Not Yielding nearly the Results of a Station near Me


#1

I have only been Broadcasting Flightaware for about a month. I found a Station close to me and he is killing the charts tons of input, but mine on the otherhand isnt doing very well. I have the 1099 Mhz antenna about 40 Feet above my house for a total of 800 ft elevation connected to system with 25 feet of LMR 240, Proper Pigtail, SMA Filter, and Amp to Raspberry PI. i feel like im missing something. Is their a setting or 2 i need to Modify in Raspberry PI? On Average my system pulls in 225-300,000 and his is 600-740,000. Their is no reason for someone less than 10 miles from me to have that much more input. Sky coverage is clear no obstructions


#2

What dongle are you using and what gain setting ?

Sent from my iPhone using Tapatalk


#3

I think you are probably fully optimized (or nearly) with your current setup and the difference is likely in the hardware your neighbor is using. He may have something better than a Raspberry Pi.


#4

The FlightAware ADSB coverage graph is showing your range maxes out around 150-200 miles while the other site is maxing out at 250+ mile range.
This small looking difference in range makes a huge difference in actual coverage area. AREA = pi * radius * radius
There is about a twice the coverage area from having a max range of 175 miles compared to a system with max range of 250 miles.

Since you are in a flat area with no obstructions most likely your receiver/amplifier is not as sensitive OR your antenna is not as sensitive. Your coax cables are fine.

To give you some information on parts we recommend at FlightAware to get around 250 miles range:
FA Antenna 6dBi with VSWR less than 1.5.
25 feet coax cable rated around 8dB / 100 feet. LMR240 is one brand what we recommend and has about 2dB signal loss per 25 feet.
The FA prostick with built in amplifier has just under 20dB extra gain while adding about 0.2dB of noise.

The difference between 250 miles signals and 175 miles is about 6-7dB when comparing similar noisy systems.
I would also be very careful of not adding in too much noise and signal losses because you can’t get it back with amplification.
IE A system with lower noise and signal losses will usually outperform a system with much higher amplification


#5

I am utilizing the FA Amp, FA 1099 Filter, Advertised FA 1099 Antenna, 25 feet LMR 240, coaxial to SMA pigtail, and a new Raspberry PI 3. Someone mentioned setting, where is their to change settings?


#6

i figured out access to fadump1090.sh it was set on -10, i hear you can go up to 45-55 what is a good level?


#7

Possible values are:-
0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6
max == 49.6
agc == -10

On Joe’s ASD-B Receiver, which I use on a RPi3, the default is max, which is configured in /etc/default/dump1090-mutability.
Suspect you are using other software as it defaults to -10, I don’t know where you configure this.

I would suggest you start at max/49.6 and work down.


#8

im using default dump1090
file location is /etc/init.d/fadump1090.sh
not sure i can use the AGC command in my config since i read -10 is auto gain and typing - max does not work i would believe thats the alternative version of dump1090 those commands work on


#9

In that case just go for the values, starting at the top. You can put in any number the software will use the nearest value I listed e.g 50 will result in 49.6.


#10

You can find the gain commands here
flightaware.com/adsb/prostick/setup/

I have seen people need to lower it to 30 to get the best results.
Try one step at a time.


#11

-10 will produce way to much noise , any luck trying a lower value?

also you should look into using adsb-receiver its uses a fork of dump1090 and also has some really good graphs you can use to compare settings


#12

Elevation makes a big difference too, perhaps his house is 100ft higher or something.

Also he could be using a better antenna or even a better receiver like a Mode-S Beast.


#13

Question do you get better results with or without the 1099 Filter? ive been reading alot of mixed reviews

Im adjusting my Gain 1 level at a time and watching it still hit and miss gonna take alot of time to figure out the right setting


#14

There is always a price to pay with a filter (insertion loss). If there are any sources of noise or signal near you, and you’re using a standard dongle (extremely wide-band), using a filter likely helps more than hurts, but every environment is different. Run a week WITH, and then run a week WITHOUT… and then check your daily stats graphs.


#15

The system you are comparing yourself to may have many small differences that may add up to the 6dB.
They may have a separate amplifier mounted right at the antenna winning back a couple of dB of cable loss as well as reducing the noise in the signal.
They may not need the filter in their location gaining another few dB.
May have a slightly higher antenna.
May have a higher gain antenna or have a directional rather than omni antenna if most of the air traffic is in one direction from their site.
May have optimised their receivers gain settings.

It’s a pity we can’t somehow link our feeder(s) to our forum profile. Then we could private message people and ask if they would mind sharing some information on their setup.
It would also be useful when offering advise if we could see and compare the publicly available feeder statistics.

Or is that feature available?


#16

It’s indirectly available in that the discussion forums use the same usernames as the rest of the FA site.


#17

I started a new topic to see if anyone was interested in making the stats more readily available.
Add feeder stats/link to user profiles or autosignature?