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--- 2m0iig-ads-b-journey [2022/10/24 18:02] – [23rd October 2022] 2m0iig
+++ 2m0iig-ads-b-journey [2023/01/20 09:14] (current) – 2m0iig
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-Low altitude tracks
+**Low altitude tracks (0-10k feet)**
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-High altitude tracks
+**High altitude tracks (10k+ feet)**
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 I noticed looking at the tracks from earlier in the experiment that planes coming into land over the city and further out over the water were blocked due to some hills and buildings, resulting in a total loss of data or a loss of positional data. I wondered if I could improve this, as well as the maximum overall range, with some more gain. I didn’t want to use a preamp as I knew I had lots more I could try first. I decided to ditch the 1/4 wave ground plane antenna and move to a coax collinear again, although I couldn’t be bothered with an 8 segment one and I also didn’t want something too tall out front that would annoy the neighbours. So I settled on 4 segments and kind of winged it.
-{{:a52e3a18-8d2a-4197-9096-8938e028cee1.jpeg?200 |}}{{:c5aaf3b2-b484-4c46-8ef0-1d7cd6388d0f.jpeg?200 |}}Unfortunately I have absolutely no pictures of the construction of the antenna, but I followed a simple guide found online and put it inside a 20mm PVC conduit capped with lots of electrical tape which won’t really hold off the elements for very long, but we’ll see. The cable comes out of the bottom and again the exit hole is wrapped with electrical tape. The plug end is a twist-on F connector which was a bit looser than I’d like, so I taped it up securely. An F-to-SMA adapter finished off the chain, resulting in a fairly clean signal path with just a small amount of loss due to the impedance mismatch.
+{{:a52e3a18-8d2a-4197-9096-8938e028cee1.jpeg?200 |}}{{:c5aaf3b2-b484-4c46-8ef0-1d7cd6388d0f.jpeg?200 |}}{{:47d4ea61-6a7c-4db6-b58e-385a4c826722.jpeg?200 |}}Unfortunately I have absolutely no pictures of the construction of the antenna, but I followed a simple guide found online and put it inside a 20mm PVC conduit capped with lots of electrical tape which won’t really hold off the elements for very long, but we’ll see. The cable comes out of the bottom and again the exit hole is wrapped with electrical tape. The plug end is a twist-on F connector which was a bit looser than I’d like, so I taped it up securely. An F-to-SMA adapter finished off the chain, resulting in a fairly clean signal path with just a small amount of loss due to the impedance mismatch.
-{{:47d4ea61-6a7c-4db6-b58e-385a4c826722.jpeg?200 |}}Hot damn, by the way. Switching the old antenna out for the new one more than doubled my message rate, although there was a small decrease in tracks seen with only one message as you can see, suggesting it wasn’t quite tuned well or wasn’t quite enough to pull in the edge case signals maybe? Or had a slightly different pattern. I also had an immediate and substantial increase in range of about 50 miles. Nuts.
+Hot damn, by the way. Switching the old antenna out for the new one more than doubled my message rate, although there was a small decrease in tracks seen with only one message as you can see, suggesting it wasn’t quite tuned well or wasn’t quite enough to pull in the edge case signals maybe? Or had a slightly different pattern. I also had an immediate and substantial increase in range of about 50 miles. Nuts.
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 ==== 21st October 2022 ====
-Yeah, definitely better. And that’s where this ends right now. I’m considering adding another feeder - RadarBox - but the CPU load is quite high now with the gain back up and tar1090 running. I’ve also enabled MLAT as well which adds more processing overhead. So CPU percentage is up to around 80% peak. And temperature at times is now edging towards 50 Celsius in mid-October. I’d hate to see that in June, but it’s still lower than the 53 Celsius from when I booted up Raspbian Lite for the first time and no tweaks carried out.
+Yeah, definitely better. I’m considering adding another feeder - RadarBox - but the CPU load is quite high now with the gain back up and tar1090 running. I’ve also enabled MLAT as well which adds more processing overhead. So CPU percentage is up to around 80% peak. And temperature at times is now edging towards 50 Celsius in mid-October. I’d hate to see that in June, but it’s still lower than the 53 Celsius from when I booted up Raspbian Lite for the first time and no tweaks carried out.
 Also, here’s a nice thing. I don’t need graphs1090 to draw graphs every 2 minutes, which is what I have it set to now. And I’ve also noticed that drawing all the graphs a really seems to take a long time as well. In fact, sometimes it looks like it may collide with the next graph draw a bit. So last night I set it to 5 minutes to see if that reduced CPU usage.
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 Update: 1085 on the ARM, 550 on the core and sdram. Nice. The CPU graphs are coming down bit by bit. The temperature is still fairly stable. It’ll be really interesting to see if this translates into better performance from dump1090-fa.
-{{:155511b7-c031-47ff-9d0b-a385d99b249b.jpeg?200 |}} {{ :e468036c-0885-407c-bb65-13ffbce0f1c6.jpeg?200 |}} And here’s both recent graphs to demonstrate this, you can see that over the course of a few hours’ tinkering I’ve managed to bring both the main CPU load down and the load of dump1090-da specifically. Any decrease is good and should give more headroom during the day tomorrow when traffic is higher.
+{{:155511b7-c031-47ff-9d0b-a385d99b249b.jpeg?400 |}}{{:e468036c-0885-407c-bb65-13ffbce0f1c6.jpeg?200 |}}And here’s both recent graphs to demonstrate this, you can see that over the course of a few hours’ tinkering I’ve managed to bring both the main CPU load down and the load of dump1090-da specifically. Any decrease is good and should give more headroom during the day tomorrow when traffic is higher.
 ==== 24th October 2022 ====
-{{:f2e54140-c929-4aaa-a276-7b8469be10a7.jpeg?400 |}}Well, a big day today. I’ve got and shortened the coax feedline by another few metres today and stuck the RPi physically to an outer wall. The result is a system that is running a full 2 degrees C cooler than it was and another slight increase in incoming signals. It’s also slightly closer to the WiFi too. I think I’ve Moneyballed this as much as possible now. I’ll only get bigger improvements with hardware upgrades I think. There’s not much point forcing more messages into such a slow system though, as it won’t be able to cope. There’s an argument for pairing an antenna upgrade with a replacement RPi 3B or something with a bit more grunt. I’d actually wager that with some judicious use of cable clips I could lose another few cm off the lead, but I may well get a desk unit here so I need to think about that and leave enough cable to sit it on it when I get one.
+{{:f2e54140-c929-4aaa-a276-7b8469be10a7.jpeg?400 |}}Well, a big day today. I’ve got and shortened the coax feedline by another few metres today and stuck the RPi physically to an outer wall. The result is a system that is running a full 2 degrees C cooler than it was and another slight increase in incoming signals. I hit 500 messages/second today for the first time, which is a nice milestone. The new location is also slightly closer to the WiFi too. I think I’ve Moneyballed this as much as possible now. I’ll only get bigger improvements with hardware upgrades I think. There’s not much point forcing more messages into such a slow system though, as it won’t be able to cope. There’s an argument for pairing an antenna upgrade with a replacement RPi 3B or something with a bit more grunt. I’d actually wager that with some judicious use of cable clips I could lose another few cm off the lead, but I may well get a desk unit here so I need to think about that and leave enough cable to sit it on it when I get one.
-More to follow...
+==== 26th October 2022 ====
+Well, I'm having issues with stability on the Pi, including 7 hours of downtime just after I went to bed on the 25th, so I've decided to roll the overclock back a bit. We're now on 1100 for the ARM, and 575 for the SDRAM and Core. We'll see if that helps, and it's a shame that it happened on a day where I was due to break my aircraft per day and messages per day records. So we'll have another go at that another time.
+Other than that I have nothing else to report: the system is working well, the antenna seems to be still fixed well to its bracket, and I've had no reduction in performance that would suggest water has entered the tube somehow.
+==== 31st October 2022 ====
+Oh god, oh god. The Pi has been misbehaving so much over the last few days. Given how much it survived ok before the last few days with things underclocked I think it's the SD Card rather than the Pi misbehaving due to overclocking. So, I'm going to get myself a brand new Class 10+ card, 16 GB or so, and then either clone the current one or set everything up from scratch again, making sure to use the same sharing codes/IDs for the feeders.
+This is, it has to be said, a bit frustrating. Maybe it's worth using another drive like an SSD or USB stick, but I am totally out of ports on the Pi Zero, and because of the shortages at the moment Pis are as rare as rocking horse shit or cost an absolute bomb, so the idea of getting a Pi3 to replace this will have to wait a while.
+==== 6th November 2022 ====
+Well then. It’s been a shitty week for the project. The crashes and corruption got to the stage where I genuinely couldn’t log in via SSH. Like, I’d connect and the window would immediately close after it processed my login. Something was toast. So I dug out a spare 8 gig card and set it all up from scratch.
+I haven’t overclocked it at all, because I’m terrified that’s what did it in before, but I can definitely tell that I haven’t done it. Grr. The CPU temp is lower though without the overclock. I’ve also taken the lid off the Zero’s case and the temp dropped a few C. Nice! I don’t think it needs to be covered in the position it is in, so I’m leaving it off for good. I’m honestly going to just skip the overclocking. It’s not worth the hassle.
+I am pretty sure we can leave this entry here, although I did just start working on an 8 segment antenna, because I am a glutton for punishment.
+==== 7th November 2022 ====
+Oh my, the 8 segment version is fantastic! I put it outside and set it up at a similar height, but with more open coverage to the north, previously blocked by my house. I gained two more planes that the 4 segment antenna didn't receive. Very encouraging. I need to get it in some conduit and maybe install it full-time, but it is a fairly long cable run so that has to be considered too. Maybe time to invest in a pre-amp and a bias-T board.
+We've also started overclocking again, because I am a glutton for punishment. Slight changes each time, without going overboard. Seems stable so far. I'm learning a lot about the voltages for the ARM/Broadcom chips, that's for sure. In preparation for doing this I also decided to stick a crappy 5V fan that I rescued from an old netbook to the top of the RTL-SDR stick, with the exhaust pointing right at the Pi Zero. The result was a ridiculous 10 degree Celsius drop. It's the most shonky setup ever, held on with Blu Tack (not sure if that is the best thermal transfer material...). It's plugged into the Pi's GPIO pins, 5V and GND, and I'm honestly over the moon with the result.
+Finally I adjusted the antenna outside to make it a bit more straighter and not slanting to one side a tiny bit. I don't know how much difference that will make, because signals from the planes are pretty strong anyway, but it can't hurt to make it perfectly vertical. The mount I'm using is already slightly bent so I'm having to accommodate for that.
+==== 20th January 2023 ====
+Well, where to start... Since the last update the Pi Zero has been replaced by a Pi 3B+, I have written some software to help with automatic installation of all of my custom setup, I have written some software to act as a web-based dashboard with full mobile compatibility, and I've also made a Python app that can keep an ear out for certain planes matching criteria that you specify, or if a plane is over a particular specified area. Basically I've been very busy.
+The 8 segment version is inside a conduit with feedline attached, but definitely isn't going to work on the current bracket, so I'll need to think about that a bit more. The wind does tend to blow the 4 segment around a bit and makes it shift or tilt a tad, and every few days I need to shimmy up a ladder and straighten things out, so the 8 segment would be even worse given the extra weight. Maybe a summer project, but I have to be careful to not block upstairs' view (to be a good neighbour and all that).
+Plane counts are very up and down, though - I think it is because it is winter and the traffic is much less anyway, but there are still occasions where I think I've broken something, or the antenna has bust somehow. This shouldn't be possible due to me replacing the ends of the antenna recently with proper end caps instead of lots of tape...
+I do think this blog is ending here, but it has been fun and I enjoy the fact that I have a somewhat mature system now that has been going for 3 months. I won't challenge any leaderboards, but I have a nice source of data that I can look at. I've picked up lots of military action, such as F15s and Eurofighters, and I've picked up lots of royal flights. I also picked up Elon Musk going to the World Cup. You can't hide outside of America, bucko...
+I hope this was helpful for folk, and do please get in touch if you got something from this or need any advice.