According to FlightAware, I've been tracking aircraft via ADS-B signals on the 1090MHz band since about mid-2017. That's honestly so long ago that I've forgotten about what prompted me to do it (other than having a passing interest in RTL-SDR, a spare 20 bucks, and a Raspberry Pi doing not much else). I've got a picture of my first system, though. A little stubby antenna next to my larger HDTV antenna in my attic.
Not much to look at, to be sure, but things progressed slowly but surely from there. Sometime in 2020 or 2021 I got a new antenna, and the switch made a HUGE difference. You can see me switching the antenna over in the video below.
Not too long after that I started with the Balena ADS-B project, and sometime in 2022 I started pulling in 978MHz UAT signals as well. It's been fun and a nice outlet for my amateur radio adjacent desires.
But, sometime a few months ago, my reception quality dropped precipitously. I hadn't changed any setup stuff, and there hadn't been any recent upgrades. The antenna installation on the roof looked ok, too, so the only think left to do was poke around in the attic to check out if something was awry there. I grabbed a spare laptop and climbed up the ladder to check things out.
Everything looked more or less fine, so I unplugged the USB cable from the Raspberry Pi and plugged it into the laptop (also running dump1090-fa) to see if the laptop fared any better. Slightly? But also the USB cable was quite loose when unplugging it from the Raspberry Pi, so I plugged it back into the Pi firmly and went back down into the house, a little dejected.
Suddenly the signal was a whole lot better! Was it the USB cable all along? Since everything in the attic was just sort of sitting on a shelf, I decided to fasten the equipment more firmly and get some new USB cables. Here's the result of my handiwork.
(There's a newer HDTV tuner under all the ADS-B stuff, and the splitter will eventually be hooked up once everything ends up being sorted)
Securing everything and making the signal path look more tidy (as well as getting new USB cables) did absolutely nothing. In fact, it went back from the week of being much better to bad again.
After another week of watching my stats fall, I took another crack at it. Did something about my laptop setup change the USB receiver? Looking at both the setups, they were identical. Was the automatic gain control (even though both the laptop and the Pi did it) the problem? No. I dragged the laptop back into the attic again to see if switching the connection back and forth would "fix" the problem.
I had the Pi feeder up on the laptop screen so I could do a before and after comparison, but before I switched the USB receiver over to the laptop I took a moment to tidy up the antenna cables.
My signal was back!
It turns out the antenna cable has been "not great" for a while. I'm not sure what caused this, but (unfortunately) the other end is bonded to the antenna, so just replacing the cable isn't an option. Thinking that the problem is in the last ten feet or so and having a lot of slack, I've ordered a new connector and we'll see if that can clear it up. For now, my stats are rising again.
I also wrote a quick script to grab the stats file from the Pi and print it to a log every few minutes. Maybe I should start a github for this sort of thing.
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