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Re: Encode and modulate a test message on GNU Radio 3.8

From: Marcus Müller
Subject: Re: Encode and modulate a test message on GNU Radio 3.8
Date: Wed, 14 Jul 2021 12:51:01 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0

Hi Rodrigo,

a "welcome" through this channel, too!

On 14.07.21 12:40, Rodrigo Ruiz wrote:
> Hello, I want to create a flowgraph in order to send a "Hello World" using my 
> LimeSDR-Mini.

> The thing is that I want to encode the "Hello World" using NRZ, Manchester, 
> etc coding
> techniques, 

These are line codes, not really that useful for RF, in general. You'll not 
find them in
any of the modern digital communication schemes ("modes"), because the problem 
solving is not applicable to wireless communications in the same form. You'll 
find them in
legacy ham modes, only. (I'd be delighted to be proven wrong here, but neither 
the DC
balance nor the transition timing recovery problem are relevant to wireless 
comms; you
sync differently)

> but I don't know if this is possible. 

It definitely is! Everything that you can do in finite time to a band-limited 
signal is
possible :)

> Also I would like to modulate on FM, for
> example.

FM is an analog transmission scheme, but you want to send digital data: I think 
directly want to use FSK instead.

> But as the input from the WBFM Transmit block is a float, I don't know if my 
> File
> source block could be a float or I should use a conversion block.

You need to interpret the bytes from your file source as symbols, then put 
these on a
waveform and send that to your limesdr for transmission.

How exactly you want to do this depends on a lot of things, and you've not 
described your transmission scenario yet, so I'm not sure how to give you a 
start there.

> I hope someone can help, thanks in advance.

Yeah, sure! That's exactly why we have the GNU Radio academy:


Chapter 1,2,4 and 5 will be necessary to really understand the bits and pieces 
of GNU
Radio. Then, you'd probably want to do the FSK or the QPSK example. Finally, 
read and
adapt chapter 7 to your needs :)

Best regards,

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