Primarily for general aviation discussion, but other aviation topics are also welcome.
#1817707
On New Year’s Eve two aircraft departed Clench Common and flew to Dunkeswell in formation at 3000’ approx. Both aircraft had Pilotaware and ADSB out (one 17 & one 18), which allows the flights to be replayed on Aircrew.co.uk ground station playback. https://aircrew.co.uk/playback/groundst ... 1609419600

I spent a few hours reviewing the flights, taking various screen shots of particular events and then tabulated these events below. I did this to help me understand the performance of my ground station (CalneW) and to see how each EC system compares to each other. I have recently changed changed the PAW antenna on CalneW from a 7db one sources from Europe to a 5db one supplied originally by Pilotaware, I also have a 5db ADSB antenna the same make as the PAW one.

ADSB 17: The replay shows ADSB out via a transponder clearly wins hands down for range and all stations receiving this picked it up first and held it for longer.

PAW: One of the aircraft was picked up long range by Kemble & Zoyland but the other was not so good. I suspect one may have external antennas and the other internal. CalneW picked up one PAW first and held it for longer than the other, with Bath only tracking one PAW. Similar tracking of one first was seen by other stations, however Dunkeswell picked bot PAW’s up at long range about the same time. Possibly due to flying directly to that ground station and the positioning of the internal PAW have a good view forward.

ADSB 18: Both CalneW & Bath tracked the aircraft (with possibly a SE2) better than the two PAW units and this was also evident with Tolland too. However Zoyland was not so good and much better tracking one of the PAW aircraft but similar for the other PAW.

I’ll post the screen grabs I have taken but go look at this flight, as it does show IMHO ADSB Out is the way to go.

I run CalneW, have two PAW units and two SE2 (only need one now, thanks Tim a week earlier would have save me 250 quid).

Vince

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ls8pilot, gaznav liked this
#1817757
Interesting - thanks also for pointing out the Playback site, a good tool for seeing which receivers were getting your transmissions. The guys who are providing all this stuff are doing a fantastic job. Looking forward to getting our Atom/Grid setup when Covid finally allows a working party back in the clubhouse!
Straight Level, VinceGod, exfirepro and 1 others liked this
#1817847
Hi VG,

I've been doing a bit of testing on the new Pilot Aware analyser for use by ground station owners.
It shows the various polar plots of the different protocols and also the effect of local and distant topographical features.

Handy for checking performance and comparing to other ground stations to see the effect of changes and improvements.

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SL
#1818124
Straight Level wrote:Hi VG,

I've been doing a bit of testing on the new Pilot Aware analyser for use by ground station owners.
It shows the various polar plots of the different protocols and also the effect of local and distant topographical features.

Handy for checking performance and comparing to other ground stations to see the effect of changes and improvements.

SL


Hi SL,

Would be interesting to understand / see the Antenna setup at PWEGBT as the PAW reception is very impressive. Or is this due to the 227,146 pilotaware contacts over 48 days compared to only 20576 ADSB-DF18 (CAP1391) contacts over 28 days?

The devil is in the detail and antenna type, gain, coax, etc can make a big difference. The data/ shots above of PWCalneW are with the same make and gain of antenna for ADSB & Pilotaware using the same coax cable and length so making it as like for like as possible.

The Vector plots will be really useful for me when I move my antenna’s from the garage roof to the house roof and should show the better coverage 360.

Here are the CalneW plots:

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gaznav liked this
#1818178
VinceGod wrote:
Hi SL,

Would be interesting to understand / see the Antenna setup at PWEGBT as the PAW reception is very impressive. Or is this due to the 227,146 pilotaware contacts over 48 days compared to only 20576 ADSB-DF18 (CAP1391) contacts over 28 days?

The devil is in the detail and antenna type, gain, coax, etc can make a big difference. The data/ shots above of PWCalneW are with the same make and gain of antenna for ADSB & Pilotaware using the same coax cable and length so making it as like for like as possible.

The Vector plots will be really useful for me when I move my antenna’s from the garage roof to the house roof and should show the better coverage 360.

Here are the CalneW plots:

Hello Vince,

The comparison of 48 days vs 28 days is that in a 60 day period, (it was slightly less than 60 days as the database had not fully populated) there were 48 days when a PAW signal(s) was received and in that same period there were 28 days when at least 1 CAP1391 device was received. (i.e if just one data point is received on one day, that counts a 1 day for that particular protocol).
I can only assume the reason for the lower number of CAP 1391 data points is there are fewer of these EC devices and/or the range is less. If the CAP 1391 range was similar to PAW, the range plots would show these at a greater range, just at a lower occurrence than the PAW data points.
(note: the ADSB receiving antenna has a lower gain than the PAW antenna and I think there are some tests being undertake to make a more accurate range comparison using matching PAW /CAP1391 antennas).

The installation of EGBT is as per the pilot aware standards, the recommended antennas and minimum length runs of LMR400 coax, from memory about 3 to 4m . The station does have a big advantage of being on the top of Turweston tower (its high up, even more so when looking down :shock: ) and the local topography provide a good view, particularly in the N-S directions. To the West is reduced due to Edge hill ridge shadowing and BHX CTA, but this area is covered by other stations.

SL
James Rose liked this
#1818215
The interesting thing for me, is what makes a CAP1391 ADS-B device detectable at 55km, then just 20-30km in other directions:

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Are we still drawing incorrect conclusions from these “heat maps” by trying to make them look like antennae gain polar diagrams? They obviously aren’t, so we’re back to only knowing the “known knowns”?
#1818238
gaznav wrote:The interesting thing for me, is what makes a CAP1391 ADS-B device detectable at 55km, then just 20-30km in other directions:

Image

Are we still drawing incorrect conclusions from these “heat maps” by trying to make them look like antennae gain polar diagrams? They obviously aren’t, so we’re back to only knowing the “known knowns”?


No one is "trying to make them look like antennae gain polar diagrams" :roll:

In answer to your Q, the same reason Flarm plot also shows stronger north to south range due to optimum topography and that's where most flying is undertaken, which is verified by just about every heat map, including those made public by NATS.
ADSB shows a more circular plot most likely because of higher altitude CAT, so not affected by edge hill ridge (already mentioned) ADSB is also truncated at about 60KM so likely also show a stronger N-S bias if the full range is shown) and CAT doesn't carry Flarm or CAP1391 at the 'ADSB' altitudes.
#1818251
@Straight Level

that's where most flying is undertaken


Exactly! Which is why it is only showing “known knowns”. What we can’t say for sure is that the reception is any poorer elsewhere as we don’t know if there is anyone there to be received in these diagrams. :thumright:
#1818266
gaznav wrote:@Straight Level

that's where most flying is undertaken


Exactly! Which is why it is only showing “known knowns”. What we can’t say for sure is that the reception is any poorer elsewhere as we don’t know if there is anyone there to be received in these diagrams. :thumright:


OK then, we agree.
So if you would be kind enough to fly the test flight I suggested, (when LD3 is lifted) approx 40nm South to 40nm North of Turweston with a couple of orbits at the start and end points, that would provide a good starting point for comparison. :thumleft:

Perhaps it would be better if you started another thread showing the results of your own testing and data, instead of bombing VGs thread which is discussing his ground station :wink:
PaulSS liked this
#1818406
Perhaps it would be better if you started another thread showing the results of your own testing and data, instead of bombing VGs thread which is discussing his ground station :wink:


Yeah, I could call it “Yet another SkyEcho2, PilotAware, ADSB out thread”? :lol:

On a serious note, I think it is sensible to discuss matters on the same threads if they are connected to the same broad subject title - aka SkyEcho, ADSB and PilotAware. :thumright: