Re: [Discuss-gnuradio] Setting up a simple packet radio in 3.7.7.2

Hi Julian,

I've verified that it works with the setup you provided (it was very similar to a test I did initially before I switched to TCP sources/sinks).  The reason I want to use a TCP source/sink is that I want to be able to send application data through the radio (fairly slow and small data packets, i.e. occasional application commands).  

I then switched over the Time sink to a TCP sink: address 127.0.0.1, port 9001, client mode

I ran the code again with the sine wave still outputting as the source and opened up a terminal with nc -l 9001 (to connect to the tcp sink client).  I was immediately able to see the data was flowing through still (it was garbled, but data regardless in the terminal window).  

I then switched the Signal Source to the TCP source: address 127.0.0.1, port 9000, server mode

I ran the code again and got nothing as I entered data into the TCP source terminal window (using nc 127.0.0.1 9000).  I added a QT GUI Number sink to the output of the encoder and saw that the output as always 0. 

I believe I am still getting blocked at the packet encoder whenever I use my TCP source.  I've tried changing the data links between the TCP source/sink and Packet Encoder/Decoder to bytes, but still didn't change the output of the encoder at always being 0.

Any other ideas?  I feel like there must be some simple setting or method I am using incorrectly at this point.

Thanks for your help!

Priyank

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From: Julian Arnold <julian.arnold@ettus.com>
Sent: Tuesday, August 25, 2015 5:04 AM
To: Patel, Priyank
Cc: discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] Setting up a simple packet radio in 3.7.7.2

 

Hi Priyank,

I rebuild your setup without the TCP source and it is working for me [1]. Can you run it without using TCP?
You have to wait a little for the output to appear on time sink though.

Is there something I need to do for the terminal messages I am sending through the tcp-source in order for the encoder block to properly process it?

No, generally everything should be handled within the packet encoder.

[1]

​

Cheers,

Julian

 

On Mon, Aug 24, 2015 at 9:47 PM, Patel, Priyank <Priyank.Patel@gtri.gatech.edu> wrote:

Hi Julian,

Thanks for responding so quickly!  I've attached a picture of the current setup (if it gets through).  I've tried looking at the output of the encoder and am seeing nothing come out of it and so there is no signal from that point on (through the gmsk mod->gmsk demod->decoder->tcp-sink).  Is there something I need to do for the terminal messages I am sending through the tcp-source in order for the encoder block to properly process it?

I am currently just simulating it locally by going directly between the gmsk-mod->gmsk-demod as I wanted to make sure everything goes through before I add in the USRPs.

Thanks,

Priyank

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From: julian.arnold@ettus.com <julian.arnold@ettus.com>
Sent: Monday, August 24, 2015 3:16 PM
To: Patel, Priyank
Cc: discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] Setting up a simple packet radio in 3.7.7.2

 

Hi Priyank,

The packet decoder is checking for a preamble sequence in the data stream.

If there is no output coming from the decoder the preamble is probably not being detected. 

How does the output of the gmsk demod look like?

Also, are you transmitting the signal or are you just simulating locally?

Cheers,

Julian 

Am 24.08.2015 um 21:05 schrieb Patel, Priyank <Priyank.Patel@gtri.gatech.edu>:

Hello,

 

I am trying to get a simple packet radio GRC working but so far have had no luck with the following scheme:

 

tcp-source (port 9000) -> packet encoder -> gmsk mod -> gmsk demod -> packet decoder -> tcp-sink (port 9001)

 

If I remove the encoder/decoder and the gmsk mod/demod and go directly between the ports, then I am able to clearly see everything (I am using two terminals, one for tcp source and one for tcp sink).  If I add back in the gmsk mod/demod I see stuff in my other terminal window (although it is garbled).  Once I add the packet encoder nothing gets through again. 

 

I've been trying to follow some examples of this done in the past, but they were with much older versions of GNU radio and some of them used GR-extras which is no longer supported in GnuRadio 3.7.

 

Any help would be greatly appreciated.

 

Thanks!

 

Priyank Patel

 

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Julian Arnold