Here you will find informations about the GPSResults-program, which allows to evaluate
GPS-data (trackpoints) with respect to the achieved speed, how you can read the measured
data from your GPS, and how to download a free trial-version of the GPSResults-program.
The GPSResults program can be used to calculate and evaluate the track-velocities
from measured GPS-data.
Download and save your GPS-data in gpx-format
First of all the data (trackpoints) have to be read from your GPS, transferred to
your computer, and saved as gpx-file. The trackpoints can be downloaded from the
GPS directly using GPSResults (only for Garmin Geko 201, Foretrex 101 oder Foretrex
201: File - Download Trackpoints from GPS ...: select COM-Port, press Read Trackpoints
and finally save as gpx-file). For the Garmin eTrex Legend C with USB interface there
is also the option USB for a much faster download od the trackpoints directly via
the USB-port. Don´t use this option if you use an USB-serial-adaptor!
Alternatively the freeware program g7towin can be used (e.g. for GPS devices not
supported by GPSResults), it can be downloaded from the internet.
After starting GPSResults you can open and read one or several gpx-files that have
been transferred from your GPS and saved using g7towin. In the File-menu click Open...
and select the data files to be loaded. If several files shall be loaded select them
sequentailly with the Ctrl-Button pressed or select a whole range with the Shift-button
pressed (select last file first and then the first file of the range with the Shift-button
pressed). Press the Open button after selection of the filenames.
Evaluation of the GPS-data
All selected files (four in this example) are loaded into the programm, the Trackpoints
are displayed in the right panel and the evaluation is performed for all selected
Tracks that are contained in the data files. Tracks can be selected/deselected in
the uppermost section.
The Tracks consist of Tracksegments which can be selected/deselected in the second
section of the left panel.
Finally the Tracksegments contain Trackpoints which are displayed in the third section
of the left panel. In the lower half of the left panel the up to ten best results
of the actual evaluation are shown, the mode can be adjusted by the checkboxes and
radio buttons in the upper half of this section:
Interpolation: With this checkbox the selected track- or time-lengths will be interpolated
exactly from the GPS-data, leading to more accurate and often slightly improved results. When
Lin. Interpolation is switched off the track- or time-segments will be added conventionally
until the selected value is reached. For example with 2sec measuring intervals the
average of 6sec-segments will be used for the 5sec measure. The same is true for
e.g. the 500m selection where the average over at least 500m will be used (the really
travelled distance is displayed as second number in best five list). When Lin. Interpolation
is switched on, the average speed of the exact track- or time-lengths is computed
by linear interpolation of the first or last tracksegment, depending on which piece
was the slower one. Thus, only as much as necessary of the slower interval is used.
In most cases this leads to slightly better average speeds. Only in cases where e.g.
the first and the last sections were faster then the middle sections, the conventional
method gives better, but more inaccurate averaged results, since then the average
of the longer distance is better than the average of the really wanted distance.
Projection controls projection of the travelled distance to a straight line instead
of using the really travelled distance for speed computations (with and without linear
interpolation). Results in slightly slower speeds because the travelled distance
is in general longer than the projected distance.
Altitude With this checkbox the often rather inaccurate elvation measurements of
the GPS can be ignored for the evaluation (mostly results in rather small differences).
One/Leg: shows one result per run only. Run start and end are defined by velocities
below 8knots (defined in the Limits-section) or direction changes larger than 90degrees
in 20seconds (not possible together with Gates or Max.).
min. Sats: minimum number of satellites (NMEA-data or GPX-data with these informations
only). Invalid trackpoints are not considered during the evalution of speeds and
are shown with a red background in the trackpoints-list.
max. HDOP: maximum HDOP (horizontal dilution of position -NMEA-data or GPX-data
with these informations only). Invalid trackpoints are not considered during the
evalution of speeds and are shown with a red background in the trackpoints-list.
max. m/s²: Maximum Acceleration [m/s²] determines the maximum allowed acceleration
in m/s², it is useful to suppress outliers (spikes) in the GPS-data. The affected
trackpoints will not be deleted, but just ignored during the speed computations.
The default value of 3m/s² can be lowered until all spikes are vanished.
Gates shows the best speeds within the gates for all trackpoints of the selected
Tracks/ Tracksegments with the corresponding times. See below howto determine the
Max. shows the best speeds from all trackpoints of the selected Tracks/Tracksegments
and the corresponding times.
100m / 250m / 500m / 1852m shows the best speeds over at least 100m/250m/500m/1852m
from all trackpoints of the selected Tracks/Tracksegments with the corresponding
2sec / 10sec / 20sec / 1min / 1hour shows the best speeds over at least 2sec, 10sec,
20sec, 1min or 60min from all trackpoints of the selected Tracks/Tracksegments with
the corresponding times .
Average: shows the average of best and second best speed
Average: shows the average of best five velocities (results in lowest row without
Play>, Stop, < Play, adjustable delay time, and Tracks can be used to replay or reverse
replay of the trackpoints. The start timepoint has to be selected first by clicking
into the lower right window (speed over time).
If any of the result rows is clicked with the left mouse button, the corresponding
trackpoints are connect by bold orange lines und the corresponding times are highlighted
by red vertical lines in the lower right panel. Furthermore the corresponding trackpoints
in the trackpoint list are highlighted.
The display of the tracks is automatically scaled to fit the upper right window area,
the Zoom factor can be adjusted by the mouse wheel or the + und - keys. The whole
window content can be shifted by dragging with the right mouse button pressed or
by using the arrow keys (press Shift & arrow keys simultaneously).
In the lower right section the speed is display over the time. If one clicks with
the left mouse button into this part of the window, the corresponding time is selected,
the trackpoints are highlighted and shown as bold lines. The B- and N- keys can be
used to jump the previous or next timepoint.
Display all results
Show Bestspeed List ... displays all results in a separate resizable dialog window:
Determine Gates for setting a defined measuring track
There are several possibilities to define a certain measuring area (track) where
for example the speeds of all competitors are evaluated and a ranking list is computed.
Pressing ‚Shift’ and clicking with the left mouse button into the main window sets
the fist gate (start gate). A small blue rectangle appears that defines the middle
of the start gate. The second Shift & left click defines the finish gate (red rectangle).
Both gate positions can be modified by dragging the rectangle symbols with ‚Shift’
and the left mouse button pressed. The gate positions define the center line of the
measuring area (dashed rectangle), the Tracklength can be adjusted from 100 to 1852m,
the Gatewidth can be set from 10 to 100m. Both options can be found under Extras:
In order to compute the average velocity between the gates the intersections of the
trackpoint- and the gates-lines are determined (pink circles, see below). From the
intersections the start- and finish times are computed by linear interpolation, assuming
a constant speed between consecutive trackpoints. Finally the average speed between
the gates is determined from the given tracklength and the time-difference. The really
travelled distance is at least the tracklength and is shown in brackets in the result
file (see below). If the gate lines are not crossed, if the course is surfed in the
wrong direction or left between the gates, no results are computed.
The gate positions, track length and width, magnification and shift can be saved
to (Save Gates ...) and retrieved from (Load Gates ...) a text file. For the example
data (pier in Grossenbrode-Germany) 119_150904.gpx there is a corresponding gates
When both gate positions are set, an evaluation of all trackpoints is performed and
the result is displayed in the lowest part of the left panel. Again the average of
the two best speeds and both best speeds with times are shown.
both gate positions can also be determined by measured Waypoints. The waypoints have
to be read from your GPS and saved as gpx-file (see above). Load the file by clicking
Extras, Load Waypoints ... and select start and finish gate positions (press OK to
actually use the selected positions):
Both gates can be reset by selecting Delete Gates.
Set Timelimits ... resctricts all evaluations to a certain time range (for example
90min sessions in speed surfing competitions, Cancel resets the timelimits):
Finally the ranking list from several imported gpx-files can be displayed by selecting
Show Ranking.The list can be saved for further processing with Save Results ....
All evaluations (runs within the gates) and the ranking list can be saved as text
file using this option (see below).
Content of a saved result file (Save Results ...), if Gates were defined and selected
(otherwise the results of the Best Speed List (see above) are saved e.g. for printing
or further processing), in parenthesis one can also see the actually travelled distance
between the gates and the corresponding speed:
Mit Show Polar Diagram... displays the directions and the velocities of all runs
on a compass rose. Runs from different tracks are displayed in different colors.
represents an approximation to the wind direction:
Load Background-Image... loads maps as background image. The maps are adjusted (coregistered)
by the content of another file with the same basename as the *.jpg or *.bmp-imagefile
and extension "*.cor". For example PSL.bmp and PSL.cor. If the *.cor-file does not
exist, the image will be displayed with its origin in the upper left corner. The
trackpoints have to dragged and scaled (the bmp-image can also be scaled, see Help-window
below), until everything fits.
After correct alignmant of the background image, press Ctrl & F in order to save
the shift and zoom-parameters to the *.cor-file. Next time te image data are loaded,
the corresponding *.cor-file will be read automatically and the alignment is restored.
There are cases where the maps are distorted by projection and have to be differently
scaled in x- and y-direction. This can be done by using e.g. the freely available
image processing tool `Irfanview´ (it can scale both directions independently e.g.
x by 85%, y unchanged (100%)).
Maps can be found in the Internet and screenshots can be made (Alt + PrtSc), processed
(e.g. clipped (Ctrl + Y) or merged to form a panorma view) by Irfanview, and finally
saved as jpg-file.
Help displays the program version and the machine number of your computer. The machine
number is necessary to get an unlimited version of the program after the free 30
days trial period. For further informations, comments, and suggestions please contact: