Re: [Discuss-gnuradio] Tag preemption USRP sink

[Bastian Bloessl]

Hi,

I replaced the Frequency Xlating FFT filters with FIR filters, used the 
Low-Pass Filter Taps block to generate taps (since I can’t get my head around 
this notation), and removed the filter from the first conversion.

Now, it seems to work. At least it receives frames. If you still have problems 
I can send you the flow graph.

Best,
Bastian


> On 15 Dec 2015, at 10:05, Saulo Queiroz <address@hidden> wrote:
> 
> Each stream has been shiffted with the xlating block.
> The intention is to "split" a 20 MHz wide analog channel into two of 10 MHz.
> Each 10 MHz channel transmit its own ofdm frame.
> I attached the flowgraph for more details.
> 
> thanks in advance.
> 
> On 15 December 2015 at 17:42, Martin Braun-2 [via GnuRadio] <[hidden email]> 
> wrote:
> tP indicates you're using corrupt tagged streams, maybe your add block 
> is overlaying them? I'm also not entirely sure what you mean by 
> 'simultaneous parallel transmissions'. Are they on different 
> frequencies? Are you mixing them together in baseband? 
> 
> Cheers, 
> Martin 
> 
> 
> On 15.12.2015 04:10, Saulo Queiroz wrote:
> 
> > Hi all, 
> > 
> > I'm trying to Tx a same tagged stream simultaneously through two analog 
> > orthogonal channels. 
> > 
> > The flow path of each stream copy is: resampling, adjust tag lenght and 
> > xlating FFT filter (with shifting). After this I take the output of each 
> > filter and put into and add block then to the USRP sink. I also do the 
> > reverse process at the Rx side. 
> > With some packets are successfuly receive but with so many losses. At 
> > the Tx side I get many "tP". Any tip on how to set simultaneous parallel 
> > transmissions without this? 
> > 
> > I'm using gr-ieee80211 (thanks Bastian and team :) that has worked 
> > nicely with the single channel scenario. 
> > 
> > thanks in advance 
> > 
> > BR 
> > 
> > -- 
> > Saulo Jorge bq 
> > - "Beware of bugs in the above code; I have only proved it correct, not 
> > tried it." 
> > Donald Knuth. 
> > 
> >
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> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >
> 
> 
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> 
> -- 
> Saulo Jorge bq
> - "Beware of bugs in the above code; I have only proved it correct, not tried 
> it." 
> Donald Knuth.
> 
>  wifi_tx_rx_loopback.grc (134K) Download Attachment
> 
> View this message in context: Re: Tag preemption USRP sink
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--
Dipl.-Inform. Bastian Bloessl
Distributed Embedded Systems Group
University of Paderborn, Germany
http://www.ccs-labs.org/~bloessl/