Yes all the settings are the same except for the gain, which is 15 with the RTL-SDR and 19 with the Uptronics.
It’s not much to look at but here is my setup. The whole rig is in the attic. I added the SAW filter this week which joins my FA antenna and blue FA dongle. The dongle plugs directly into a Pi B3+, the SAW plugs in via a USB pigtail. The antenna isn’t visible because it is on the other side of a big round run of ducting.
1 Like
Without a reference system, you are really flying blind.
As you can see here, I’ve been making changes to this site - most show a definite improvement in performance:
Except I haven’t.
Nothing has changed on this site for well over a year - there is simply more traffic this week.
2 Likes
Seems like you could use a few nearby ADS-B sites as a rough reference point - if they all stayed relatively flat during the week and your site improved by 20%, your current config is probably better than the previous config.
That’s what i do once i made changes. I compare it to nearby sites. If my performance drops and i see that these other sites having the same drop, i am not concerned
Wow, i haven’t seen so far that the filter is almost the same size as the Raspberry itself…
Cavity and interdigital filters are by their very nature a physical device. That is, their performance is a function of the wave length and physical size.
1 Like
Which metrics do you use for the comparison and how long after you make a change before you can get a meaningful comparison using a neighbour site?
I also have two systems running in parallel. One stays as a reference and the other is the experimental.
When I make a change to the experimental I can see almost immediately if the stats on the Skyview page vary. Total Aircraft, Aircraft With Positions And Messages per Second are all there in real time.
I can also look at the RADAR maps and see if I am seeing the same aircraft and the trails give me a very quick and reliable indication of the quality of the signals I am receiving.
My interest is to maximise the number of aircraft I can see and to maximise the distance I can see them. The above two Pi setup makes it very easy to quickly see the effects of changes to antenna, amp, filter, gain et.
I also watch the stats of a fairly close station who sees a few more planes per day so I know I still have a bit of improvement to eke out but unfortunately that will require a 6 metre mast to get over a neighbour’s second story.
YMMV
S.
2 Likes
That’s a lot of aluminium foil, almost looks like a metal roof!
Your reception is quite good though!
What gain do you run, 25 maybe?
1 Like
Yes, by volume it is pretty much the same size as my Pi 3 case. It’s very light though.
Yes, in my area water heaters and HVAC systems (except the compressors) are in the attic. The ducting is wide diameter with aluminum on the outside. I did a bit of experimenting and I don’t think it mess with the reception but of course without a real reference system there is no way to be sure.
I just added the filter and am in the experimentation phase on gain. Pre-filter it was 48 and I’ve lowered it in a couple of steps to 33.8. The Monday holiday here in the US (military stand down) and weather the past few days has made comparisons pretty difficult but this gain seems to be working pretty well. I plan to lower it until I see some loss of range and then see how that compares in terms of overall planes and messages received. I also want to add UAT at some point.
That’s not fully reliable and can be used only if you make changes having a huge impact. Even a gain setting change from one value to the neighbour value cannot be tracked here.
With the variety of aircraft in the air on every single minute it is simply not possible to get smaller changes recognized.
In the sentence immediately before the one you quote, the poster says that they have two systems - one reference, and the other experimental. When you add that information to what you quoted, it seems reasonable to infer that there are two instances of SkyAware running simultaneously. If a change to the experimental system causes that SkyAware to display (greater/fewer/the same) number of (aircraft/messages/tracks) as compared to the reference system…it would seem to be fair to assume that the change caused the difference.
2 Likes
Thankyou for correcting me.
Could you please advise what methodology you would recommend to accurately measure the effects of changes to my receiving environment.
S.
What a ridicules thing to say.
To observe a receiver hears 100 planes tell you very little.
To observe Receiver A hears 100 planes and Receiver B simultaneously hears 101 show a difference that is obvious to anyone.
(determining if it is significant is the next step)
1 Like
The great thing about hobbies like this is that each gets to enjoy them as they would like. There’s moments when I’m just winging it, and others when I am doing ( or trying to do) hard science. At the end of the day, it is up to each of us to decide what the proper balance of each approach is for the results we are trying to achieve.
I find RF stuff to be wildly inexplicable at times, with theory conflicting with empirical evidence at every turn- or maybe its the other way around ? Every time I think I understand how it works I realize that I don’t really know how it works.
Like @SweetPea11 I have a couple of nearly identical setups that I tinker with. So far, I have found numerous ways in which I cannot materially affect ADS-B reception on them.
3 Likes
Spent a few bucks giving the antenna of gns-electronics.com a try.
Device is currently still mounted on my indoor RPi, but it shows 10% better signal level with the same gain setting
Also the message rate has been slightly improved. Not that much, seem to be that my DIY antenna is already in a good shape.
Will test the device over weekend on my outdoor feeder where an optimized antenna is already in use.
The shop also offers it without housing where the details what’s inside can be seen.
2 Likes
I wonder why they claim 6dBi on an antenna that can’t possibly be greater than 2.15dBi
Is your DIY antenna a 1/4 λ on a ground-plane?
If so, then your dipole will be an improvement.
1 Like
Looks interesting. I will have a look.
Nope, it’s a spider which i built earlier based on instructions of abcd567
The new antenna is now outdoor and performs similar to my previous handcrafted antenna which i got from a guy via eBay This one is now operating my 3B indoor looking north where the outdoor antenna is covered by the roof.
I haven’t expected any miracles but the price was worth to get a second one in a good outdoor housing as my DIY skills are very limited 
.