Re: [Discuss-gnuradio] OFDM Blocks

[Martin Braun]

On 07/25/2014 01:18 AM, Md. Anjum wrote:
> Hello,
> 
> I'm working with USRP OFDM blocks. I'm confused about how to use
> built-in OFDM Transmitter and OFDM Receiver blocks. 
> 
> 1. How to set the fields- occupied carriers, pilot carriers, sync word
> and pilot symbols?

Before I go into this, did you read the manual page? If yes, what
specifically is unclear? Also, did you go through the examples in
gr-diigtal/examples/ofdm?

> 2. I'm using N200 board. I transmitted signal using OFDM Mod block UHD
> Sink block. It seems it       transmits properly. But when I receive the
> signal using OFDM Demod and UHD Source block then it   looks the signal
> is not received properly. The received signal shows a quite different
> pattern than the transmit one. It looks it receives something different
> signal, not the transmitted one. Note: I'm using same USRP board to
> transmit and receive signal simultaneously.

I recommend sticking to the OFDM Transmitter and -Receiver blocks.

> 3. Again, I need to control the frequency offset of the subcarriers. How
> can I do that using the built-in blocks? 

Do you mean the sub-carrier spacing? If so, of course you can control that.

> 4. And is there any way to control the transmit signal power? 

There are many ways to control the transmit power. You can vary the
signal amplitude digitally, you can increase the tx gain... just make
sure you don't distort your signal.


> 5. Well, does the OFDM Mod2 block works? If it is then how to use that one?

No, it doesn't. That's actually spurious XML.

M

> 
> I already asked a lot of questions. Thanks for your patience.
> 
> 
> Regads
> Nashid Anjum
> Graduate Student
> South Dakota School of Mines and Technology
> 
> 
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