Steve Kroop at Flytec <<info>>
writes:

On any given flight, being able to find really weak lift can often
really make a difference in staying up when conditions get soft. For this reason
many pilots adjust their acoustic vario threshold very low (or zero) so they can
tell if they are in really light lift. Instruments set up this way are the ones
always beeping when just sitting in the take-off area. This method will work if
the encountered lift is strong enough to net a zero to positive vertical speed.
However, it is important to understand that absence of accent tone does not mean
absence of lift, it only means that your vertical speed is below zero. Remember,
your vertical speed is the vertical movement of the airmass minus your glider's
sink rate (at that speed). This means that with a standard acoustic variometer
(set to the lowest possible threshold), lift weaker than your glider's sink rate
will go unannounced. The importance of being able to detect this weak lift
becomes abundantly clear as soon as any pilot finds himself in survival mode. A
vertical speed less than your gliders sink rate means not only are you
preserving altitude, it also means there is lift present. When in survival mode,
searching out this weak lift may allow you to find the thermal that is nearby or
has just not come together yet.

Fortunately, the 6030/6020/6015 (and comparable Brauniger models) have a feature
(Nascent Thermal tone) to help you detect this weaker lift. When activated, the
instrument will give a unique tone when your vertical speed falls within a
specific range. The bottom of the range is the user-set Nascent/Near Thermal
Tone Threshold and the top of the range is the Acoustic Vario Threshold (see
diagram). The nascent thermal tone is only active in flight to prevent
unnecessary and distracting beeping while standing at launch waiting to
take-off. Since the nascent tone will inform you of weak lift, it is no longer
necessary to set your acoustic vario to 0 ft/min to detect weak lift. Setting
your acoustic vario threshold of 20ft/min and activating the nascent thermal
tone, you will be able to hear the difference between a weak thermal with no net
gain and a thermal that is yielding a climb.

6030 v3.33g or later, you can turn on the Nascent Thermal tone and set the lower
threshold in Menu > Settings > Acoustic vario > Near thermal tone. To avoid confusion
with the acoustic vario tone you can also set the pitch (pulse-pause ratio) of
the nascent thermal tone in this menu. The pitch can be adjust between 10% and
100% where 10% gives a short beep with a long pause and 100% yields a steady
tone.

6020 v3.08k or later, you can turn on the Nascent Thermal tone and set the lower
threshold in Menu > Settings > Acoustic vario > Near therm. Tone. To avoid confusion
with the acoustic vario tone you can also set the pitch (pulse-pause ratio) of
the nascent thermal tone in this menu. The pitch can be adjust between 10% and
100% where 10% gives a short beep with a long pause and 100% yields a steady
tone.

6015 v1.2.13 or later, the lower threshold of the Nascent Thermal tone can be
set the in Menu > Climb aud > PthermThr. To avoid confusion with the acoustic
vario tone the nascent thermal tone is a short double beep. The nascent thermal
tone can be toggled on/off in the run mode with a long press of the Alarm key
and then a short press of the F1 key.