OpenTX - Application Note 09
Variometer Set Up
Set up a variometer sensor to indicate and announce altitude and vertical speed.
A variometer is especially useful for glider pilots who want to know when their glider is ascending or descending.
The data can also be logged for later display on the Log Viewer in OpenTX Companion. For logging and data viewing, refer to Application Note 8.
The sensor is connected via the smart port as shown in this photo.
After power up, the sensor continuously sends altitude and vertical speed data to the receiver which continuously transmits them to the Taranis radio. In the Taranis telemetry data, altitude is ‘Alt’ and the vertical speed is ‘VSpd’.
Switch SD, in this example, is used to turn the vario and audio announcements on and off as follows.
Audio Announcements Setup
Special functions are used to set the SD switch mid position to announce the altitude and vertical speed every 5 seconds. SF10 and SF11 are used in this example.
A special function is used to set the SD down position to turn on the vario. SF12 is used in this example.
When the variometer is on, beeps with varying pitch represent the vertical speed. When the vertical speed is zero (i.e constant altitude), the pitch is the ‘Pitch at Zero’ value. The higher the ascent rate, the higher the pitch above ‘Pitch at Zero’. The higher the descent rate, the lower the pitch below ‘Pitch at Zero’. The tones used are set by the parameters in the Radio Setup screen under ‘Variometer’
The default values of the parameters are as follows.
Null the Vario Around Zero Vertical Speed
(Thanks to Danny for this idea.)
If you wish to mute the vario tone when the vertical speed is around zero, use the following method. A logical switch is used to enable the vario only when the absolute value of the vertical speed is greater than 0.4m/S AND when switch SD is down. The logical switch is set up as follows.
The logical switch is then used as the source in the special function to turn on the vario. (Note that just SD↓ was used as the source before.)
When the SD switch is in the down position, and the ascent rate or descent rate is greater than 0.4 m/S, the vario tone is on. Otherwise, the vario tone is off.