Page | 10 Revision 1.4 15 January
2015
Record operation in detail
LabSat 3 uses SD card and HDD memory for storage and playback of GNSS data. It is important to note that
Class 10 or higher cards must be used to sustain the transfer speeds required. When recording two
constellation types, the data rate is approximately 8.2MB (Mega Bytes) per second. To ensure that data is
collected without error, the card should be able to sustain 10MB per second. Spare cards and HDDs may be
purchased from Racelogic.
It is important that cards are formatted as FAT32. LabSat 3 is able to format cards and HDDs in FAT32 with
the optimum configuration for high speed recording. When a card or HDD is formatted by LabSat 3, it will
also carry out a performance test to determine whether or not the media can sustain the required
bandwidth and inform the user if this is not the case.
For record capable systems, the LabSat will be supplied with a magnetic mounting GNSS antenna. The
antenna is an active device with approximately 28dB of gain. The LabSat provides a 2.85V DC bias for
antenna power on the centre pin of the RF IN connector. It is also possible to use third party antennas
providing they are compatible with the 2.85V bias. If connecting LabSat to an antenna which requires a
higher bias voltage (e.g. 12v), the antenna bias must be supplied by the user and an appropriate DC block
(such as DCB from
http://gpsnetworking.com/attenuators.asp
) must be inserted at the LabSat 3 RF IN
connector to avoid damage to the LabSat.
There are a number of GNSS systems currently in operation or in a test phase. These operate on 3 main
frequency bands. These are:-
Depending on the model, LabSat 3 will have 1, 2 or 3 RF channels. This allows recording of 1, 2 or 3
frequency bands so, for example, a 2 constellation LabSat 3 may record the band containing GPS L1/Galileo
E1 and the band containing GLONASS L1 simultaneously. Recording of the desired constellations is
configured in the CONSTELLATION menu. In this menu, the user can tick up to three of the desired
constellation groups (depending on version). If only one constellation is ticked, then an additional option
for 2bit will be available to allow 2bit quantized recording for the selected constellation.
Once the constellations are configured, exit the menu and press the REC button to begin recording. A new
file will be created each time recording starts. The file name used corresponds to the constellations
selected. For example, if GPS and GLONASS are selected for recording, the file created will be GPSGLO_nnn
where nnn is a number that increments with each new recording. Details of the LS3 file format are
available on request from Racelogic.
During recording, pressing the OK button will switch the display to show satellite levels for either GPS or
GLONASS satellites. In this display mode, the up and down arrow keys will toggle between GPS or GLONASS
constellations. BeiDou constellation is not currently supported by the internal monitor but BeiDou B1
signals can still be recorded and replayed.
To maximize battery life during recording, LabSat 3 has a power save mode which is enabled by default I n
the setup menu. Power save mode recognizes when running from battery power and will dim the display
backlight and power-down the internal GPS/GLONASS monitor after 30 seconds of user inactivity.
If recording from passive antennas such as the Maxtenna M1516HCT-SMA GPS/GLONASS antenna, enabling
the power-save mode will also provide the highest possible sensitivity by ensuring that unused modules
within LabSat 3 are switched off.
Frequency Band
Constellations
1575.42MHz
GPS L1, Galileo E1, QZSS, SBAS
1602MHz
GLONASS L1
1561.098
BeiDou B1
