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Flarm

Cumulus can be connected to a Flarm device, and is able to process the proprietary sentences emitted by that device. On the map display it shows the positions of the most important (collision-threatening) aircraft or ground obstacles, as well as one selected object. Furthermore, as an alternative to the map view, a radar view display is provided showing all received Flarm contacts.

Warning

Please note: Cumulus does not warn you of dangerous objects: that is Flarm's job! Cumulus is not a replacement for Flarm, it is only an addition to it!

Flarm connection

Flarm devices only have a bidirectional serial RS232 interface. Cumulus can be connected to a Flarm device via this interface or by means of a RS232-USB or RS232-Bluetooth gadget. Which you use all depends on your available PDA hardware. The use of a USB connection requires the USB port to support the OTG (On-the-go) mode. This is the case for the Nokia Internet Tablets N8x0, but not for the N900 model.

Flarm configuration

To get the specific Flarm data, you have to enable the NMEAOUT option in the FLARM setup menu. Activate the sending of GPRMC, GPGGA, GPGSA, PGRMZ plus the FLARM proprietary sentences. As transfer speed, you should select 57.6 kBaud. Cumulus sends no initialization data to Flarm, so you must set up the Flarm device by using an initialization file flarmcfg.txt. This is contained on a micro SD card and put into your Flarm device before power-up, or can be set using the Flarm Tool on a PC. For more information, see FLARM DATA PORT SPECIFICATIONS, found at www.flarm.org.

Cumulus GPS settings

In the Setup/General/GPS menu select a serial, bluetooth or USB device according to your available hardware and set the transfer speed to 57600. Futhermore, as Altitude Reference select the entry Pressure. This ensures that the data of the Flarm pressure sensor are used as altitude. Calibrate the altitude shown to the expected altitude by using the altitude dialog (Leveling). This can be opened by tapping on the altitude display in the map view.

Flarm radar view

You can open the Flarm radar view by tapping on the Track (Trk) display in the map view. The view consist of an inner and outer circle with a cross in the centre. The upper end of the vertical line points to 12 o'clock (straight ahead as seen from the cockpit). In the upper left corner you can see the current selected display scale, while at the right side of the window you have, from top to bottom, the following operational buttons:

Scale: Pressing the zoom button toggles through three different scales (0.5, 1.0, 6.0 Km), displayed in the upper left corner.
List: Pressing the list button opens a new window with a list of all the just-received Flarm contacts.
Time: Pressing the time button toggles the refresh interval of the radar view through 1, 2 and 3 seconds. Default is 2 seconds. The refresh rate also has an influence on the processor load and the object selection.
Aliases: Pressing the monkey button opens a new window with a table of your defined Flarm alias names.
Plus sign: The plus button is only to see, if you have selected a Flarm object. Pressing the plus button opens a dialog window where you can enter an alias name for the selected Flarm object. The entered name is added to the alias list, if you leave the dialog via the ok button. An existing entry will be updated with the new passed data.
Close: Pressing the cancel button (red with white X) returns to the map view.
In the radar view, Flarm objects are displayed with different shapes according to the information they contain:

Square: If no track information is available, the Flarm object is drawn as a square. The square is also used to indicate a ground obstacle contained in your Flarm's database.
Arrowhead: If track information is available, the Flarm object is drawn as an arrowhead pointing in the direction of movement.
Objects are drawn in different colours according to their assigned alarm level, or to indicate selection. The colours used are:

Black: The alarm level of the object is low. This includes both the "no alarm" and "low-level alarm" levels described in the Flarm Dataport Manual.
Orange: The alarm level of the object is important. This means that there is less than 13 seconds to go to a predicted collision.
Red: The alarm level of the object is urgent, i.e., less than 8 seconds to a predicted collision.
Magenta: The object has been selected by the user. In this case the alarm level of the object is not considered.

Note! The Flarm Operating Manual v4.06 uses different (English) terms for the above-mentioned alarm levels.

If you tap on a Flarm object in the radar view, you will get additional information displayed, if available. The information, drawn in magenta, is as follows:

Flarm identifier: The identifier of the selected Flarm object is displayed in the lower left corner as a 6-digit hex value. If an alias name has been defined for the Flarm identifier, this name replaces it.
Distance: The distance to the selected Flarm object is displayed in the lower right corner of the window.
Vertical separation and climb rate: The vertical separation and the climb rate of the selected Flarm object are displayed in the upper right corner of the window.

Flarm list view

Pressing the list button in the radar view opens a new window giving a list of all just-received Flarm contacts. The following information may be displayed:

Flarm identifier: The identifier of the Flarm object as 6-digit hex value. If an alias name has been defined for the Flarm identifier, this name replaces it.
Distance: The distance of the Flarm object from one's own position.
Vertical separation: The vertical separation of the Flarm object above (positive value) or below (negative value) one's own position.
Relative bearing: The relative bearing to the Flarm object as an arrowhead.
Ground speed: The ground speed of the Flarm object.
Rate of climb: The rate of climb of the Flarm object. Can be positive or negative.
Any entry in the list can be selected by tapping on it. If you then press the Select button, the window is closed and you will return to the radar view. The additional data of your selected entry are now displayed there. A selection can be reset by pressing the Unselect button followed by the Close button.

Flarm alias list

Pressing the monkey button opens a new window giving a table view of your defined Flarm alias names. A 6-digit Flarm hex identifier can be replaced by a more easily-remembered name. The length of an alias name is limited to 15 characters. To add a new alias name, press the Plus button. This appends a new row with two columns at the end of the table. In the left column enter the Flarm identifier to be translated and in the right column your desired alias name. An existing entry can be changed by clicking on the cell to be modified. Note! If you add the same Flarm identifier to the table more than once, only the last entry is saved. If you want to remove one or more entries, select them and press the Trash-bin button.

Leave the window with the Ok button to store the changes you made, or with the Cancel button to discard all changes.

If you select a row in the table and leave the window with the Ok button, the selected Flarm object will become your new selection in the map and radar views. To make a deselection of a selected object in the radar view, go into the alias window, do not select anything and return via Ok to the radar view.

Flarm alias file

The content of the Flarm alias table is stored in a file with the name cumulus-flarm.txt. This file name is hard-coded and the file is stored in the user's Data Directory.

The file format of the Flarm alias list is very simple. A comment line starts with a hash mark or a dollar sign in the leftmost position and ends with a new line. A valid entry has the following format:

<Flarm-Id> '=' <Alias-Name>

Example:

# Flarm alias file, comment line
$ another comment line
ABCDEF=My best friend
Note that no white spaces are allowed on either side of the equals sign!

Flarm data up-to-dateness

Flarm data age very fast, especially if the objects are circling. Flarm normally sends data every second about the objects in view. If a Flarm contact moves out of the receiver range, Cumulus will no longer get new data about it. To clean up such old collected data, all Flarm contacts that are not updated within three seconds are automatically removed.

In order to reduce the processor load, the data in the Flarm list views are only updated every three seconds.

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