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<html><head><title>DominoEX Modes</title></head><body bgcolor="#ffffcc" link="#cc0088" text="#666644" vlink="#995544">
<font face="Verdana, Arial, Helvetica" size="-1">
</font><h1><font face="Verdana, Arial, Helvetica" size="-1">DominoEX Modes</font></h1>
<p>
</p><hr>

<h3><font face="Verdana, Arial, Helvetica" size="-1">General Description</font></h3>
<font face="Verdana, Arial, Helvetica" size="-1">DominoEX is a family
of offset incremental multi-frequency shift keyed modes with low symbol
rate. A single carrier of constant amplitude is stepped between 18 tone
frequencies in a constant phase manner. As a result, no unwanted
sidebands are generated, and no special amplifier linearity
requirements are necessary. The tones change according to an offset
algorithm which ensures that no sequential tones are the same or
adjacent in frequency, considerably enhancing the inter-symbol
interference resistance to multi-path and Doppler effects.
</font><p>
<font face="Verdana, Arial, Helvetica" size="-1">The mode is normally
used without Forward Error Correction, as it is very robust. The
default speed (11 baud) was
designed for NVIS conditions (80m at night), and other speeds suit weak
signal LF, and high speed HF use. The use of incremental keying gives
the mode complete immunity to transmitter-receiver frequency offset,
drift and excellent
rejection of propagation induced Doppler.
</font></p><p>
<font face="Verdana, Arial, Helvetica" size="-1">The mode was developed by Con ZL2AFP and Murray ZL1BPU.
</font></p><h3><font face="Verdana, Arial, Helvetica" size="-1">Protocol</font></h3>
<font face="Verdana, Arial, Helvetica" size="-1">These are unconnected, manually controlled message asynchronous symbol synchronous simplex chat modes, normally used
without Forward Error Correction. The FEC option is rarely used. The default calling mode is DominoEX11.
</font><h3><font face="Verdana, Arial, Helvetica" size="-1">Coding and Character Set</font></h3>
<font face="Verdana, Arial, Helvetica" size="-1">A nibble-based varicode with ASCII-256 user interface is used. Lower case characters are sent faster. An ASCII-128
secondary character set allows a fixed (typically ID) message to be sent whenever the transmitter is idle.
Modulation is nibble-wise symbol synchronous, differential.
</font><p>
<font face="Verdana, Arial, Helvetica" size="-1">The FEC option uses a
binary varicode with modified ASCII-128 user interface. Lower case
characters are sent faster. Modulation uses two dibit pairs, symbol
synchronous, differential.
</font></p><p>
<font face="Verdana, Arial, Helvetica" size="-1">The FEC option uses binary convolution to generate two dibits per varicode bit, and halves the corrected data rate
for the same symbol rate. Rate R=1/2, Constraint length K=7, default Interleaver L=4 (16 bits), using a matrix interleaver.
This is a NASA standard system. The default
interleaver is too short for effective burst correction, and performs best with L=10 or more.
</font></p><h3><font face="Verdana, Arial, Helvetica" size="-1">Operating Parameters</font></h3>
<table bgcolor="#eeeeff" border="1">
<tbody><tr bgcolor="#eeffff">
<td><small><b>Mode</b></small></td>
<td><small><b>Symbol Rate</b></small></td>
<td><small><b>Typing Speed<sup>1</sup></b></small></td>
<td><small><b>Duty Cycle<sup>2</sup></b></small></td>
<td><small><b>Bandwidth<sup>3</sup></b></small></td>
<td><small><b>ITU Designation<sup>4</sup></b></small></td></tr>
<tr>
<td><small>DominoEX4<sup>5</sup></small></td>
<td><small>3.90625 baud</small></td>
<td><small>~ 2.5 cps (25 wpm)</small></td>
<td><small>100%</small></td>
<td><small>173 Hz</small></td>
<td><small>173HF1B</small></td>
</tr><tr>
<td><small>DominoEX5<sup>5</sup></small></td>
<td><small>5.3833 baud</small></td>
<td><small>~ 3.1 cps (31 wpm)</small></td>
<td><small>100%</small></td>
<td><small>244 Hz</small></td>
<td><small>244HF1B</small></td>
</tr><tr>
<td><small>DominoEX8<sup>5</sup></small></td>
<td><small>7.8125 baud</small></td>
<td><small>~ 5.0 cps (50 wpm)</small></td>
<td><small>100%</small></td>
<td><small>346 Hz</small></td>
<td><small>346HF1B</small></td>
</tr><tr>
<td><small>DominoEX11<sup>6</sup></small></td>
<td><small>10.766 baud</small></td>
<td><small>~ 7.0 cps (70 wpm)</small></td>
<td><small>100%</small></td>
<td><small>262 Hz</small></td>
<td><small>262HF1B</small></td>
</tr><tr>
<td><small>DominoEX16</small></td>
<td><small>15.625 baud</small></td>
<td><small>~ 10.0 cps (100 wpm)</small></td>
<td><small>100%</small></td>
<td><small>355 Hz</small></td>
<td><small>355HF1B</small></td>
</tr><tr>
<td><small>DominoEX22</small></td>
<td><small>21.533 baud</small></td>
<td><small>~ 14.0 cps (140 wpm)</small></td>
<td><small>100%</small></td>
<td><small>524 Hz</small></td>
<td><small>524HF1B</small></td>
</tr></tbody></table>
<font face="Verdana, Arial, Helvetica" size="-1"><small><br><b>Notes:</b><br>1.
WPM is based on an average 5 characters per word, plus word space.
Values are approximate because a variable length code is used.<br>
2. Transmitter average power output relative to a constant carrier of the same PEP value.<br>
3. This is the "Necessary Bandwidth" as defined by the ITU.<br>
4. A summary of the ITU Designation system can be found at <a href="http://en.wikipedia.org/wiki/Types_of_radio_emissions">http://en.wikipedia.org/wiki/Types_of_radio_emissions</a><br>
5. Double spaced mode.<br>
6. Default and normal calling mode.</small></font></body></html>

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