<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head>
<meta content="text/html; charset=ISO-8859-1" http-equiv="content-type">
<title>Thor</title><meta content="w1hkj" name="author"></head>
<body style="color: rgb(0, 0, 0); background-color: rgb(255, 255, 204);" alink="#000099" link="#000099" vlink="#990099">
<span style="font-weight: bold;"></span>
<h1 style="text-align: center;">Thor</h1>Thor is a new forward error
correcting incremental frequency shift keyed communications mode.
It was developed specifically to meet the needs of ARQ transfers
in the HF spectrum. It is particularly well suited under
conditions of atmospheric static noise. Thor borrows from two
current modem technologies, MFSK and DominoEX. Fldigi can operate
in the following Thor modes:<br>
<ul>
<li>Thor-4 - double spaced mode</li>
<li>Thor-5 - double spaced mode</li>
<li>Thor-8 - double spaced mode</li>
<li>Thor-11 - single spaced mode</li>
<li>Thor-16, - single spaced mode and</li>
<li>Thor-22 - single spaced mode</li>
</ul>
The sound card sampling rate is 8000 Hz for the 4, 8 and 16 modes.
It is 11025 Hz for the 5, 11 and 22 modes. This change in
sound card sampling rate will be seen in the drop rate on the waterfall. See: <a href="Modes/THORdesc.htm">Thor Technical Description</a>.
Thor emits a distinctive double rising tone sequence at the
beginning of each transmission. It is used to flush the receive
decoder and also provides a visual and audibal clue to its being used.<br>
<br>
The modem code for Thor uses a wide band multiple frequency
detector that can lock on and detect the incoming signal even when
badly mistuned. Frequency domain oversampling is used to allow
proper tone detection with the need for AFC. The AFC control does
not alter the decoder in any way.<br>
<br>The waterfall and digiscope will appear as:<br>
<br>
<div style="text-align: center;"><img style="width: 787px; height: 198px;" alt="" src="images/Thor-1.png"><br>
<br>
<div style="text-align: left;">The text displayed in the status area is
the secondary text being sent by the transmitting station. When
the keyboard buffer is empty the Thor modem transmits text from the
secondary text buffer. Your secondary text buffer can be edited
on the Thor configuration tab.</div>
<br>
<div style="text-align: left;">The digiscope display is similar to the DominoEX display and represents the tone pairs moving through the tone filters.
You can also use an alternate digiscope display (left click on
the digiscope display area).<br>
<br>
<div style="text-align: center;"><img style="width: 117px; height: 117px;" alt="" src="images/dominoex-1a.png"><br>
<br>
<div style="text-align: left;">In this display mode the red line
represents the center of the multiple tone bins that are in the
detector. The dots will be blurry if the AFC is not locked on and
become very distinct when AFC lock has been achieved. The tone
dots will move from bottom to top (opposite the direction of the
waterfall).</div>
</div>
</div>
</div>
<br>
This is the same signal mistuned:<br>
<br>
<div style="text-align: center;"><img style="width: 871px; height: 115px;" alt="" src="images/dominoex-2.png"><br>
<div style="text-align: left;"><br>
and with the signal badly mistuned:<br>
<br>
<div style="text-align: center;"><img style="width: 871px; height: 117px;" alt="" src="images/dominoex-3.png"><br>
<br>
<div style="text-align: center;"><a style="font-weight: bold;" href="index.html">Contents</a><br></div>
</div>
</div>
</div>
</body></html>
