Bluetooth Vario

We have reworked and rewritten the bluetooth connectivity completely. The XC Vario will let you now choose from a list of bluetooth varios. You can connect to your preferred bluetooth vario and your preference is being stored for next time. So, in case your phone isn’t equipped with a barometer you can connect theFlightVario apps to external varios via Bluetooth Low Energy (BLE).

Note: all of the following is available in the beta release only and will move to production later.

But first and just to make sure:

What Is A Bluetooth Vario

A bluetooth vario is an external device providing especially barometer readings via bluetooth to another device. In paragliding this other device is usually some application running on a device with no built in barometer. This can be a tablet, phone or maybe an eInk display for better readability for information needed when paragliding. While visualizing this information about waypoints, airspaces, altitudes and heading, the important information of pressure and with this the altitude and climb rate is added from the bluetooth varios. So instead of trying to find that one device having all necessary sensors, you can combine two devices.

Selection Of Bluetooth Devices For Bluetooth Connectivity in the XC Vario (XC Tracer, MipbipS+, Flybeeper, Skybean2 and more)

Bluetooth varios range from simple beep only barometric varios up to FLARM, Fanet and GPS enhanced instant varios with a heavy price tag easily equaling well equipped phones or other dedicated flight instruments. Apart from that it is relevant to know that basically two types exist: bluetooth low energy and classic bluetooth varios. We support and focus completely on low energy only which is standard by now.

Connect XC Vario to a bluetooth vario

Connecting a bluetooth vario is straightforward. You open the Quick Feature Dialog by long clicking the Feature Icon above the climb rate on the main screen. Once the Quick Feature Dialog opens, you will need to click the bluetooth receiver field to search for bluetooth devices around. Select one and the XC Vario will try to connect. In case the XC Vario is already connected to a bluetooth vario, it will disconnect that device first since only one device can be connected at a time. Technically multiple bluetooth devices can be connected at the same time, we are just limiting this for now.

Auto Connect Bluetooth

Sounds like a lot of steps for connecting a bluetooth vario? Don’t worry! You will need to do this setup only once. There is now an Auto Connect feature included. Next time you start the XC Vario it will connect to the last device connected as soon as it is discovered. So turn on XC Vario and you should be all set, as long as your device is (re-)using the same mac address over and over again. This is the 'cryptic' characters you see below the name of the the device.

Audio Setup

Whenever you have connected a bluetooth vario you need to decide which audio you prefer.

You can turn off the device's audio and have the XC Vario take over audio. In this case you can use preset or customized vario tone curves. Or you can keep the device’s audio on and mute the XC Vario app’s audio. In this case you can go to Settings -> Audio and set the Vario Tone Volume to Zero.

open the quick features above the climb rate indicator and tap Receiver

here we select another phone running XC Vario and acting as bluetooth vario

the connected bluetooth vario (phone) is found above the climb rate indicator

Have XC Vario act as bluetooth vario

But the XC Vario can do more! It can be connected to a bluetooth vario. But it can also do the other way round. Given that your phone comes with an internal pressure sensor, you can have the XC Vario app also act as a bluetooth vario.

Wait, it can do what, function as a bluetooth vario itself? Yes, it can! You can choose whether your phone shall act as a receiver, this is the typical use case of receiving data from a bluetooth vario connected to your phone. But you can also choose to have your phone act as bluetooth vario. This is the use case of providing data via bluetooth to another device. So in case you have a phone but the display might not be big enough and you got maybe one of those rugged tablets, you could for instance try that. Only limitation for now is that it is limited to devices running the latest beta XC Vario app. It is a feature that is still undergoing some more testing before being released to all versions. Of course this will work best on newer phones as not all support acting as bluetooth peripheral.

As with most bluetooth varios, the update rate is currently set to match 10 times a second. But we also tested 50 times a second :-) - which worked. Each update contains the pressure, climb rate, latitude and longitude as well as wind direction and speed although currently used is only the pressure and climb rate. All of the data is specifically encoded to be using only as little data as possible for each update. So, if you connect to the bluetooth vario with some testing software or devices you will see for now just some characters. There is still some refinement pending before this feature will be pushed to production version of the XC Vario.

Auto Connect

Auto connecting the XC Vario itself is currently not possible. Due to privacy limitations, Android shuffles the mac address when acting as a bluetooth vario itself. Let's see what future solutions might exist.

turn your phone into an external vario using Act As Bluetooth Vario (optional), you will need to restart the app for this

open the quick features above the climb rate indicator and tap Sender and your phone will advertise as peripheral

Frequently Asked Questions

Can theFlightVario Act As Bluetooth Vario For My Tablet?

We had this on our (somewhat longer) list of future features and with the current beta version of the XC Vario it can be now tried out.

Which Protocol Should I Use For My External Vario?

Most of the external variometer talk LK8EX1 and this is fine. If your vario can talk LXWPW to include wind information (e. g. XC Tracer) go with LXWPW. _PRS should be the last option since this is transmitting raw pressure values and introduces unnecessary complexity and lag in processing theses values into a climbrate. In case you need to stick to _PRS, you should use the calibration of theFlightVario in order to process these reading optimally. In case you fly with a blueFlyVario you can easily change the standard _PRS setting to LK8EX1 using the blueFly configuration tool when setting the outputMode to BOM 1 (see manual). For all other vendors, please stick to their manual.

Which Protocol Does My Bluetooth Vario Use?

theFlightVario won't show this information. If you want to find out what protocol is used by your vario, check out the Serial Bluetooth Terminal app.

Which Protocol Does My USB Vario Use?

theFlightVario won't show this information. If you want to find out what protocol is used by your vario, check out the Serial USB Terminal app.

Does My Vario Use Bluetooth Low Energy?

theFlightVario won't show this information. However, connection attempts will be in order from Bluetooth BLE to DUAL to Classic. theFlightVario will take the fastest option possible. You can use the Serial Bluetooth Terminal app if you want to find out what is sent by your bluetooth vario. This way you can also check at what rate your external device is sending (usually around 100ms).

Are There Delays Using Bluetooth?

So are there any drawbacks from using a bluetooth vario? For instance, some pilots are concerned that a bluetooth connection imposes another significant delay to the vario tone. And yes, a minor delay is introduced using bluetooth but this has less to do with bluetooth itself but rather the fact that the update rate is most of the time set to ten times a second. In comparison to that, keeping all processing within an app like the XC Vario, sensor updates and processes are occurring on average 50 times a second in some cases even 100 times a second. So, there is a delay. If you are flying with an external you might choose to use the audio from the device itself if you feel like that delay is causing a problem. Or maybe switch to a dedicated phone vario at some point in time.

What Happens If Bluetooth Is Disconnected During Flight?

theFlightVario does not drop the connection and will try to reconnect. If this is not working, the internal barometer (if any) of your smartphone will be used. We never experienced issues. Please get in touch with us if you're experiencing problems.

Are You Flying Bluetooth Or USB?

I do not fly with a bluetooth vario and I do not use a usb vario other than for testing. Why is that, you might ask? Well, I simply have no need for an extra vario. Starting with the Pixel 4a phone, really a change was introduced. With the Pixel 4a and its successors, all relevant sensors, especially a barometer are nicely integrated with the inertial measurement unit (IMU) and provide readings with a high update rate. From my testing and development there is little benefit from a dedicated vario for my paragliding.

Further Details & Troubleshooting

The rewritten bluetooth functionality in the XC Vario has been tested against XC Tracer, MipbipS+ and a Flybeeper Mini. Yes, this is a limited set of devices used for testing. But it is covering a broad range of protocols and mechanisms. And it is what I am willing as non vario user to acquire for testing. Buying all kind of devices is unfortunately out of scope.

We only provide bluetooth low energy. If your bluetooth vario does not appear in the list, it might be due to the fact that it is not a bluetooth low energy vario or it is not advertising as being available for connecting.

Second, there are some standard services that the XC Vario will look for and which are expected to work for most bluetooth varios. Each service is associated with a UUID.

Supported Devices

While most bluetooth varios rely on UART/ COM/ Serial emulation sending NMEA messages, Flybeeper uses the standard service 0x181A within Environmental Sensing and with that the intended and up to date mechanism for transferring data via bluetooth low energy. With both of these tested, there should be no limitation to connecting bluetooth varios as long as they use any of the supported protocols below and the UUID for identifying the service is known . You can read more about services, characteristics and associated UUIDs in Bluetooth Specification or search for Environmental Sensing in the Assigned Numbers. Beware it is very technical and only meant for the interested reader.

Supported UUIDs

We are aware of these UUIDs being used:

VARIO_SERVICE_UUID "0000ffe0-0000-1000-8000-00805f9b34fb"

VARIO_MEASUREMENTS "0000ffe1-0000-1000-8000-00805f9b34fb"

TJA_SERVICE_UUID "6E400001-B5A3-F393-E0A9-E50E24DCCA9E"

TJA_MEASUREMENTS_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"

TJA_MEASUREMENTS_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"

ENVIRONMENTAL_SENSING_SERVICE "0000181A-0000-1000-8000-00805f9b34fb"

PRESSURE_MEASUREMENTS "00002a6d-0000-1000-8000-00805f9b34fb"

The XC Vario itself uses this UUID:

THE_FLIGHT_VARIO_SERVICE_UUID "5b1ffd2e-511c-47ae-91bb-99e31d12da57"

THE_FLIGHT_VARIO_MEASUREMENTS "5b1ffd2f-511c-47ae-91bb-99e31d12da57"

Supported Protocols

theFlightVario paragliding variometer supports the known protocols to read, process and display data from external bluetooth varios and usb varios. These protocols are:

LK8EX1 (blueFlyVario and others)
LXWP0 (XC Tracer)
LXWPW (XC Tracer)
_PRS (FlyNet Varios)
POV

$LK8EX1 Message String

the $lk8ex1 string looks like this:

$LK8EX1, pressure, altitude, vario, temperature, battery, *checksum

theFlightVario will take the vario readings provided to display a climb rate and use the pressure readings to calculate the current altitude.

For further information on $lk8ex1 see here.

$LXWP0 Message String

the $lxwp0 string will always be preferred over an $lk8ex1 string and looks like this:

$LXWP0, kmh, baroaltitude, vario in m/s, , , , , , heading, windcourse, *checksum

theFlighVario will take the altitude, vario in m/s and the windcourse

$LXWPW Message String

the $lxwpw string will always be preferred over an $lk8ex1 string and encodes the windspeed in the last field of the $lxwp0 string:

$LXWP0, kmh, baroaltitude, vario in m/s, , , , , , heading, windcourse, windspeed*checksum

theFlighVario will take the altitude, the climb rate, windcourse and windspeed.

$PFLAU Message String

the $pflau string, as part of the flight and alarm system FLARM contains information to alert pilots of potential collisions, looks like this:

$PFLAU, Rx, Tx, Gps, Power, Alarm Level, Relative Bearing, Alarm Type , Relative Vertical, Relative Distance, Id

$PFLAA Message String

the $pflaa string, as part of the flight and alarm system FLARM contains data on other proximate aircrafts and looks like this:

$PFLAA, Alarm Level, Relative North, Relative East, Relative Vertical, IDType, Track, TurnRate, GroundSpeed, ClimbRate, AcftType

For further information on $pflau or FLARM see here or at flarm.com.

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