Message rates depend mostly on the amount of air traffic for a given location. Most of my setups have several connectors and 10 meters of LMR200, a 1090 MHz bandpass filter and an LNA. Gain is generally set at 20.7 though gain can be in the 40’s on some days. Message rates vary between 500 and 800 on any given day.
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Thanks for sharing the graph. Can you help me interpret the graphs? What are they showing and how can I use them to optimize my system?
Thank you @jimMerk2 . I just reread your response about just using adapters and not coax runs. I plan to have my antenna mounted on a mast above my roofline and my Pi down low at ground level or in my house. Am I missing something? Would I need coax to connect the LNA, mounted up high, to the Pi mounted at ground level (or in my house)?
Ok, I didn’t realize the antenna would be outside, so sure you would need coax to connect antenna to the LNA. The LNA isn’t designed to withstand the elements.
My setup is an antenna +LNA + dongle in the attic crawl space all connected with coax adapters. Then a USB extension cable running down to a closet with the RPi. So I have easy access to the RPi.
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Unless the USB extension is of the highest quality, better performance can be obtained by placing the dongle in the closet next to the RPi.
The graph is showing the number of messages per second being received over time.
You can see how the rate drops at night when there are fewer aircraft around.
Not all messages contain position information and the lighter, lower line shows the number of messages per second that have position information over time.
Note however, that I am in the UK and the number of messages per second received here and in the rest of Europe are higher than those received in North America and other parts of the world.
Agree, you need a good quality USB extension cable. I have used this:
Don’t know why that says 1.5ft, it’s 5 meters (16 ft).
Basically you need to keep the loss between the antenna and the LNA as low as possible and the losses from the LNA and the dongle don’t really matter that much. You could either place the LNA in a waterproof housing close the the antenna with a short length of cheaper co-ax, or inside in a sheltered location with a longer run of more expensive co-ax to achieve the same loss. You can then use relatively cheap co-ax for the longer run between the LNA and the pi. I would (and do) keep the dongle close to the pi. Longer runs of USB cables have their own problems of potentially radiating noise. I use a very short (150mm) USB extension just to allow some movement without introducing stress on the connectors by having the dongle plugged directly into the pi.
My setup is currently located in my attic. My plan is to get the right components to optimize my setup. Then after it is optimized, I will mount the antenna on a mast outside above my roofline, put the LNA in a weatherproof enclosure at the antenna and either put the Pi in a different weatherproof enclosure outside (accessible from the ground level) or put the Pi inside my house.
I need to find suitable weatherproof enclosures and figure out how to pass the cables into the enclosure, while keeping the elements from getting in to the enclosure.
Does anyone have suggestion on enclosures and how to pass the cables through?
There’s a thread on here that shows how people have weatherized their setups:
Suffice it to say, there’s 30,000 FA users ( or is it sites ?) and there’s probably 10,000 variations on the setups people have used.
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Use an upside down beverage bottle for the filter and LNA. Keep the RPi inside out of the weather.
There are several threads showing different housings.
This is one:
Try searching for “waterproof” it should show a few of them.
These would be perfectly adequate and quite a bit cheaper.
One other point to note is that if you are adding an attenuator at the dongle you will need to power the LNA from an external bias-t injector. You won’t be able to use the one in the dongle as the attenuator will be in the way. I use something like this.
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@LawrenceHill @retman1222 If I get this cable (or do you suggest a specifc type of cable with even less loss?) to connect my antenna to the LNA, what types of cable would you suggest to connect the LNA to the dongle/Pi that would be in my house at a distance of approximately 10 meters from the LNA?
i use the “ultra flex” version of LMR400. it’s very low loss at 1090MHz. they have a “regular” version that is less flexible so if you have some reasonable bend requirements as far as getting from the LNA to the dongle the ultra flex version makes it much easier. the cable you referenced will work but just have higher losses. i use Infinite Cables in Ontario Canada (they ship to the states as well). they will custom make for you with various connectors. Now comes the hard part, when the antenna is outside and a cable running from outside to inside there are usually code requirements or 'best practices" for grounding before the cable enters the house. i am not comfortable recommending a configuration. others on this forum may have more expertise in this area or you can (and should) consult with someone in your area that installs antennas and is familiar with the applicable codes.
I use a 10m run LMR200 between my LNA and the pi, but LMR195 would be fine.
The short length of LMR195 between the antenna and the LNA should be ok too, although Ultraflex would be better 
However, I doubt you would actually notice the difference on such a short run.
Thank you for pointing me to Infinite Cables. So you use LMR-400 Ultra Flex for both segments (antenna to LNA and then LNA to dongle)?
What I got from one of Lawrence’s prior posts is that I would want a reasonable amount of attenuation between the LNA and the dongle. He seems to use an attenuator. I was thinking a longer/higher loss coax after the LNA might attenuate the signal enough before it arrives at the dongle.
Yes. Grounding is another subject that I need to investigate.
the only reason to have excess loss in the cable, or to use an attenuator is if there is too much gain in the dongle. if you use an LNA at the antenna then there is no reason to use a dongle with a built in LNA…(too much of a good thing). from antenna to LNA you can use LMR 195 or LMR 240 etc. that cable should be as short as possible as you want the LNA as close to the antenna as possible.
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@tomvdhorst About 24 hours ago I replaced the FA Pro Stick, noted in my setup listed above, with the FA Pro Stick Plus (blue dongle with 1090 Mhz filter). I don’t really see any change in the performance of my system. Below are the graphs for the last 24 hours. Do you see any changes compared to the graphs I posted last week?
It does not seem that the weakest signal level changed much. Does anyone have suggestions? (In a couple of days, the shipment with an LNA and unfiltered dongle with a built-in bias tee should arrive).
I don’t see much change at the moment. I use the prostick plus and additional barrel filters due to my location being in an urban area with lots of cell towers nearby.
I think the biggest improvement might to move the setup outside instead of your attic. Is there some kind of shielding there in your attic ? Your message rate is still low indeed, but that’s also depending on your location.