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RACELOGIC Support Centre

05 - LabSat 3 Recording and Replaying


LabSat 3 units use an SSD Drive or SD cards to record and playback GNSS data.

We recommend that you use an SSD Drive (such as the LS03WSSD-1TB) to record and replay GNSS data. This is to make sure that you get the best and most stable data transfer possible. 

LabSat 3 Triple Constellation Variant

If you need to use an SD card, it is important to note that due to the high-speed transfer rates and data transfer methods used by the LabSat 3 Triple Constellation variant, specific SD cards are required, such as SanDisk Extreme Pro 32 GB (RLACS352)


If you get a Buffer Overflow message when you are recording large amounts of data, your SD card is not able to sustain the data transfer. In this case, you can either use another SD card that is compatible with larger data transfers or you can use a high-speed SSD Drive.


  • SD cards used with Racelogic products must be formatted as FAT32. LabSat 3 can format cards and HDD units to FAT32 with the optimum configuration for high-speed recording.  When LabSat 3 formats a card or HDD unit, it will also carry out a performance test to determine whether or not the media can sustain the required bandwidth. If it determines that the card is unsuitable it will display a warning message. 
  • You can purchase these SSD Drives and SD cards directly from Racelogic.

For record-capable systems, the LabSat will be supplied with a magnetic mounting GNSS antenna. The antenna is an active device with approximately 28 dB of gain.  The LabSat provides a 2.85 V 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 2.85 V bias.  If connecting LabSat to an antenna which requires a higher bias voltage (e.g. 12 V), the antenna bias must be supplied by the user and an appropriate DC block (such as DCB from must be inserted at the LabSat 3 RF IN connector to avoid damage to the LabSat.

Frequency Bands

There are several GNSS systems currently in operation or in a test phase. These operate on 3 main frequency bands.

Frequency Band Constellations
1575.42 MHz GPS L1, Galileo E1, QZSS, SBAS
1561.098 BeiDou B1

Depending on the model, LabSat 3 will have 1, 2 or 3 RF channels. This allows recording of 1, 2 or 3 frequency bands.

For example, a 2-constellation LabSat 3 may record the band containing GPS L1/Galileo E1 and the band containing GLONASS L1 simultaneously. 

You can configure the recording of the desired constellations in the CONSTELLATION menu. You can select up to three of the desired constellation groups (depending on the version you have). If you only select one constellation, an additional option for 2-bit will be available to allow 2-bit quantised recording for the selected constellation.

When you have configured the constellations, you can exit the menu and press the REC button to begin recording. The unit will create a new file each time it starts recording. The file name will correspond to the selected constellations. 

For example, if you have selected GPS and GLONASS for recording, the file will be named GPSGLO_nnn where nnn is a number that increments with each new recording.  You can get further details of the LS3 file format on request from Racelogic.

If you press the OK button while the unit is recording, it will switch the display to show satellite levels for either GPS or GLONASS satellites. In this display mode, you can use the UP/DOWN buttons to toggle between GPS or GLONASS constellations. The BeiDou constellation is not currently supported by the internal monitor, but you can still record and replay BeiDou B1 signals.

Battery Life

To maximise battery life during recording, LabSat 3 has a power-save mode enabled by default. You can change this setting in the setup menu. The power-save mode recognises when the unit is 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 you are recording from passive antennas, such as the Maxtenna M1516HCT-SMA GPS/GLONASS antenna, having the power-save mode enabled will also provide the highest possible sensitivity by ensuring that unused modules in LabSat 3 are switched off.


LabSat 3 uses SD card or HDD memory for storage and playback of GNSS data. You must use SD cards of Class 10 or higher to sustain the required transfer speeds. We recommend SanDisk Extreme Class 10 cards for the best performance.

The 1 TB USB HDD supplied contains a selection of pre-recorded scenarios from around the world. These scenarios can easily be copied to the SD card for replay. The HDD supports either USB 2.0 or USB 3.0. For optimum data transfer performance from an HDD to an SD card, we recommend that you use a PC that supports USB 3.0.

The RF OUT connector is a 50 Ω output which can be connected directly to the antenna input of the GNSS receiver being tested. The RF OUT connector of LabSat 3 is DC blocked internally so almost any device can be connected to this port. When a file is selected for replay, the LabSat will configure constellation frequencies and digital channels automatically before starting replay. If a triple constellation file is selected for replay on a single channel LabSat, all three constellations will be displayed before replay allowing the user to select one.

During replay, pressing OK will show a live histogram of satellite levels detected by the internal GNSS receiver. The internal receiver currently only supports GPS and GLONASS constellations. This does not affect the LabSat 3 unit's ability to record or replay BeiDou signals. When displayed, the UP/DOWN buttons switch between GPS and GLONASS monitor modes. Please note that when switching between GPS and GLONASS display modes, the internal receiver will take some time to re-acquire satellite signal levels.  In the case of GLONASS signals, it may take over a minute to show the satellite signal information.

LabSat 3 comes with an internal 31 dB attenuation capability. To increase the attenuation press the up arrow, this will increase the attenuation by 1 dB. The down arrow will decrease the attenuation level.

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