PowerFlarm Range Analysis for "WX" - 15M Nats Yreka 2014

[WaltWX]

Gentlemen,

Here's my range analysis for the 15M Open U.S. Nationals, two practice days and eight contest days. One has to divide files into 4MB chunks or smaller, so there are Parts 1, 2 and 3:

https://www.dropbox.com/s/cr9fasl47zwewp1/15MNats2014_Yreka_WX_PF_8EH_Part1.IGC?dl=1

https://www.dropbox.com/s/zs76x6en6lrw4ll/15MNats2014_Yreka_WX_PF_8EH_Part2.IGC?dl=1

https://www.dropbox.com/s/ahz8go0e2cugw1f/15MNats2014_Yreka_WX_PF_8EH_Part3.IGC?dl=1

Pretty good coverage averaging 6-9km in range for whole contest. Here's my antenna arrangement on the Discus 2A. Not particularly clean, but very effective. Since then I've cleaned up the angle acrylic plastic brackets that the dipoles are double stick taped to. Antenna mounts are velcroed on the panel.

https://www.dropbox.com/s/lufmnwn9ewmsgo7/PowerFlarm_Ant_Discus2A_WX_SideView_800x600.jpg?dl=1

https://www.dropbox.com/s/t3rbjrwp0x8z4z9/PowerFlarm_Ant_Discus2A_WX_800x600.jpg?dl=0

Walt Rogers WX

[WaltWX]

UPDATED LINKS - Version 1.0

Gentlemen,

Here's my range analysis for the 15M Open U.S. Nationals, two practice days and eight contest days. One has to divide files into 4MB chunks or smaller, so there are Parts 1, 2 and 3:

https://www.dropbox.com/s/ltumxv22hizwec3/FLARM_RangeAnalysis_WX_Yreka_2015_15MNats_Part1.png?dl=1

https://www.dropbox.com/s/l1gycgqije3vx1k/FLARM_RangeAnalysis_WX_Yreka_2015_15MNats_Part2.png?dl=1

https://www.dropbox.com/s/x15wlx0bg4c56k8/FLARM_RangeAnalysis_WX_Yreka_2015_15MNats_Part3.png?dl=1

Pretty good coverage averaging 6-9km in range for whole contest. Here's my antenna arrangement on the Discus 2A. Not particularly clean, but very effective. Since then I've cleaned up the angle acrylic plastic brackets that the dipoles are double stick taped to. Antenna mounts are velcroed on the panel.

https://www.dropbox.com/s/lufmnwn9ewmsgo7/PowerFlarm_Ant_Discus2A_WX_SideView_800x600.jpg?dl=1

https://www.dropbox.com/s/t3rbjrwp0x8z4z9/PowerFlarm_Ant_Discus2A_WX_800x600.jpg?dl=1

Walt Rogers WX

[waremark]

Your performance is way better than my Euro Flarm fitted inside the LX 9000.

My problem with the range analysis tool is that it only tells you where you did pick up gliders. It does not tell you about the Flarm equipped gliders which you did not pick up. Did you never get contacts (or gliders) 'suddenly' appear closer than say 2k?

Mark Burton

[WaltWX]

Well, over my last two seasons of flying nobody seemed to "sneak" up on me with the flarm signal. However, it is obvious when following others that when you get behind and slightly below them in a glider with a carbon fuselage, that the signal drops out pretty quickly... say in less than one mile. One possible solution would be to put a second antenna (receive only is all that's available) on the bottom. That way, someone else couldn't sneak up on me. Does anyone else out there have experience with a second flarm antenna?

Walt Rogers

[Tango Whisky]

I have an antenna splitter installed. First antenna is a stripe antenna in the canopy (laterally & slightly behind my head), second antenna is the standard lambda/4 "toothpick" by the gear door. The Ventus cM is all carbon, and I have 5 km reception all around with a Flarm 5.

[Dan Marotta]

...And you don't mind the approximately 50% loss (3.5 dB) in signal strength due to the splitter?  I don't want to figure out how that affects detection range.

<snip>

I have an antenna splitter installed. First antenna is a stripe antenna in the canopy (laterally & slightly behind my head), second antenna is the standard lambda/4 "toothpick" by the gear door. The Ventus cM is all carbon, and I have 5 km reception all around with a Flarm 5.

--
Dan Marotta

[Steve Koerner]

On Wednesday, March 25, 2015 at 7:13:59 AM UTC-7, Dan Marotta wrote:
> ...And you don't mind the approximately 50% loss (3.5 dB) in signal

It doesn't work that way Dan. With two antennas gathering energy from the same surroundings, the effect is primarily an alteration of pattern.

The greater concern might be polarization. PowerFlarm is a vertical polarization system. I'm not exactly sure what TW means by "stripe antenna in the canopy (laterally & slightly behind my head)". That doesn't sound vertical polarized; hopefully I'm just not visualizing that correctly.

[Dan Marotta]

You're right, Steve!  I was thinking of 1 antenna feeding two receivers.

Dan

--
Dan Marotta

[Darryl Ramm]

As pointed out an antenna splitter is not what you should be using. That will lead to signal reinforcement or cancellation depending on the relative phase of the signals from each antenna. It might help you when one receiver antenna is significantly blocked from receiving the transmitter signal but can cause serious reception problems when a transmitter signal is visible to both antenna. This is just not the way to to this. The proper way is to utilize a device designed for two antennas, like with the PowerFLARM, which essentially contains two separate receiver front ends, one for each antenna. And various FLARM documentation specifically says don't use an antenna splitter... for this exact reason.

[Tango Whisky]

The splitter I have is from Bernd Dolba (www.dolba.de - German only, sorry for that...)and was designed for Flarm's. Both antennas are polarized 30-45° from vertical.
I don't care about limiting contact range to 5 km, but I care a lot about not having blind spots. With an all-carbon fuselage, you can't avoid blind spots if you're just using one antenna.

Cheers
Bert

[soa...@yahoo.com]

On Tuesday, March 24, 2015 at 12:32:03 AM UTC-7, waremark wrote:

I ran FLARM range files for ~dozen of the contestants I flew with in a contest last year by downloading their IGC contest files. Most had 4-6 km ranges (including mine) except for 2. One was a portable, the other was a Euro Flarm in an LX8000, both had ranges of around 1 km.

If gliders are "suddenly appearing" you might check some of their IGC files (OLC?) and see if that helps to sort out if the problem is their installation and/or yours.

[Darryl Ramm]

OK, thanks for that pointer. Looks like they know what that are doing and hopefully try to avoid purchasers doing silly things with dual antennas.

Darryl

[threeu...@gmail.com]

I contacted Walt, on private email, to praise him for his excellent range.
It appeared to be significant better than mine, with similar make, model and antenna placement.
My different files were showing significant irregularities, side lobes, skewed to one side, etc.
While I dug a bit deeper into this, I noticed in the range analysis image that Walt published above, shows a huge number of contact points. Like 11000 points in his biggest file.
When reviewed my analysis output, I only noticed about 400 points on several 400k flights.
Now, I fly in the "big air" of the Sierras, where contacts with other Flarm equipped gliders can be far and between.
And Walt mentioned that his files were taken during a contest, which, I guess, means a lot of close proximity flying.
So, I decided to concatenate a few of my long IGC file and uploaded the larger file (2000 points) to the analysis tool. Now my pattern look much better, much more homogeneous with good range.
Conclusion: Be careful about drawing conclusions from your Range Analysis output when you only have few contact point (< 500 points).
If in doubt, concatenate some files into a big file and run this big file through the analysis to see if that yield a better result.
Also notice that the analysis reports maximum ranges in the 30-40 km range. Don't know if that is real and if it includes ADS-B pings. If it is Flarm range, that's very good !
3U

[WaltWX]

3U's comments are correct. I concatenated all the practice and contest days at the Nationals to get 11000 points. So, a large sample at an event with lots of flarms is important. BTW, my flarm antenna is the rear most one on the panel at the highest point in the cockpit. Antennas are the stock dipole that came with the core PF with a 4-5ft length of coax. At one point recently, I considered shortening the cable by resoldering, but decided that my performance was "good enough" and tampering with things seemed inadvisable. How much better would the performance have been by shortening the coax to 2 ft (I need extra length so the canopy cover can easily be removed)?