[Arduino] Morse decoder project underway

[Karl W4KRL]

Paul W4RI gave me the new ARRL book "Arduino for Ham Radio" by Glen Popiel,
KW5GP.. I will eventually do a review but thought it would be a unique and
valuable experience to actually build a project from the book start to
finish. I was immediately taken by the Morse decoder. Turns out that there
is a good Morse library for the Arduino; something I had not known before
looking at the book. The project uses an LM567 tone decoder to filter the
received audio from a CW signal. I didn't have any in my junk box but Tayda
Electronics (a supplier I highly recommend) had them for $0.39 each and
they came in today's mail four days after ordering.

Meanwhile, I looked into doing the filtering in software and quickly found
the Goetzel library. TI has a nice description as does Wikipedia.

The graph shows the results from running a test last night using one of
Frank's military surplus signal generators (thanks Frank!). The data is a
bit crude as the dial is marked in 20Hz divisions so it took some creative
(but honest) eyeballing.

Minimum signal detection is at 0.27Vrms. At half a volt the bandwidth is
100Hz (14%) - not great but it would probably work on a clean signal. There
are some software parameters to play around with and perhaps a tighter
filter response is possible.

Next step is to prototype Glen's project using the LM567 and an Arduino Pro
Mini. Eventually I will lay it out on a veroboard.

One change I had intended to make was to substitute a 20 by 4 line LCD
display for the 16x2. A vendor in New Jersey had one for $10 delivered but
when it came today it turned out to be a 16x2 so back it goes.

This project may be a very good "Make" session as Terry suggests. Totals
parts cost is $20, the circuit and software are simple, and the project
uses some important basics like amplification, filtering, driving an LCD
and programming a PIC. It could all be done on a cheap plug in breadboard
so no soldering is needed. Plus it is a useful ham radio device when
finished.

73 Karl W4KRL


>From Terry WB4JFI:

[snip]
In particular, I would like to throw out the idea of AMRAD having some
ham-radio specific "Make" sessions.  Maybe at member's homes or at Frank's
shop, if he is willing.  Gin up a project, and have a group of members
attack it.  Not a generic Arduino or Teensy or other "light the LED" thing,
but a real, ham radio project, even if it's a morse code sender or somesuch.

I would also propose that AMRAD to something similar with software.  Maybe
take an existing ham radio project (such as for an Arduino or Pi), and have
someone walk others through the software needed to accomplish the project.
This could even be done on a Tuesday evening session, along with some
previously-created documentation on the AMRAD web site.

I'm sure there are AMRAD people building stuff, and others that would be
interested in following along.  Even (and especially) if the project is not
completed yet.

[snip]

I am also interested in any projects that AMRADers are working on.  Please
put a short description of what you are working on here on tacos, even if
not completed.  One of AMRAD's main goals is to further Amateur Radio
technology, along with learning about technology.  I encourage members to
share what they are doing.
73, Terry, WB4JFI

​
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