path: root/sirfmon.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE refentry PUBLIC 
   "-//OASIS//DTD DocBook XML V4.1.2//EN"
   "docbook/docbookx.dtd">
<refentry id='sirfmon.1'>
<refmeta>
<refentrytitle>sirfmon</refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo class='date'>23 Mar 2005</refmiscinfo>
</refmeta>
<refnamediv id='name'>
<refname>sirfmon</refname>
<refpurpose>monitor and control a SiRF GPS in binary mode</refpurpose>
</refnamediv>
<refsynopsisdiv id='synopsis'>

<cmdsynopsis>
  <command>sirfmon</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>sirfmon</application> is a monitor that watches
packets coming from a SiRF GPS (the SiRF chipset is the one by far the
most commonly used in GPS mice and other consumer-grade GPSes, about
80% of them and rising in early 2005).  This program is primarily
useful as a diagnostic aid for troubleshooting
<application>gpsd</application> problems; it deliberately uses decoder
logic that different from the decoder in the
<application>gpsd</application> SiRF driver, so behaviors that show up
in both are unlikely to be due to logic bugs in either.</para>

<para><application>xgps</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>sirfmon</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> You will probably need to be root to run this program, as the
serial devices and control socket it uses are normally
privileged.</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 comands are available while 
<application>sirfmon</application> is running:</para>

<variablelist>
<varlistentry>
<term>n</term>
<listitem>
<para>Switch device to NMEA mode at current speed and exit.</para>
<para></para>
</listitem>
</varlistentry>
<varlistentry>
<term>b</term>
<listitem>
<para>Change baud rate.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>c</term>
<listitem>
<para>Set (c1) or clear (c0) 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 lsrge jumps.</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>s</term>
<listitem>
<para>Send hex bytes to device. Following the 's' you may type hex
digit pairs; end with a newline.  These will become the payload of a
SiRF control packet shipped to the device.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>t</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 'c' command.</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>

</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>

<para>The logic for hunting the GPS's baud rate is vulnerable to
various sorts of RS232 flakiness. If it hangs for longer than a few
seconds, kill the program and restart.</para>

</refsect1>
<refsect1 id='see_also'><title>SEE ALSO</title>
<para>
<citerefentry><refentrytitle>gpsd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>xgps</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>gnuplot</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
</refsect1>

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

<para>Eric S. Raymond <email>esr@thyrsus.com</email>, based on code
originally by Rob Janssen, PE1CHL.  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>