that a timed transmit came too early. Say you want to transmit exactly every second (via timed samples), but you provided UHD with a burst of 2 seconds of data. You will have a new timed command before the first burst is finished. Hence, UHD will print "tP". I'm guessing with this info you can work out why there are too many samples per timed command going into the UHD sink.

The "U" as you note is an underrun; as these are happening just at app startup, and not during steady-state runtime, I'd guess it has something to do with getting the data flowing between the E310 and your host running GR that you can safely ignore.

Hope this is useful! - MLD

On Wed, Jun 26, 2019, at 1:40 PM, Ramazan Çetin wrote:

Hi Michael,

We have implemented one channel OFDM using rational resampler and pfb synthesizer and multiply tag block. It's working and we can receiver packets over the air. Thanks for suggestions.

We have also tried to implement two channels. We have resampled OFDM signals to 500KHz using rational resampler and combine them using synthesizer. When we run the FG, we can receive from both of the channels in the receiver but i am seeing lots of tPtPtPtP and some Us. The log is given in below:

root@rcetin-W540:~/workarea/installs $ /home/rcetin/workspace/gohm/bitbucket/physicallayergnuradio/resampled_ofdm.py

linux; GNU C++ version 7.3.0; Boost_106501; UHD_003.009.002-0-gf18abe54

-- Initializing core control...

-- Performing register loopback test... pass

-- Performing register loopback test... pass

-- Performing register loopback test... pass

-- Performing CODEC loopback test... pass

-- Performing CODEC loopback test... pass

-- Setting time source to internal

-- Asking for clock rate 16 MHz

-- Actually got clock rate 16 MHz

-- Performing timer loopback test... pass

-- Performing timer loopback test... pass

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ControlPort Monitor running.

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gr::log :INFO: controlport - Apache Thrift: -h rcetin-W540 -p 37521

monitor::endpoints() = -h rcetin-W540 -p 37521

running: ['gr-perf-monitorx', 'rcetin-W540', '37521']

Press Enter to quit: tPtPUtPtPUtPUtPtPtP/home/rcetin/workarea/installs/bin/gr-perf-monitorx requires networkx and matplotlib. Please check that they are installed and try again.

tPUUtPtPtPtPtPUtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPUtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPUtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPUtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtPtP

So, do you have any idea what the reason of PtPt?

Another problem is U (underrun). Does underrun related with CPU capability or network (We are using E310 in network mode)?

Thank you so much for suggestions. The FG is attached.

Best regards.

Ramazan