What is it ?
HELLoIP is a
CWirc extension to
do Hellschreiber over the internet, using
gMFSK.
Hellschreiber (and FeldHell, the variant implemented by gMFSK), is a radio
and landline digital mode transmission invented in 1929. It's essentially an
early kind of facsimile system to transmit text. Hellschreiber is a "fuzzy"
digital mode, which means that, unlike RTTY which transmits coded characters
for example, it transmits images of the characters instead, which makes it very
reliable with weak signals and noisy radio environments, because of the
information redundancy, and the fact that it exploits the ability of the
receiving reader's brain to successfully decode even very degraded characters.
Despite transmitting images of characters, Hellschreiber is a low-bandwidth
mode, and many people today have rediscovered it, traffic in this mode, and
Hellschreiber contests are held regularly.
NOTE: HELLoIP used to be distributed as a patch against gMFSK-0.6beta1. It is
now included in the main gMFSK distribution (thanks Tomi!).
Why do Hellschreiber on the internet ?
Why not! It's fun, and if you're curious, the patch allows you to try
Hellschreiber without having to have a radio transceiver.
What you need
- A Linux, FreeBSD or NetBSD system with CWirc installed
- The gMFSK multimode HF terminal program
How to set up CWirc and gMFSK
- Install and configure CWirc. Please refer to the
CWirc manual for details.
- Download, and untar the gMFSK archive
- Build and install gMFSK normally with ./configure ; make ; make install as root.
- Make CWirc aware that it can use gMFSK as an extension program by making
a symlink to where the gmfsk binary was installed into the CWirc extension
directory. For example, if gmfsk is in /usr/local/bin and the CWirc extension
directory is /usr/lib/cwirc/extensions, invoke the following command as root:
ln -s /usr/local/bin/gmfsk /usr/lib/cwirc/extensions/Feldhell
Then, start (or restart) CWirc. A new tab should appear in the CWirc panel,
containing a button with the name of the symlink you made to gMFSK (in the
example above, "Feldhell").
Using gMFSK with CWirc
Start X-Chat and CWirc, and join a suitable CWirc IRC channel like you normally
would to do Morse. Click on the new extension button in the CWirc panel to
start gMFSK in slave mode.
In slave mode, gMFSK sends and receives sound to and from CWirc, no matter
what the sound device settings are, any external PTT device is disabled, and
only the FELDHELL mode is available. If you also use gMFSK normally however
(i.e. not just with CWirc), running it in slave mode doesn't modify your
settings at all.
Once gMFSK is started, you can start trafficking in Hellschreiber normally
as you would with a real radio transceiver.
Sending Hellschreiber text with CWirc
- Set the channel you want to send to in the CWirc panel
- Switch to send mode in gMFSK with the red lightning icon at the top
- Type what you want to send in the text line under the scrolling band,
making sure you end with a space to trigger the transmission
- When you're done, go back to receive mode with the green lightning icon
Note: when you're done sending, avoid leaving gMFSK in send mode for too
long, to minimize the chance of getting kicked out of the IRC channel for
flooding, and so you can receive the answer :-)
Receiving Hellschreiber text with CWirc
- Set the channel you want to receive from in the CWirc panel
- When the transmission arrives, if the reception in the scrolling band
isn't neat, or looks weak, center the receive frequency cursor in the
waterfall at the bottom on the main audio frequency of the transmission,
or shift the receive audio tone in the CWirc panel.
Note: it is normal in Hellschreiber mode to see the received text slant
up or down a little, since the transmission format has no provision
for sender/receiver synchronization. If the text is slanted, either
you or the person sending the transmission has a sound card or a RTC
device that runs a little too fast or too slow. If all the
transmissions you receive are similarly slanted, it's probably you.
Using QRN and propagation simulation
To simulate a real Hellschreiber QSO more realistically, try enabling
QRN, propagation and sporadic-E simulation in CWirc : depending on where
the other parties on the IRC channels are (and if they send their grid
locations in their signal), you'll see degraded or fading characters,
noise, and if there is more than one sender at a time, the characters from
the different senders will appear superimposed with different shades of gray,
etc ...
Note on bandwitdh usage
When gMFSK sends Hellshreiber with CWirc, depending on the Hellschreiber
font you selected, the amount of traffic that's sent to the IRC server is the
equivalent of regular Morse at 100 to 150 WPM. That's quite a lot of data,
and usually it's pretty close to the flood limit. Therefore, unless you're
using a fast IRC server with little or no lag, try to limit your transmission
to short phrases, and switch back to receive mode as soon as possible, so
the IRC server "cools off" before it decides to kick you.
Where to find active CWirc channels
- Channels containing "cwirc"
Note: if you create a channel, please put "CWirc" somewhere in the channel
name or topic so it can be listed on
SearchIRC
Screenshot
