<!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>Throb</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;">Throb</h1> <div style="text-align: center;"> <div style="text-align: left;"> <div style="text-align: center;"><br> <div style="text-align: left;"> The THROB family of modes use two tones at a time. These tones are also amplitude modulated and can be a single tone for some symbols. <p>The mode has no Forward Error Correction, and is difficult to tune. It is fairly sensitive and moderately robust. Keyboard-to-keyboard QSOs are reasonably fast. Tuning must be very accurate, and the software will not tolerate differences between transmit and receive frequency. </p> <p>The amplitude modulation component of THROB is a raised cosine AM modulation of each symbol. This combined with two tones transmitted at the same time, means that a very linear transmitter is required. It also gives the mode its very unique sound. You will never mistake Throb for any other mode. </p> For THROB, nine tones are used, spaced 8 or 16 Hz. For THROBX, 11 tones are used, spaced 7.8125 or 15.625 Hz.<br> <br> Fldigi supports the following Throb baud rates and tone spacings:<br> <br> <table bgcolor="#eeeeff" border="1"> <tbody> <tr bgcolor="#eeffff"> <td><b>Mode</b></td> <td><b>Symbol Rate</b></td> <td><b>Typing Speed</b></td> <td><b>Bandwidth</b></td> </tr> <tr> <td>THROB1</td> <td>1.0 baud</td> <td>1.0 cps (10 wpm)</td> <td>72 Hz</td> </tr> <tr> <td>THROB2<sup>5</sup></td> <td>2.0 baud</td> <td>2.0 cps (20 wpm)</td> <td>72 Hz</td> </tr> <tr> <td>THROB4</td> <td>4.0 baud</td> <td>4.0 cps (40 wpm)</td> <td>144 Hz</td> </tr> <tr> <td>THROBX1</td> <td>1.0 baud</td> <td>1.0 cps (10 wpm)</td> <td>94 Hz</td> </tr> <tr> <td>THROBX2</td> <td>2.0 baud</td> <td>2.0 cps (20 wpm)</td> <td>94 Hz</td> </tr> <tr> <td>THROBX4</td> <td>4.0 baud</td> <td>4.0 cps (40 wpm)</td> <td>188 Hz</td> </tr> </tbody> </table><br>Waterfall appearance and the sound of each throb mode can be seen and heard at <a href="Modes/index.htm">Sight & Sound</a>.<br><br> </div> <div style="text-align: center;"><a style="font-weight: bold;" href="index.html">Contents</a><br> </div> </div> </div> </div> </body></html>
