Re: [Discuss-gnuradio] USRP Packet Decoder and Encoder

[Mojtaba Mansour Abadi]

Hi Brian,

 

From my experience, if packet decoder is not receiving any detectable preamble bit sequence there will be no output.

From your email I realised that you’re receiving noise-like signal if decoder is bypassed. So I also agree with Derek that either you probably are not receiving any signal or the modulation/demodulation procedure is not performed correctly.

Try your system back-to-back without any packetisation mechanism. Use a very short length vector source with couple of numbers as data. Make sure you are receiving the same sequence at the Rx side.

 

If you don’t. Try a loopback system without any USRPs and see if your data is received at the Rx side.

 

Cheers.

 

Sent from Mail for Windows 10

 

From: Derek Kozel
Sent: 04 July 2017 08:48
To: Brian
Cc: GNURadio Discussion List
Subject: Re: [Discuss-gnuradio] USRP Packet Decoder and Encoder

 

Hello Brian,

It will be difficult to provide useful advice without seeing your flowgraph. Does your file correctly get written if you bypass the actual radios and simply connect the transmitter and receiver flowgraphs together? If it does then you probably need to add synchronization to your receiver.

Another good check is to look at the received raw spectrum and ensure that the signal is being received at an appropriate power level. How do you have the two USRPs connected? Antennas or coax with an attenuator?

Regards,

Derek

 

On Mon, Jul 3, 2017 at 11:29 PM, Brian <address@hidden> wrote:

I have a flow graph that currently has a packet encoder at the transmitter and an encoder at the receiver.

I am attempting to send a file from one usrp to the other.

On investigating the output of the receiver it would not appear that it is processing anything possibly because of the access code but I have conformed they match and are suitably long and random.

The file I get out is 0bytes.  If I bypass the decoder a large file is created, although large and unusable (noise)

Any advice on how to proceed will be gratefully received and a pre-configured tx and rx flow graph will be most welcome.

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