I need help with PowerFlarm problem

On Saturday, July 19, 2014 1:06:38 PM UTC-7, Andy K wrote:
Here is my configuration:

PowerFlarm brick and Trig T22 mod S transponder. PowerFlarm configured with the transponder code to disregard it.



I get constant notifications of my own transponder; yesterday probably 100 times, not kidding. I will have to unplug LX9000 from the PowerFlarm as it is not possible to use it as the PowerFlarm warnings just take over the screen.



I have had this problem with ASG-29 and ASH-26E. In the first glider the PowerFlarm antenna was set up high over the glare shield in the second glider (the 26E) the PowerFlarm antenna is in the fuselage cone as front part of the fuselage does not have any carbon. The 26E has a transponder antenna at the gear door. There is no carbon interference between the two antennas. I have good coverage as proven by experience flying with others.

Any help how to get to the root cause of this problem is appreciated. I can accept sporadic alerts but yesterday it was simply unacceptable.



On the other hand it was really nice to see a couple of twins with ADS-B out doing big circles around me.



AK

An issue here is that you can correctly set the type and ICAO ID of your transponder in your FLARM so that the Flarm will ignore the Mode-S replies of that transponder. However every Mode S transponder also has to reply to Mode C interrogators, and when your Trig TT-22 does that, there is no ICAO address included in that transmission and your PowerFLARM then has to reply on altitude correlation (and RF power) to guess this is the local transponder. But it should be pretty good at doing this becuase it should be reading the Mode-S altitude from the transponder. You might get into problems where you have very spotty interrogations, or mostly Mode-C only interrogations (e.g. if below say SSR radar coverage and being interrogated by older GA TCAD systems which issue Mode C only interrogations). If you are anywhere near busy airspace/civil or military SSR radar covered airspace that issue should not happen.

Double check you have *all* the PowerFLARM settings correct including transponder type (must be mode S.. that gets the PowerFLARM using the transponder's own altitude) and have the correct ICAO code entered without any base conversion errors.

Check all your cables and cables, try swapping the FLARM 1090MHz antenna/cable with known good ones.

Earlier ASH-26Es had fairly poorly installed transponder antennas right behind the gear doors. If yours is like that you really should install the antenna from behind the engine bullhead (requires engine removal) as described in the current TN. I'd do that even if a current install right behind the gear door appeared to be OK with biannual transponder tests. Use new RF cable and put the TT-22 RF box as close as you can to the antenna... ideally mounted remote behind that engine bullhead.

I don't understand what you mean by "carbon interference". I'd be surprised but it might be possible there is too much carbon/ground plane obstructing the transponder signal to the PowerFLARM.

Are there warning happening in flight at decent altitude? Or when low or on tow (does the tow plane have a transponder?). Are there any nearby transponder equipped gliders? Where exactly are you flying/at what altitude (covered by what SSR facility etc.).

If you can't track down anything I would try borrowing a PowerFLARM Portable from somebody to do an A/B test with.