Q: max. Values in graphs1090 -> Messages per second (local)

[GK367]

Hello,

(without consideration of: own location and antenna)

I want to know:
a) which receiver do you use and
b) your maximum Value in Graphs1090 ---> Messages per second (local)

Because it seems that there are a 'boundary'/limit about ~1.350 Msg/Sec.

I don't know why ... is it, because:
1.) too much trafffic at 1090MHz with overlapping signals,
2.) or is my system the limit (Pi4B2GB + Nooelec NESDR SMART v4)?

... so I want to know, what are possible values.

Thank you ...

[Gaskippy]

I am using the Nooelec NESDR Mini USB RTL-SDR with modified antenna that came with the unit with a max msg per second of 7 in the last 24 hrs on Graphs1090.

[GK367]

Hello Gaskippy,

thank you for your answers.

Sorry, my quastion was not meaningful/concrete enought ... I mean the highest "LOCAL"(blue line) value in the table "ADS-B Maxima" ... NOT "ADS-B Message Rate per Aircraft".

Because I want to know where the technical limits are ... like:
- "What is the technical possible maximum of recieving msg/sec?"
- "And why is that the limit?" ... is it the reciever, or is it the capacity of the frequency in combination of the quantity of messages per second
... and that im combination of the users hardware

[Oblivian]

Given people have 2 variables that are not fixed - range, and number of targets. I wouldn't expect a definitive answer

The only knowns seem to be, aircraft xmit an average of 4.2 messages per second. And 1Mb/s datarate. Depending on capabilities.

Depending on the receiver, or software doing the decoding. There might have a queuing option. Or it may need to drop them and have a max processing limit based on chipset, CPU for CRC checks and so on or memory writes. Some have optimization and filtering for ADSB which makes the processing job easier than if it was full of noise and causing extra drops

Some receivers have a fPGA - where they can do 400 messages/s happily. https://wiki.jetvision.de/wiki/Mode-S_Beast:Performance

Then there are reports of people with filters reaching 1200 msg/s

Here you can only get about 20 targets in range at any one time, some in other countries will have hundreds

The majority of users, don't take any notice AND come to forums to interact. They're mostly here when stuff breaks, or to look at database info and never any other time.

[Gaskippy]

GK37,

I have 125 msgs per second as you asked for.

[GK367]

GK37,

I have 125 msgs per second as you asked for.

Thank you!

[GK367]

Given people have 2 variables that are not fixed - range, and number of targets. I wouldn't expect a definitive answer

The only knowns seem to be, aircraft xmit an average of 4.2 messages per second. And 1Mb/s datarate. Depending on capabilities.

Depending on the receiver, or software doing the decoding. There might have a queuing option. Or it may need to drop them and have a max processing limit based on chipset, CPU for CRC checks and so on or memory writes. Some have optimization and filtering for ADSB which makes the processing job easier than if it was full of noise and causing extra drops

Some receivers have a fPGA - where they can do 400 messages/s happily. https://wiki.jetvision.de/wiki/Mode-S_Beast:Performance

Then there are reports of people with filters reaching 1200 msg/s

Here you can only get about 20 targets in range at any one time, some in other countries will have hundreds

The majority of users, don't take any notice AND come to forums to interact. They're mostly here when stuff breaks, or to look at database info and never any other time.

Hello Oblivian,

thank you for the detailed informations.

I started feeding in 01/2021 with a blank 6,9cm CopperWire -> PoorMensGroundplane -> ColLins -> CoLins with LNAs (and filter) -> and now I'm working and beam antennas (unfortunately indoor on the attic). Yes, filters and LNA's are very helpfull.

When I look at my graphs1090 I can recognize, that since january the "ADS-B Messagerate per Aircarft and second" (max was 18,5msg/s) getting smaller because the number of seen/traced aircrafts increases. (see picture)

Yes, I've also >1.200msg/s ... its dependend from traffic and the weather.

[f14driver]

Hello,

(without consideration of: own location and antenna)

I want to know:
a) which receiver do you use and
b) your maximum Value in Graphs1090 ---> Messages per second (local)

Because it seems that there are a 'boundary'/limit about ~1.350 Msg/Sec.

I don't know why ... is it, because:
1.) too much trafffic at 1090MHz with overlapping signals,
2.) or is my system the limit (Pi4B2GB + Nooelec NESDR SMART v4)?

... so I want to know, what are possible values.

Thank you ...

On average 350 msg/sec on 3 of my 4 flightfeeders.
1 has an average of 550, the difference is the use of LMR400 super low loss cable on this specific reciever
The other recievers have LMR 200 cables.

All equipment is identical, flightaware blue prostick plus, and a FA 1090Mhz filter.
Antennas are 2 x FA antenna and 2x Vinnant Antenna

[GK367]

Hello f14driver,

thank you, for your answers!

On average 350 msg/sec on 3 of my 4 flightfeeders.
1 has an average of 550, the difference is the use of LMR400 super low loss cable on this specific reciever
The other recievers have LMR 200 cables.

All equipment is identical, flightaware blue prostick plus, and a FA 1090Mhz filter.
Antennas are 2 x FA antenna and 2x Vinnant Antenna

The difference in cable types is intersting!
Hm ... have you try to change the LMR400 against a LMR200 cable ... so that you can be sure that the cable is the reason?
(I use ecoflex 10 ... it's "nearly" the same as your LMR400, at 1000MHz.)

Two questions:
- Does your 4 receivers work at different or at the same location(s)?
- Antenna: Which one do you prefere the FM or Vinnant?

[f14driver]

Hello f14driver,

thank you, for your answers!




The difference in cable types is intersting!
Hm ... have you try to change the LMR400 against a LMR200 cable ... so that you can be sure that the cable is the reason?
(I use ecoflex 10 ... it's "nearly" the same as your LMR400, at 1000MHz.)

Two questions:
- Does your 4 receivers work at different or at the same location(s)?
- Antenna: Which one do you prefere the FM or Vinnant?

In anwer to your questions, I did try the two cable types on the same antenna. So I'm convinced that the cable does make the difference. Antenna was running with the LMR200 cable for 2 years and then changed to the LMR400.

The 4 recievers are all running from the same location.
As I live at the 3rd level of a 9 story building I had to cater for the blocking of the signal by the building itself. It's a location in an urban envrionment on the outskirts of Amsterdam with some high rise building nearby. And two cell towers within a 1 KM radius as well that might cause interference.
Antenna's are placed facing NE/SE/SW/NW that way I can work around the building and I have an view of approximatly 320 degrees, the other 40 degrees are blocked and can't be reached.

Antenna wise there is no difference in performance between the FA antenna or the Vinnant Antenna. I have two outdoor and two indoor antenna postions, the Vinnant antenna's are used for the outdoor positions and the FA ones for the indoor positions.
The difference would be in price, the price of an FA antenna is € 63 without shipping, the Vinnant antenna is € 29,50 without shipping. So for the price of a FA antenna you would have two Vinnant antennas.
I think the Vinnant Antenna has a better suited connection for outdoor use, I doesn't need weather tape to seal the connecters against water ingress ( The FA one will need that).

[GK367]

Hello f14driver,

I'm sorry for my late answers ...
Thank you for your detailt answer, now I understand what you mean.

I don't have any FA Antenna, but I also had used Vinnant Antenas ... and I agree you, Vinnat is a good quality, they are very good for outdoor use!

By the way, I work with a LNA (RTL-SDR.com ADS-B Triple Filtered LNA - Bias Tee Powered - 1090MHz), that gives you some additional Power and Range.
When you work with a LNA, you should change the gain settings of the SDR-Stick from automatic (-10) to manuel!
"Gain Settings" suggestions for:
Nooelec NESDR SMART v4=> set Gain to: 20.7, 22.9 or 25.4
Flightaware Pro Stick Plus => seit Gain to: 3.7 or 7.7
These values works well at my system. Less overrides, and a good averange between max. simultaneous Aircraft and max. Msg/s.

Without to know where your location and whats your traffic is, I think you can rise your msg/s 800, on the system with the LMR400.

Last weeks I change SDR-Stick from the Nooelec to the Flightaware.
Until now ... I can't find big differences except (a) sensitivity and (b) the device temperature (the Flightaware Stick is much cooler).

But now back to the max. possible msg/s.
Meanwhile I think the border/maximun will be around 1.500/1.600 msg/s, per Receiver/Stick

[f14driver]

I don't work with an LNA. I have the FA pro sticks in use with additional FA filters.
The Prostick has an builtin LNA ( not as good as an external one) but it suits my needs.
I live in a urban environment (Amsterdam Netherlands) with lots of high rise buildings so adding an LNA would be a minimal improvement. multiply that times 4 and the investment to get more isn't worth it at the moment
The gain for the Flightaware sticks already was tuned manually. I had front side of the building on 38.5 and the back side of the building 43.5. It just depends where your antenna is located, in reality they are only 10 meters apart from each other.

Yesterday I implemented the new Piaware v 6.0 software and the new dump1090-fa v 6.0.
These will enable dynamic gain, the system itself will determine the gain based on the environment needed.
Checks are every hour so more tuned into the needs of that specific moment.
In the last 16 hrs I had more positions and more aircraft but have to compare over 24 hrs to look at the total picture.

[GK367]

Ah ... okay!

I've also upgrade dump1090-fa to v6.0, but the automatic won't work so well for me ... because I work with a LNA.

My first setting was:
inital gain: 7.7
min gain: 2.7
max gain: 15.7

... but graphs1090 show me, that there was more than 12% > -3dBFS (that is to much red)
So I set max gain down to: 7.7

dump1090-fa_v6.0_on_automatic.jpg
To see what the signal strength is/says, I also like to use "tar1090".

For the gain value setting in "dump1090" I orient myself at the "RSSI" Values in "tar1090".
I lookt that in tar1090 the RSSi values between -1,9(strong) and -35(weak).
For example: Just in the moment I'd 178 aircraft, 3 of the are between (-1,9 till -2,8) and 30 between (-31 till -35).


Compare between old an new settings: I prefer to compare a longer time, one week. Because the Weekdays are so different in my area.

[f14driver]

I also compare over a longer time period and use the same graphs.
I had them tuned manually to max 5% of >-3DdBFS and now I'm seeing max 8% of them with dynamic gain enabled.
In return I got 6,5% more aircraft and around 12.5% more positions when averaged over the 4 stations.
Weekends are usually a little less in traffic but today was a good day. Also there's a nice tropo layer that enhances range at the moment due to the good weather today and in the upcoming days.
After a week I can say more about the tuning.
Untill now 139 automatic changes have been made in 3 days so adaptive gain does adapt when needed.