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| author | Eric S. Raymond <esr@thyrsus.com> | 2009-03-07 15:32:23 +0000 |
|---|---|---|
| committer | Eric S. Raymond <esr@thyrsus.com> | 2009-03-07 15:32:23 +0000 |
| commit | 0f3dfccad575ac35ef0c41beb3c6340c1b2d1939 (patch) | |
| tree | 3ffde35783e7d84a842f61597bca19992a551038 /gpsd.xml | |
| parent | 964fa5d02a151ed772a7eb36df0543fa98b9ab39 (diff) | |
| download | gpsd-0f3dfccad575ac35ef0c41beb3c6340c1b2d1939.tar.gz | |
.cycle_chars is gone, replaced by min_cycle.
Diffstat (limited to 'gpsd.xml')
| -rw-r--r-- | gpsd.xml | 37 |
1 files changed, 33 insertions, 4 deletions
@@ -291,9 +291,9 @@ channel.</para> <para>If the driver has the capability to change sampling rate, this command always returns "C=%f %f" giving the current cycle time in -seconds and the minimum possible cycle time at the current baud rate. -If the driver does not have the capability to change sampling rate, -this returns, as "C=%f", the cycle time in seconds only.</para> +seconds and the minimum possible cycle time. If the driver does not +have the capability to change sampling rate, this returns, as "C=%f", +the cycle time in seconds only.</para> <para>Either number may be fractional, indicating a GPS cycle shorter than a second; however, if >1 the cycle time must be a whole number. Also @@ -305,7 +305,36 @@ this works.</para> first full packet has been received from the GPS, because the GPS type is not yet known. To set up conditions for a real answer, issue it after some command that reads position/velocity/time information from the -device.</para></listitem> +device.</para> + +<!-- +<para>The second field of the C return may be 0, indicating no hard +lower limit on the cycle time. On an NMEA device of this kind it is +possible to try to push more characters through per cycle than the +time to transmit will allow. You must set the time high enough to let +all sentences come through. Here are the maxima to use for +computation:</para> + +<table frame='all'> +<tgroup cols='2'> +<tbody> +<row><entry>ZDA </entry><entry>36</entry></row> +<row><entry>GLL </entry><entry>47</entry></row> +<row><entry>GGA </entry><entry>82</entry></row> +<row><entry>VTG </entry><entry>46</entry></row> +<row><entry>RMC </entry><entry>77</entry></row> +<row><entry>GSA </entry><entry>67</entry></row> +<row><entry>GSV </entry><entry>60 (per line, thus 180 for a set of 3)</entry> </row> +</tbody> +</tgroup> +</table> + +<para>The transmit time for a cycle (which must be less than 1 second) +is the total character count multiplied by 10 and divided by the baud +rate. A typical budget is GGA, RMC, GSA, 3*GSV = 82+75+67+(3*60) = +404.</para> +--> +</listitem> </varlistentry> |