Hello, I'm having trouble interpreting data about signal strength I get from two different antennas. This is a screenshot out of "graphs1090": The "dip" in the middle is where I connected a different antenna. At the end, I switched back to the first one. What is this telling me? At first, I thought the new antenna clearly degraded my reception compared to the first one. But only then I noticed that the dark green line shows noise floor, not (averaged) signal strength as I assumed before. And I do want a low noise floor, don't I? At the same time, I seem to have noticed a drop in decoded messages (a little hard to say because I'm in a low traffic area.) So when just changing the antennas, the new one indeed appeared to perform worse. But is this really the antenna's fault, or can there be other factors at play here? I've not yet looked at the spectrum (with SDR#) in direct comparison, but could it be that the second antenna just needs a different gain setting on the receiver (currently set to -10/maximum on the NooElec Mini 2+) to perform well? Regards
Could be the coax you're connecting the antenna with. Range is a pretty good indicator if the message /position rate is too traffic dependant. Antenna in the middle looks much worse. It's about the signal to noise ratio ... And really more signal is gonna be better at the same gain. (if it really would be much more signal you would reduce the gain but you're nowhere near that)
Yes, range certainly wasn't great during that time either: (same timespan as above)) cable: I can't rule that out of course, but it's a commercial antenna (not self-made) with a fixed cable that has rarely been used, so it shouldn't be wear and tear. But it could well be assembled wrong. This is the antenna in question: https://www.amazon.de/Team-Electronic-SC9505-SkyScan-MKII/dp/B000E6FTHO It's supposed to cover 25 - 1300 MHz. It comes disassembled, you have to insert the four rods yourself. I'm not sure whether it makes a difference which rod you mount where. Of course, if they are all connected in parallel anyway, without any electronics between them, that should not matter. What do you think? Regards
It's a scanning antenna and is likely just bad. Then you're probably using some adapter and or the coax isn't made to be low loss for the higher frequencies. Don't use a scanning antenna .... You seem to have a whip ... modify it as follows: Instead of cutting just attach wire as shown above. Also add the can with the approximate dimensions as shown above .... the exact dimensions aren't super critical.
You're right on all counts (long cable, adapter MCX-to-BNC, antenna not very well suited even if it isn't faulty to begin with.) In the meantime, I just got fed up with all this sub-par stuff and ordered a dedicated 1090 MHz-antenna. With all the effort I already spent to setup this thing, I decided not to waste it all and put a mediocre antenna in front of it. I found this one: https://www.amazon.de/AirNav-1090MHz-Außenantenne-RadarBox-FlightStick/dp/B07TZG3KMQ/ref=pd_sbs_2?pd_rd_w=Zmim3&pf_rd_p=368fb9c4-dbef-44cc-98c0-80b189d2eca9&pf_rd_r=4E77K0QRGHVHBFG1VV2D&pd_rd_r=f8e54016-2933-4428-bfb3-638cb548e35b&pd_rd_wg=wXW17&pd_rd_i=B07TZG3KMQ&psc=1 This is a bundle deal of an "AirNav" antenna and a "Radarbox FlightStick", the one with integrated preamp and 1090 filter. (Yes, I read the stories about RadarBox, but the equipment wasn't rated too badly in comparison tests and I have no intention on connecting to RadarBox24 anyway.) This will free up the scanner antenna for "playing" and the ADS-B can stay up 24/7. BTW: I used a lot of your scripts to setup my Raspberry pi. Everything, and I do mean everything, just breezed through on the very first try. The core parts (readsb, adbx-feed, tar1090, graphs1090, autogain) I had up and running basically in notime. Your tutorials and scripts were absolutly flawless and made it extremly easy. A big thanks for that!
That's great! The bundle isn't bad at all, i don't have any reservations about it. And if the stick dies at some point ... easy to replace. Just take care not to damage the coax as it can't be replaced Thanks for feeding!
Hi ...ok just for your information.... What you have is a broadband antenna means you are receiving different band alltogether. Thats not a good idea for receiving ADS-B . By the way all rod antennas are broadband. The second thing is the polarization....rod antennas has to be installed vertically always ! and the best reception is done by an also vertical transmitter antenna.....so you will have drop outs if a plane is flying sharp curves for example. I am developing ADS-B antennas since years and I can tell you ADS-B receiption this is not easy especially if you are working together with a RASPI for example My new antenna which I have tested and which works for me perfect is a patch antenna I have attached a picture I can use it horizontal or vertical it doesn´t matter As you can see...something brand new. If you want to test ...shoot me an email cu
I need me some of this kinda hotness. I'm not going to understand 84% of it, but I'll learn the words and just throw them into conversations periodically to make people think I'm smart. Awesome plan! Seriously though, I need me some 1090Graph thingy
