Re: [Discuss-gnuradio] Packetloss and Ber simulation using OFDM

[Michael Dickens]

I'll second what Marcus said: a little tidier GRC flowgraph would help.

That said, it looks like you're using nice and simple GR OFDM for Tx and then you've expanded the GR OFDM Rx into its hier block equivalent form ... then connected the output to PER and BER blocks and output those results to the Qt GUI. I can't say for certain that all of the parameters are "stock", but those I can see look like they are. Is this correct?

What I'm wondering is where you're seeing the "55db drop in the signal" you specifically note? GR's default OFDM has zeros in the frequency spectrum in some locations. I don't see anything specifically "wrong" nor "out of place" with the spectrum you posted, but since this is just a screenshot it's difficult to tell what's going on beyond that it's an OFDM waveform. Hence my query to what exactly you're referring.

Hope this is useful! - MLD

On Wed, Feb 27, 2019, at 1:32 PM, Müller, Marcus (CEL) wrote:

Hi Nishant, I'm afraid you'll have to first tidy up your flowgraph.

I've been staring at it for a while, and it's just too confusing.

Best regards,

Marcus

On Wed, 2019-02-27 at 11:41 -0500, Sai Parepalli Laxman wrote:

> Hello,

> 

> This is Nishant. 

> 

> I have a pair of N210 USRP modules and two pairs of LFTX/LFRX daughter boards. I have an unexplained 55db  drop in the signal where a signal with amplitude bounded between -1 to 1, shows a -30db peak rather than a 0 dB peak on Qt GUI Frequency Sink and I am wondering if the amplifier is wrong or something that I am not doing right.  

> 

> I am using Ubuntu 18.04.1 gnuradio version 3.7.11 and UHD_003.010.003.000

> 

> I have attached the flowgraph and the transmitter output below.