FlightAware Discussions

ADS-B 1090 MHz 38DB gain amp

Hi All! I am very knew to all this stuff. I was wondering if adding an amp to strengthen the signal coming from my antenna (roof mounted) will help me see planes from farther away? I am also planning increasing the height of my antenna another 10’. Any feedback would be greatly appreciated.

ADS-B is usually limited more by line of sight than by signal strength. If you can raise the antenna so that it clears nearby obstructions, that’ll probably give you more improvement than adding an amplifier.

If you’re using a rtlsdr dongle that already has an extra LNA on the frontend (like the Prostick) then an extra amplifier is probably counterproductive. If your dongle doesn’t have an extra LNA, you might see some range improvement, but it depends a lot on your RF environment.

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Before trying to improve with investing into additional hardware, you should first check via http://www.heywhatsthat.com/ the max range you can get based on your location.

You should then verify this with the range you currently achieve and then you can think about additional hardware.

On that site you can also change the parameter of antenna height and verify the results.

Quick how to:

  • Create a new view using the tab “New Panorama”
  • Enter your location or select it from the map
  • Enter your antenna height from ground level in the appropriate field
  • wait until the profile is generated
  • Go down to the map and select the button “Up in the air”
  • Below that you will find two values where you should enter the altitude of the aircrafts you’re expecting to see
  • Zoom out and you will see two range circles on that map. That’s the max you can get based on your location and flight altitude you’ve selected.
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My ‘workflow’ is:

  1. Increase antenna height;
  2. Use a better antenna;
  3. Use good coax cable;
  4. Find optimum gain setting;
  5. Use a better receiver;
  6. Add a filter (receiver may include one, but it may not be enough);
  7. Add an amplifier (if receiver does not have one built-in);
  8. If a long cable run, amplifier is best installed at the antenna;
  9. Move to a better location. :wink:
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I agree with @Dxista

The two most common amps that I have seen being talked about, that include filters, are rtl-sdr (28 db gain)
https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

and uputronics 16 db gain.
https://store.uputronics.com/index.php?route=product/product&path=59&product_id=50

The Uputroncis version (I have several) seems to be more susceptible to interference. I have to put a cavity filter between it and the antenna.

My location is only 70ft/20M AMSL and I can see out to 200NM, in the directions that are not blocked by buildings or terrain.

The RTL-SDR Blog LNA/Filter combo, in its past form, is no more. The main part is EOL. The designer said a re-designed replacement is planned, but it’ll depend on finding the right chip.

One may want to try the RTL-SDR Blog wideband version with an external filter as a replacement. I have not tried it yet.

  1. Increase antenna height;
  2. Use a better antenna;
    .
    .
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Position 9 might become the most expensive one at some point :slight_smile:

Just be careful when installing this filter.

The solder joints can break with overtightening or loose initial connections.

I learned a $30 lesson the hard way.

A redesign where the female connectors are adhered to the casing would improve reliability in this area, such as a tack weld or a keyed mounting plate/female adapter to maintain a secure fit and to minimize opportunity for damage inside.

@Ericandlil - I’ve been exploring this too and for what it’s worth…

I use the ADSB user stats page to see how I’m doing relative to others near me. It’s not perfect but to a first approximation it shows you if you are significantly different from others with similar terrain and elevation. You can compare your stats with theirs and especially check how your range and azimuth compares. If you are lucky you’ll have some boomers nearby that can be a good yardstick for improvement/comparison. They may have very different hardware though so it may not be an apples to apples comparison.

The orange FlightAware receiver is good but if you have strong cell towers nearby you might want to consider the dark blue receiver since it has a SAW filter right at the antenna connection that cuts out a lot of other frequencies. I am using the orange Pro receiver and the light blue can filter but neither discriminates that hard against other nearby frequencies. There is a particularly good discussion in the Do I Need A Filter thread here that explains how to use your receiver as a spectrum analyzer to tell you what you need.

Separating the Pi from your antenna by a bit also seems to help a lot. The Pi can give off a fair amount of RF that the antenna can pick up and feed into the receiver. The dark blue Pro Plus receiver with the SAW filter will help but when I moved my Pi about 20 feet away from my antenna, my stats really started banging up. There was a coax change in there too, but something really improved signal to noise.

Using the receiver as a spectrum analyzer would reveal this issue just like a close cell tower, but if you or your neighbors have cell phone boosters, that’s like having a little cell tower of your own too.

There’s another good discussion here of LNA’s and filters and what effects different orders and placements have.

Last, if your receiver has a built-in amp, check that out. The FlightAware receivers do but the default is to auto gain range which doesn’t work that well. Tuning your gain can yield big improvements depending of how far away most of your traffic is. I turned mine down significantly and got much better position counts and tracks - near and far.

Good luck!

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