My Attempt at a $115 ADS-B Receiver Build for Foreflight

Has someone taken apart a stratus to look at their antenna design?
 
I'm going to load the software tonight and I'm conflicted. The original post called for a specific antena for the software (Dump 978) but the new software is Dump1090. What's a flyer to do?
Do I use the Dump978 since I have the antenna?
Do I have to get a new antenna to use Dump1090?
Will Dump 1090 work with my old antenna?
Do I need two antennas to get all the traffic?
 
I'm going to load the software tonight and I'm conflicted. The original post called for a specific antena for the software (Dump 978) but the new software is Dump1090. What's a flyer to do?
Do I use the Dump978 since I have the antenna?
Do I have to get a new antenna to use Dump1090?
Will Dump 1090 work with my old antenna?
Do I need two antennas to get all the traffic?

Yes, you need two antennae (well, SDR dongles) to see all the traffic.

Load whatever the latest image is.
 
Yes, you need two antennae (well, SDR dongles) to see all the traffic.

Load whatever the latest image is.

Yes, 2 SDR dongles for sure, but possibly single antenna and a splitter with the proper impedance matching.
 
Technically a half-wave antenna is resonant, and can be matched, but at impedance a that generally are difficult to match & fairly sensitive. It can be done, I've done it, at AM MW stations.There are a bunch of Halfwave AM broadcast antennas put there.

That said, I wouldn't do it at UHF, especially in an environment where the antenna and matching circuit can be used like a theremin.

Well, theoretically, a half-wave above perfect ground has an infinite input impedance that would require an infinite matching network ... but CLOSE to half a wavelength it can be matched ... at ONE precise frequency ... and the closer you get to true antiresonance the more finicky the matching network becomes. Bandwidths of fractions of one percent. And, as you said, there is the theremin effect of handwaving.

Tell y'all what. If I publish the design for a homebrew antenna will somebody make one up and try it out? I'll give figures for both 986 and 1090 and you can make whichever one you want.

Somebody said something about a splitter. The problem is that you have just increased your input loss by half the power, or 70% of the range, however you choose to say it. They are trivially easy to make, cost less than a buck plus whatever connectors you need.

With all these goings-on there MUST be a homebrew page somewhere with folks that have worked in low microwave and understand how easy this stuff is. No?

Jim
 
Well, theoretically, a half-wave above perfect ground has an infinite input impedance that would require an infinite matching network ... but CLOSE to half a wavelength it can be matched ... at ONE precise frequency ... and the closer you get to true antiresonance the more finicky the matching network becomes. Bandwidths of fractions of one percent. And, as you said, there is the theremin effect of handwaving.

Tell y'all what. If I publish the design for a homebrew antenna will somebody make one up and try it out? I'll give figures for both 986 and 1090 and you can make whichever one you want.

Somebody said something about a splitter. The problem is that you have just increased your input loss by half the power, or 70% of the range, however you choose to say it. They are trivially easy to make, cost less than a buck plus whatever connectors you need.

With all these goings-on there MUST be a homebrew page somewhere with folks that have worked in low microwave and understand how easy this stuff is. No?

Jim
Jim,

I am designing a custom case for the components that I'm 3D printing. I could ship you a completed box that you could then build a good antenna for if you're interested.
 
EAA stratux article.

da59745584ed42aaacaaa2c191cf1be6.ashx
 
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With all these goings-on there MUST be a homebrew page somewhere with folks that have worked in low microwave and understand how easy this stuff is. No?


Not a lot of crossover between the data geeks and RF geeks from what I've seen.

What you do see is photos of completed units where you see a nice SMA setup and a homebrew antenna and you can tell THAT guy or gal "gets it", but is just posting a "here's mine" photo, and not really intending to engage on how they made their antenna.

And most of the data geeks think "an antenna is an antenna" and don't think to ask them why that silly looking piece of copper wire soldered into a connector is what the person used, instead of the cheapie little rubber ducks on everyone else's photos.

Someone recently sent a note in their renewal to the ham club asking if we'd do a senior discount. The BoD internally joked that if we did, the club's revenues would drop by whatever discount we offered. Heh.

Not a WHOLE lot of younger folk playing with RF these days, Jim. And when they do, they're pretty excited they got their $30 Baoufang (sp?) hand held to key an FM repeater. They're used to just poking buttons on the smartphone to communicate. It "just works".

Low microwaves might as well be landing on the moon.

Not meant as an insult to them, they just don't have the background or interest. They think broadcast stuff is "ancient".

'Round here, I'm working on getting the new to me 60' tower up so I can clear off the roof tower on the garage and make that into the rotatable microwave antenna/toy location. If I keep the wind load low enough the Yaesu rotor should survive it.

1.2 GHz will be at the top of the big tower, via a long yagi and 7/8" hardline, but stuff above that in frequency is going to be fed into a dish on the lower rooftop tower where I can get at it and make changes easier, while standing on the roof.

Want to put my 10 GHz station back on the air and then work on getting a real 10 MHz clock source going in the shack so I can lock that silly thing down. (It's fun to chase the frequency all over the place while it's warming up, but totally silly now that it'll be fixed instead of mobile/roving.) Need to also get 2.4 back on the air.
 
There is a new thread on reddit discussing power supply issues. It's clear that USB power cables are the main potential culprit. Even a perfect USB supply that can deliver mega-amps at 5V would not help if your cable/connector impedance is too high, as it would be for the cheaper brands. The solution is to use high quality USB power cables and connectors, as short as possible (every inch counts!).


Replaced power cable with a 1 ft cable that got good reviews on amazon and it works great. Using wing x pro with iOS and wing x updated.

Here is the amazon link....http://www.amazon.com/gp/product/B002GH8OCG?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
 

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Rough size of box?

16cm by 8.5cm rectangle right now. Probably going to end up around 3cm in height. Not sure yet.

Dimensions can change. Really I can change the case by whatever means is needed to have a good internal antenna solution. An external antenna really complicates the design and quite frankly shouldn't be needed (in my uneducated opinion). The official Stratus does great with whatever its internal antenna is.

I do hold, or maybe it expired, amateur radio license but it's been 10 years since I've touched any of that..and I don't remember jack about antennas.

I should have a pretty good 3d model completed by this time next week. I can send you the renderings and drawings of that with the components included. From there you could let me know if you think there's enough space to do an antenna or how I should modify the case to best pull it off.
 
1.2 GHz will be at the top of the big tower, via a long yagi and 7/8" hardline, but stuff above that in frequency is going to be fed into a dish on the lower rooftop tower where I can get at it and make changes easier, while standing on the roof.

Want to put my 10 GHz station back on the air and then work on getting a real 10 MHz clock source going in the shack so I can lock that silly thing down. (It's fun to chase the frequency all over the place while it's warming up, but totally silly now that it'll be fixed instead of mobile/roving.) Need to also get 2.4 back on the air.


???? Is there an app for all that !!! :D
 
Apart from some cable tidy up, we are good to go...
 

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There is a new image just posted a few hours ago.

https://github.com/cyoung/stratux/releases/tag/v0.2r1


1090ES on/off toggle - working now.

Interface improvements.

Data replay - stops sending data when app is not in foreground or iPad screen is off. Buffers data and sends it when app is in the foreground and screen is on again.

Callsign / tail number for TIS-B traffic. (ie removes "u" & "e" from tail numbers)
 
16cm by 8.5cm rectangle right now. Probably going to end up around 3cm in height. Not sure yet.

Dimensions can change. Really I can change the case by whatever means is needed to have a good internal antenna solution.

I will share the secrets of RF with you if you will share the secrets of 3-d programming for 3d printing.

Now, to the antenna. Ever try to carry a long pipe horizontally through a doorway? Difficult to impossible, isn't it. Same for radio waves. The ground station is transmitting vertically (up and down with respect to the earth's surface). The airborne antenna should be doing likewise. To do this, the airborne antenna needs to be vertical with respect to the ground station in normal straight and level flight.

But just like the pipe, we can bend the antenna to fit. The only problem is that the only part that will really work afterwards is the part that is vertical. THe rest of it is just there for the ride.

Let's pose another problem. As I understand it, some of the signals you want to intercept are coming from stations on the ground, and some from airborne aircraft. Since you don't really have a clue about where in 3-d space the aircraft are going to be, you need what is called an isotropic antenna. An antenna with a reception pattern like an orange, with the aircraft at the dead center of the orange. Theoretical; practically impossible to do.

The ones coming from the ground need to "see" the antenna from an optical point of view. That is, at these frequencies there is damned little twisting and turning of the signal as it progresses from the ground station to the aircraft antenna. Engines, cowls, instrument glare shields ... all these things get in the way of a straight line signal.

So we try and solve all these problems in software, which can be done, at the expense of making the hardware nearly perfect.

That being said, send me a drawing (back of the envelope pencil sketch is fine) of what you think the thing is going to look like and I'll send you back a pencil sketch of what I think we ought to do to make this thing work.

Jim
 
My Stratux/Foreflight combo had been working great since I put it together about two weeks ago. On my most recent flight, however, it started picking up my plane as a traffic target (freaked me out until I realized it was me) and also showing all other traffic targets at same altitude. Strangely, if I tap on the target for the more info box it showse the true altitude.

Anybody else happen to be experiencing something similar?
 
My Stratux/Foreflight combo had been working great since I put it together about two weeks ago. On my most recent flight, however, it started picking up my plane as a traffic target (freaked me out until I realized it was me) and also showing all other traffic targets at same altitude. Strangely, if I tap on the target for the more info box it showse the true altitude.

Anybody else happen to be experiencing something similar?

Are you running the latest release from yesterday ?

https://github.com/cyoung/stratux/releases/tag/v0.2r1
 
Flew 2 and a half hours with it today, swapped out the hub for two USB extension cables, no brownouts and solid performance the complete time.

Interesting we also had a skyradar onboard streaming to another iPad and skyradar was showing less traffic that the Pi version using stock antennas.
 
Made my first flight with the Stratux on Friday - to the 6Y9 fly-in. :)

Used ship's power - a 12v usb adapter with 3 ports, the second of which was powering my Nexus 7, and the third unused.

Just tossed the antenna on the glareshield and had coverage over the entire 350+ nm route, including over rather remote area.

Was great to have METARS so I could monitor conditions ahead as I was over the top.
Only had traffic depicted once in 2.5 hours.

On the flight home, I couldn't connect to the Stratux WiFi.
Upon closer inspection, it seems the SD card is corrupt - my PC won't recognize it.
Wondering whether this might be related to the hard shutdown corruption issue. Perhaps it's time for me to look into one of the software shutdown solutions...

(I've since loaded the latest image on another card.)
 
Yes, you need two antennae (well, SDR dongles) to see all the traffic.

Load whatever the latest image is.

This is a software radio. Why can't the radio switch between frequencies?

Just asking....
 
This is a software radio. Why can't the radio switch between frequencies?

Just asking....

:dunno:
Just answering cgrab's question about working with the current Stratux stuff...

Why don't you ask the stratux guys or start digging into the code yourself?
 
:dunno:
Just answering cgrab's question about working with the current Stratux stuff...

Why don't you ask the stratux guys or start digging into the code yourself?

Or if you have young kids, get them to look at it !!!!
 
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Is there a write up on how to install the gps chip? I'm sure I missed it somewhere
 
This is a software radio. Why can't the radio switch between frequencies?

Just asking....



It can. The device only has a bandwidth of 3MHz, and 978MHz and 1090MHz are "far" apart. So any time it's "listening" on one frequency is time that it's not "listening" on the other frequency. Since you can't predict when another 1090ES plane is going to come into range, or a ground tower is going to transmit weather (I guess maybe you could, but it'd be a lot of trouble), you'll have an incomplete picture of both the 1090ES and UAT transmissions if you're trying to listen to both with one device.
 
:dunno:
Just answering cgrab's question about working with the current Stratux stuff...

Why don't you ask the stratux guys or start digging into the code yourself?
Joe- I wasn't making a dig at you, just putting my question into context. There may be an "obvious" reason to not do this, though it may not be obvious to me.

It can. The device only has a bandwidth of 3MHz, and 978MHz and 1090MHz are "far" apart. So any time it's "listening" on one frequency is time that it's not "listening" on the other frequency. Since you can't predict when another 1090ES plane is going to come into range, or a ground tower is going to transmit weather (I guess maybe you could, but it'd be a lot of trouble), you'll have an incomplete picture of both the 1090ES and UAT transmissions if you're trying to listen to both with one device.

I suspect it matters if there are both in the area at the same time, but in a quiet area, it may be good to toggle between then rapidly and listen to whatever comes up, sort of like an old scanner.
 
One thing I over looked was that you needed to enable "traffic" upon start up... That may be a reason I have never seen traffic LOL!
 

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One thing I over looked was that you needed to enable "traffic" upon start up... That may be a reason I have never seen traffic LOL!

I am biting my tongue on this one.......:D
 
I guess that's why I didn't see any traffic yesterday...

I did get 5 towers at 1200' from deepinnahearta the SFRA, though.
 
Is this the USB hub you're using?
http://www.amazon.com/gp/product/B00PF9NDOG/ref=pd_luc_rh_sbs_01_03_t_img_lh?ie=UTF8&psc=1

What antenna's are you using for that setup?

Yes for the hub.

The antenna are off a damaged skyradar unit, one is labelled 987 and the other 1090 but I don't think that really manners

Still shopping for antenna but all the sites seem to be in China and they are not getting my credit card info !!!:D

Correction. http://adsb.skyguardtwx.com/store/ has them for $10 each
 
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What are folks doing for mounting?
 
Yes for the hub.

The antenna are off a damaged skyradar unit, one is labelled 987 and the other 1090 but I don't think that really manners

Still shopping for antenna but all the sites seem to be in China and they are not getting my credit card info !!!:D

Correction. http://adsb.skyguardtwx.com/store/ has them for $10 each
Thanks for the link, looks interesting. But, does it matter for the antenna's, concerning the 978 or 1090 freq's? Just buy two, one for each SDR dongle?
 
Thanks for the link, looks interesting. But, does it matter for the antenna's, concerning the 978 or 1090 freq's? Just buy two, one for each SDR dongle?

SkyGuardTWX website does not list separate ones but Skyradar does, which is weird. You will need these as well..
http://www.amazon.com/gp/product/B00V0Y4WDQ?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00


On the subject of mounting, an IKEA visit is required, I have seen some clear containers that might be useful but I can't find them on their website.

Drill a few holes for cables and air flow, some Velcro ... Done (hopefully !!!)
 
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Well, theoretically, a half-wave above perfect ground has an infinite input impedance that would require an infinite matching network ... but CLOSE to half a wavelength it can be matched ... at ONE precise frequency ... and the closer you get to true antiresonance the more finicky the matching network becomes. Bandwidths of fractions of one percent. And, as you said, there is the theremin effect of handwaving.

Tell y'all what. If I publish the design for a homebrew antenna will somebody make one up and try it out? I'll give figures for both 986 and 1090 and you can make whichever one you want.

Somebody said something about a splitter. The problem is that you have just increased your input loss by half the power, or 70% of the range, however you choose to say it. They are trivially easy to make, cost less than a buck plus whatever connectors you need.

With all these goings-on there MUST be a homebrew page somewhere with folks that have worked in low microwave and understand how easy this stuff is. No?

Jim

For home use, I made up a couple of collinear antennas using Rg6, heat shrink, and some PVC pipe. Works great on 1090, but I'll need to do a Yagi to get the 978 base station. I have an old 950 STL dish I might try to resurrect, too.

Plans for the 1090 antenna are online somewhere. Simply scale the element lengths for other frequencies.

Yes, 1/2 wave is theoretically near infinite resistance in a perfect world. But then the real world comes into play. I use Mininec for modeling. Really works pretty well as long as you understand the limitations.

Only one time have I achieved near-zero current - in a folded unipole de tuning skirt - managed to throw foot-long arcs across a vacuum capacitor.... With only 5 kW of power (at medium wave).
 
Anyone have it working on FlyQ V2.0 ? I know you have to change the SSID to "Stratus12345" for it to recognize it but the app loses traffic after about 30 seconds.

Rock solid on WingX the complete time.
 
What are folks doing for mounting?

I was thinking of using something like this

http://www.amazon.com/Rubbermaid-Pl...4&sr=8-14&keywords=kitchen+plastic+containers

Drill a few holes in the side for air flow, cables etc and two in the lid for the antenna wires or rubber duck antenna. PI would be attached using velcro.

Preferred to get an all white container to help reflect the sunlight, worst case just paint it white, with maybe a corner left clear so I can see the Pi power light.

Still on the fence using battery versus 12v, 5w 2.1 AMP USB adapter.

Decisions decision.......
 
As you guys add Hardware, antennas, and cases, can you take pictures and post them in this thread?

Sometimes a picture is worth 1000 words.



Sent from my iPhone using Tapatalk
 
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