Carl Olsson | 24 May 18:46 2015
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How to start and stop recording without exiting the flowgraph

Hi all,

I would like to use two filesink blocks to record signals from two USRP:s with MIMO Cable. I am interested in the phase offset of an incoming signal so I first need to calibrate and then start recording. I haven't found how this could be done in an easy way, does anyone have any ideas?

To clarify:
I would like to start my flowgraph then when I press a button in the GUI start recording and then press the button again and stop recording.

Thank you all in advance.

Regards

Carl
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Markus Heller | 24 May 15:17 2015
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Software Defined Academy Programme almost ready

Dear List,

the programme of the Software Defined Radio Academy on June 27 2015 in
Friedrichshafen (sub-conference to HAMRADIO) is almost complete. But it
is already now so interesting that I don't want to wait any longer and
present the list of talks to you:

http://www.sdra-2015.de/pages/programme.html

As soon as we have an exact time schedule for the talks (which is not
yet fixed), I will send another note. 

I'll be happy to welcome you to the SDRA if you plan to attend. Please
note that you'll get the entire HAMRADIO (biggest European HAM festival)
plus the MakerWorld with one single ticket.

http://www.hamradio-friedrichshafen.de/

vy73 / br
markus
dl8rds
Surya Agam | 24 May 10:54 2015
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BPSK output abnormal

Hi everyone,

I try to simulate file transfer using BPSK with block diagram

File Source --> PSK Mod --> PSK Demod --> File Sink

The block setting is
File Source :
-file type = .jpg (282,8 kB (282.765 bytes))
-repeat = no
-vec length = 1

PSK Mod :
-num of constellation = 2
-gray code = yes
-diff. encoding = yes
-sample/symbol = 2
-excess BW = 0.35
-verbose = off
=log = off

PSK Demod :
-num of constellation = 2
-diff. encoding = yes
-sample/symbol = 2
-excess BW = 0.35
-frequency BW = 6.28/100.0
-timing BW = 6.28/100.0
-phase BW = 6.28/100.0
-gray code = yes
-verbose = off
-log = off

File Sink
-vec length = 1
-unbuffered = on
-append file = overwrite

The size of input file = 282,8 kB (282.765 bytes)
but the size of output file = 2,3 MB (2.262.066 bytes)

What's wrong with my fg?

Thank you,
Surya Agam
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Surya Agam | 23 May 05:52 2015
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Error using Packet Encoder --> Packet Decoder

Hello everyone,

I want to simulate file transmission using BPSK modulation, with block diagram


File Source --> Packet Encoder --> BPSK Mod --> BPSK Demod --> Packet Decoder --> File Sink


But the result is 0 kB. Then I remove the Encoder-Decoder and Modulation block.

File Source --> File Sink

Then I have the file and it's operable (-5 bytes from original file)

Next step I add Packet Encoder - Decoder

File Source --> Packet Encoder --> Packet Decoder --> File Sink

But the file size is 0 kB

I don't know what is wrong with the Encoder-Decoder.


Thank you


Regards, Surya Agam
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Francisco Albani | 23 May 02:38 2015
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Need of delay=58 in the PSK Symbol Recovery Guided Tutorial

Hi, I managed to successfully replicate the results of this tutorial:

https://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_PSK_Demodulation

and, of course I understand the reason for a delay between the bits of
the source and the receiver.

But then I was struck by this: considering that the 2-input QT GUI
Time Sink consumes one sample of each at the same time and waits
otherwise, wouldn't this act as an "involuntary" synchronizer for the
bit streams?

Of course this is not happening so I'm making a bad assumption some
place and thats the reason I'm here asking for help.

(I know I could devise some debugging code for testing all my
hypothesis, but I'm still to newbie)

Many thanks!
Marcus D. Leech | 23 May 00:35 2015

Re: [USRP-users] N200 with DBSRX2 raw video

On 05/22/2015 05:13 PM, Venkatesh Sandilya wrote:
I meant that I would like the output of the log 10 block to be terminated by, lets say some value of a resistor before it goes to the scope. Is that even possible or would that be a hardware set up?

This is all digital.  If you find that the magnitude is too high, you can adjust the parameters of the scope.

In Software Defined Radio, most things you do to signals are in the digital, post-sampled domain.


On Wed, May 20, 2015 at 5:34 PM, Marcus D. Leech <mleech <at> ripnet.com> wrote:
On 05/20/2015 04:43 PM, Venkatesh Sandilya wrote:

Thanks much. That did produce a flatter top. Is there any way to terminate the output of the log 10 block before it goes to the scope input? I am searching for any such blocks in GRC but coming up with nothing.

What do you mean by "terminate the output"??

There's the null sink, if that's what you want.



On May 8, 2015 3:43 PM, "Marcus D. Leech via USRP-users" <usrp-users <at> lists.ettus.com> wrote:
On 05/08/2015 02:58 PM, Venkatesh Sandilya via USRP-users wrote:
Hello

I am comparing raw video observed from the N200 with DBSRX2 with one of the receivers that we have which has a logamp that converts RF to base band. The pulses that I get from the output of our receiver (as observed in a scope) seem to be of the same amplitude where as the pulses I observed coming out of the N200 (as observed in GnuRadio scope sink) seem to vary a lot. Attached are the plots and the grc flowgraph. I am wondering if there is anything else I should do (in the flowgraph) to get the pulses more smoother and somewhat of the same amplitude. Appreciate any response to this.

Thanks


_______________________________________________ USRP-users mailing list USRP-users <at> lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
Well, one of your views (the log-amp) is showing logarithmic scale, while the GNu Radio plot is showing linear.  Over-the-air there will be small variations
  in the time domain, and that's exactly what your plot is showing.    You could stick a log10 block in there to show on a log scale.  That might produce a
  flatter "top".



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marco Ribero | 22 May 21:20 2015
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Basic theory of IIR filters

I've switch back with filters, and I'd like to implement a IIR filters,also because I've seen that there are different papers about IIR filters in CUDA,but I didn't see any implementation.

I've see that actually gnuradio is using a direct form I implementation,which cannot be easily ported.

So I've looked about cascade and parallel FIR filter. My question is: which is best in terms of stability?Is acceptable to decompose the transfer function in sub-function with only one pole?or could it cause instability?(e.g. conjugate poles).
Otherwise,due to the fact that both approaches(parallel and cascade) require only the previous output,I think what the implementaion would be not difficult: thanks to the expansion of recurrence expression, is "sufficient" something like a parallel sum prefix.

Thanks,
Marco Ribero

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Martin Braun | 22 May 21:00 2015

Re: How to "declare_sample_delay" in C++?

Not sure what you're asking, the command is wrapped from C++ to Python,
and hence the same in both domains (see also
http://gnuradio.org/doc/doxygen/classgr_1_1block.html#acad5d6e62ea885cb77d19f72451581c2).

Also, 0 is the default.

M

On 22.05.2015 11:26, khalid.el-darymli wrote:
> Hi list,
> 
> I am doing some (polyphase) decimation with GNURadio in C++. I
> constructed my filters, I wrote some wrapper, and my script compiles
> perfectly. However, I am a bit unclear about "declare_sample_delay".
> 
> Assume that I have the block: pfb_decimator_ccf_0_5. To set the sample
> delay for this block to 0, in python, one uses:
> 
> self.pfb_decimator_ccf_0_5.declare_sample_delay(0)
> 
> 
> What is the proper way to do the same command in C++?
> 
> 
> Thanks in advance.
> 
> Best wishes,
> Khalid
> 
> 
> 
> _______________________________________________
> Discuss-gnuradio mailing list
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> 
khalid.el-darymli | 22 May 20:26 2015
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How to "declare_sample_delay" in C++?

Hi list,

I am doing some (polyphase) decimation with GNURadio in C++. I constructed my filters, I wrote some wrapper, and my script compiles perfectly. However, I am a bit unclear about "declare_sample_delay".

Assume that I have the block: pfb_decimator_ccf_0_5. To set the sample delay for this block to 0, in python, one uses:

self.pfb_decimator_ccf_0_5.declare_sample_delay(0)


What is the proper way to do the same command in C++?


Thanks in advance.

Best wishes,
Khalid

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marco Ribero | 22 May 19:22 2015
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Choose thread

Hi,
I've a question about thread management..I like the fact that scheduler can launch blocks in different threads, but I'd like to execute some blocks inside the same thread(CUDA require to perform all operations from a single thread)..for the moment I'm using GR_SCHEDULED=STS,but it blocks at all multithreading..Is it possible to set a thread affinity?(I've looked https://gnuradio.org/doc/doxygen/page_affinity.html, but it doesn't help)

Thanks,
marco
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Keyur Parikh | 22 May 19:20 2015
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GNU Radio IIR Filter Taps

Hello,

I've been trying to move the fm De-emphasis (an IIR filter, I'm pretty sure) functionality of the WBFM_Receive block into an FPGA, and I'm a little confused as to how the taps work.

I'm in fm_emph.py and can see the taps listed as

btaps = [b0, b1]
ataps = [1, a1]

I had assumed this is a first-order IIR filter, and am basing my simple algorithm on a structure as seen in this link


Is there something I'm missing? I don't seem to be getting the correct results based off my input data.

Thanks,
Keyur


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