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Re: [Discuss-gnuradio] OFDM_TX_RX
From: |
Marcus Müller |
Subject: |
Re: [Discuss-gnuradio] OFDM_TX_RX |
Date: |
Sat, 25 May 2019 22:02:25 +0200 |
User-agent: |
Evolution 3.30.4 (3.30.4-1.fc29) |
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" <address@hidden>:
> > 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" <address@hidden>:
> > > > > 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
> > > > >
> > >
> > > _______________________________________________
> > > Discuss-gnuradio mailing list
> > > address@hidden
> > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>
>
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- [Discuss-gnuradio] OFDM_TX_RX, farid mihoub, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, Marcus Müller, 2019/05/25
- Message not available
- Re: [Discuss-gnuradio] OFDM_TX_RX, Marcus Müller, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, Marcus Müller, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, farid mihoub, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX,
Marcus Müller <=
- Re: [Discuss-gnuradio] OFDM_TX_RX, farid mihoub, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, Marcus Müller, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, farid mihoub, 2019/05/25
- [Discuss-gnuradio] OFDM / softcast / rate distortion theory (was:Re: OFDM_TX_RX), Marcus Müller, 2019/05/25