ARLA/CLUSTER: Episódio 209 da série "Foundations of Amateur Radio"

[João Costa > CT1FBF]

Foundations of Amateur Radio #209


*When digging gives you more understanding, the magic of software*
Today I'm going to go sideways to move forward. In amateur radio we
consider circuits, components such as transistors, inductors, capacitors,
crystals and how they're connected to each other. The framework in which
that exists is embodied by the field of electronics and how these
components can be mixed together to shape a radio that you can build or buy.

In a software defined radio there are electronics and components to be
sure, but the bulk of the work is done in the field of software and today
I'm going to look at that.

Computers surround us, in our work place, in our home, on the street, in
our hospitals, across our society. Each of these devices is running a thing
called software, as opposed to hardware - a physical thing, software is
intangible, in much the same way as your date of birth is intangible. You
cannot hold your birth date in the air and point at it. You could write it
down onto a piece of paper and point at the piece of paper that has the
date on it, but you'd be pointing at a piece of paper, not your actual
birth date.

Computers work in much the same way.

You cannot point at software, nor can you hold it in your hand. You can
print it out onto paper, and point at that, but you'd end up with a
deforestation problem that far exceeds the stripping of all the trees in
the Amazon rain forest. To make matters more complex, there are at least
two types of software, human readable and computer readable. You can
translate human readable source code into a computer readable executable
with a tool called a compiler, but doing it in the other direction is much
harder.

Think of the ink on the paper that describes your date of birth. You can
put the ink on the paper, but putting it back into the pen is more complex.

All this is leading somewhere, I promise.

A little while ago I started digging into how Software Defined Radios work
and if you've been following along on my journey, there'll be parts that
you can follow, parts that you sort of get, and bits that seem like black
magic. This will be different for each person. My black magic is not going
to be the same as yours and the things I understand without thinking might
make your head explode. If that's not enough, the goal posts keep moving.

As I said, I started digging, much like peeling an onion, removing layer by
layer, I've been exploring and learning and hopefully sharing my excitement
along the way.

The other day a mate of mine came by with a new toy. A QRP or low power HF
radio. The device itself is entirely driven by software, that is, it's a
Software Defined Radio. It has some knobs and buttons, a display, a power
socket, a plug for a microphone, an antenna, a speaker port and some other
bits and pieces, but underneath all that is software.

What's special about this radio is that the software is Open Source, that
is, you can peek inside and see what the code looks like before it becomes
ink on the page, the human readable source code, rather than the computer
readable executable.

I've touched on Open Source before and perhaps I should spend some time on
that soon, but for now, think of it as a set of rules that dictate how you
are allowed to use source code.

As any self-respecting IT geek, I went to the website where the software is
available and downloaded it.

What struck me was that it was much simpler than I had expected. Don't get
me wrong, this is a complex piece of software, not something I'm expecting
to pick up in an hour or even a week, but it's simple as in digestible. I
can point at different bits and understand what they do. This part does
Morse Code, that does FM, over here is RTTY and look, over here is FreeDV.

If you're wondering, I'm describing the UHSDR, or Universal Ham Software
Defined Radio project. Built originally by Chris M0NKA and Clint KA7OEI and
sporting an impressive list of contributors, this software offers insight
into receiving and transmitting using an SDR across a variety of amateur
radio modes, including SSB, AM, FM, Synchronous AM, FreeDV, RTTY, CW as
well as CAT or Computer Aided Transceiver, sometimes referred to as rig
control or remote control, a way of using an external computer to control a
radio.

The beauty of this software lies in its simplicity. Unlike many other
projects, there is no code dealing with Windows, or with Mac OS, there is
no mouse, touch screen, or other complex user interface. There is a limited
set of buttons, a few dials and a screen for output. The end result is that
the level of complexity is much lower than you'd find if you were to start
digging into something like PowerSDR or some other code-base.

The point is that the UHSDR project is a really accessible way to start
digging into the software behind a software defined radio and another path
into this magical hobby of amateur radio.

I'm *Onno VK6FLAB*
------------------------------

*•* This article is the transcript of the weekly 'Foundations of Amateur
Radio' podcast, produced by *Onno Benschop, VK6FLAB* who was licensed as
radio amateur in Perth, Western Australia in 2010. For other episodes,
visit http://vk6flab.com/. Feel free to get in touch directly via email:
cq  vk6flab.com

*•* If you'd like to join a weekly radio net for new and returning
amateurs, check out the details at http://ftroop.vk6flab.com/, the net runs
every week on Saturday, from 00:00 to 01:00 UTC on Echolink, IRLP, AllStar
Link, Brandmeister and 2m FM via various repeaters, all are welcome.
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