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1.1       misho       1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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                      3: <html>
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                      5:        <head>
                      6:                <meta http-equiv="content-type" content="text/html;charset=iso-8859-1">
                      7:                <title>Gadget Box PPS Level Converter and CHU Modem</title>
                      8:                <link href="scripts/style.css" type="text/css" rel="stylesheet">
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                     11:        <body>
                     12:                <h3>Gadget Box PPS Level Converter and CHU Modem</h3>
                     13:                <img src="pic/gadget.jpg" alt="gif" align="left">A Gadget Box built by Chuck Hanavin
                     14:                <br clear="left">
                     15:                <h4>Related Links</h4>
                     16:                <p>
                     17:                        <script type="text/javascript" language="javascript" src="scripts/misc.txt"></script>
                     18:                        <br clear="left">
                     19:                </p>
                     20:                <h4>table of Contents</h4>
                     21:                <ul>
                     22:                        <li class="inline"><a href="#intro">Introduction</a></li>
                     23:                        <li class="inline"><a href="#ckt">Circuit Description</a></li>
                     24:                        <li class="inline"><a href="#file">Files</a></li>
                     25:                </ul>
                     26:                <hr>
                     27:                <h4 id="intro">Introduction</h4>
                     28:                <p>Many radio clocks used as a primary reference source for NTP servers produce
                     29:                        a pulse-per-second (PPS) signal that can be used to improve accuracy to a
                     30:                        high degree. However, the signals produced are usually incompatible with the
                     31:                        modem interface signals on the serial ports used to connect the signal to
                     32:                        the host. The gadget box consists of a handful of electronic components assembled
                     33:                        in a small aluminum box. It includes level converters and a optional radio
                     34:                        modem designed to decode the radio timecode signals transmitted by the Canadian
                     35:                        time and frequency station CHU. A complete set of schematics, PCB artwork,
                     36:                        drill templates can be obtained via the web from ftp.udel.edu as <a href="ftp://ftp.udel.edu/pub/ntp/hardware/gadget.tar.Z">gadget.tar.Z</a>.</p>
                     37:                <p>The gadget box is assembled in a 5&quot;x3&quot;x2&quot; aluminum minibox containing the level converter and modem circuitry. It includes two subcircuits. One of these converts a TTL positive edge into a fixed-width pulse at EIA levels and is for use with a timecode receiver or oscillator including a TTL PPS output. The other converts the timecode modulation broadcast by Canadian time/frequency standard station CHU into a 300-bps serial character stream at EIA levels and is for use with the <a href="drivers/driver7.html">Radio CHU Audio Demodulator/Decoder</a> driver.</p>
                     38:                <hr>
                     39:                <script type="text/javascript" language="javascript" src="scripts/footer.txt"></script>
                     40:        </body>
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                     42: </html>
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