What Flarm really needs...

Standing a glider on its nose is certainly possible, see http://noss.ws/ssc/LS4_OnNose.jpg . (OK, this was actually XZ helping HR with a difficult retrieve, but it can be done....)

Many glider repair shops have "rings" they can mount a fuselage in to turn it over and work on the side, bottom, or whatever. And they often have the parts needed to connect any fuselage to the "ring". So, this could be a side business for a sailplane repair shop. Ask Paul Gaines about his "ring".. If it could be borrowed, you could place your fuselage in the ring, turn in 90 degrees onto its side, and get a straight down pattern, turn it 45 degrees and get a thermal bank pattern.

Steve Leonard

If the attenuator is not on the portable, but is on the brick would it still work though? Is the brick also RF leaky?

Well, since my last professional experience with RF was in 1970, I'll
defer detailed comments to others more up to date like Dave (ZL). All I
can say about the below statement is: Shoddy engineering! How many
harmonics are bouncing around behind your panel?

Now I begin to understand why the FAA is so hard over on TSO equipment
for such things as ADS-B...

On 6/19/2015 11:17 PM, Steve Koerner wrote:
The real world throws curve balls sometimes (actually, almost all the time)...

Britton Bluedorn has conducted some tests using his brick and portable PowerFlarm. He and I have been in email interchange through his testing. What we've found is that the portable unit is RF leaky. That is, a lot of energy gets in and out of the box without going through the antenna connector. This isn't a flaw really, it's just the way it is. There's not a compelling reason that the PowerFlarm RF section needs to be well shielded.

The upshot is that the 40 dB attenuator scheme isn't workable. There is an alternative. Instead of 40 dB, use a 20 dB coaxial RF attenuator. That makes the range factor 10X instead of 100X. That means, of course, that the test site has to be bigger -- an airstrip would work.

In addition to the attenuator change, one should shield the portable box by wrapping it up in aluminum foil. The battery should be inside the shielded system and the foil should wrap tightly all around the unit and be taped in place. The foil shield should be pressed against the connector junction between the attenuator and the antenna or antenna cable with tight tape wrapping there for best effectiveness.

--
Dan Marotta

In all transparency while I am an engineer I'm not an EE or RF professional. That stated I would *not* use my one data point as gospel. Looking forward to someone else performing the experiment again with Steves instructions and reporting back.

Britton

On May 5th weather cooperated and I flew. Flarm Range tool applied to that flight log showed all points outside 2km and several at 4km range.

June 6/7 flights show almost zero range and inflight I only picked the one known FLARM equipped glider that weekend when I got within about 300 yards. I'm pretty sure I've got some sort of issue, so that's where this thread started.

I bought a 40db attenuator and the adapters and put that inline with the FLARM A antenna for my core unit and borrowed a portable this morning.

I was able to maintain communication between the units to a distance of about 150' which I thought from the earlier posts was a good sign. However, when I removed the attenuator and tried again I lost contact with the portable at around 300-500 yards, not a good sign.

When I removed the antenna from the attenuator I happened to notice that I didn't lose contact with the portable unit. The portable was sitting on my wing about 1/2 way out, but it was curious that the units were still making contact. Perhaps the Core is leaky as well and the test with the attenuator is flawed? Wrapping everything up in tin foil seemed like a pain so I didn't take the time to mess with that.

Unfortunately, almost the entire season has been rained out here in Houston and we won't fly tomorrow either so I'll have to wait until maybe next weekend to hope for another flight to see what happens in the air.

Back to my original idea, it sure would be nice to have a rentable box that would definitively diagnose an issue while on the ground.....