ADS-B Site Upgrade Reconditions

[jaymot]

Hi.
Regarding whether you need a filter or not, here’s how to find out:

Do I Need A Filter?

The space around ADS-B antenna contain not only 1090 MHz signals, but also lot of other signals at different frequencies. The closer the frequency of a signal to 1090 MHz, your ADS-B antenna picks it stronger. For example if there are three signals of equal strength, one at 144 MHz, 2nd at 850 MHz and 3rd at 950 MHz, the ADS-B antenna will pick 950 MHz one the strongest, 850 MHz one a bit less stronger, and 144 MHz one much fainter. As the Cell/Mobile/Pager signals exist in the range 850 MHz to…

Your noise level is rather high in your signal level graph. That could be due to interference in which case a filter would help, or because your gain is set way too high.

Thoughts on optimizing gain

The topic of gain comes up often enough and unlike some i don’t like the gain optimization script. Aircraft fading in and out of view make short term number gathering not that useful. The metric i like most for optimizing gain is the percentage of what dump1090 calls “strong_signals”. Those “strong_signals” are messages that get close to getting clipped. If you don’t care about some background you can scroll down to the next post for the HOWTO This is a clipped signal, the wa…

If you’re using the piaware 6.0/6.1 image or dump1090-fa 6.0/6.1 on a Raspbian install you can enable it’s adaptive gain features.

Announcing the release of PiAware 6

Today we’re excited to announce the release of PiAware 6! This version includes a new adaptive gain feature, updates to the PiAware LCD image, performance improvements for Raspberry Pi’s with slower CPUs, and more. Read the full release notes below: Adaptive Gain: Adjusts receiver gain automatically to find a reasonable gain setting for the local RF environment. Adaptive gain is enabled by default on new installations only. For existing systems that are upgraded from an older version to 6…

For other demodulators you can use this:

Automatic gain optimization for readsb and dump1090 fa

Compare yours to mine:

This is with a cheap Chinese PC board antenna in a plastic case (it’s actually a decent antenna, being a 4-element colinear) with an RTL-SDR Blog triple-filtered LNA next to it followed by 10 meters (33 feet) of LMR240 coax, a bias-t injector board powered by USB, and a Nooelec NESDR SMArt dongle. The antenna’s around 9.4 meters above ground. My gain’s currently set to 22.9. Before I added the LNA near the antenna I was using a FlightAware Pro orange dongle like yours and my noise level was typically around 34dB, always 30 or less anyway.

If any issues you’re having are due to high noise moving the Pi closer to the antenna will either do nothing or make it worse.

It certainly wouldn’t hurt to upgrade the Pi Zero to a more powerful model. I have no experience with the new Zero 2s as I have a 3B+ but from what I understand their hardware is so new that Raspbian or PiAware that’s based on Debian Buster won’t run on them, they need Bullseye-based operating systems. PiAware 7 will be coming soon which is Buster-based.