Re: Problems with Correlation Estimator in GNURadio

[Shruti Gupta]

Hi!

Thanks for your reply.

While I'll work on installing and working with GRC 3.8, I was just 
wondering will the over the air communication be bad enough to not even 
receive a single correct packet? Is it to do with loop_bw for FLL, PFB 
and Costas_Loop or the digital gain values (a multiply block for the 
source signal) in RX? What is the logic behind setting of the loop_bw of 
these blocks?

Thanks and Regards
SG

On 15/05/20 6:34 pm, Shruti Gupta wrote:
> Hi!
>
> I have been trying to use the packet communication examples under 
> gr-digital in GNURadio(v 3.7.14.0) on ubuntu machines with LimeSDR 
> Mini for over the air communication.  I am using the 
> usrp_packet_tx.grc and uspr_packet_rx.grc  to transmit and receive 
> BPSK modulated packets respectively. I have modified these examples 
> for LimeSDR Mini by including LimeSDR source and sink blocks and 
> setting up the parameters. Now, I am running TX on one machine and RX 
> on another machine tuned to same frequency. However, when I keep the 
> gain values for RX low since the distance between TX and RX is few 
> feet and eliminating the possibility of RX saturation, the packets are 
> not being detected, while for higher gain values packets get detected 
> but the correlation start tags are tagged before the position of 
> estimation tags. I am not too sure if that's how it is suppose to work.
>
> Moreover, even after being detected the packets are not decoded and I 
> receive following message  on console:
>
> INFO: Parser returned #f
>
> I think this is due to either incorrect header decoding or incorrect 
> packet detection which freezes the header/payload demux block in the 
> flowgraph. Also, even for very few packets that are decoded, the 
> header is incorrect so why does the packet even gets decoded? Is there 
> a way to work around this problem? Can we use some other block for 
> packet detection?
>
> Any suggestion or help is highly appreciated.
>
> Thanks in anticipation
> SG