25.05.2019, 22:07, "Marcus Müller" <mmuel...@gnuradio.org>:
After reading the original paper, you've meant "2D- or 3D-DCT" :)
On Sat, 2019-05-25 at 21:20 +0100, farid mihoub wrote:Hi,
Discrete cosine transform
25.05.2019, 21:02, "Marcus Müller" <mmuel...@gnuradio.org>:
> hi, what's 2DCT_or_3DCT?
>
> Best regards,
> Marcus
>
> On Sat, 2019-05-25 at 19:38 +0100, farid mihoub wrote:
> > My application is to broadcast a video using softcast approach.
> > Video-->2DCT_or_3DCT-->Floating coefficients-->complex_mapping
> > -->ofdm_phy
> > My video quality (PSNR) will depend linearly to my SNR so no
> > need to
> > have an adaptive modulation.
> >
> >
> > 25.05.2019, 18:27, "Marcus Müller" <mmuel...@gnuradio.org>:
> > > 1- So, you have an SNR of best-case 16 dB; that's not high for
> > an
> > > OFDM
> > > system.
> > >
> > > 2- No, there's no power normalization. Hint: you can look all
> > this
> > > up
> > > by actually looking inside these blocks! This would make a lot
> > of
> > > sense, since it sounds you don't actually want to use tzhe
> > OFDM
> > > blocks
> > > at all. The whole advantage of the OFDM blocks compared to
> > just
> > > doing
> > > an IFFT of your transmit vector is that you get a header and
> > > modulation
> > > scheme.
> > >
> > > 3- Not quite sure what "information is linearly related to
> > complex
> > > symbols" means? Can you elaborate?
> > > 3b- A case where you *don't* do FEC is either a non-
> > communications
> > > system (i.e. you don't actually want to do OFDM for the reason
> > of
> > > transmitting information) or the extremely-bad-SNR case (where
> > FEC
> > > makes your BER better). For both cases, the existing OFDM
> > blocks
> > > are
> > > more of an obstacle than a solution.
> > >
> > > What are you building? What is your overall application.
> > Please
> > > paint
> > > the bigger picture – it's a bit frustrating to try to help
> > you, but
> > > then only get told that "this is not how I want to do it".
> > >
> > > Best regards,
> > > Marcus
> > >
> > > On Sat, 2019-05-25 at 18:39 +0200, Marcus Müller wrote:
> > > > Dear Farid,
> > > >
> > > > please always respond on the mailing list.
> > > > Thank you,
> > > > Marcus Müller
> > > >
> > > > On Sat, 2019-05-25 at 17:36 +0100, farid mihoub wrote:
> > > > > 1- For the noise : in the TX side the output is in the
> > order
> > > > of 2A,
> > > > > the noise 0.05A.
> > > > > 2-Second even without noise, the const does not affect the
> > > > > transmission, is there any sort of power normalization?
> > > > > 3-For the FEC and the modulation I want to try my custom
> > > > mapping
> > > > > where information is linearly related to complex symbols,
> > and
> > > > my
> > > > > application doesn't require error correction.
> > > > >
> > > > > Thank you.
> > > > >
> > > > >
> > > > > 25.05.2019, 17:06, "Marcus Müller" <mmuel...@gnuradio.org>
> > :
> > > > > > Hello Farid,
> > > > > > On Sat, 2019-05-25 at 15:59 +0100, farid mihoub wrote:
> > > > > > > Hello,
> > > > > > >
> > > > > > > In the OFDM_tx, rx examples in gr-digital :
> > > > > > > 1- Why just a low level of noise affect the
> > transmission
> > > > and
> > > > > > > cause it
> > > > > > > to stop.
> > > > > >
> > > > > > "low" is relative. It seems it's high enough to cause
> > packet
> > > > > > losses,
> > > > > > iff it's actually the noise.
> > > > > >
> > > > > > > 2- in the the Tx output and the Rx input no matter the
> > > > value
> > > > > > > of
> > > > > > > the
> > > > > > > multiply constant we apply
> > > > > > > that would not affect our transmission.
> > > > > >
> > > > > > Then it's probably not only the noise!
> > > > > >
> > > > > > > 3- Is there any way to separate channel estimation and
> > > > > > > tracking
> > > > > > > from
> > > > > > > data transmission, sometime I get the error "invalid
> > > > packet
> > > > > > > detected!" form the packet parser, also I need my data
> > to
> > > > > > > bypass
> > > > > > > FEC
> > > > > > > and QAM.
> > > > > >
> > > > > > Um, prior to QAM demodulation there is no data, and
> > prior to
> > > > FEC
> > > > > > decoding there is no information bits, so I'm not sure
> > what
> > > > you
> > > > > > want?
> > > > > >
> > > > > > > My purpose is to stream raw complex data to the I/Q
> > > > > > > components
> > > > > > > directly.
> > > > > >
> > > > > > Then it seems you don't want an OFDM transceiver but
> > maybe
> > > > just
> > > > > > simply
> > > > > > a single IFFT? Not quite sure what you have in mind.
> > > > > >
> > > > > > Best regards,
> > > > > > Marcus
> > > > > >
> > > >
> > > > _______________________________________________
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> >
> >
> >
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