AIrNav FlightStick vs FA Pro Stick Plus

[GlynH]

Well its taken the best part of two years for me to get round to comparing my existing AirNav FlightStick vs. FA ProStick Plus but as it really is as easy as Plug & Play I thought I’d give it a go before I start updating any of the software as it would be good to retain a baseline to compare against.

So using SkyAware on the LAN I took a screenshot of the current green ANFS and this is what I saw;
Aircraft: 256
Positions: 225
Messages: 1946.2/sec

Shutdown the Pi, swapped them over and first of all noticed how big the blue FAPS+ was. So big in fact that it impacted the small USB->microSD Card adaptor I keep in one of the slots to the point where it wouldn’t fit into any of the three remaining slots! Not the end of the world as I can always put one of the USB devices on a short extension cable much as I hate using extensions/adaptors of any sort but easy enough to do.

Switched on the Pi and gave it 5 or 6 minutes to settle but the performance seemed dismal compared to the AN dongle to the point where I’m wondering if there is a problem with the FA dongle? Problem is I bought it nearly two years ago so way past its return date. You can see the difference here;

Aircraft: 148
Positions: 90
Messages: 273.9/sec

Over 100 aircraft and 1,600+ messages/sec lower? That can’t be right can it?

I regularly see over 300 aircraft and 2000 messages/sec at various times of the day using the AN device and was expecting the FA device to be at least the same but probably better so it was a shock to see this.

I swapped back to the AN dongle and after a few minutes took another screenshot in case I had inadvertently disturbed something that affected the readings but it went back close to what it was before;

Aircraft 275
Positions: 224
Messages: 1827.4/sec

What could possibly cause this? Both AN & FA were used without filters as I believe they already have filters and an LNA built-in but I do have the FA Blue 1090MHz filter here if I ever get round to trying it although I don’t expect to see that make up the difference.

I also have an AirSpy Mini and R2 that I would like to try but this would entail a complete reconfiguration of the Pi and also mean getting the ladders out, dropping the antenna pole, sticking the Kuhne LNA 1090 A TM amplifier inline and fitting the Kuhne bias tee in the loft as the AirSpy only has 4.5v/50mA output vs the 8-15v/130mA the LNA needs so has put me off for the last couple of years!

I still can’t understand why the huge difference between the two dongles unless the FA is faulty or it takes much longer to ‘ramp up’ than the AN device. Maybe the SMA centre pin is not making a good contact with the FA device but I didn’t delve any deeper today.

I might take another look tomorrow to prove/disprove todays findings but I’m really keen to update the system software first as I mentioned in another thread as it’s long overdue…

-=Glyn=-

[abcd567]

@GlynH

What could possibly cause this? Both AN & FA were used without filters as I believe they already have filters and an LNA built-in but I do have the FA Blue 1090MHz filter here if I ever get round to trying it although I don’t expect to see that make up the difference.

The difference is in location of built-in SAW filter chip.
In ANRB Green stick it is before built-in LNA
In FA Blue it is after built-in LNA

In strong RF Noise areas, the FA Dongle’s LNA gets overloaded and makes dongle deaf for weaker signals.

As you have FA Blue filter, add it just before the FA Blue stick, and most likely it’s performance will jump up

Spektrum - How-to Speedily Scan RF Noise in band 24MHz ~ 1800MHz

 

 

 

 

[iandrews]

Also, what about gain setting. I know you said that both have a LNA built in but they may be different power levels, so maybe you either need to drop or increase the gain when you have the FA stick plugged in.

[abcd567]

@iandrews

both have a LNA built in but they may be different power levels, so maybe you either need to drop or increase the gain when you have the FA stick plugged in.

Yes, true.
Worth trying gain adjustment also,
However better will be to first add Filter to FA stick and see, then remove filter and try adjusting gain.

[foxhunter]

Neither the Airnav stick nor the FA stick is capable to have a message rate of +1900/sec as shown on your screenshot.

Radarcape seem to have issues that they are catching Mode-AC aircraft, as long as it’s not disabled in config. That almost doubles the total amount of messages.

I had a similar issue which occured always once RB24 feed is installed.
Maybe that’s a source of that significant difference

[GlynH]

Thanks for the suggestions.

Plan to try the FAPS+ with filter tomorrow when aircraft start to pick up.

Gain is/has been set to 60 although I did play around with Adaptive Gain when it was introduced.

This time of night (9pm) shows less than half the aircraft I see at any one time during the day;

Aircraft: reduced to 153
Positions: 151
Messages: increased to 2127.6

That last figure is weird then as it is even higher than the previous but with less aircraft - maybe that signifies something?

I do have rbfeeder installed and in addition to FA I also feed FR24 and ADSBExchange.

More investigation methinks…

Thanks & kind regards,
-=Glyn=-

[GlynH]

Other graphs for the last 24 hours if that might shed more light on what is going on here?

Thanks & kind regards,
-=Glyn=-

[abcd567]

Messages > -3 dBFS (15.1% of messages)

Try to reduce gain to bring down 15.1% to 10%

 

[wiedehopf]

@foxhunter

Neither the Airnav stick nor the FA stick is capable to have a message rate of +1900/sec as shown on your screenshot.

I wouldn’t be so sure about that, you can have that in very good locations.

I suppose graphs1090 is showing a bit less … which is pretty normal.
The 2130 messages per second might be with modeA/C included … idk.
Whatever.

[jaymot]

@GlynH

Gain is/has been set to 60 although I did play around with Adaptive Gain when it was introduced.

That means AGC is on all the time! Do you really mean to max out you tuner’s gain in addition to having a built-in LNA, to try to compensate for lossy coax or a poor antenna placement or something like that?

[foxhunter]

@wiedehopf

I wouldn’t be so sure about that, you can have that in very good locations.

Sure i have seen good installations bringing up to 1500/sec, but not 1900 or even 2000.
Whatever

If i am not wrong @keithma is usnig an FA stick on his second feeder:
http://essexradar.co.uk:1090/graphs1090/

[foxhunter]

@GlynH

Other graphs for the last 24 hours if that might shed more light on what is going on here?

Try reducing gain step by step, leaving it fot 10-15 Minutes and check. Number of messages > 3dBFS should be 5% or less.

Possible gain values documented here:

Optimizing gain

With these values you should reduce it to at least 42.1 and check it again. If still too high, reduce it further

[wiedehopf]

@foxhunter

Sure i have seen good installations bringing up to 1500/sec, but not 1900 or even 2000.

Well 1900 i haven’t seen either i suppose: https://discussions.flightaware.com/t/thoughts-on-optimizing-gain/44482/235?u=wiedehopf
But 1700.

And 1700 is what is graphs are showing.
So i’d guess the 200 extra in tar1090 are modeAC or messages that couldn’t be associated with an established plane.

[iandrews]

I can get over 2000 with my Blue FA Stick. This is just now.

[foxhunter]

As said, if Mode-A/C is enabled, this can be.

I am not saying you have it enabled, this is a general statement

I had > 3500 on my Airspy before i identified that Mode-A/C was enabled and active after i’ve installed the Radarbox-Feeder

[iandrews]

@foxhunter

Mode-A/C

I have no idea if Mode-A/C is enabled (any way to check). This is a build using wiedehopf scripts (tar1090, graphs1090 etc) and then the FlightAware client.

[geckoVN]

If you are using the FA image, have a look in the config file.
Look for (or add):

# Should PiAware enable reception of Mode A/C messages when requested?
# You may need to disable this if processing Mode A/C overloads your receiver.
allow-modeac no

[wiedehopf]

I’d say these numbers haven’t been seen before due to it being much more busy this summer over the UK.

That’s an airspy station but the aircraft count is much higher than last year and higher than 2020 as well, though the numbers might be skewed by equipment changes.

In other words, if you cram enough aircraft in a small space, you can get higher numbers with any SDR

[GlynH]

Many thanks for taking the time to reply…advice very much appreciated.

@abcd567

Messages > -3 dBFS (15.1% of messages)

Try to reduce gain to bring down 15.1% to 10%

@foxhunter

Try reducing gain step by step, leaving it fot 10-15 Minutes and check. Number of messages > 3dBFS should be 5% or less.

Possible gain values documented here:

Optimizing gain · wiedehopf/adsb-scripts Wiki · GitHub

With these values you should reduce it to at least 42.1 and check it again. If still too high, reduce it further

It’s been a while since l have played with Gain settings but I seem to recall when I reduced the gain the amount & range of aircraft seen reduced as did my position in the RadarBox UK Ranking slipping outside the Top 10 for the first time so knee-jerk reaction was to put it back to where it was! I’ll make this my first point of interest based upon what you knowledgeable guys are suggesting.

@jaymot

That means AGC is on all the time! Do you really mean to max out you tuner’s gain in addition to having a built-in LNA, to try to compensate for lossy coax or a poor antenna placement or something like that?

Well I doubt that lossy coax or poor antenna placement is an issue here! Using a Watson 1090 Radar Extender fed by 8m Westflex 103 fitted with N-Type connectors mounted on top of a 16 foot pole bolted to the apex of a two-storey house on a hill 142m asl which is just about the highest point in my town! Base of the antenna is 152m asl and has a unobstructed 360 view. I have always enjoyed excellent TV, Radio, ATC, CB/SSB etc. reception over the years. This photo was taken in 2008 and the TV, FM and DAB antennas have long gone leaving the 1090MHz all on its own.

Polar diagram here;

@wiedehopf

I wouldn’t be so sure about that, you can have that in very good locations.

I suppose graphs1090 is showing a bit less … which is pretty normal.
The 2130 messages per second might be with modeA/C included … idk.
Whatever.

Well unless dump1090-fa enables Mode A/C by default I don’t have it enabled in the config and looking at SkyAware all 300+ aircraft currently listed are showing altitude but half-a-dozen of those might be missing speed, distance or heading if that is anything to go by?

With your continued help I will focus on trying to optimise my station rather than worry about comparing AN vs FA or updating any of the software for the time being so I have set the gain to 42.1 as suggested as from now and will see what difference that might make.

Thanks & kind regards,
-=Glyn=-

[GlynH]

A quick sudo systemctl status dump1090-fa returns;

● dump1090-fa.service - dump1090 ADS-B receiver (FlightAware customization)
   Loaded: loaded (/lib/systemd/system/dump1090-fa.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2022-07-26 11:38:30 BST; 23h ago
     Docs: https://flightaware.com/adsb/piaware/
 Main PID: 521 (dump1090-fa)
    Tasks: 3 (limit: 4915)
   CGroup: /system.slice/dump1090-fa.service
           └─521 /usr/bin/dump1090-fa --quiet --device-type rtlsdr --gain 60 --fix --lat 52.***** --lon -1.***** --max-range 360 --net-ro-port 30002 --net-sbs-port 30003 --net-bi-port 30004,30104 --net-bo-port 30005 --json-location-accuracy 1 --lat 52.****** --lon -1.****** --write-json /run/dump1090-fa

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.

Not sure why I should have two separate instances of lat/lon but the first instance goes to 5 decimal places where the second instance is to 6 decimal places which mirrors the entry in etc/default/dump1090-fa;

# dump1090-fa configuration
# This is sourced by /usr/share/dump1090-fa/start-dump1090-fa as a
# shellscript fragment.

# dump1090-fa won't automatically start unless ENABLED=yes
ENABLED=yes

# SDR device type. Use "none" for a net-only configuration
RECEIVER=rtlsdr
# serial number or device index of device to use (only needed if there is more than one SDR connected)
RECEIVER_SERIAL=""
# Initial receiver gain, in dB. If adaptive gain is enabled (see below) the actual gain
# may change over time
RECEIVER_GAIN=60

# Adjust gain to try to achieve optimal dynamic range / noise floor?
ADAPTIVE_DYNAMIC_RANGE=no
# Target dynamic range in dB (leave blank to autoselect based on SDR type)
ADAPTIVE_DYNAMIC_RANGE_TARGET=
# Reduce gain when loud message bursts from nearby aircraft are seen?
ADAPTIVE_BURST=no
# Gain range to allow when changing gain, in dB (empty = no limit)
ADAPTIVE_MIN_GAIN=
ADAPTIVE_MAX_GAIN=

# Turn on options to reduce load on slower CPUs, at the expense of slightly worse decoder performance.
# Setting "auto" will enable these options only if the CPU appears to be a slow CPU (currently this
# means armv6 only, e.g. Pi Zero)
SLOW_CPU=auto
# Local wisdom file used to select DSP implementations; uses built-in ranking if the file is missing
WISDOM=

# Correct CRC errors where possible
ERROR_CORRECTION=yes

# Receiver location, used for some types of position decoding. Provide the location as
# signed decimal degrees. If not given here, dump1090 will also try to read a receiver
# location from /var/cache/piaware/location.env (written automatically by PiAware, if installed)
RECEIVER_LAT=
RECEIVER_LON=
# Maximum range, in NM. Positions more distant than this are ignored. No limit if not set.
MAX_RANGE=360

# Network ports to listen on for connections
NET_RAW_INPUT_PORTS=
NET_RAW_OUTPUT_PORTS=30002
NET_SBS_OUTPUT_PORTS=30003
NET_BEAST_INPUT_PORTS=30004,30104
NET_BEAST_OUTPUT_PORTS=30005

# Accuracy of location written to JSON output
JSON_LOCATION_ACCURACY=1

# Additional options can be added here:
EXTRA_OPTIONS=" --lat 52.****** --lon -1.******"

# If OVERRIDE_OPTIONS is set, only those options are used; all other options
# in this config file are ignored.
OVERRIDE_OPTIONS=""

# This is a marker to make it easier for scripts to identify a v6-style config file
CONFIG_STYLE=6

My installation is a package version not the image version if that makes a difference?

Thanks & kind regards,
-=Glyn=-