http://altair.no-ip.org/

https://youtu.be/gzzkXXu7B2M

I ran this test with the XCTracer (damping factor = 0),
https://www.xctracer.com/en/the-xc-tracer/?oid=1854&lang=en, and the Flytec
6030 (with vario response delay set to 4  - fast, I normally set it to 0,
and "damp" set to 1, its lowest value - normally set to 8),
http://flytec.com/6030.html, and got the same result.

I also checked to see how the varios compared just as I started to raise them
up. Did they start beeping at the same time? I set the Flytec 6030 "Lift Audio
Threshold" to 0 (normally set to 4 out of a range from 0 to 39, "damp" to 1,
response delay to 4) and the XCTracer ClimbToneOnThreshold=0.0 (it is normally
set to 0.2 m/s) and damping factor = 0. They started beeping at the same time.

The XCTracer damping factor is set to 0, so there should no delay in response to
changes in altitude.

With the two varios set on my desktop and all the values as above, the Flytec
6030 was happily beeping away while the XCTracer was quiet (even though I set
beepOnlyWhenFlying=no).

Steve Kroop at Flytec USA writes:

This is a complicated issue with many variables. If there is any
breeze the 6030 will beep in your trailer, as the wind blows over the trailer it
creates low pressure inside, same for cycling A/C. Exhaust fans, open/closing
doors, etc.. There will be the same effect outside in the lee of structures.
This will be very evident with a lift threshold of 0. If the other device is not
beeping, then it likely has a higher threshold regardless of what the setting it
displays. Or it may use an accelerometer to help with filtering (i.e., a change
in pressure w/o corresponding acceleration could be used to suppress beeping).

With respect to lift threshold and filtering, like I said, I set all 6030s
filtering (vario response delay) to 3 and threshold to ~4 and I recommend that
for you. It will not be twitchy but you may get some “false indication" on the
ground and to that I say so what, we fly in the air not on the ground. There is
virtually no time in the air that we are fixed height like we are waiting to
take-off. The point is the false indications will only be on the ground where it
does not matter.

Dampening of 8 is good.

The XCTracer manual states:

XC Tracer is using multiple data sensors, 9 degrees of freedom
inertial measurement unit, pressure sensor, GPS to compute the real time climb
rate and altitude, avoiding the undesired time lag that conventional variometers
suffer from due to data filtering.