freebsd-dev/contrib/ntp/html/driver9.htm

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<TITLE>Magnavox MX4200 GPS Receiver</TITLE>
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<H3>Magnavox MX4200 GPS Receiver</H3>
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<HR>
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<H4>Synopsis</H4>
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Address: 127.127.9.<I>u</I>
<BR>Reference ID: <TT>GPS</TT>
<BR>Driver ID: <TT>GPS_MX4200</TT>
<BR>Serial Port: <TT>/dev/gps<I>u</I></TT>; 4800 baud, 8-bits, no parity
<BR>Features: <TT>ppsclock</TT> (required)
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<H4>Description</H4>
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This driver supports the Magnavox MX4200 Navigation Receiver adapted to
precision timing applications. It requires the <TT>ppsclock</TT> line
discipline or streams module described in the <A HREF="ldisc.htm">Line
Disciplines and Streams Modules</A> page. It also requires a <A
HREF="gadget.htm">gadget box</A> and 1-PPS level converter, such as
described in the <A HREF="pps.htm">Pulse-per-second (PPS) Signal
Interfacing</A> page.
<P>This driver supports all compatible receivers such as the 6-channel
MX4200, MX4200D, and the 12-channel MX9212, MX9012R, MX9112.
<P>
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<A HREF="http://www.leica-gps.com/"><IMG align=left HEIGHT=143 WIDTH=180
SRC="pic/9400n.jpg" ALT="Leica MX9400N Navigator"></A>
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<A HREF="http://www.leica-gps.com/">Leica Geosystems</A> acquired
the Magnavox commercial GPS technology business in February of 1994.
They now market and support former Magnavox GPS products such as the
MX4200 and its successors.</P>
<BR CLEAR=LEFT>
Leica MX9400N Navigator.
<P>
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<H4>Operating Modes</H4>
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This driver supports two modes of operation, static and mobile, controlled
by clock flag 2.
<P>In static mode (the default) the driver assumes that the GPS antenna
is in a fixed location. The receiver is initially placed in a "Static,
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3D Nav" mode, where latitude, longitude, elevation and time are
calculated for a fixed station. An average position is calculated from
this data. After 24 hours, the receiver is placed into a "Known
Position" mode, initialized with the calculated position, and then
solves only for time.
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<P>In mobile mode, the driver assumes the GPS antenna is mounted on a moving
platform such as a car, ship, or aircraft. The receiver is placed in "Dynamic,
3D Nav" mode and solves for position, altitude and time while moving. No
position averaging is performed.
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<H4>Monitor Data</H4>
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The driver writes each timecode as received to the <TT>clockstats</TT>
file. Documentation for the <CITE>NMEA-0183</CITE> proprietary
sentences produced by the MX4200 can be found in
<A HREF="mx4200data.htm">MX4200 Receiver Data Format</A>.
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<H4>Fudge Factors</H4>
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<DL>
<DT>
<TT>time1 <I>time</I></TT></DT>
<DD>
Specifies the time offset calibration factor, in seconds and fraction,
with default 0.0.</DD>
<DT>
<TT>time2 <I>time</I></TT></DT>
<DD>
Not used by this driver.</DD>
<DT>
<TT>stratum <I>number</I></TT></DT>
<DD>
Specifies the driver stratum, in decimal from 0 to 15, with default 0.</DD>
<DT>
<TT>refid <I>string</I></TT></DT>
<DD>
Specifies the driver reference identifier, an ASCII string from one to
four characters, with default <TT>GPS</TT>.</DD>
<DT>
<TT>flag1 0 | 1</TT></DT>
<DD>
Not used by this driver.</DD>
<DT>
<TT>flag2 0 | 1</TT></DT>
<DD>
Assume GPS receiver is on a mobile platform if set.</DD>
<DT>
<TT>flag3 0 | 1</TT></DT>
<DD>
Not used by this driver.</DD>
<DT>
<TT>flag4 0 | 1</TT></DT>
<DD>
Not used by this driver.</DD>
</DL>
Additional Information
<P><A HREF="refclock.htm">Reference Clock Drivers</A>&nbsp;
<HR>
<ADDRESS>
David L. Mills (mills@udel.edu)</ADDRESS>
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