Do I Need A Filter?

This past Sunday I replaced my FA orange dongle with the RTL-SDR V3 and their 1090 LNA. My avg max range has increased by about 25nm and my positions reported have gone up over 30%. Aircraft count is up also.

The LNA is attached directly to a FA 50 inch antenna with an adapter. There is 40 ft of RG6 with a pigtail on each end between the LNA and the dongle.

I am very pleased with the performance.

Thank you for posting your results. Interesting that the position reports went up over 30% but the range increased “only” 25nm…
Guess that I’ll wait a bit and read more comments/results from other people before making a purchase of a LNA/filter. Ssems that using the FA pro stick plus + uputronics LNA will be the best way to achieve the best range with my currently FA antenna.

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I have heavy tree cover 360 degrees. My antenna is up 40 feet AGL but the trees are about 80 feet tall and dense. So dense that I have problems with local TV reception. Typical max range went from around 190nm to 215nm. I have been using the Prostick without the filter, which is better in my area. I used it with and without the external filter for extended times to verify which was better. One week in and so far the aircraft count has gone from a 1450 avg to 1750 this week. The prostick is the easiest way to go, by far, but like these new numbers!

@MUVR2007 I have that combination – Pro Stick Plus, Uputronics SAW filtered bandpass preamp and FA antenna. The preamp works brilliantly with the Pro Stick Plus and the FA antenna, allowing you to extract the most performance from the higher gain of the excellent FA antenna. The Pro Stick Plus filter and the external bandpass filter complement each other well in the signal path. My gain is unchanged at -10 AGC. Go for it.


At ~200nm, a 25nm increase is a 30% area increase, so the position reports isn’t a big surprise (assuming uniform traffic density).

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Guess Im doing good. Im using Prostick + with FA Filter and FA Antenna. Here is my scan. Looks clean

Thanks for posting this info. I’m enjoying toying around with my setup (it’s been running a bit over a year).

I ran a scan on my Pi3 FA Pro (built in filter). I’m not sure how to interpret the results though and don’t know if it means I should add an additional/external filter. There some strong-ish signals in the cellular band area. Thoughts?

My Scan Result


Cutouts from your full scan:



Strong Cell Phone signal 850 to 900 mhz and 930 to 940 mhz.

An external filter will most likely improve reception, but only after trying you can know.

As a first step before purchasing a filter, try different reduced gain settings such as 45, 40, 35, 30, 25 etc. Reducing gain is likely to improve reception. Adding a filter is likely to improve further.

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Many thanks all for your contribution!
I’m now playing with the gain values in order to achieve the best results with my current setup. For sure I’ll try adding a filter later on due to strong GSM signals present according to the frequency sweep scan I got.
I’ll also keep an eye in the prostick dongle from Flightaware.

Here is the FlightAware Pro Stick Plus + FlightAware external antenna + Uputronics 1090Mhz SAW filtered preamp. You can see what a great job the preamp does of removing comms and mobile signals and boosting ADS-B.

Click the image once to open, and a second time to zoom to normal size, then scroll left and right to view the comparisons at different frequencies.

You can see that the Pro Stick Plus does a good job of filtering but still picks up a fair bit of unwanted stuff, and the filtered preamp nicely takes care of that.

I’m in the UK. You can see digital TV, comms and GSM signals present without the preamp.

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Very interesting to see the comparison between having or not having the uputronics 1090 SAW filter preamp.
I guess that I really need to buy that filter+lna to further improve my ADSB reception. Seems to be a winning combination! That SAW filter really made a significant difference in out-of-band signals.

We should not also forget that FA antenna has not only low VSWR in ADSB band… - which gives a harder job to the dongle.

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Indeed, I think the filtered preamp works brilliantly with this antenna, allowing you to get the most from the high gain where it’s wanted and keeping it in check everywhere else.

The upper scan is ProStickPlus only
The lower scan is ProStickPlus + Uptronics

The lower scan is combined effect of two filters, one in ProStickPlus, other on Uptronics. Attributing all credit of combined effort to uptronics only is not fair.

A fair comparison is:

ProStickPlus+FA antenna
Generic DVB-T+Uptronics+FA antenna


I’m not doing any such thing. I’m showing that the Pro Stick Plus’s filter does a good job but allows some stuff through, and I’m showing the effect that the Uputronics has on top of the Pro Stick Plus for anyone who already has the latter and is considering buying the former. Clearly the Uputronics filtered preamp makes a big difference. This is mirrored by the improvement in positions and aircraft seen after adding it.

This post is about filters:


That is great but what is the effect on your message rate, the number of aircraft you can see and range?

The filter and amplifiers are certainly having an effect but how does it translate into better stats for your receiver?

It is very difficult to see the effect of a change as the traffic is continually changing. I run two separate systems with one kept unchanged as a reference and the other used for experimenting in improving performance. Looking at the Skyview pages side by side in real time gives me a good and quick indication of the actual effect of a change in amplifier, filter, antenna and Gain.

If you don’t have two complete systems a comparison with a nearby station over a 24 hr period from 0000UTC is useful but a lot slower.


The Uputronics increased the number of my messages, aircraft seen and range over a period of a couple of days, compared with previous days and the same days the previous week. Chatting with the designer he also said that he has never had anyone yet tell him the LNA doesn’t increase the number of messages.

Was that on 11/4 when you had a quite significant jump in stats?


Up to the 28th was without the preamp, from the 28th to the 9th was with the preamp, from the 10th (the part you mention) was changing to the external antenna indoors. Averaging from 20th-26th and from 3rd-9th (to avoid the UK Easter bank holiday weekend and some network admin here) and comparing there’s around a 20% improvement in reported positions and a 12% improvement in reported aircraft.

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I missed that the antenna was moved outdoors. I was looking at the wrong data. :slight_smile:

The numbers of positions and aircraft reported has gone up. Has the range increased also?

Whilst your plots show the out of band signals have significantly decreased, the inband noise seems to have gone up considerably. It is possible that the signals you want are now overloading the dongle receiver.

Have you tried dropping the dongle gain by about 20 or 30 dB?