I was on here before feeding to FlightAware months ago. I hooked up my RPi a couple days ago. Last night something happened to my Pi or something. I am able to look at the planes on the map under Dump1090, but my data feed and says it’s not live. So I’m not sure what is causing that. I tried another sd card with a new Image on it and that didn’t help.
I hooked up my old Samsung S3 and got it hooked up and working. I never tried the Android feeder before and thought I would try it out. So far so good. Can anyone answer why I am getting more “Positions reported” then I get with the RPi?
I have another cell phone with a hotspot on it. Can I have my S3 and antenna in my car and send data to FlightAware while I’m moving in my car? I didn’t know if you would be able to do that or not, because of the antenna not being in the same place.
It’s perfectly reasonable that you are getting more position reports per plane on Android than on PiAware.
The Android app has a little bit better capability to resolve positions from each aircraft because the device has a GPS chip in it and knows where it is. That helps the ADS-B decoder figure out where the plane is. Android also does 1-bit error correction, where PiAware does not.
I think Baron is talking about the default configuration of the Flightaware dump1090 package, which is starting to show its age. The Android demodulator is approximately the same as dump1090-mutability @ 2.4MHz configured for 1 bit correction with a location configured.
I work in the Wireless field. So when I go to each cell site. When I get to a cell site, I can be there from minutes to hours, so I can run flight feeder on my old S3. I have a unlimited hot shot that I can use to send the data to FlightAware.
Maximum Range of a receiving antenna on Cessna when flying at 5000 feet = 399 miles/347 nm/642 kms.
Maximum Range of a receiving antenna on Cessna when landed = 299 miles/260 nm/481 kms.
Please see calculations below:
Due to “Line of Sight” nature of microwaves, curvature of earth determines maximum range (refer to sketch below).
Overall Range = Range of Transmitting Antenna + Range of Receiving Antenna
= 1.41 x √h1 + 1.41 x √h2 miles,
where
h1 = height of transmitting antenna in feet.
h2 = height of receiving antenna in feet.
With receiving antenna (Cessna) at 5,000 feet, and transmitting antenna (highest flying aircraft tracked) at 45,000 feet:
Maximum range = 1.41 x √45000 + 1.41 x √5000 = 299 + 100 = 399 miles = 347 nm = 642 kms
Please note that major portion of this range (299 mi out of 399 mi) is contributed by the height of Aircraft tracked, and much smaller (100 mi out of 399 mi) is contributed by height of Cessna (receiving antenna).
With receiving antenna (Cessna) on Ground, and transmitting antenna (highest flying aircraft tracked) at 45,000 feet:
Maximum range = 1.41 x √45000 + 1.41 x √0 = 299 + 0 = 299 miles = 260 nm = 481 kms
Conversely: the range is much more sensitive to the height of the Cessna! If the Cessna climbs by 100ft, you get around 1.0mi more range. If the jet climbs by 100ft, you get 0.3mi more range.
(This is why there’s such a big effect if you can move a ground-based antenna higher - you’re on the steep part of the square-root curve)
If we increase antenna height from Ground Level to 65 ft (20m), incurring the cost of 65 ft (20m) high tower, the maximum range changes as follows:
For Aircraft flying at 45,000 feet (FL 450) = Max range changes from 299 miles to 310 miles - an increase of 11 miles only!
For Aircraft flying at 20,000 feet (FL 200) = Max range changes from 199 miles to 211 miles - an increase of 12 miles only!
**The transmission of microwaves being “Line of Sight”, the receiving antenna picks signal only from those planes which it can “see”. The vision of antenna at ground level is normally severely obstructed by surrounding tall objects (trees, houses, buildings etc). Raising the antenna takes it above these obstructions and greatly improves its vision & consequently increases the number of planes & range.
Actually it is worth to raise the antenna up to the point where its vision becomes clear of obstructions (surrounding buildings, trees, etc), and it can “see” the horizon all around. Any increase in antenna height beyond this point is a mere waste of effort & money with almost negligible gain in range.**
BTW - your factor of 1.41 includes a fudge factor for propagation effects; it’s not the line of sight. If you want line of sight, the miles-from-feet factor is more like 1.225.
Assuming that the earth is a perfect sphere with no terrain irregularity, and earth’s atmosphere has no effect on propagation, The miles-from-feet factor is something like 1.225.
The above factor does not take into consideration the effect of atmosphere on the propagation path of RF signals. In fact, RF signals in earth’s atmosphere do not propagate in perfect straight lines. Because of the refractive effects of atmospheric layers, the propagation paths are somewhat curved. Thus, the maximum range of the transmission is not equal to the line of sight (geometric) distance. It results in 15% extra range which makes the miles-from-feet factor = 1.225 x 115% = 1.41
That is exactly what I have said in my post above (the post with a table), and I quote it here again:
"*The vision of antenna at ground level is normally severely obstructed by surrounding tall objects (trees, houses, buildings etc). Raising the antenna takes it above these obstructions and greatly improves its vision & consequently increases the number of planes & range.
Actually it is worth to raise the antenna up to the point where its vision becomes clear of obstructions (surrounding buildings, trees, etc), and it can “see” the horizon all around. Any increase in antenna height beyond this point is a mere waste of effort & money with almost negligible gain in range.*"
To further muddy the waters, at microwave frequencies there is atmospheric ducting. Although small at 1Ghz, it can be significant. It occurs where there are significant discontinuities in moisture and temperature of various weather fronts or even meteor showers and aurora. A tunnel or duct can form where the microwave signal will travel much like a waveguide. You can then occasionally see position reports far afield of the line of sight limitations following the curvature of the earth. Joe K4AA
Tested the FlightFeeder Android app on a tablet with a Nvidia K1 after reading this thread.The positions reported have jumped by nearly 200% as compared to Rpi2 running Piware+dump1090-muta.
This probably means you should change your dump1090-mutability config
The android demodulator is basically the same as the dump1090-mutability demodulator with --oversample --fix
(Or do you mean “positions as reported in the flightaware stats”? That’s not a great comparison, because there are various different versions of the position-reporting code in use)
