abcd's script is an artefact of it's time, it's not a good way to optimize for gain these days
#Gain
wicked sierra
atomic wigeon
No but it's a start.
wicked sierra
i wouldn't even say it's a good start, instead you should be looking at percentage of strong messages or maybe even signal to noise ratio if you're into that
atomic wigeon
I have a 12.1db antenna. My signal strength is always high I have pretty good noise floor
wicked sierra
then adjust your gain based on the percentage of strong messages
rotund wraith
i wouldn't even say it's a good start, instead you should be looking at percenta...
This is the method used by the script on the ADSBx official image.
atomic wigeon
This is based on 3 runs.
I ignored messages to start with instead looking at positions and planes. I an trying 38.6 for 24 hours or so. But the number of messages confirmed my decision. After that i will try the ads-b exchange method and see how it compares.
Gain Messages Positions Planes
===========================================================================
-10 51,303 (285.02 m/s), 7,360, 147
60 52,528 (291.82 m/s), 7,650, 148
49.6 75,140 (417.44 m/s), 11,130, 147
48.0 79,518 (441.77 m/s), 11,635, 140
44.5 80,638 (447.99 m/s), 12,244, 133
43.9 78,640 (436.89 m/s), 11,990, 133
43.4 79,223 (440.13 m/s), 11,819, 137
42.1 81,565 (453.14 m/s), 12,284, 129
40.2 84,876 (471.53 m/s), 12,580, 128
38.6 88,818 (493.43 m/s), 13,355, 128
37.2 85,528 (475.16 m/s), 12,772, 124
36.4 79,149 (439.72 m/s), 11,708, 128
33.8 81,024 (450.13 m/s), 11,987, 127
32.8 79,490 (441.61 m/s), 11,884, 132
29.7 79,687 (442.71 m/s), 11,897, 122
28.0 78,579 (436.55 m/s), 12,018, 125
25.4 75,109 (417.27 m/s), 11,415, 113
22.9 72,423 (402.35 m/s), 10,850, 109
20.7 67,308 (373.93 m/s), 10,086, 98
19.7 60,447 (335.82 m/s), 9,132, 97
16.6 55,404 (307.80 m/s), 8,659, 90
15.7 51,241 (284.67 m/s), 8,017, 80
14.4 45,096 (250.53 m/s), 7,047, 75
12.5 36,079 (200.44 m/s), 5,627, 71
8.7 27,598 (153.32 m/s), 4,261, 56
7.7 21,314 (118.41 m/s), 3,383, 47
3.7 13,855 ( 76.97 m/s), 2,265, 32
2.7 12,391 ( 68.84 m/s), 2,020, 27
1.4 4,720 ( 26.22 m/s), 885, 16
0.9 4,840 ( 26.89 m/s), 794, 13
0.0 2,838 ( 15.77 m/s), 501, 9```
I am averaging 880 messages per second, with good distribution and ranges.Pretty happy with it.
rotund wraith
Problem with your method is it promotes range over closing blind areas and seeing nearby low flying aircraft, 50+ feeders are going to pick up that airliner at 40000ft that is 200 miles away from you so while its cool to see on your feeder aircraft that far out its not "valuable" as tons of others do to. Now what is much more "valuable" is that helicopter buzzing your house at 500ft as you may be the only one to see it due to its low altitude, but because your gain is set high to maximize weak signals it overloads your SDR so it can't be decoded and the website is missing part of its flight from the map. If you are curious yes this is calculated into the rankings through the Unique Aircraft metric and its heavy weight.
atomic wigeon
Thank you for your input. However, I believe there’s a misconception about my approach. I consistently maintain over 97% unique aircraft detections, demonstrating that my setup effectively balances both distance and the number of aircraft tracked. In my city, there are about 7-8 other sharers, all of whom are much closer to the three airports than I am.
While many feeders pick up high-altitude airliners from hundreds of miles away, my goal has always been to achieve a comprehensive tracking range. This includes not just distant signals but also low-flying aircraft in my immediate vicinity. I understand the importance of capturing low-altitude aircraft, such as helicopters flying at 500 feet, which may not be visible to other feeders due to their low altitude.
To prevent my SDR (Software Defined Radio) from being overloaded by strong nearby signals, I regularly fine-tune the gain settings. This allows me to decode both weak and strong signals effectively, ensuring the website receives accurate flight data without gaps. My focus has always been on creating a well-rounded receiver setup that minimizes blind spots and maximizes coverage.
I tend to focus on maximizing the message rate to increase the number and frequency of positions I can report, thereby improving the accuracy of my tracking. As you can see from my previous image showing my distribution and ranges, I am very successful at tracking airplanes, including those flying almost directly overhead with little to no issue.
Due to my high-gain antenna, you can't judge my tracking abilities solely based on the number of strong signals. My antenna has almost double the gain (12.1 dB) of most antennas. When I try to follow the common wisdom, I massively reduce total range and distribution without significantly improving my short-range coverage.
From day one, my strategy has been to track and share a wide array of planes via ADS-B, ensuring I capture both close-in and distant aircraft. This holistic approach provides valuable data to the network, enriching the overall tracking experience for everyone involved.
worthy stirrup
You miss the point - a strong signal whether from a high gain antenna or an LNA will overload the input of the SDR and compromise its reception. "Fine tune" away all you want, but looking for maximum range and ignoring the resulting strong signals will by its very definition cause overload and reception loss.
atomic wigeon
Reread what I posted; I am after balanced coverage, not solely range. Look at the attached image I posted and note the coverage.
Here’s what I said about it: "I am averaging 880 messages per second, with good distribution, and ranges." The term "ranges" in that statement references both close and long-range coverage, and "distribution" meant there were no major coverage holes.
I selected the gain I am testing based on the script’s results, but my order of consideration was based on empirical data: the number of positions first, followed by planes, and finally by message rates. Maximizing my range was dead last on that list. If I find issues caused by that gain, I will work on fixing them and thus improving my reception—it's a learning process.
My goal is to maximize overall coverage while minimizing blind spots, not just maximizing range at the expense of missing nearby aircraft due to receiver overload. I have a high-gain 12.1dB antenna, which allows me to receive weaker distant signals, but I am very aware of the need to prevent overloading from strong nearby signals through careful gain tuning.
I am always open to constructive suggestions on how to improve reception, but not to unwarranted criticism and dogpiling based on my selection of equipment and method of choosing my initial settings. If that continues, I am on the verge of ending my participation on this Discord. I hope it doesn't come to that.
If ADS-B Exchange wants to donate their choice of antenna and receiver for my use, I will be happy to let them dictate how it is set up.
