How to boost up the message rate


#1

Hi everyone,

Has some of you tips how to boost up the message rate?
I see planes enough via dump1090 but the message rate is to low.

Best regards,
NL3EHV (Ruud)

I use Raspberry Pi3 and Flightaware (blue) filter.
http://62.251.100.171:1090
https://nl3ehv.nl/graphs.php
http://62.251.100.171:8888/status.html
http://www.nl3ehv.nl (Dutch website)


#2

What kind of antenna and coax system do you have? A masthead amp may be an option for long coax runs.
How high is your antenna?
I couldn’t find your feeder stats to look at your range. Are you feeding Flight Aware?
Have you looked at optimising the gain settings to improve your range?
Have you looked into whether or not you need an external filter? Even the Blue Pro plus dongle may require an external filter in some locations.
I put my RPI and dongles in metal cases to reduce noise.
I also using RF chokes on the USB power cable and USB pigtail(for the dongle) to reduce noise.


#3

Antenna: FlightAware 1090MHz ADS-B N-Type Antenna 26" - 5.5dBi (don’t look at the picture, that’s an old antenne)
How High: take a look at http://www.nl3ehv.nl - i guess 50 meters?
Yes i’m feeding 4 website including FlightAware.
I receive planes at 1200KM (see picture at website)
Gain: yes i have tried less gain, for now it is on max.
Filter: I have a FlightAware filter, works very good, 30 meters from my location (on the roof) there are several GSM transmitters for mobile phone.
Noise: My noise result are in a graph at https://nl3ehv.nl/graphs.php but i don’t know if they are good or bad. I think good :slight_smile:
Question what are RF chokes?


#4

There are two ways to increase performance. Increase the signal or decrease the noise.
The two biggest improvements are to use an amplifier (increase the signal) and add a filter (decrease the noise).

The RF choke is used on the input power side (USB connector side) and will remove noise on the data cable.
Search amazon for “ferrite beads”.
The noise coupled in from the usb connector is usually very small.


#5

Aha, ferrite… yes i can try that.
But,… what is normal to receive, at this moment i receive 140 planes (positions) and 1027 message/sec.
And while i am looking it drops to 964/sec.
Maybe something is interfering?


#6

Check your my-ADSB stats page for what is normal for your area. More planes = more messages.

When you see drops is messages/sec it is usually because some planes went out of range.
IE. the ratio of planes and messages should be about the same
so 140 planes / 1027 messages = 7ish
if you are getting 964 messages the number of active planes being tracked should be around 137ish


#7

I have taken your advise and put a ferrite on the usb cable.
Seems to help a little bit. And the advise of jonhawkes2030:
"I put my RPI and dongles in metal cases to reduce noise."
i consider to do, must be ground to i guess.
So, thanks for the advice!


#8

Awesome antenna height and nice stats for someone who only has a 180° clear view, isn’t it possible to move the antenna further back to the corner of the building or is that already someone else’s balcony?
Very cool performance graphs Ruud, I guess they’re also running on your Pi?
May I know where you got them from?


#9

indeed, I don’t think my neighbor like to have my antenna on her balcony :slight_smile:
So 180 degree it is… and on top is also not an option, i need 220v and internet.
Strange that i can stil receive airplanes at the other side of the building, the building is very big.

Yes i’m running it on a Pi3 ( http://62.251.100.171:8888/status.html )
The graphs i got from here: https://github.com/jprochazka/adsb-receiver/releases
I’m running v2.60 and i now see v2.61 is out, :slight_smile:

Make first a backup from you Pi.
Succes!

Update: https://github.com/jprochazka/adsb-receiver (and how to install)


#10

If someone know why i can receive airplanes at the other side of my (big) appartment, please let me know.
I don’t have a clou, till 1240KM i receive them ?!?
See also http://62.251.100.171:1090/ and http://www.nl3ehv.nl for a screenshot.
Is it a kind of reflection?


#11

Most probable cause to receive UHF-signals so far below the horizon could be tropospheric ducting, it’s quite rare but still possible.


#12

I just checked your map at http://62.251.100.171:1090 and I’m surprised, 500 to 600nmi (flights from Austria and Poland) from the other site of a concrete building is something extraordinary!


#13

Haha yes indeed, from the other side of a concrete building…
If i see the planes on the 180 degrees site (the west side) i’ll be not supprised.
But seeing them on the east side… ??

UHF is possible and there is a big buidling on the opposite side so maybe a reflection from that building.
My building is 13 stories high and i’m on the 11 floor. (west)
If i look out of my window i see Eindhoven Airport (Netherlands) it’s about 8KM to the west.


#14

And right now, new record 1300,7KM !
I have to put that screenshot on my website :slight_smile:


#15

Great performance Ruud, I never heard of someone getting above 1300km/700nmi!
There’s a topic called ‘what’s your farthest plane’, you need to post your record breaking distance from Holland to Ukraine over there with a link to the screenshot.
Cannot believe you’re complaining about the message rate while going over 700nmi :wink:


#16

The distance is indeed not the problem but i think i could receive more message per aircraft.

I’m now in the process of translating my website to english, if you see something rare pls tell me my english is so not good. :slight_smile:
Thanks!


#17

The line of sight for the location given a plane height 40000 feet, and an antenna height 120 feet (11 story, each10 feet/3 meters) is 298 miles/480km.
http://www.calculatoredge.com/electronics/lineofsight.htm

As you can see all those abnormal flights have dotted lines, so they are not directly observed ADS-B signals.
Maybe there are some reflections on upper atmosphere (doubtful at 1090MHz, but sporadically can happen as “Tropospheric ducting”) or those are re-broadcasted messages by a closer located station.


#18

Yes indeed, i think also they are reflections.
But then very often, on a daily basis.
Most of the lines are dotted, also close by.
Maybe that is the reason my message rate is to low.


#19

In my case lowering the receiver gain improved the message rate. You might loose the long range though…
Trial and error…

Also, installing some filters helped me too (like the FA one), but that’s just because I am close to cell towers and airport radar.


#20

I’m a fairly new ADS-B hobbyist/enthusiast, so pardon the question.

Why is message rate so important? I would think the number of planes seen is the goal. Messages are just the ‘chaff’ that comes with the ‘corn’. What am I missing?

Thanks.