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Settings - GPS and other peripheral devices

GPS

This page is used for entering the connection information for the primary GPS device used by Cumulus for navigation. Please refer to your GPS manual for these connection values. Cumulus can also accept and process data from other peripherals such as Cambridge, Volkslogger, Flarm or LX Navigation.

Under Android this page is nearly empty. Please use the Android menu key to switch on/off your desired GPS device.

Cumulus can provide you with some status information concerning your GPS reception. If you want to know what satellites are in view, where they are, how strong their signal is, or if you want to take a look at the raw NMEA stream of your GPS, use the G key or click on the GPS status indicator in the status bar. This will open a status dialog for the GPS. The dialog can be closed with the "close" button.

GPS Device
In the combo box you can select the connection type to be used for your GPS or peripheral connection. The following alternatives are available:

Item Description
GPS Location only for using the Location Service provided by the Internet Tablets N8x0/N900. Users of the N8x0 or N900 can make use of the option in the tablet's own Settings/Control panel/GPS location to use either the built-in GPS receiver or an external Bluetooth GPS device.
BT Adapter for direct connection to an external Bluetooth device. In this case Cumulus will automatically scan your environment for a reachable device, and, if it finds one, will open up a combo box dialog from which you can make the appropriate selection. A wrong selection will mean that you will have to restart Cumulus!
/dev/ttyUSB0 for a USB GPS device or, e.g., a USB-serial adaptor
/tmp/nmeasim for the Cumulus NMEA Simulator

Serial devices and RS232-USB adapters also need to be given a speed rate for their operation. The default serial NMEA connection speed is 4800 bps but we recommend always to use the maximum supported speed.

If your device is not found in the selection list, you can change one of the predefined entries to what you need, e.g. /dev/ttyS0 for an RS232 serial device or /dev/rfcomm0 for a Bluetooth device.

Speed (bps):
This will have the greyed-out default value unless e.g. the connection selected above is to a device whose speed can be manually set.
Altitude Reference
Item Description
GPS The default selection is GPS. Most GPS devices send MSL (mean sea level) altitudes, but some send HAE (Height above ellipsoid).
Pressure Some logger devices can deliver altitude values derived from a pressure sensor. If you want to use these pressure data, select this alternative.
Please note! If you have selected the pressure item, Cumulus expects to receive the appropriate NMEA records from the connected peripheral device. Without these you will not get any altitude data displayed at all, nor will you get a variometer reading, unless this information is supplied separately by the peripheral!

If your displayed altitude always deviates by a constant factor from the expected value, you can correct this in the altitude dialog. This is opened by tapping on the altitude display in the map view. Add your correction value in the spin box labelled "Leveling". Positive values will be added to and negative values subtracted from the delivered altitude value. For pressure values, the correction will be applied immediately. For GPS values, the correction will only be applied when a GPS fix is established.

Processed data from supported devices

Cumulus processes additional data from the devices listed below, if they are connected, but only if the data sentences have a valid checksum. Data from external devices are the first choice for Cumulus before its own calculation is started. This means that the wind, variometer and MacCready data from these peripheral devices will be accepted and used automatically, if they are available. The MSL and STD altitudes derived from a pressure sensor, however, are only made use of if specifically asked for, i.e., "Pressure" must be selected in the menu.

Device Processed data
Cambridge This can deliver altitude values (MSL and STD) derived from a pressure sensor. Cumulus also uses the QNH, wind and McCready data from the Cambridge !w proprietary sentence (see below).
Volkslogger This can deliver the STD altitude derived from a pressure sensor. To get the right MSL altitude, you have to set the correct QNH value in the Cumulus Preflight Settings/Common or in the altitude dialog. Furthermore, in the Volkslogger setup menu, you have to enable the sending of PGCS records.
LX Navigation This can deliver altitude values derived from a pressure sensor and wind data. Some devices can also deliver McCready and variometer data. Enable the sending of LXWP records in the LX setup menu, as follows (e.g. on an LX20 device you will have to enter the password - the default is 96990): go to the NMEA menu, where you should set the entry LXWP? to 'Y'. Set the transfer speed in Cumulus to 4800 bps - the LX20 device uses this speed for NMEA transfer regardless of the selected PC transfer speed.
FLARM Hardware version 2 or later. This can deliver altitude values derived from a pressure sensor, as well as aircraft and ground obstacles information. Enable the sending of these data in the FLARM setup menu. Look also at the page Cumulus Flarm for more information.

Sync Clock
If the option Sync Clock is activated, Cumulus is able to synchronize the PDA system clock to the GPStime, but this will only work, if Cumulus is running as user "root". On the Nokia Internet tablet this feature is switched off, because user processes are not normally running under the root user.
Save NMEA Data
If the option Save NMEA Data is activated, the received NMEA data stream is logged into a file. The file is stored in the user's data directory and it has the name CumulusNmea.log. After each new start of Cumulus or if this option is activated in the setup menu, a new log file is opened. The content of the previous file is save as backup copy with the name CumulusNmea.log.old. You can use this option to save the GPS NMEA data for a later analyze or any other post-processing. We recommend to use this option only for special purposes because it has also influence to the performance in general.
Processed GPS sentences
Cumulus processes the following NMEA and proprietary sentences:

NMEA Id Description
$GPRMC Recommended Minimum Specific GNSS Data
$GPGLL Geographic Position - Latitude and Longitude
$GPGGA Global Positioning System Fixed Data
$GPGSA GNSS DOP and Active Satellites
$GPGSV GNSS Satellites in View
$GPDTM Map datum
$PGRMZ Garmin and FLARM proprietary sentence with barometric or GPS altitude data
$PFLAU FLARM proprietary sentence with status, intruder and obstacle data
$PFLAA FLARM proprietary sentence with data about other aircraft around
$PCAID Cambridge proprietary sentence with STD altitude
!w Cambridge proprietary sentence with MSL altitude, QNH setting, wind direction, MacCready value, wind speed and variometer data
$PGCS Volkslogger proprietary sentence with STD altitude
$LXWP0 LX Navigation proprietary sentence with MSL altitude, variometer and wind data
$LXWP2 LX Navigation proprietary sentence with McCready data
$MAEMO0 Cumulus internal proprietary sentence, if LibLocation from MAEMO 5 is used
$MAEMO1 Cumulus internal proprietary sentence, if LibLocation from MAEMO 5 is used
$Android Cumulus internal proprietary sentence, if the Android device delivers only own location updates and no NMEA data.

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