Goodmorning,
My name is Ger from Holland.
I have a question: Is someone now if it is possible to use two or more RPI for receiving ADS-B signals and put these together.
I live in appartment, the roof is to high but I can look to all wind directions.
I read on “www.satsignal.eu” that it is possible, but perhaps someone has other solutions.
Thanks and greetings
The best solution is to just install both Pis with piaware/dump1090-fa, so you feed FA from each pi.
(If you would combine the data first, then feed them to FA, MLAT won’t work)
Then you can combine the results on one of the RPis for example with this: GitHub - wiedehopf/combine1090: Combine data from multiple ADS-B receivers into one readsb decoder / tar1090 webinterface
This will give you a map with the combined signals from both receivers.
You could also use VRS to combine both receivers.
There is also other solutions i believe.
But if you just want them combined in another dump1090-fa map then the solution above should work very well.
(You can still access both receivers maps separately)
hi wiedehopf,
Thanks for replay. it sounds good and i am going to try.
What i also want is to use all the data for feeds.
When it is possible i will feed from one home ip-address.
Can you send mee another link you wrote (http://192.168.2.33/combine1090) because i cannot open it.
Greetings Ger
It needs to be the IP address where you install the combine1090.
You will also need to edit the configuration file like it is described in the readme.
As i said due to MLAT it is better to install separate feeds.
Of course if you don’t want MLAT i suppose you can use those data.
But worry about that after you have it running i would say 
yep, i read to fast.
Later i saw the meaning
I did tried to “combine” two receivers and indeed the MLAT was failing because it would receive the SAME data sample, from the same airplane, with different timing stamps (from each receiver/Pi).
However, if the antennas are seeing only separated parts of the sky, like in this case one on North and another on South window, the airplane signals might not overlap, so the MLAT will not receive the SAME samples. Except maybe only on the “border” of reception zones, where they might overlap a little bit.
So all those data signals, coming from non-overlapping areas, will be OK for MLAT.
Adding more than that antennas, will overlap reception zones and again the MLAT will fail for signals in those overlapping areas.
In my case I was considering directional antennas, but after testing with raising the antenna, I decided that… that is a better way to go.
Actually this will still fail. The problem is that the mlat server needs to build a model of the particular clock characteristics of a single receiver in order to do clock synchronization. If you combine data from two different receivers in a single feed and try to feed that to FlightAware’s mlat system, it won’t be able to do that.
Thanks for clarification, I stand corrected.
I don’t know how that model is built, that’s why I assumed that if they don’t “see” each other samples it would work.
Hello all,
What is the differend between the system of wiedehopf (what looks nice) and ADS-B dump1090, alinea : Running two Raspberry Pi cards on different sides of the house.
In this artikel they dont talk about the MLAT.
Their setup wouldn’t allow you to have MLAT on both receivers, it would only work on one of the receivers.
(They don’t run an extra dump1090 which is just there to combine the data.
Instead they combine the data on one of the dump1090 that is already running)
With my setup you can run piaware on both receivers, and it will also display the MLAT results in the combined map.
Their setup also only has 2 maps so to say. 1 map with only one receiver, the other map with both receivers combined. With my setup you get 3 maps, both receiver maps and the combined map.
Also it seems you only installed piaware on one of the two receivers (Ger S ADS-B Feeder Statistics - FlightAware)
If you want MLAT results from both receivers you need to install piaware on the second Pi as well.
Oke wiedehopf, that makes sense. Clear explanation, thanks for that.
Did the installation give you any trouble?
Should i place the remark about the IP above the link? 
I think everything is clear.
I am going to try and when i run in to problems i place a message.
Good morning wiedehopf,
Your programm runs fine.
Very good and thanks for this.
Question : How many ip-address can i conect and there is no possibility to feed Piaware with all these data also to make my statistics higher?
Thanks anyway and try more of your nice scripts.
Ger
There will be probably a bandwidth necessary of around 15kB/s per receiver you connect. Could also be 30 kB/s for a very busy receiver.
Apart from the bandwidth there should be nothing from stopping you connecting as many IP-addresses as you want.
As i said if you feed the combined data, you lose MLAT (Multilateration (MLAT) - FlightAware).
I would therefore recommend install piaware and claiming each receiver separately.
But you can also disable MLAT on the FA stats page and feed the combined data.
Note: won’t work on a piaware sd-card image
For that you need to enable the beast out port on combine1090:
In /etc/default/combine1090 change --net-bo-port 0 to let’s say 29005 like this:
NET_OPTIONS="--net --net-heartbeat 60 --net-ro-size 1000 --net-ro-interval 0.2 --net-ri-port 29001 --net-ro-port 0 --net-sbs-port 0 --net-bi-port 29004 --net-bo-port 29005"
Then with piaware-config you set the following config options:
receiver-host localhost
receiver-port 29005
receiver-type other
But again i would recommend using piaware on each receiver, that way you also get the MLAT data for your local map.
(Right now you only have piaware on one receiver as your stats page shows only one)
His router DHCP might have something to say about that?
Talking program not network limitations. If you don’t know how to set up a network for more than 255 computers, then you probably won’t anyway.
Anyway just tried 100 connections to the same computer over WiFi.
Limiting for me in that case was the wireless bandwidth.
The CPU of the pi was also at the limits.
So let’s just say the bandwidth is limiting and more than 100 will probably create other problems as well.
Some routers come pre-configured with even a more limited range of DHCP addresses. Probably to save their limited computing power?
My routers had to be “dual core ARM” to handle my network. So yes, 100 clients would be a reasonable limit in my case, but it could be much worse on other (cheap) routers.
If you want all of your ADS-B applications running on the same PC, then the only IP address you need to worry about is 127.0.0.1. (This is known as loopback address, so it tells your PC to connect to itself.) If you’re running apps on different PCs across your network, then you’ll need to know the IP addresses of all of the involved machines, and in the instructions below substitute those IP addresses for 127.0.0.1 where appropriate.
Computer networks are comprised of a number of ports. Applications access these ports basically in one of two ways: they either listen for data, or they serve data. Think of it like a radio station: only one transmitter can broadcast on any given frequency, but any number of people can listen in.