RE: [ Beginner ] - Please advise on dongle to receive both 1090Mhz and 978Mhz

What kind of antenna do you have? Inside or outside?

Thanks.

The flightaware 978 antenna, inside, up in the peak of the attic, so roughly 30ft off the ground.

I’m trying to decide if I am receiving all the traffic that I should. My house is 12 miles from the Birmingham airport, 13 miles from the Bessemer airport, and 10 miles from the Shelby County Airport. I have not received any aircraft in the traffic pattern at any of those airports. Last night I made a 6 element colinear antenna, like a guy on YouTube made, and I am using it now. The weather is not good here today so not many GA airplanes are flying. The airplanes I have seen live have all been within 10 miles of my house. The statistics page shows I have received a few airplanes within the 40-80 mile range but I have not been watching when those planes were received. I read about people getting a 100 to 200 mile range. The antenna is in the attic. I can put it outside which will raise it about 10 feet higher.

What do you think? Is my receiver and antenna working properly or do I have a problem?

ADS-B is mostly line of sight, and no one here know if you are surrounded by a wall of trees, so you will have to figure that one out. Inside vs outside antenna is up in the air. Some people do fine with indoor antennas, while others find that something in their building construction is killing the signal.

When I first started out I was easily seeing 100+ miles with a crap little antenna in the window of my 2nd floor bedroom. Strange thing was that my window faced north, but I seemed to get good range to the south as well. Much better now, though, since I have gotten a better antenna and moved it to the roof.

My suggestion would be to start out by figuring out what you could get, and then narrowing down to what you should get.

Go to www.heywhatsthat.com in your web browser.
Click on the New Panorama tab at the top center of the page.
Enter your latitude and longitude, if known, or search for your address.
You can ignore #2 for these purposes.
Enter the actual height of your antenna above ground level.
Click the Submit Request button

A map will be generated after a few moments. Scroll down to the overhead view map and click the Up in the Air button at the top right corner of the map. Use the map’s + and - buttons to zoom out until you can see two irregular circles. By default, the map shows you the max range for items at 10,000 feet and at 30,000 feet. You can change these values at the bottom of the map. Here is an example of what I get in my location:

This is the maximum range that you are likely to get, assuming that there are no organic or man-made obstructions at your location.

Now go to www.flightaware.com. Move and/or scale the map to closely approximate your range rings shown by heywhatsthat. The planes that show here are what you could get. What you actually should get will depend on your antenna, mounting location, obstructions, gain setting, etc. If you see 50 planes within 50 miles of your location, and you are only getting a dozen on your local receiver map, then the troubleshooting should begin.

Here is what the FlightAware map looks like for my location:

And my local map:

If you aren’t getting what you think you should, stick around - there are a bunch of folks here who are very knowledgable about the hardware, software and antenna options and settings.

I hope some of that helps you to get started!

Thank you so much. I will follow all your suggestions.

I just did the heywhatsthat.com and generated the map. It is interesting to see the 10,000 map. Most of the traffic I have seen has been around 5,000 feet. So I may not be doing too bad. I’m actually making another colinear antenna now that is the correct length for 978. I found the forumla today and the one I made last night was actually for 1090. I’m about to go hook up the new antenna but since I am only doing 978 and most of the traffic on 978 is VFR day, it will be tomorrow before I have any idea if it is doing better.

Thanks again.

For reference purposes, make a very easy DIY antenna QUICK SPIDER.

In above how-to, the dimension for central whip and radials are given as 69 mm, which are for 1090 MHz. For 978 Mhz, instead of 69 mm, use 76 mm.

For ease of making, you may also use only 4 radial, though 8 radials give somewhat better performance.

 

Thank you. I really like the idea of this antenna. I saw something similiar a week or so ago but it required a connector. It was built around the connector. I went to the local electronics supplier to buy that connector, I think it was an so239 or something like that and they said they had not stocked those for 10 years. The only thing I don’t like about this is stripping 8 pieces of coax to get the center wire. But I will make one in the next few days.

I appreciate all the help from the people on this forum.

@johndyoung1

If you are going to use RG6 coax to build Quick Spider, then you will need one of the following two pigtails to connect Quick Spider to FA Pro Stick. Alternatively you may use a coax on which SMA male connector can be fitted directly.

30 / 50 / 60 cm, F-female to SMA-male pigtail RG316 / RG58 / RG174

pigtail-F-female to SMA-male- RG316

pigtail-F-female to SMA-male- RG174

This is another version of Quick Spider. It does not require striping of core insulation. :slight_smile:

GROUNDPLANE ANTENNA MADE OF COAX ONLY - Without SO239 Conctr

I just ordered a couple of those adapters from Amazon after reading you last post. I the adapters will arrive Saturday so I will build the antenna before then.

I am eager to see what happens tomorrow with the newer antenna up there. It has also been bad weather in Birmingham the last few days and tomorrow and Saturday are supposed to be good weather. So there should be more GA airplanes that only have 978 flying in the next couple of days.

Thanks.

@johndyoung1

Great.
It is much easier to built the Spider with 4 radials rather than with 8 radials, and there is not big difference in performance between 4 radials & 8 radials.

Something to keep in mind is that 978 traffic seems to be a very small percentage of the total traffic. I am between Portland, OR and Seattle, WA and average 750-800 flights per day on 1090 at this time of year.

I have four private airfields within 5 miles of me, I am also within ~15 miles of Vancouver WA’s Pearson Field (KVUO), Troutdate OR airfield (KTTD), and Woodland WA airfield.

All that to say, I have a bunch of GA airfields near me. And out of all of that, I pick up less than 40 aircraft per day at this time of year. Sometimes a lot less. In the past 30 days, seven of them had 5 or fewer. Half were 10 planes or less.

I am not an aviation expert, but I have read on here that a lot of GA aircraft use 1090 and don’t bother with 978. In the 7 months or so I have had both, my results have consistently been that 978 counts are running at 1%-5% of my 1090 counts.

My point is that there may not actually be that many more flights than what you are seeing.

You are right. A lot of GA airplanes installed mode s transponders when upgrading to ADS-B out and therefore are on 1090. Plus any airplane that goes about 18,000 has to have 1090. But there are a good number of GA aircraft that only have 978 because it was an inexpensvie alternative to 1090. I own two airplanes. One has 1090 and one 978. I started with 978 because there are very few 978 receivers and I never see that airplane on Flight Aware. I thought if I installed a 978 receiver I would see my own airplane on Flight Aware. But after seeing how few there really are, I think I will buy the 1090 dongle and have both installed. I plan to make two ground plane antennas like you suggested and will start with them. If they work well in my atic, I will stay with them. If they don’t, I will probably buy the Flight Aware antennas and put them outside.

My surprise is that I thought I would be able to see airplanes in the traffic pattern at the three airports near me, all abut 10 miles, and I can’t see them.

I do appreciate your posts and help.

978 was supposed to fix a number of issues.

  1. 1090Mhz is over utilised. I can see 6000 packets per second when I enable Mode A/C on my radarcape or airsquitter. I normanlly see 1,800 packets per second. I am only 30ft AMSL but am in NYC so have three major and several minor airports within 30 miles. 978 Mhz is a lot quieter.
  2. 978 is US only. Any overseas travel requires 1090, as does anything above FL180.
  3. 978 was to be cheaper. There are simple systems that are a lot cheaper than 1090 systems
  4. 978 provides FIS-B(1090 does not). This provides weather, Notam and other information.
    https://www.faa.gov/nextgen/programs/adsb/pilot/#fisb

I just recently(a few days ago) got my UAT RPI setup working properly.

The range is a lot less than 1090 because the aircraft fly a lot lower than 1090mhz(Although I have seen 978 aircraft above FL180, I thought it was supposed to disable itself at that level). Pre-covid QF11 (A 747) would boom its 500W into my little site 180NM out from my location.

As more UAT RPIs are installed, coverage will improve. You may need to enable auto-gain on the UAT978 setups to better cope with the widely varying signal levels.

If I had my own aircraft and flew into a lot of GA and Commercial locations, I would want to have both 978 and 1090, in and out for situational awareness. There are a lot of locations that are not covered by ADS-R/TIS-B. This is not cheap at the moment, however, Dual band in/out transponders may become cheaper in the future.

I have seen two aircraft on my 978 unit that were at 40,000 feet. Both were Citation 560’s. I was surprised to see them and I thought all aircraft that flew above 18,000 had 1090 only. But it may be some aircraft have both.

I own two aircraft, one with 1090 and one with 978. I put 978 in the one because it was much cheaper. I have never had a problem with air traffic control seeing this aircraft. But flight aware does not have near as many 978 receivers and my 978 aircraft would not show up on flight aware unless I had requested flight following. I have done 2 flights since I installed my 978 until and both flights have shown up on flight aware. And when I look at the track, it is my station that is receiving it.

Today I saw an aircraft on my reciever that was at 8,500 feet and it stayed on my screen until it got 17.5 miles away. That is the the most distance away that I have seen an aircraft on my screen.

I am getting ready to move my antenna outside and it will be at least 5 feet higher. It will be interesting to see what that does to my coverage.

1 Like

Here is a Lear 60 going past at FL230 120 NM away

Not a lot of traffic today because of the weather.

Looks busy compared to what I get out in NJ.

I have another station in Staten Island, based on what I see from your location think I’ll add a UAT receiver to that station at some point.

The UAT decoder likes strong signals less than the 1090 decoder.

Consider reducing your gain so the weakest signal sits around -30 … or -24 if like.

1 Like