Re: Total SDR Newbie

[Kevin McQuiggin]

Hi Arnie:

Welcome!  Marcus gave good advice.  SDRs still rely on the physical world to 
transmit and decode signals.  This means that there will always be issues with 
things like noise, interference, and propagation problems: the same things that 
affect analog radio.  Amateur radio experience (or study of material like the 
ARRL Handbook, as Marcus suggests) can help you as a newbie to understand the 
constraints that the physical world place on radio systems.  SDRs can describe 
radio systems mathematically to great accuracy, but that does not mean that 
these systems will function well in the physical world unless you design them 
to be able to.

Many people from the software world come to SDR experimentation and are 
surprised when their working “flowgraph” (the gnuradio term for a radio system) 
suddenly stops working when they take it out of simulation and hook it up to 
real SDR hardware that transmits and receives actual radio signals.  
Interference, phase errors and the like come to the fore and the flowgraph 
doesn’t work anymore.  This is usually because the designer did not take 
physical world factors into account in the system's design.

The commonality in the messages we see here could be paraphrased as “everything 
worked really well in my flowgraph, but it doesn’t work at all after I hooked 
the flowgraph up to a physical SDR.  Help!"

An understanding of basic radio, propagation and interference issues can help 
you design an SDR system that is able to cope with all the real world issues.  
That is part of the fun of working on this stuff!  Experimentation is what it 
is all about when you are starting out.

On the DSP side, I’ll give you another reference book.  It is free and 
available online.  It’s called “The Scientist’s and Engineer’s Guide to Digital 
Signal Processing” by Steve Smith.  It’s at http://www.dspguide.com/.  I found 
it online when I was starting out, and liked it so much that I bought a 
hardcopy.

Hope this info helps,

Kevin


> On Jul 27, 2023, at 7:41 AM, Arnie Shore <shoreas@gmail.com> wrote:
> 
> While I have experience developing free, Open Source software in other 
> environments like Computer-Aided Dispatch, Gnu radio has piqued my current 
> interest.  Me and hardware haven't gotten along too well over the years -- I 
> barely have a handle on Ohm's law -- but SDR  has my current attention.
> 
> I wonder if you can point me at interesting/useful postings/articles for me 
> to get a handle on some practical examples.  Thanks, all.
> 
> AS

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