I’ve been running a default install for several years (Flightaware Pro, antenna mounted on my house). I live in San Diego, east county. I notice I get decent (about 120 miles) coverage to the NE, OK (about 100 miles) to the North and SE, and less coverage other directions.
I live about 8 miles east of SAN. I don’t think terrain is my issue, b/c there’s lots of terrain between me and traffic to the NE. Shouldn’t I be getting really good coverage to include the LA area?
I’m wondering if there are tuning options that may help to improve my coverage. I’ve attached my coverage graph, in case that provides any clues. Thank you!
As the Radio Waves at microwave frequencies travel in straight line, similar to light, the maximum range attainable is limited by curvature of earth and terrain around the antenna
First determine maximum possible range attainable from your antenna location & antenna height by method:
Thanks for your response! I wasn’t aware of that tool. The result pretty closely mirrors what I’m seeing, so apparently I’m getting expected results. I attached that result, for comparison with my coverage graph.
The only thing that doesn’t match with results I’m seeing, is regarding traffic to the NW (LA area). According to the “Heywhatsthat” site, I should be seeing traffic in the LA area even at 10k, but most definitely at 30k. But I see nothing in the LA area regardless of altitude. Could there be interference issues that make that traffic disappear? I just now watched an airline at 35,000 feet heading westbound; it dropped as soon as it passed San Bernardino.
Again thank you - it’s nice to know I’m pretty much seeing what I should.
Terrain (i.e. hills and ridges) isn’t the only thing that will block line-of-sight radio signals such as ADS-B. Buildings and houses will too. So will trees to a lesser extent (they’re not solid objects like buildings, there are small gaps between the limbs, branches and foliage that a few ADS-B messages may get through.) If you live in a one-storey bungalow with your antenna on the roof and most of your neighbors live in two-storey McMansions, there’s your problem.
As you mentioned you’re using a FlightAware Pro SDR dongle (which is the same kind I have, the orange one with a built-in LNA but no filter) also see Do I Need A Filter? I don’t think interference would affect maximum actual range as much as it would overall message count and aircraft seen, but I suppose it could do. It doesn’t hurt to check. Being in a highly-populated area like that I expect there are cell phone towers everywhere so the odds are that you need a filter anyway.
How high is your antenna, how long is your coaxial cable, and what kind of coax is it?
Scroll down to following item and follow instructions:
Note:
The command given in that old post was for dump1090-fa map which has been replaced by Skyaware map. Therefore in that command /dump1090-fa/ should be replaced by /skyaware/. The updated command is as follows:
(1) SCROLL RIGHT TO SEE & COPY FOLLOWING LONG COMMAND IN FULL (2) In this command replace XXXXXXXX by you actual heywhatsthat ID
I bought the entire unit (FlightAware Pro, 1090 antenna, filter, and 15 meter coax) from the FlightAware store about 2 years back. Is there a way I can tell what sort of coax it is…I can’t find the original order details. Elevation where I live is about 350’, and I have the antenna mounted on top of my single story house.
I live in an area of rolling hills, and I do have terrain that interrupts my line of site to the west. So I’m not at all surprised that I lose low altitude aircraft as they approach SAN airport. I was considering purchasing an antenna mast, and trying to increase height by 50’ or so. But if the “heywhatsthat” site estimation is correct, that increased antenna height would result in very little, if any impact.
Thanks - another feature I wasn’t aware of!! I’ll give this a shot.
Edit: Looking at the wget command, I see it references a specific ID and parameters (id=XXXXXXXX&refraction=0.25&alts=12192). The instructions you provided say to replace the id with my heywhatsthat ID. Will that also update the refraction & alts parameters? I’ll look at the FlightAware article you referenced and try to get this going!
No, the heywhatsthat ID wont change refraction & alts.
The parameter refraction is NOT to be changed even manually. It is fixed for RF frequency range in which 1090 MHz falls.
The parameter alts is for altitude of aircraft in meters.
The alts=12192 is 40,000 in feet. That can be manually changed by you to say alts=9144 which is 30,000 in feet.
If you bought the coax from FlightAware we can assume that it’s low loss at 1090MHz.Some people go out and buy RG58 which performs poorly for ADS-B due to the high loss at the frequency.
50 feet, while nice, is probably overkill unless you live in a low area or are surrounded by multistory buildings or are in the middle of a forest. You didn’t answer my question about whether there are 2-story houses around where you live, but assuming there are, a 2 story house with attic will be around 26-27 feet tall. A single-story house with attic is around 16 feet or so, so a 10-12 foot mast along with a tripod roof mount and guy wires. meant for rooftop TV antennas would be ideal. If you don’t feel comfortable installing it yourself, hire a professional antenna installer or if you know any ham radio operators ask them for help (don’t forget to provide lunch and refreshments.)
If antenna is below the height of surrounding objects, increase in it’s height is beneficial, every feet of height increase counts. Once the antenna attains a hight which is slightly above surrounding objects, any further increase in antenna height gives negligible benefit.
Double-check your heywhatsthat panorama and make sure you didn’t make a mistake in entering your antenna height above sea level or above ground, like entering your height in feet when “metric” was selected at the bottom of the map, for instance. If that’s all correct then you have some other issue, either non-terrain blockage by buildings or trees, receiver gain maladjustment (too high saturates and desensitizes the front end, too low and it can’t receive anything) or interference by other transmitters.
@jaymot I confirmed that the heywhatsthat settings are correct. While there I noticed something else of note. I previously mentioned I’m only seeing a discrepancy with traffic the the NW (LA area). But I realized there’s an even bigger issue with traffic to the West - over the ocean. The heywhatsapp map shows I should be receiving way out. Estimating at least 100NM at 30k feet. But in reality I lose everything within 5 miles of the west coast. Let me attach a few shots to show the difference.
The outlines from your screenshot are for aircraft at 30000 / 10000 ft?
One possibility for discrepancy is using AGL vs MSL height when creating the panorama. (this happens regularly)
Some buildings or close by obstacles might not be present in the heywhatsthat data as they are a couple years old i believe.
Really, you’d need to confirm the obstacles towards the north when putting your head or a camera next to the antenna.
Could be for example that the antenna is mounted in a way not overlooking the building its on … stuff like that.
Also if you’d want to further speculate on this, you’d mostly have to take pictures of how the antenna is mounted / pictures of the horizon from where the antenna is mounted to further discuss this.
I really appreciate yours, and other responders expertise and suggestions. I’ll look to provide additional information you’ve suggested.
Please consider one more point, regarding traffic to the west (west coast and beyond). I’ve previously stated there’s a hillside to my left (west) that goes above my antenna. I eventually lose traffic approaching SAN airport, as it gets below 1,000’ MSL. But I don’t think that explains why I can’t see traffic that’s 10,000’ or higher, in the same direction? Or maybe I’m missing another important factor?
I’ll look at the resource you provided and see if I can gain additional insight. Thanks again!
Edit: to answer your first question - you are correct. Outlines are from 10,000’ (yellow), and 30,000’ (blue).
This kinda calls the theoretical outline into question unless you have no hill to the east.
Really you can specify line of sight graphs to be shown after creating the panorama.
So you can click on the map and then define the height of the object you’re trying to receive / look at.
It will then show the line and how its occluded by terrain or not.
It’s all about the elevation above the horizon. The closer the hill, the shorter the distance you can see aircraft at 10k ft.
If your feeder is near a busy airport most of the nearby aircraft will be departing from it or landing so will be at low altitudes where your range is less. Also the normal air routes and waypoints there could be such that there just aren’t many planes out over the ocean.
Over the past month I installed the extension I had previously purchased, and was laying in my backyard. I didn’t expect much improvement; especially after playing around with height settings at the “heywhatsthat” site. It showed very little difference even when I added 50 or 100 feet elevation, so I figured it would be minimal improvement. It turned out I was wrong. With the mast installed, I’m now getting results fairly close to what’s depicted on the HWT estimate, including traffic approaching LA and out over the Pacific (to Catalina Island and beyond). I’m including before and after images here to show the difference. Although still not what I was hoping for, I’m much happier with the results. Thanks to everybody here for your input and advice!
