Re: [Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f
Bump. Alex Roberts | Research Engineer | Applied Power Division (11) Southwest Research Institute | (210) 522-6014 | alex.robe...@swri.org<mailto:alex.robe...@swri.org> [SwRI Logo]<http://www.swri.org/> From: Roberts, Alex S. Sent: Tuesday, April 10, 2018 1:13 PM To: discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f Looks like I only replied to Michael and not the list... The example is included with gnuradio is available on the gnuradio github. https://github.com/gnuradio/gnuradio/tree/master/gr-digital/examples/packet >From my understanding of this particular example, OFDM carrier allocation and >all the good stuff that comes along with OFDM is not part of the example. It >just performs constellation encoding, header/payload muxing, correlation >estimation, carrier frequency recovery w/ costas loop, and header / payload >demuxing. Thanks, Alex. -- Alex Roberts Research Engineer Applied Power Division (11) Southwest Research Institute Office: (210) 522-6014 | Pager (210) 513-1672 ________ From: Roberts, Alex S. Sent: Wednesday, March 28, 2018 8:56 AM To: Michael Dickens Subject: RE: [Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f The example is included with gnuradio is available on the gnuradio github. https://github.com/gnuradio/gnuradio/tree/master/gr-digital/examples/packet >From my understanding of this particular example, OFDM carrier allocation and >all the good stuff that comes along with OFDM is not part of the example. It >just performs constellation encoding, header/payload muxing, correlation >estimation, carrier frequency recovery w/ costas loop, and header / payload >demuxing. Thanks, Alex. From: Michael Dickens [mailto:michael.dick...@ettus.com] Sent: Wednesday, March 28, 2018 8:44 AM To: Roberts, Alex S.; discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f Hi Alex - If you want to share your GRC file with me (privately) and/or the list, we'll see what we can figure out. Guessing it's an OFDM sync issue, since GR's OFDM implementation is for async messages, and those are on a message by message basis. - MLD On Tue, Mar 27, 2018, at 8:50 PM, Roberts, Alex S. wrote: Michael that provides insight into the error, unfortunately it does not explain the behavior of the example. The example uses the tx_packet and rx_packet hierarchical blocks. The output of the tx is routed to the input of the rx. I bypassed the example channel model and I'm not using hardware at the moment, so I would expect the example would have little issue with poor SNR and would maintain sync. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f
Looks like I only replied to Michael and not the list... The example is included with gnuradio is available on the gnuradio github. https://github.com/gnuradio/gnuradio/tree/master/gr-digital/examples/packet >From my understanding of this particular example, OFDM carrier allocation and >all the good stuff that comes along with OFDM is not part of the example. It >just performs constellation encoding, header/payload muxing, correlation >estimation, carrier frequency recovery w/ costas loop, and header / payload >demuxing. Thanks, Alex. -- Alex Roberts Research Engineer Applied Power Division (11) Southwest Research Institute Office: (210) 522-6014 | Pager (210) 513-1672 ____ From: Roberts, Alex S. Sent: Wednesday, March 28, 2018 8:56 AM To: Michael Dickens Subject: RE: [Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f The example is included with gnuradio is available on the gnuradio github. https://github.com/gnuradio/gnuradio/tree/master/gr-digital/examples/packet >From my understanding of this particular example, OFDM carrier allocation and >all the good stuff that comes along with OFDM is not part of the example. It >just performs constellation encoding, header/payload muxing, correlation >estimation, carrier frequency recovery w/ costas loop, and header / payload >demuxing. Thanks, Alex. From: Michael Dickens [mailto:michael.dick...@ettus.com] Sent: Wednesday, March 28, 2018 8:44 AM To: Roberts, Alex S.; discuss-gnuradio@gnu.org Subject: Re: [Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f Hi Alex - If you want to share your GRC file with me (privately) and/or the list, we'll see what we can figure out. Guessing it's an OFDM sync issue, since GR's OFDM implementation is for async messages, and those are on a message by message basis. - MLD On Tue, Mar 27, 2018, at 8:50 PM, Roberts, Alex S. wrote: Michael that provides insight into the error, unfortunately it does not explain the behavior of the example. The example uses the tx_packet and rx_packet hierarchical blocks. The output of the tx is routed to the input of the rx. I bypassed the example channel model and I'm not using hardware at the moment, so I would expect the example would have little issue with poor SNR and would maintain sync. packet_loopback_hier.grc Description: packet_loopback_hier.grc ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f
Michael that provides insight into the error, unfortunately it does not explain
the behavior of the example. The example uses the tx_packet and rx_packet
hierarchical blocks. The output of the tx is routed to the input of the rx. I
bypassed the example channel model and I’m not using hardware at the moment, so
I would expect the example would have little issue with poor SNR and would
maintain sync.
Thanks,
Alex.
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On Tue, Mar 27, 2018 at 6:37 PM -0500, "Michael Dickens"
<michael.dick...@ettus.com<mailto:michael.dick...@ettus.com>> wrote:
Hi Alex - The OFDM "#f" printouts means that the header didn't decode
correctly, which in turn means its Rx-computed CRC8 didn't equal the embedded
CRC8 from the header generation. This in turn generally means that OFDM sync
has been lost, which in turn generally means that the Rx "SNR" isn't high
enough ("SNR" here being the average power in the OFDM band divided by the
average power outside the OFDM band but still within the sampling frequency
range). I can't say specifically for the example you cite what's going on, but
maybe the above helps? - MLD
On Tue, Mar 27, 2018, at 6:54 PM, Roberts, Alex S. wrote:
> I'm playing around with some of the packet and ofdm examples with the
> eventual goal of streaming udp packets generated by gsrteamer encoding a
> webcamera. Unfortunately, I've been having some difficulty with the examples
> that I can't understand. For example, running the packet_loopback_hier
> example, it will run fine for some period of time (seems to be different
> amount each run) then it stops printing message debugs and spams the console
> with
>
> header_payload_demux0 - Parser returned #f
>
> Occasionally, the flowchart will crash and stop running.
>
> In the current run I have open, the correlation plot looks good, the transmit
> Time Freq and Constellation Plots are active, and the receive plots are no
> longer updated (probably because nothing is being decoded?)
>
> I've tried looking a the archives to see what causes this problem, but have
> not found a good answer.
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[Discuss-gnuradio] Meaning of header_payload_demux0 - Parser returned #f
I'm playing around with some of the packet and ofdm examples with the eventual goal of streaming udp packets generated by gsrteamer encoding a webcamera. Unfortunately, I've been having some difficulty with the examples that I can't understand. For example, running the packet_loopback_hier example, it will run fine for some period of time (seems to be different amount each run) then it stops printing message debugs and spams the console with header_payload_demux0 - Parser returned #f Occasionally, the flowchart will crash and stop running. In the current run I have open, the correlation plot looks good, the transmit Time Freq and Constellation Plots are active, and the receive plots are no longer updated (probably because nothing is being decoded?) I've tried looking a the archives to see what causes this problem, but have not found a good answer. -- Alex Roberts ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
