Maximizing Plane and Position Counts: Where should I concentrate my efforts

[mihanson]

Hi,

I’m still new (about 30 days in) to ADS-B/UAT tracking (AIS too!) and I am trying to figure out where I should concentrate my efforts to balance/maximize my plane and position count. Here is what I’m currently working with:

ADSBExchange 1090/978 antenna (+5.5 dB, pole mounted outdoors, ~20ft AGL / ~75ft ASL) > 25ft KMR240 (~2 dB loss) > FlightAware Light Blue 978/1090 filter (~2 dB loss) > Mini-Circuits ZAPD-21 splitter (3.18 dB loss) > SMA barrels > FlightStick Pro (978) / FlightStick Pro Plus (1090) > 6ft USB3 w/ferrite rings on both ends > Proxmox VE > Debian 12 (Bookworm) amd64 LXC container (Base Debian image w/abcd567’s install scripts).

My antenna is located roughly halfway between KLAX and KSMO, about 2.5 miles from the ocean. I’ve been futzing with my gain settings and somewhere between 29.7 and 36.4 seem to give me my best results based on percentage of signals > -3dB on graphs1090 and my “gut” feeling (I wasn’t taking detailed notes) on plane count and positions. I’m still trying to decide on what gain setting to settle on, but I’m leaning toward 33.8.

HeyWhatsThat.com shows that my theoretical maximum range is to the west and southwest of my antenna location (i.e. out over the Pacific Ocean) and is ~240 miles (I assume HWT is in statute miles) or about 208 nautical miles. Simulating my antenna on a higher pole (+5-10ft) doesn’t seem to help much (< +5 miles) and I’m not certain the time, money and effort to raise the pole is worth it (Diminishing returns + WAF (wife acceptance factor) = Not worth it ).

I have tried using the ADSBexchange 1090MHz SAW filter, Nooelec SAWBird+ ADSB (LNA/Filter) and I feel that neither made plane/position counts any better than this current rig mentioned above. In fact, I think the SAWBird+ was detrimental to my counts (I think the +35dB of the SAWBird’s LNA was overloading my SDRs, even when I had my gain set to zero).

Here are some heatmaps showing my RF environment:

Antenna > Generic SDR, no filters:

Antenna > ADSBexchange 1090MHz SAW filter > Generic SDR:

Antenna > Splitter > Nooelec SAWBird+ ADSB > FlightStick (Blue):

Antenna > Splitter > Nooelec SAWBird+ ADSB > FlightStick (Orange):

Antenna > FlightAware Light Blue 978/1090 Filter > Splitter > FlightStick (Orange):

Antenna > FlightAware Light Blue 978/1090 Filter > Splitter > FlightStick (Blue):

My best day for planes was 3100 and my best position day was 1.13 million. I’d say I average about 2800-2900 planes and 950k-1 million positions. Don’t get me wrong. I understand that some would kill for those numbers, but I’d like to get an idea of what I should tweak to maximize my counts. Try different SDRs? Use an external LNA (i.e. RTL-SDR Blog Wideband LNA - I know I’d need an SDR with a BIAS-T for this) before my filter and splitter (and maybe use an attenuator?) and with different SDRs? Different filters? I’m interested in any ideas you may have. Thank you!

My feeder stats

[foxhunter]

Looks like your setup is already highly maximized.

What you can consider is replacing the Flightaware Stick with an Airspy. This usually improves the reception on the same setup by 5-15%

Here’s a megathread about it:

HOWTO: Airspy mini and Airspy R2: Piaware / dump1090-fa configuration

Automatic installation scripts: GitHub - wiedehopf/airspy-conf: Configure airspy_adsb for use with readsb or piaware. Manual installation / configuration: Manual airspy configuration to work with dump1090 fa and piaware · wiedehopf/airspy-conf Wiki · GitHub

[jafrank]

Your range to the west estimate probably isn’t very useful. Yes, you would detect planes that are out there, but how many planes are bypassing LAX at 200+ miles offshore? You will get some to/from Hawaii traffic from LAX, but you would get those anyway as they get closer to shore. Same with Australia traffic. You might see some MEX<> Asia flights, but they will be much closer to shore.

I am north of PDX and typically get 200+ miles to the north and south. I’m constrained by the Cascade mountains to the east and only get 125 or so that way. To the west, HWT says that I should be able to pick up flights out to 150 miles over the ocean, but I don’t think I have ever seen anything more than 50-75 miles. I catch SEA<>Hawaii flights out to 50 miles offshore, I see a lot of Asia <> LAX & SFO, but those hug the coast and aren’t usually more than 25 miles off.

All of that a just a long way to say that good range is good, but you can only see planes where the planes are.

[mihanson]

@foxhunter

Looks like your setup is already highly maximized.

What you can consider is replacing the Flightaware Stick with an Airspy. This usually improves the reception on the same setup by 5-15%

Thanks, I’ll consider this.

[mihanson]

@jafrank

Your range to the west estimate probably isn’t very useful. Yes, you would detect planes that are out there, but how many planes are bypassing LAX at 200+ miles offshore? You will get some to/from Hawaii traffic from LAX, but you would get those anyway as they get closer to shore. Same with Australia traffic. You might see some MEX<> Asia flights, but they will be much closer to shore.

Point taken re: range to the west. If I could improve that range, my thinking was not that I would get more planes, but I would see them longer resulting in more positions.

All other directions, I’m terrain limited.

[mihanson]

Just an update on some tweaks I have made that have helped squeeze out a bit more performance…

1. Remounted my antenna and it is now roughly 2-1/2ft higher.

2. The remount of the antenna required a longer cable run, so I switched from 25ft KMR240 to 35ft KMR400. The KMR400 is definitely harder to work with, but despite the extra 10ft of KMR400, I was able to reduce my attenuation by about 0.5dB (per the supplied specs – I didn’t actually measure myself).

3. I swapped out the light blue flight aware filter for a 1090 MHz cavity filter and a 978 MHz cavity filter.

4. I changed the order of inline hardware, swapped out the FlightAware SDRs for Nooelec Smartee v2’s and added Nooelec LaNA’s. The signal path now looks like this:
   Antenna > KMR400 (35ft) > ZAPD-21 Splitter > Cavity filter > LNA > SDR

These changes yielded a slight uptick in plane counts, but a big increase in positions reported. Early results show I now get over 1.2 million positions with my best day so far being 1.34 million positions. I think the biggest help has been the cavity filters. My RF environment is much cleaner. Now, if I could just move those mountains out of the way…

[abcd567]

@mihanson

Now, if I could just move those mountains out of the way…

No need to move mountains. Russians tied their antenna to a baloon to overcome such obstacle by gaining height.

http://russianpatents.com/patent/232/2320058.html

[jbelvin]

This is exactly what I am looking for. I will still be using the FA+ for 1090, with the DPD antenna with LMR600 (had extra from a helium install). Still new to upgrading, so I haven’t ventured from FA or Radarbox. I would really like to try an airspy eventually. Are you able to post any graphs on this setup?
Thanks

[CraigWoodThomas]

Seems like made a lot of changes all at once. Did the total change happen all at once or was it staged one new component at a time so you could track what made the biggest or smallest difference in performance? Hard to make sense of what happened if it was a wholesale change. No offense meant, just looking for clarification. I used to work in Test Engineering and wholesale changes are not allowed.

[mihanson]

Here’s the 978 heatmap. It was taken early in the morning, so there wasn’t much traffic at 978 MHz at the time, but it can show you what isn’t there:

ADSBExchange 978/1090 Antenna > KMR400 (35ft) > Mini-Circuits ZAPD-21 Splitter > Cavity filter > Nooelec LaNA > Nooelec Smartee v2 SDR

I don’t have a heatmap radily available for 1090 MHz at the moment. I’ll have to post one for you later. Of course your results may vary as all RF environments vary.

Edit:
Here’s a 1090 MHz heatmap:
ADSBExchange 978/1090 Antenna > KMR400 (35ft) > Mini-Circuits ZAPD-21 Splitter > Cavity filter > Nooelec LaNA > Nooelec Smartee v2 SDR

[mihanson]

A valid question! Yes, things were incrementally changed. The first change was the cavity filters and they made the biggest difference. Antenna height/cable change made the least difference. Adding LNA(s) saw the small bump in aircraft seen. Changing the hardware order and swapping SDRs were probably the least beneficial.

[CraigWoodThomas]

Thanks for the clarification detail. I appreciate the feedback.

[jbelvin]

Wow, thats solid! Thoughts on Sawbird vs Uputronics?

[foxhunter]

@mihanson

Remounted my antenna and it is now roughly 2-1/2ft higher

If it doesn’t bypass any obstacles, this difference is too small to make a difference.
I tried my antenna on a 5 meter pole (15ft) and didn’t see a difference to my “normal” 2 meter solution because the direct view did not change. I would need to change it to 100 ft or more to get a difference.

So it all depends on the environment.