Re: [Discuss-gnuradio] Data loss during transmission (OFDM .bmp file)

2019-05-07 Thread Simran Kaur
Hi Ben,
I am trying to transmit an image using USRP Tx/RX by implementing OFDM in
GNU Radio. I am losing one offset of 96 bytes. I am suspecting there is
problem with my synchronization which is not detecting that offset
(packet_len = 96 bytes) or probably discarding it. I also tried inserting
padding using burst shaper and removing those bits using correlator. But
that is not working either. Can you suggest something how to make this
right?


Best,

Simran Kaur

On Tue, May 7, 2019 at 3:33 PM Ben Hilburn  wrote:

> Hey Simran -
>
> All of this is to say that your communications system design does not
> appear to be robust to the impairments and complexities of wireless
> channels, some of which Marcus mentioned. Can you share what your specific
> goal is or why you're undertaking this work? Depending on what you are
> trying to achieve, you might not need something quite so complex.
>
> Cheers,
> Ben
>
>
>
> On Sun, May 5, 2019 at 2:11 PM Kevin McQuiggin  wrote:
>
>> Read, read read!  Simple questions often lead to very complex answers.
>>
>> You might start your studies with "The Scientist & Engineer's Guide to
>> Digital Signal Processing” by S. Smith.
>>
>> Kevin
>>
>> > On May 5, 2019, at 9:46 AM, Marcus Müller 
>> wrote:
>> >
>> > Well, noise happens, and synchronization isn't instantaneous. Things
>> > that aren't detected can't be received, and bit errors that the FEC
>> > can't correct are bit errors in the received data.
>> >
>> > That's the beauty and the curse of wireless communications.
>> >
>> > Best regards,
>> > Marcus
>> >
>> > On Sat, 2019-05-04 at 20:26 -0400, Simran Kaur wrote:
>> >> Hello All,
>> >> We are trying to transmit a .bmp file using USRP Tx/Rx. However, I am
>> >> getting bogus header data at the receiving end. I tried transmitting
>> >> a text file also which clips my starting text and also it inserts
>> >> some invalid/unknown characters. We are losing some of the bytes for
>> >> e.g, the transmitted file size is of 426316 bytes, but receiving file
>> >> size is of 4,264,224 bytes.
>> >> Can somebody explain what we are doing wrong here. I have attached my
>> >> Tx and Rx .grc and snapshots for the reference.
>> >>
>> >> Best,
>> >> Simran Kaur
>> >> ___
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[Discuss-gnuradio] OFDM cyclic prefix

2019-04-13 Thread Simran Kaur
Hi Team,
I am trying to make own cyclic prefix block in C++ in GNU Radio(removing
roll-off part and keeping all other parameters same). After connecting my
cyclic_prefix block to the already present FFT block in tx_ofdm.grc, i am
getting the following error:


Executing: /usr/bin/python2 -u
/home/labuser/workarea-gnuradio/gnuradio/gr-digital/examples/ofdm/tx_ofdm.py

Traceback (most recent call last):
  File
"/home/labuser/workarea-gnuradio/gnuradio/gr-digital/examples/ofdm/tx_ofdm.py",
line 352, in 
main()
  File
"/home/labuser/workarea-gnuradio/gnuradio/gr-digital/examples/ofdm/tx_ofdm.py",
line 340, in main
tb = top_block_cls()
  File
"/home/labuser/workarea-gnuradio/gnuradio/gr-digital/examples/ofdm/tx_ofdm.py",
line 239, in __init__
self.connect((self.fft_vxx_0, 0), (self.cyclicprefix_CP_cc_0, 0))
  File "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/hier_block2.py",
line 47, in wrapped
func(self, src, src_port, dst, dst_port)
  File "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/hier_block2.py",
line 110, in connect
self.primitive_connect(*args)
  File
"/usr/local/lib/python2.7/dist-packages/gnuradio/gr/runtime_swig.py", line
5334, in primitive_connect
return _runtime_swig.top_block_sptr_primitive_connect(self, *args)
ValueError:* itemsize mismatch: fft_vcc_fftw0:0 using 512, CP_cc0:0 using 8*

*NOTE:* CP_cc is the block name that i gave when creating my own
cyclic_prefix block.
Can anyone help with your suggestions?

Thanks,
Simran Kaur
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