embedaddon/ntp/html/gadget.html - view

File: [ELWIX - Embedded LightWeight unIX -] / embedaddon / ntp / html / gadget.html
Revision 1.1.1.1 (vendor branch): download - view: text, annotated - select for diffs - revision graph
Tue May 29 12:08:38 2012 UTC (12 years, 7 months ago) by misho
Branches: ntp, MAIN
CVS tags: v4_2_6p5p0, v4_2_6p5, HEAD

ntp 4.2.6p5

1: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2: 3: <html> 4: 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"> 9: </head> 10: 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"x3"x2" 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> 41: 42: </html>