ARLA/CLUSTER: Episódio 126 da série "Foundations of Amateur Radio" - Ouvindo sinais muito fracos.

[João Costa > CT1FBF]

Foundations of Amateur Radio #126

Hearing very weak signals

This week I'm going to talk about a Digital Mode you can use with any
Amateur License, or even without an Amateur License. You can set-up
your radio, hook it to a computer and the Internet and after
installing some software, you can join the Weak Signal Propagation
Reporters.

So how do you start, what does it do and how can it help you?

First of all, WSPR, pronounced Whisper, is a way of encoding
information and transmitting it across the spectrum. At the other end
a radio receives that signal, sends it to a computer where a piece of
software attempts to decode and then log it.

This Digital Mode, invented by Joe K1JT, is one of several modes that
are gaining popularity across the Amateur Radio community because the
beauty of this mode is that it's so unobtrusive that you're unlikely
to actually hear it if you were to tune to a dedicated WSPR frequency.

If you want to find out what your station can hear, you can set
yourself up as a dedicated receive-only station and report your
findings to a central database where others can share your information
and learn what propagation is like at that particular point in time.

Of course, it also means that you can use the same information to
learn what propagation looks like in your neck of the woods with your
radio and your antenna set-up.

There's even an option that allows you to have your radio
automatically change frequency - known as band hopping - and listen
for WSPR signals across the bands that you allocate.

If you like, you can go to the wsprnet.org website right now and do a
search for my callsign, VK6FLAB and see what stations I've heard since
I turned it on. Go on, have a look, I won't mind.

My station is set-up to do band hopping across all HF frequencies all
day and night and during the grey-line it only listens to 80m, 40m,
15m and 10m, since those are the frequencies my license allows me to
transmit on and I'm particularly interested how they work at sun-rise
and sun-set.

You might have heard me before talking about how the noise at my home
is atrocious. Nothing has changed, it's still abysmal, but WSPR
signals are coming in and being decoded.

If you want to do this, you'll need a radio - any radio will work, a
computer with a microphone socket and a way to pipe the audio from the
radio into the computer, I'm using a 3.5mm male plug to 3.5mm male
plug - you don't need a fancy audio interface, you're only listening.
If you can connect an interface cable, your computer can also change
frequency for you, but that's not needed to get started.

Make sure that you turn the volume right down before you plug anything
in. Connecting a headphone output directly into a microphone input can
blow up the port if you're not careful and WSPR doesn't need much in
the way of volume. The software helps you get it set right, so read
the manual before you start.

Once you've set-up your radio and your computer, you can watch the
signals coming in on a waterfall display, a graphical representation
of the audio and frequency that shows strong signals in red and no
signal as blue. You'll find that turning up the volume too high will
actually reduce the ability to hear signals.

I'm keen to learn what I can hear and how many stations my simple 10m
vertical antenna can hear across the Amateur Radio spectrum.

I'd love to hear your weak signal stories and see what you can hear.
As I said, it seems I'm becoming a short-wave listener after-all.

I'm Onno VK6FLAB