diff options
Diffstat (limited to 'gpsprof.xml')
| -rw-r--r-- | gpsprof.xml | 67 |
1 files changed, 8 insertions, 59 deletions
diff --git a/gpsprof.xml b/gpsprof.xml index a46a9b53..0daa841e 100644 --- a/gpsprof.xml +++ b/gpsprof.xml @@ -34,12 +34,12 @@ BSD terms apply: see the file COPYING in the distribution root for details. <refsect1 id='description'><title>DESCRIPTION</title> -<para><application>gpsprof</application> measures the various -latencies between a GPS and its client. It emits to standard output a -GNUPLOT program that draws an illustrative graph. It can also be told -to emit the raw profile data. The information it provides can be -useful for establishing an upper bound on latency, and thus on -position accuracy of a GPS in motion.</para> +<para><application>gpsprof</application> performs accuracy and latency +profiling onm a GPS. It emits to standard output a GNUPLOT program +that draws an illustrative graph. It can also be told to emit the raw +profile data. The information it provides can be useful for +establishing an upper bound on latency, and thus on position accuracy +of a GPS in motion.</para> <para><application>gpsprof</application> uses instrumentation built into <application>gpsd</application>.</para> @@ -77,60 +77,9 @@ This is the default.</para> <listitem> <para>Plot total latency without instrumentation. Useful mainly as a check that the instrumentation is not producing significant -distortion. It only plots times for sentences that contain fixes; +distortion. It only plots times for reports that contain fixes; staircase-like artifacts in the plot are created when elapsed time -from sentences without fixes is lumped in.</para> -</listitem> -</varlistentry> -<varlistentry> -<term>raw</term> -<listitem> -<para>Plot raw data.</para> -</listitem> -</varlistentry> -<varlistentry> -<term>split</term> -<listitem> -<para>Each sentence has its RS232 latency time colored differently.</para> -</listitem> -</varlistentry> -<varlistentry> -<term>cycle</term> -<listitem> -<para>Report on the set of sentences or packets emitted by the GPS, -their send intervals, and the basic cycle time. (This report is -plain text rather than a gnuplot script.)</para> -</listitem> -</varlistentry> -</variablelist> - -<para>The instrumented time plot conveys the following information:</para> - -<variablelist> -<varlistentry> -<term>RS232 time</term> -<listitem> -<para>Time required to send the sentence from the GPS to -<application>gpsd</application>. This measured from the time of -the last zero-length read before the packet to when the packet sniffer -recognizes a complete sentence, so there is a small amount of -computational overhead mixed in.</para> -</listitem> -</varlistentry> -<varlistentry> -<term>Decode time</term> -<listitem> -<para>Elapsed time between sentence reception and the moment that -<application>gpsd</application> ships the resulting update to -the profiling client.</para> -</listitem> -</varlistentry> -<varlistentry> -<term>TCP/IP latency</term> -<listitem> -<para>Elapsed time between the moment that -<application>gpsd</application> ships the update to -the profiling client and the moment it is decoded and timestamped.</para> +from reports without fixes is lumped in.</para> </listitem> </varlistentry> </variablelist> |