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[Sticky] GPS Logger FAQ

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mm_dev
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Is the accellerometer/gyroscope output low-pass filtered prior to AD-conversion? If so, was the cut-off frequency below the Nyquist frequency (half the sampling rate)?

There is an optional low-pass filter for the gyroscope which can be configured using the control protocol. This interacts directly with the gyroscope IC, see section 8.3 in  https://www.sparkfun.com/datasheets/Sensors/Gyro/PS-ITG-3200-00-01.4.pdf  for technical details.

 


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mm_dev
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Obwohl die GPS-LED gelb blinkt zeigt Ihre GPS Logger Software für Latitude, Longitude und Elevation keine validen Werte an. Tilt, Kompass und Druck funktionieren hingegen einwandfrei.

Erst nach mehrmaligem Neustart des Geräts und der Software werden zeitweise wieder Werte empfangen.

Eine gelb blinkende GPS-LED impliziert dass aktuell noch kein ausreichend gutes Signal empfangen wird sondern der Logger noch dabei ist Satelliten zu suchen. Erst wenn die LED grün blinkt ist ein stabiles Signal vorhanden. Dies kann je nach Einsatzort (z.B. in Innenräumen) durchaus einige Minuten dauern.


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mm_dev
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Welche technische Lösung empfehlen Sie, um die aus dem Gerät produzierten Daten aus einem Fahrzeug in Echtzeit an eine Zentrale zu übertragen und sie dort auf einer Karte graphisch als Track darzustellen?

Für einen solchen Einsatzzweck ist das Gerät nicht geeignet.

USB-Streaming erfordert einen lokal angeschlossenen PC auf dem unsere Auswertungssoftware läuft. Diese ist aber nur darauf ausgelegt die Daten lokal darzustellen, eine Echtzeit-Weiterleitung der Daten ist dort nicht vorgesehen. Dies würde ohnehin noch eine entsprechende Mobilfunkanbindung erfordern was zusätzliche Komplikationen mit sich bringen würde.
 
Für eine reine GPS-Überwachung gibt es speziell dafür entwickelte Lösungen, z.B.  https://www.paj-gps.de/gps-tracker-fuer-autos/

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mm_dev
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The GPS functioned normally at first but now when the uSD card is re-inserted, after being formatted using the command prompt in the manual the power LED blinks twice and the unit does not seem to be receiving satellite communication and does not log anything to uSD card.

It sounds like the SD-card was not formatted with the required FAT16 filesystem and therefore cannot be accessed by the logger. It’s possible that some modern operating systems no longer support it directly and you may have to use a third-party application for it.


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mm_dev
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How do I calculate G or m/s^2 from the raw accelerometer data? Do you have a formula I can use?

To get G-forces you have to divide the raw values by 8192.


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mm_dev
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So if I understood well, the logger logs as soon as the two switches (on/off and log_on/off) are on. Since I need a longer logging, I'd like to power it from the USB (e.g. a power bank).

What happens if:

- When the battery is discharged, does the logging start as soon as the USB power is plugged? (both switches are on)

- When the battery is charged, the USB cable comes off, does the device continue logging (using power from the battery)?

- (variation of the previous question) Does it affect the device in any way if the USB power is switched on and off repeatedly?

The logger isn’t powered by the USB directly, it always uses the battery as it may consume slightly more power than some USB ports provide. Charging the battery at the same time over USB will just prolong its endurance. So plugging the USB cable in/out has no direct effect on the operation of the logger.
 
Please note that if both power and log_on switch are set to ON when the logger receives power, it will enter calibration mode rather than start logging. To engage logging you have to actually enable the log_on switch when the logger is already operational.

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mm_dev
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  • Is the GPS logger accessible by 3th party’s?

  • Does it for example supports Microsoft API functionality?

  • Can we access the logger/data by the laptop without running the associate software?

We do not explicitly support any third-party APIs at this time, but the data is streamed/recorded in the standard NMEA0183 format that is supported by basically every GPS hard- or software. Just establishing the communication is tricky, unlike most dedicated GPS devices our Logger requires the PC to send an activation command to transmit data over USB. Also due to the additional sensors with high recording frequency it requires more bandwidth than most other devices and therefore non-standard communication parameters which many third-party applications don’t support.

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mm_dev
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Our lab manager has now had a look at the logger and is struggling to communicate with the device. Can you give some advice which programming language to use to connect to it or even better share some sample code?

The communication with the logger uses the D2XX driver API from FTDI:  https://www.ftdichip.com/Drivers/D2XX.htm
The corresponding driver is installed together with our software. As usual for driver APIs the default programming language to access it is C, but there are also (third-party) wrappers for other languages.
 
Establishing communication involves basically the following steps:
- getting a list of FTDI devices, e.g. using FT_ListDevices()
- check which of the returned device is the logger (checking description or USB product ID)
- establish a communication channel using FT_OpenEx()
- configuring the communiation parameters using FT_SetBaudrate() and FT_SetDataCharacteristics() and FT_SetFlowControl() as outlined in our programming guide
- send commands / receive data using FT_Write() and FT_Read()
- close the communication channel using FT_Close() when done

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mm_dev
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Does the device accept any input? I would need to mark along some concrete checkpoints (timestaps) while using.

The device only has USB as input for some limited configuration and operation control. There is no option to insert checkpoints in the recorded data on the SD-Card.

 

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mm_dev
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I saw that the GPS Logger does have a height sensor. 
 
However in the datasheet, the images show tilt information, roll information but not height information.
Does it give the height value also and do you have a picture to show as an example.

Height information is included as part of the GPS data. Accuracy depends on the quality of the satellite signal.
The logger also includes a pressure sensor which can be used to track elevation changes, but as this influenced heavily by local weather (temperature and pressure) the software doesn’t use it.


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mm_dev
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We are having some trouble with the GPS logger.  The GPS logger is currently able to only go into 1 of 4 states.

State 0: With the logger turned off (logger switch either off or on) and the device plugged into a PC. The logger light is illuminated red constantly. All other lights off. 

State 1: When you turn it on with no SD card in it (logger switched either on or off) and NOT connected to a PC, the power LED is illuminated (green with 1 second/ 1x 0.5 second amber flash) repeating. All other lights are off.

State 2: When you turn it on WITH an SD card inserted (logger switch on or off), The power LED illuminates (green for 1 second/ 2x 0.5 second amber flashes) repeating. All other lights off. 

State 2.2: When you turn it on WITH an SD card inserted (logger switch on or off) While connected to a PC, The power LED illuminates (green for 1 second/ 2x 0.5 second amber flashes) repeating. The Logger Light Illuminates constant red. All other lights off.  A high pitched capacitor audible whine whose frequency and amplitude fluctuate with the pulsations of the power light. 

The GPS logger will NOT exit State 2 under any conditions.

This is a hardware defect. Please return the device for repairs.


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mm_dev
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Was haelt der Logger an Temperaturen aus? Hat er eine Temp Ueberlast eingebaut?

Alleine wegen dem Akku sollte der Logger nicht dauerhaft bei hohen Temperaturen (50°+) benutzt werden, ausserdem können extreme Temperaturen sich auch auf die Sensoren auswirken. Einen Überlastschutz gibt es nicht.

Wie empflindlich ist er auf Vibrationen im Fahrzeug?

Sehr empfindlich.

Habe das Geraet an einem Standard Mobil Phone Charger mit Ihrem USB Kabel geladen.Ladedauer ca 8 H! Was wird fuer einen schnelleren Ladevorgang empfohlen?

Und was fuer eine Powerbank als Ersatz?

Ein USB-3 Anschluss kann evtl. helfen. Und natürlich den Logger ausschalten.

Reicht eine Zigaretten Steckdose im Wagen um laufend zu laden?

Der Logger benötigt mehr Strom als über die USB-Buchse normal aufgenommen werden kann, ein Dauerbetrieb ist daher nicht möglich.

Ist die Batterie einfach entfernbar?

Dazu muss das Gehäuse geöffnet und der Stecker gelöst werden welcher nicht direkt zugänglich ist. Natürlich erlischt die Garantie wenn das Gerät modifiziert wird.


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mm_dev
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What is the content of the $PAAG,DATA,D message only the G,C B and T messages are listed in the programming guide.

The D data sentence is for internal temperature data as specified in the current version of the programming guide: http://dev.aaronia-shop.com/downloads/gps/manuals/gps_logger_programming_guide_en.pdf
This data was not available in the first revisions of the GPS logger therefore it wasn’t mentioned in earlier versions of the programming guide.

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mm_dev
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We have been trying to use another SD card with the device to increase its storage capacity, and have not had a lot of luck.  We have tried various capacities and various formats (fat16, fat32, ntfs).  We even tried a bit for bit copy of the existing card, and cannot get the logger to recognise any cards apart from the one that came with the logger.  Can you shed any light on this?

The logger only supports standard micro-SD cards using the FAT16 file system. It does not support SDHC- or SDXC-cards. Most SD cards available these days are SDHC or SDXC, as standard SD cards can only have a maximum capacity of 2 GB. Also FAT32, NTFS or ExFAT filesystems are not supported.


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mm_dev
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Is there a particular orientation that the GPS logger has to be mounted i.e. horizontal or vertical mounting, to allow the device to work correctly?

The device does not require any specific mounting orientation to work. But of course some the sensor values (like compass and tilt/accelerometer) are all based on the tip pointing forward, so you’ll have to consider that when processing the data.


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