|
The Locosys GT11 is currently the best GPS unit available on the
market today for recording your performances whether they be for
sailing, cycling, running or even flying! The reason is because it
records all doppler related data and GPS accuracy data so that bad
signal data can be identified by RealSpeed.
The GT11 also has a lot of features that make it very nice to use
including the following:
 | Virtually unlimited storage so can record for many months at one
second interval using a 2G SD card. |
| Long battery life so can be left on all day |
| A built in data logger for extra piece of mind that you wont
lose the track points |
| Display of GPS max doppler speed and max average speed over
"N" seconds |
| Ability to record only when moving so avoids recording
unnecessary data |
| Records to very small binary files which are fast to open and
process and easy to email. |
Memory Card (SD Card)
To use the GT11 with RealSpeed is very easy. Simply record the
tracks to the SD card then transfer the SD card to your computer and
open the files using RealSpeed.
The GT11 has some options as to the type of file saved to the
SD card. To configure these in the GT11 go to Memory Card / NMEA
items.
| NMEA files - these are National Maritime Engineers Association
standard text files that contain lines or sentences of information
which have codes to represent what is in each lsentence. To
configure for using NMEA select GGA, GSA, GSV, RMC and VTG to On.
Leave the BIN and ZDA off.
|
| SBN files - these are binary files based on the SiRF protocol so
can be readily created by the GPS. These files are easier to
create for the GPS, easier to read by RealSpeed and much smaller
than NMEA files. To configure the GT11 for producing these SBN
files, select the SBN option to On. This automatically deselects
all the other options. |
The GT11 will also need the following settings to be configured in
order to record to the SD card. These are settings under the Memory
Card options on the GT11:
| Log Switch - this determines if the GPS will record to SD
or not. This setting needs to be On to record all track points
whether it has a fix on the satellites of not. If set to On-Fix
(recommended) the GPS will only record good track points when it
has a fix on the satellites. Set this to Off if you do not wish to
record to SD card. |
| Min Speed - this is a great feature that determines the
minimum speed that the GPS will log track points to file. If you
set this speed to around 5 or 6 knots then only track points with
speeds equal to or faster than this speed will be recorded. This
means the files will be faster to open, faster to calculate, and
faster to display. They also make it easier to analyse. |
| File Size - The GT11 allows large recordings to be broken
into multiple files, but this is not a suitable option for our
purposes. So the setting required is Card Size to ensure that each
recording is done as one continuous file. If for some reason you
have created multiple files for a session, you can still combine
them together using RealSpeed. |
Data Logger
You can record your track points on the GT11 using the internal
Data Logger. This uses an internal flash RAM inside the GPS unit to
record up to 28,672 track points, which is around 8 hours of recording
at 1 second intervals.
However, the data logger also has the ability to record when only
over a specified speed, and this option is highly recommended. The
Data Logger is also a cyclic buffer which means that when it fills up
the space it starts recording from the beginning again. If you
configure the Data Logger with recording only when over say 5 knots,
and when combined with the cyclic buffer it is very unlikely that you
will lose any track points, even when you forget to clear the buffer.
The Data logger options are as follows:
| Interval - for the best results leave this option set to
1 second. |
| Min Speed - as discussed previously the best option here
is to set a suitable minimum speed for your sport. For sailing a
minimum speed of 2 to 5 knots should capture all the detail you
require and avoid recording the walking and waiting on the beach. |
| Data Item - select SBP or SBN to ensure you have the
right format of data. This internal binary format contains all the
data we need for analysis and record breaking, but uses only 32
bytes for each track point. This format when saved to SD has the
SBP extension (SiRF Binary Packed). |
To save the data from the internal Data Logger could not be any
easier. Simply select Save To Card in the Data Logger menu on the
GT11. This creates a file on your SD with the name of the user, the
date and the text DLG_SBN, and has a file extension of .SBP. See below
for a number of files created using both SBN (files recorded directly
to the SD card) and SBP (data recorded on the Data Logger then saved
to SD card) formats.
An alternate method is to use a utility called NaviLink which is
available with a Windows interface or can be used on the command line.
This requires the use of the supplied USB cable and you need to know
the USB port number. See the documentation provided with the GT11 for
more information on this.
Note that RealSpeed does not perform the direct download of data
from the GPS unit via USB.
| 
