PiDAR

Now not just you Cooper. I had the same artifacts on my screen as well. Maybe it was multi-path interference off the blades. :D

Someone else used a drone a while back. They had the same results. In that situation, they figured it was the electric noise of the motors that was causing the issue. I would tend to agree with that. Also it appeared that when they were in front of the van, they were getting signals. I suspect that the van was acting as a reflector. They dropped off when they hit 300 + feet, but if you looked at the screen, they were really dead before that. After a fixed amount of time with no new packets, the entries drop off the Dump1090 list. If you notice the message counts had long stopped on the assent. One thing you can do to tune your stock antenna is cut it down to a 1/4 for 1090 mhz. (68 mm) . That should improve things some. I've experimented with a lot of different designs for ADS-B antennas. The coax - co-linear has shown to be the best, However, pretty much anything mounted high, in the ball park, does well. The biggest factor is the loss from long coax runs.

My antenna is very similar. The 1/2 inch PC pipe doesn't have a lot of extra room in it. With the top of the coax anchored at the top of the pipe, the weight of the coax should pull it pretty straight. I don't think that would be hurting them that bad. I've never given it much thought, but it is an interesting theory.

My best day, so far is 1,249 aircraft with 77,772 positions logged. :)

I'm enjoying this series quite a lot. I got interested in the SDR by watching your TPM episode. The SDR's are quite contagious. A couple of thoughts on the latest show. I'm really disappointed in the number of planes you received with your antenna, given the location. I would have expected you to have received 3x the numbers you did. I have a couple of thoughts based on my own experiences. The first thing that jumps to mind the the amount of RF-noise you are getting off the active usb extension cord. I had one that completely overloaded my rtl-dongle with rf. Just by adding a short passive usb extension on the end, the noise floor drops dramatically. I've also added ferrite chokes to help as well. Your right about signal loss on the coax. The closer you can get the RTL to the antenna the better. However, that's not always practical. I'm using an in-line amplifier designed for satellite TV. Its approximately $9, and adds 20db of gain from 950-2150 mhz.. With this added at the base of the antenna, I can easily run 20 feet of coax to my SDR. I'm using an antenna similar to the one you built, but only 11 segments. It was 12, but there was an accident installing it. :) I moved away from the USB extension to a raspberry pi. Hence the user name "PiDAR". I've attached a gps to the pi with a PPS signal giving me a stratum 1 time server for my network, as well as allowing precise time stamps for calculating positions of aircraft not broadcasting their location (MLAT - Multilateration). . I'm in the Little Rock Arkansas area and am receiving aircraft well over 200 miles out, 80-90 aircraft at peak times. A friend of mine, in the same area, built an 16 element antenna and used the amplifier I suggested .Yesterday he recorded 104 aircraft at once, with a max of 250 miles out.