path: root/gpsmon.xml

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<!DOCTYPE refentry PUBLIC 
   "-//OASIS//DTD DocBook XML V4.1.2//EN"
   "docbook/docbookx.dtd">
<refentry id='gpsmon.1'>
<refmeta>
<refentrytitle>gpsmon</refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo class='date'>17 Feb 2009</refmiscinfo>
</refmeta>
<refnamediv id='name'>
<refname>gpsmon</refname>
<refpurpose>monitor and control a SiRF GPS in binary mode</refpurpose>
</refnamediv>
<refsynopsisdiv id='synopsis'>

<cmdsynopsis>
  <command>gpsmon</command>  
      <arg choice='opt'>-h </arg>
      <arg choice='opt'>-v </arg>
      <arg>-F <replaceable>control-socket</replaceable></arg>
      <arg choice='opt'>
	<group>
	  <arg choice='plain'>
            <replaceable>server</replaceable>
            <group> 
	      <replaceable>:port</replaceable> 
              <group><replaceable>:device</replaceable></group>
            </group>
          </arg>
          <arg choice='plain'><replaceable>device</replaceable></arg>
        </group>
      </arg>
</cmdsynopsis>
</refsynopsisdiv>

<refsect1 id='description'><title>DESCRIPTION</title>

<para><application>gpsmon</application> is a monitor that watches
packets coming from a GPS and displays them along with diagnostic
information. It supports commands trhat can be used to tweak GPS
settings in various ways; some are device-independent, some vary
with the GPS chipset type.</para>

<para><application>gpsmon</application> accepts an -h option that
displays a usage message, or a -v option to dump the package
version and exit.</para>

<para>This program may be run in either of two modes, as a client for
the <application>gpsd</application> daemon (and its associated control
socket) or directly connected to a specified serial device.  When run
with no argument, it attempts to connect to the daemon.  If the
argument looks like a server:port specification it will also attempt
to connect to the daemon.  If the argument looks like a bare server
name it will attempt to connect to a daemon running on the default
gpsd port on that server.  Only if the device argument contains
slashes but no colons will it be treated as a serial device for direct
connection. In direct-connect mode <application>gpsmon</application>
will hunt for a correct baud rate and lock on to it
automatically.</para>

<para>The -F option is only valid in client mode; it specifies a
control socket to which the program should send device control
strings.  You must specify a valid pathname of a Unix-domain socket on
your local filesystem.</para>

<para>The -D option enables packet-getter debugging output and is
probably only useful to developers of the GPSD code.  Consult the
packet-getter source code for relevant values.</para>

<para>After startup, the top part of the screen reports the contents
of several especially interesting packet types.  The bottom half of
the screen is a scrolling hex dump of all packets the GPS is issuing.
Dump lines beginning &gt;&gt;&gt; represent control packets sent to the
GPS.</para>

<para>At SiRF firmware level 231, the "UTC" time displayed is not real
UTC, as it is not leap-second-corrected.  This is due to an inadequacy 
in the SiRF firmware.</para>

<para>To interpret what you see, you will need a copy of the
<citetitle>SiRF Binary Protocol Reference Manual</citetitle>.</para>

</refsect1>
<refsect1 id='commands'><title>COMMANDS</title>

<para>The following device-independent comands are available while 
<application>gpsmon</application> is running:</para>

<variablelist>

<varlistentry>
<term>c</term>
<listitem>
<para>Send hex bytes to device. Following the 'c' you may type hex
digit pairs; end with a newline.  These will become the payload of a
control packet shipped to the device.</para>
</listitem>
</varlistentry>

<varlistentry>
<term>i</term>
<listitem>
<para>Enable/disable subtype probing and reinitialize the driver. In
normal operation, <application>gpsmon</application> does not send
configuration strings to the device (except for wakeup strings needed
to get it to send data, if any). The command 'i1' causes it to send
the same sequence of subtype probes that
<application>gpsd</application> would.  The command 'i0' turns off
probing; 'i' alone toggles the bit. In either case, the current driver
is re-selected; if the probe bit is enabled, probes will begin to be
issued immediately.</para>

<para>Note that enabling probing might flip the device into another
mode; in particular, it will flip a SiRF chip into binary mode as if
you had used the <quote>n</quote> command.  This is due to a
limitation in the SiRF firmware that we can't fix.</para>
</listitem>
</varlistentry>

<varlistentry>
<term>l</term>
<listitem>
<para>Toggle packet logging. If packet logging is on, it will be
turned off and the log closed.  If it is off, logging to the filename
following the l will be enabled.  Differs from simply capturing the
data from the GPS device in that only whole packets are logged.
The logfile is opened for append, so you can log more than one
portion of the packet stream and they will be stitched together
correctly.</para>
</listitem>
</varlistentry>

<varlistentry>
<term>n</term>
<listitem>
<para>With an argument of 0, switch device to NMEA mode at current
speed; with an argument of 1, change to binary (native) mode. With no
argument, toggle the setting. Will show an error if the device doesn't
have such modes.</para> <para></para>
</listitem>

<varlistentry>
<term>q</term>
<listitem>
<para>Quit <application>gpsmon</application>.  Control-C, or whatever
your current interrupt chracter is, works as well.</para>
</listitem>
</varlistentry>

</varlistentry>
<varlistentry>
<term>s</term>
<listitem>
<para>Change baud rate. Follow it with a number interpreted as bits
per second, for example "s9600".</para>
</listitem>
</varlistentry>

<varlistentry>
<term>Ctrl-S</term>
<listitem>
<para>Freeze display, suspend scrolling in debug window.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Ctrl-Q</term>
<listitem>
<para>Unfreeze display, resume normal operation.</para>
</listitem>
</varlistentry>
</variablelist>

<para>The following commands are supported for SiRF GPSes only:</para>

<variablelist>
<varlistentry>
<term>A</term>
<listitem>
<para>Toggle reporting of 50BPS subframe data.</para>
</listitem>
<varlistentry>
<term>M</term>
<listitem>
<para>Set (M1) or clear (M0) static navigation. The SiRF documentation
says <quote>Static navigation is a position filter designed to be used
with motor vehicles.  When the vehicle's velocity falls below a
threshold, the position and heading are frozen, and velocity is set to
zero. This condition will continue until the computed velocity rises
above 1.2 times the threshold or until the computed position is at
least a set distance from the frozen place. The threshold velocity and
set distance may vary with software versions.</quote></para>

<para>Non-static mode is designed for use with road navigation
software, which often snaps the reported position to the nearest road
within some uncertainty radius.  You probably want to turn static
navigation off for pedestrian use, as it is likely to report speed
zero and position changing in large jumps.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>P</term>
<listitem>
<para>Toggle navigation-parameter display mode.  Toggles between
normal display and one that shows selected navigation parameters from
MID 19, including the Static Navigation bit toggled by the 'M' command.</para>
</listitem>
</varlistentry>
</variablelist>

</refsect1>
<refsect1 id='files'><title>FILES</title>

<variablelist>
<varlistentry>
<term><filename>/var/run/gpsd.sock</filename></term>
<listitem>
<para>The default location of the control socket.</para>
</listitem>
</varlistentry>
</variablelist>

</refsect1>
<refsect1 id='bugs'><title>BUGS AND LIMITATIONS</title>

<!--
Debug window dumps of control message sends to the GPS (preceded
by '>>>') are only supported for the following drivers: NMEA, SiRF,
EverMore, Navcom, UBX, TSIP, iTalk, Garmintxt. This feature will not
work for Zodiacs and not always work for Garmins in binary
mode.
--> 

<para>This tool used to be called 'sirfmon', and worked only on
SiRF devices (and the command set has changed to resemble the command
switches of <command>gpsctl</command>). It now has support for generic
NMEA devices; support for other device types is a work in progress. It
will behave sanely, just dumping packets, when connected to a GPS type
it knows nothing about.</para>

</refsect1>
<refsect1 id='see_also'><title>SEE ALSO</title>
<para>
<citerefentry><refentrytitle>gpsd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gps</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>libgps</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>libgpsd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gpsprof</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gpsfake</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gpsctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>gpscat</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
</refsect1>

<refsect1 id='maintainer'><title>AUTHOR</title> 

<para>Eric S. Raymond <email>esr@thyrsus.com</email>.  This code is
part of the gpsd toolset; there is a project page for
<application>gpsd</application> <ulink
url="http://gpsd.berlios.de/">here</ulink>.</para>
</refsect1>

</refentry>