What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Stratus wanna-be (Stratux)

Raymo

Well Known Member
For those that like a challenge and have some technical skills, here is an inexpensive (~$120) way to get ADS-B in the cockpit. Improvements are on-going, according to the author.

https://www.reddit.com/r/flying/related/3fscia/the_11390_adsb_receiver_for_foreflight_or_pretty/

EDIT: Follow-up post with the latest info from the author.
https://www.reddit.com/r/flying/comments/3g7urb/the_11390_adsb_receiver_for_foreflight_or_pretty/

I already bought a Stratus II but thinking of doing this anyway in the next month or so.
 
Last edited:
That is awesome. I have ADS-B-in running on a home PC with RTL-SDR and it works very well.

It looks like EFIS's like my GRT Sport use the GDL90 protocol for this info, I am wondering if I can make it work via serial link with my display...

Chris
 
Last edited:
I suspect there will be a lot of FS: Stratus II ads here and on ebay in the near future!

At least I hope so! And when I find how to get a GDL-3D clone going I'll be all over that myself!
 
It looks like EFIS's like my GRT Sport use the GDL90 protocol for this info, I am wondering if I can make it work via serial link with my display...

If someone figures this out that would be awesome! I'd love a low cost ads-b in alternative to feed my AFS 4500 until the right and right priced in/out solution presents itself. The lowest cost solution so far is around $600 and that's pretty steep for something I see as temporary. :D
 
Sweet! For that price I'll give Stratux a try. If it's lame there's a lot of other things I can do with a Raspberry Pi and a USB battery pack.
 
Last edited:
I haven't tried getting it to talk to Foreflight, but I do have a Pi and a USB DVB-T receiver sitting here... it does a pretty good job of showing me what's flying around the area, even with a teeny little POS antenna inside the office.
 
I have all of the parts in stock (from my iGate projects).

If there is a local[ish] pilot to 53VG and who uses ForeFlight, I'll have one of these assembled before this weekend.

PM or email me if you're up to doing some flight testing.
 
I'm only kind of techy but this looks like an easy one. Plug all the stuff together, install the image file on the micro SD card, plug it in and power it up.

We'll see how true that all is when UPS delivers the stuff tomorrow. ;)

Basically correct. The guy working this seems to be doing his best to make it easy. There is an updated reddit as well that I will put in my original post but all the parts in the his original post.

EDIT: Latest info from the author that makes the process easier:

https://www.reddit.com/r/flying/comments/3g7urb/the_11390_adsb_receiver_for_foreflight_or_pretty/
 
Last edited:
Friendly Warning: the authors instructions (and the latest img) are a great jumpstart. However ...

It assumes you buy exactly the pieces he links. I have a common but different wifi dongle it is does not work "out of the box". I'm having ot recompile a number of pieces. I should have it all working by the end of the day. (infamous last words)
 
One thing to be aware of with the digitizer dongles is that the sensitivity of these devices is much lower than for dedicated designs. These USB sticks are meant to pick up TV stations that output 1,000,000 watts from 30 miles away, while an ADS-B ground station is 250 watts and can be 100+ miles away.

The dedicated designs like a Stratus, the Garmin GDL-39, or the Dynon ADS-B box have incredible sensitivity because they are specifically tuned to receive only the frequency they are designed for. SDR boxes like the USB TV sticks inherently need to have huge front end bandwidth, which hurts selectivity and sensitivity.

You may easily find that the SDR ADS-B works fine 30 miles away from the ADS-B ground station, but not the 200 miles that a specialized receiver can do.

Now, clearly I'm biased because I work at Dynon and we like our ADS-B box a lot. This sounds like a fun project. Just don't judge the coverage and performance of the ADS-B system based on one of these receivers.

--Ian Jordan
Dynon Avionics
 
Hi Ian,

I don't think any of us are [sufficiently] delusional to believe the SDR+RPi is "the same thing" as a Stratus or GDL39 (as least I'm not :) )

At the same time, this project fits nicely with the experimental nature of our operational domain.

Quick update: I recompiled the necessary modules to get the RT5370 based wifi dongles to work. My ground tests successfully connect with ForeFlight (but obviously I am not receiving any weather data).

The local offer still stands for anyone who wishes to test flit this weekend.

IMG_9735-575x431.jpg
 
Agree. Fun project to play around with and maybe pick up weather (if close enough to the airport) and traffic overhead while working.

Others have flown with these and found that they have to get a good bit higher (3000+ ft AGL) compared to their *real* ADS-B device that might pick up stations at lower altitudes (500 ft AGL).
 
Xavier, when you say "works good on the ground" can you provide some details an what info/data/statistics you are seeing?
 
Hi Ian,

I don't think any of us are [sufficiently] delusional to believe the SDR+RPi is "the same thing" as a Stratus or GDL39 (as least I'm not :) )

At the same time, this project fits nicely with the experimental nature of our operational domain.

Quick update: I recompiled the necessary modules to get the RT5370 based wifi dongles to work. My ground tests successfully connect with ForeFlight (but obviously I am not receiving any weather data).

The local offer still stands for anyone who wishes to test flit this weekend.

IMG_9735-575x431.jpg

What are you using for an antenna? A properly tuned antenna, oriented vertically, will provide the best reception. Then again, reception on the ground *at all* will be difficult in many places due to LoS restrictions.
 
Hi Brad. I just swapped my "quick test" antenna (in the picture) for an antenna tuned for 978Mhz. But I'm sure the majority of the deficiency is that I'm still located on the ground :)
 
DIY Stratux PIREP

I shirked my duties this morning and flew with the Stratux up on my glare shield. As a point of comparison, I have a GDL39 with a dedicated antenna on the bottom of my aircraft back under the RV-8 rear baggage area.

I had no problem getting my iPhone 6P to connect to the Stratux wifi. The first problem came when I tried to get ForeFlight to recognize the Stratux (FreeFlight) device. It took 20 minute of random ideas and then it connected. None of this surprised me since I had the same problem yesterday in my bench. Subsequent boot-ups of the Stratux had no problem with connecting. I'll classify it as one of those random things.

During ground ops and in flight I noticed the ForeFlight "connection" to FreeFlight would drop. This again was random. When I looked closely at the videos linked to the reddit posts I notice it happened to his system as well.

I picked up the first tower at 650' AGL. It was unreliable. I would lose it frequently. The direction and orientation of the aircraft would contribute to the loss. At 2500' AGL I had two towers but that would fluctuate often back to one and zero. By comparison, the GDL39 had five towers. At 3500' AGL I had three towers with the Stratux ranging from 30-50nm while the GDL39 had seven towers from 30-90nm.

I did receive a 4 local radar frames and 1 national radar frame with the Stratux during the test flight. I also received 280 text reports. I checked three local airports and had METAR and/or TAF for each. I don't know the data for the GDL39 but I had radar animations and weather reports for the four airports I checked.

I tested with both a 1/4 antenna tuned to 978 mhz and the little SDR supplied antenna. It's a guess but I think the tuned antenna was better. Both antennas were affected by the orientation of the airplane. I observed a tower 30 miles away while flying toward it and lost that tower when flying away from it.

My initial conclusions are:
  • antenna location is important - a tuned belly antenna will likely perform better than my tests
  • connectivity is variable - I can't compare with a real Stratus unit and my GDL39 is hard wired to my panel and uses Bluetooth to ForeFlight and Garmin Pilot on the iPhone. (for those who were wondering, "yes", ForeFlight on the iPhone immediately recognized my G3X Touch Connext)
  • Reception quality is "OK" - I knew going into the tests that the SDR would not be as discriminating and sensitive as the GDL39. As my altitude increased, the Stratux data improved but the GDL39 was working well at 1000' AGL and when the Stratux was at its best, the GDL39 was still 2x better on towers.

Remember, the Stratux is closest to a first generation Stratus 1.

It was a fun experiment and from that measure, it was a success. However, having flown with a first generation GDL39 for three years now, it's not reasonable to consider them in the same category. If you've got the parts readily available or you enjoy Raspberry Pi projects, it's a fun little project.

I captured lots of notes and screen grabs but since I consider this an educational experience, I'll leave those as "an exercise for the student".
 
Last edited:
would this antenna work with the SDR dongle?

http://www.deltapopaviation.com/UAT_Antenna.html

Also, would installation on top of the fuse (behind the my sliding canopy when open) be the best place? I have comm antennas under the fuse (below the seats).

I shirked my duties this morning and flew with the Stratux up on my glare shield. As a point of comparison, I have a GDL39 with a dedicated antenna on the bottom of my aircraft back under the RV-8 rear baggage area.

I had no problem getting my iPhone 6P to connect to the Stratux wifi. The first problem came when I tried to get ForeFlight to recognize the Stratux (FreeFlight) device. It took 20 minute of random ideas and then it connected. None of this surprised me since I had the same problem yesterday in my bench. Subsequent boot-ups of the Stratux had no problem with connecting. I'll classify it as one of those random things.

During ground ops and in flight I noticed the ForeFlight "connection" to FreeFlight would drop. This again was random. When I looked closely at the videos linked to the reddit posts I notice it happened to his system as well.

I picked up the first tower at 650' AGL. It was unreliable. I would lose it frequently. The direction and orientation of the aircraft would contribute to the loss. At 2500' AGL I had two towers but that would fluctuate often back to one and zero. By comparison, the GDL39 had five towers. At 3500' AGL I had three towers with the Stratux ranging from 30-50nm while the GDL39 had seven towers from 30-90nm.

I did receive a 4 local radar frames and 1 national radar frame with the Stratux during the test flight. I also received 280 text reports. I checked three local airports and had METAR and/or TAF for each. I don't know the data for the GDL39 but I had radar animations and weather reports for the four airports I checked.

I tested with both a 1/4 antenna tuned to 978 mhz and the little SDR supplied antenna. It's a guess but I think the tuned antenna was better. Both antennas were affected by the orientation of the airplane. I observed a tower 30 miles away while flying toward it and lost that tower when flying away from it.

My initial conclusions are:
  • antenna location is important - a tuned belly antenna will likely perform better than my tests
  • connectivity is variable - I can't compare with a real Stratus unit and my GDL39 is hard wired to my panel and uses Bluetooth to ForeFlight and Garmin Pilot on the iPhone. (for those who were wondering, "yes", ForeFlight on the iPhone immediately recognized my G3X Touch Connext)
  • Reception quality is "OK" - I knew going into the tests that the SDR would not be as discriminating and sensitive as the GDL39. As my altitude increased, the Stratux data improved but the GDL39 was working well at 1000' AGL and when the Stratux was at its best, the GDL39 was still 2x better on towers.

Remember, the Stratux is closest to a first generation Stratus 1.

It was a fun experiment and from that measure, it was a success. However, having flown with a first generation GDL39 for three years now, it's not reasonable to consider them in the same category. If you've got the parts readily available or you enjoy Raspberry Pi projects, it's a fun little project.

I captured lots of notes and screen grabs but since I consider this an educational experience, I'll leave those as "an excessive for the student".
 
I shirked my duties this morning and flew with the Stratux up on my glare shield. As a point of comparison, I have a GDL39 with a dedicated antenna on the bottom of my aircraft back under the RV-8 rear baggage area.

I had no problem getting my iPhone 6P to connect to the Stratux wifi. The first problem came when I tried to get ForeFlight to recognize the Stratux (FreeFlight) device. It took 20 minute of random ideas and then it connected. None of this surprised me since I had the same problem yesterday in my bench. Subsequent boot-ups of the Stratux had no problem with connecting. I'll classify it as one of those random things.

During ground ops and in flight I noticed the ForeFlight "connection" to FreeFlight would drop. This again was random. When I looked closely at the videos linked to the reddit posts I notice it happened to his system as well.

I picked up the first tower at 650' AGL. It was unreliable. I would lose it frequently. The direction and orientation of the aircraft would contribute to the loss. At 2500' AGL I had two towers but that would fluctuate often back to one and zero. By comparison, the GDL39 had five towers. At 3500' AGL I had three towers with the Stratux ranging from 30-50nm while the GDL39 had seven towers from 30-90nm.

I did receive a 4 local radar frames and 1 national radar frame with the Stratux during the test flight. I also received 280 text reports. I checked three local airports and had METAR and/or TAF for each. I don't know the data for the GDL39 but I had radar animations and weather reports for the four airports I checked.

I tested with both a 1/4 antenna tuned to 978 mhz and the little SDR supplied antenna. It's a guess but I think the tuned antenna was better. Both antennas were affected by the orientation of the airplane. I observed a tower 30 miles away while flying toward it and lost that tower when flying away from it.

My initial conclusions are:
  • antenna location is important - a tuned belly antenna will likely perform better than my tests
  • connectivity is variable - I can't compare with a real Stratus unit and my GDL39 is hard wired to my panel and uses Bluetooth to ForeFlight and Garmin Pilot on the iPhone. (for those who were wondering, "yes", ForeFlight on the iPhone immediately recognized my G3X Touch Connext)
  • Reception quality is "OK" - I knew going into the tests that the SDR would not be as discriminating and sensitive as the GDL39. As my altitude increased, the Stratux data improved but the GDL39 was working well at 1000' AGL and when the Stratux was at its best, the GDL39 was still 2x better on towers.

Remember, the Stratux is closest to a first generation Stratus 1.

It was a fun experiment and from that measure, it was a success. However, having flown with a first generation GDL39 for three years now, it's not reasonable to consider them in the same category. If you've got the parts readily available or you enjoy Raspberry Pi projects, it's a fun little project.

I captured lots of notes and screen grabs but since I consider this an educational experience, I'll leave those as "an exercise for the student".


humptybump, you're not using the recommended hardware, correct? The WiFi dongle is $10 and worth it to not deal with issues, they're all hit or miss and the one in the original hardware setup doesn't seem to be causing issues for others.


In terms of reception, try using the antenna that comes with it in its retracted position. Most people report good reception with this. Some guys on beechtalk actually reported better reception than Stratus 2. At 1500' AGL I get a steady 2-3 towers.
 
One thing to be aware of with the digitizer dongles is that the sensitivity of these devices is much lower than for dedicated designs. These USB sticks are meant to pick up TV stations that output 1,000,000 watts from 30 miles away, while an ADS-B ground station is 250 watts and can be 100+ miles away.

The dedicated designs like a Stratus, the Garmin GDL-39, or the Dynon ADS-B box have incredible sensitivity because they are specifically tuned to receive only the frequency they are designed for. SDR boxes like the USB TV sticks inherently need to have huge front end bandwidth, which hurts selectivity and sensitivity.

You may easily find that the SDR ADS-B works fine 30 miles away from the ADS-B ground station, but not the 200 miles that a specialized receiver can do.

Now, clearly I'm biased because I work at Dynon and we like our ADS-B box a lot. This sounds like a fun project. Just don't judge the coverage and performance of the ADS-B system based on one of these receivers.

--Ian Jordan
Dynon Avionics


TV stations in the US transmit at a maximum of 50,000W. I don't know about ADS-B ground stations but don't think your number for that is accurate either.

Sensitivity isn't a great differentiator in this case, it's not like a comm radio where you need to catch a single message. Having recorded some UAT messages with an RTL-SDR dongle, in the span of 30 minutes I got spammed with all local airports' METARs an average of 5 times over. Maybe if it were more sensitive I'd get the exact same METAR message another 5-10 times...
 
Okei,
UHF TV stations in the USA are allowed up to 5 million watts if analog and 1 million if digital (which they are all now). That's 470 to 890 MHz, and of course we're talking 978 MHz or 1090 MHz, above the TV frequencies.

It's only VHF channels 2-6 that are limited to 45 KW digital and channels 7-13 are 160 KW.

My number for ADS-B ground stations is inaccurate, you are right. Many GBT's are only 25 watts. But the FAA is allowed to tune them up to +58 dBm (630W) to get the appropriate coverage.

The issue with sensitivity is actually quite important if you are flying cross country, where you may actually care what the weather is doing in front of you while relying on the FAA's ground station spacing based on a UAT receiver meeting the TSO sensitivity. Totally agree that if you are only flying locally in a dense area it matters a lot less.

--Ian
 
Last edited:
Okei,
UHF TV stations in the USA are allowed up to 5 million watts if analog and 1 million if digital (which they are all now). That's 470 to 890 MHz, and of course we're talking 978 MHz or 1090 MHz, above the TV frequencies.

It's only VHF channels 2-6 that are limited to 45 KW digital and channels 7-13 are 160 KW.

My number for ADS-B ground stations is inaccurate, you are right. Many GBT's are only 25 watts. But the FAA is allowed to tune them up to +58 dBm (630W) to get the appropriate coverage.

The issue with sensitivity is actually quite important if you are flying cross country, where you may actually care what the weather is doing in front of you while relying on the FAA's ground station spacing based on a UAT receiver meeting the TSO sensitivity. Totally agree that if you are only flying locally in a dense area it matters a lot less.

--Ian


Do you have, by chance, the TSO sensitivity specs for UAT receivers? I'm curious to quantify the difference between the published specs on an RTL-SDR dongle vs that.


EDIT:
Ian, you probably know a lot more about this than I do. ICAO "Doc 9861 AN/460" says:

"All UAT aircraft receivers have the same receiver sensitivity requirements. The receiver sensitivity at the PMP, for 90 per cent message success rate in the absence of interference, is –93 dBm for long UAT ADS-B messages, –94 dBm for basic UAT ADS-B messages and –91 dBm for ground uplink (ground-to-air) messages."


http://superkuh.com/gnuradio/R820T_datasheet-Non_R-20111130_unlocked.pdf is the documentation I could find. It shows:

FFT:8k,QPSK,CR:1/2 Sensitivity -97.5dBm

Lower at higher data rates.
QPSK,CR:1/2 I see is 0.62 bits/sec per Hz


The same ICAO doc says the data rate is 1041667 bit/sec for UAT. So that's less than 0.01 bits/sec per Hz.


Am I looking at this the right way? From this it seems like it actually exceeds spec for sensitivity.


1.041667 Mbps.
 
Last edited:
humptybump, you're not using the recommended hardware, correct?

Correct. I experimented with what I had on hand.

In terms of reception, try using the antenna that comes with it

I tested with a tuned antenna and with the SDR's original antenna. There was not a big difference.

The towers received will depend on where they are and what interference is in the area. Comparing different geographic areas will have many variables.

BTW: when I reviewed the reddit author's videos, I noticed he was in the Detroit area and did not see towers until he was around 3000' AGL and a close look shows he edited out more than an hour of video. During a period of maneuvering at just over 300' AGL, he see 7 then 4 then 2 then 3 towers. There is also a brief moment when he too had the "not connected" status. I had the same experiences.

This is a great experimental project and encourange anyone who likes tinkering with Raspberry Pi projects to give it a try. I had fun and learned a few things along the way.
 
Last edited:
Other project

This is another project along the same lines.
www.pilotaware.com
It has a transmitter which might be illegal to use in some countries.
Some good informations on the project's forum.
I don't know if it will work without the transmitter installed, I will ask the author as soon as I get access to the forum.
Depending on which parts I receive first I'll try this one or the stratux.
 
Correct. I experimented with what I had on hand.


BTW: when I reviewed the reddit author's videos, I noticed he was in the Detroit area and did not see towers until he was around 3000' AGL and a close look shows he edited out more than an hour of video. During a period of maneuvering at just over 300' AGL, he see 7 then 4 then 2 then 3 towers. There is also a brief moment when he too had the "not connected" status. I had the same experiences.


You're referring to the timestamp just above "FreeFlight, 0 towers"? That's the last update on the current radar frame. The video wasn't cut, just sped up. Whole flight is there. The towers don't show up until 3000' AGL because it was an experimental version of the project and the backend wasn't running until then :). You can see that it would have gotten towers by 500-1000' AGL by getting 2 or so towers 300' AGL. If there's no signal, it the tower will disappear within a few seconds.
 
Haven't flown with mine.

I had no problem getting my iPhone 6P to connect to the Stratux wifi. The first problem came when I tried to get ForeFlight to recognize the Stratux (FreeFlight) device. It took 20 minute of random ideas and then it connected. None of this surprised me since I had the same problem yesterday in my bench. Subsequent boot-ups of the Stratux had no problem with connecting. I'll classify it as one of those random things.

I had the same problem so I don't think it's random. it happened with both the code I compiled myself and the pre-configured image. I continued to tinker with the pre-configured image I installed and found that the NooElec must be in a certain USB port on the Pi. Mine worked with the NooElec on the lower right hand port (with the network and USB ports facing you). I powered down, and switched the port the receiver was in and it wouldn't work unless it was plugged into the port previously mentioned.

I have not tried to troubleshoot with the self compiled code. I'll probably give it a try later this weekend.

I also noticed that the number of towers seen depends on how much I extend the antenna. Again, this was tried indoors.

There's no GPS support in the pre-configured version. If you compile yourself and add a GPS receiver (RY835AI 18Hz USB GPS is reported to work) to your Pi then you'll also have GPS (or use the internal GPS in your device if equipped, or a bluetooth GPS). Apparently someone is working on adding code for AHRS.

YMMV
 
Hi Xavier! Thanks for your update.

This project reminds me of many RPi projects I've done - something's work "first time" and some things need "trial and error". Once everything is figured out, it's important to "leave it as it is".

Enjoy the project. I'll be interested in more reports!
 
You're referring to the timestamp just above "FreeFlight, 0 towers"? That's the last update on the current radar frame.

Thanks for the correction. I'm not a ForeFlight user and it looked suspicious when the time jumped forward.
 
First Stratux test flight

I put the Stratux together yesterday with the parts listed on the site and using the SD image file. I also made the read-only modification from here, because I figured I'd be just unplugging the power when I was done trying it, and it seems this might keep the file system from getting corrupted when I yank the power.

We tried a test flight this morning (didn't get an early start, so it was a little hot and bumpy).

I put the Stratux between the seats:
2zyvg5f.jpg


and did a fancy install of the antenna:
a27vok.jpg


Sue monitored Foreflight on the iPad while we were climbing out, and then we both explored the data a bit.

We had one ADSB tower available still on the ground (KAEG is line-of-sight to the top of the Sandias), and we picked up a second by 1000AGL. During our brief flight, we generally had three towers show up - once it dropped to one, and once we had five, at a time when we had climbed to 4000AGL.

The local radar updated, and we were able to get METARs and TAFs with no problem. I haven't flown with a Stratus or equivalent, but the performance was good enough to inspire some more tests.
 
R820T vs R820T2

Given the different PIREPs, I did some reading about various SDR-RTL dongles.

For APRS I've used the old E4000 chipset SDRs. These have proven to be somewhat superior on the 100-450Mhz range. However, they are getting scarse and are typically $40 when compared to the RTL2832U R820T based units which center around $15.

Recently, a few sellers have been offering an updated design for the low cost units. These newer dongles use an R820T2 chip and a few better tolerance supporting components.

The result is the newer units show improvement in sensitizing and reduced noise above 800Mhz.

I hope to test one of the newer units and will update my PIREP above.
 
On Friday I received my Amazon order and put everything together. I downloaded and wrote the image to the micro SD card. After that I turned it on and stratux showed up as a Wi-Fi on my iPad. (I suggest waiting 45 secs or so because the Rasberry Pi does need to boot.) I selected it and then opened Foreflight. When I went to devices, "Free Flight" showed that it was connected. Everything seems to be working.

Saturday I was excited to try it out and was wheels up about 6:30am.

For now I just set it on the passenger seat.
Img_0585.jpg


The antenna has a magnetic base and I found that my pinch welt has some steel in it. Good enough for a quick test.
Img_0584.jpg


All ready to go, no towers showing up on the ground. Ipad mini with built in GPS (4g).
Img_0586.jpg


Climbing out I picked up 2 towers at about 1300 ft and then had all 4 in my area by about 2300. Reception did seem to vary between 2 and 4 towers depending on my heading. (likely antenna position)

Weather Radar was working but there were not returns yesterday.

I didn't see any traffic but figured out later that I hadn't turned it on in Foreflight.

All in all it exceeded my expectations and seems to work quite well. Granted I was pretty much local in the Puget Sound area the ground stations were relatively close.
Img_0583.jpg
 
Last edited:
A little later my friend Darin showed up to the airport so we took it for another flight in his 9A. This time I brought my full size iPad this time because he'd be flying and I could mess around with it with the larger screen. The problem was I forgot that this iPad was wifi only so I didn't have a position source. We almost went back for my iPad mini but Darin suggested connecting to his GDL 39 by Bluetooth. It worked! Now we had GPS position by Bluetooth and the Stratux was still connected by WiFi.

Darin has a really nice new panel with all the ADS-B stuff so we could compare.
Img_0587.jpg


This time I just stuffed it in his side pocket.
Img_0588.jpg


Again I found some steel and stuck on the antenna.
Img_0589.jpg


About the same reception I experienced this morning only this time we were receiving traffic. (because I turned it on, duh:rolleyes:)
IMG_0590.JPG


We went to Chehalis for fuel and then climbed to the South to see how long it'd take to pick up a ground station in Oregon. By 4000ft or so we started picking up the Scappoose station. It took some time to update and populate. Here at 5634ft we were picking up from 2 to 4 stations depending on our heading.
IMG_0592.JPG


If you've heard on the news about the Pacific Northwest being on fire, they're not lying. I've never seen it this bad.
IMG_0591.JPG


So far so good. I'm very excited how well this works. On this flight at least it was very comparable to Darin's Garmin system. We both seemed to get weather and traffic at about the same time.

I'm not going to say at this point that Stratux is totally comparable to the good stuff because I really doubt it is. I'll need to get out on a long cross country to see how it really performs. Today though, it was awesome and soooo worth $106. :D
 
Given the different PIREPs, I did some reading about various SDR-RTL dongles.

For APRS I've used the old E4000 chipset SDRs. These have proven to be somewhat superior on the 100-450Mhz range. However, they are getting scarse and are typically $40 when compared to the RTL2832U R820T based units which center around $15.

Recently, a few sellers have been offering an updated design for the low cost units. These newer dongles use an R820T2 chip and a few better tolerance supporting components.

The result is the newer units show improvement in sensitizing and reduced noise above 800Mhz.

I hope to test one of the newer units and will update my PIREP above.


E4000 and R820T will not work for this, you'll get spotty results.
 
Hi "okie". I'm not sure who/where you are or your background. You're profile is blank. You only appear to be associated with this thread.

E4000 and R820T will not work for this, you'll get spotty results.
The R820T will work. I was explaining that independent testers have data showing the R820T2 is a better option.

I hope I was clear to others in saying the E4000 has its uses in the lower frequencies (such as APRS), the R820T units are prolific (so many may have one lying around), and this project seems to benefit from the newer R820T2 devices.

I was trying to give some data to those who might be experimenting and to help with choosing the better component hardware.


The reddit user has given links to Amazon for the RPi bundle and others pieces (and may be making money from every purchase). Some of us may already have pieces and are experimenting with what we have. As I identify differences I'm trying to share to help others. We are here to learn and share.


BTW: for anyone trying to use one of the RT5370 based wifi dongles (common with the canbit bundles and used by many vendors) I have built the latest stable code for hostapd with the necessary support. I'm happy to post them somewhere if you're not comfortable doing raspberry Pi builds.
 
Last edited:
R820T

The R820T will work. I was explaining that independent testers have data showing the R820T2 is a better option.

... the R820T units are prolific (so many may have one lying around), and this project seems to benefit from the newer R820T2 devices.

I had an R820T on hand and put together a Stratux receiver with it- seems to work just fine with reception comparable to my GDL39

-Greg
 
I had an R820T on hand and put together a Stratux receiver with it- seems to work just fine with reception comparable to my GDL39

Thanks for the PIREP Greg. I'm glad you got good results!

I also tried an SDR-RTL based on the R820T. My results were not as good as my permanent mounted GDL-39. This may be attributed to the superior installation and antenna of my GDL-39 or something else.

I like this experiment so I'll try the different dongle and share what I learn.
 
I was trying to give some data to those who might be experimenting and to help with choosing the better component hardware.


Well, at least with 1090MHz ADS-B, it has been tested ad nauseum and R820T2 always comes out the winner. If you were using either an E4000 or R820T RTL-SDR, that is likely the cause of bad "reception" as the qualities of these are inferior for this application.


The reddit user has given links to Amazon for the RPi bundle and others pieces (and may be making money from every purchase).


If you're against him making money off of the links, just type in the name of the product on Amazon. They're not custom made for Stratux :)
 
Well, at least with 1090MHz ADS-B, it has been tested ad nauseum and R820T2 always comes out the winner.

"ad nauseum" is an exaggeration. The R820T2 has better test results. All of the Internet searches I conducted eventually link back to the same two tests.

Most pilots testing Stratux in this thread are focused on the weather data which is on 978Mhz.

At least one poster has had good results with the R820T. I had marginal results.

If someone has a RPi2 and the older R820T, they can get the Stratux to work. If they are buying everything new, it's beneficial to get the R820T2.
 
I am buying everything new (except for the Kmashi, which I have), especially after reading from the Reddit OP, "Yeah, a unit that has a good GPS, pressure sensor, and the AHRS sensors is coming for development. It'll add another ~$50 to the parts list." REALLY glad I did not buy something retail recently, as I intended to do.
 
Why not....

implement the required pi software routines as an app for android and/or ios?

Sorry for my flagrant display of ignorance; the last real programming I did was back in the mid '70s (previous century).

But if the SDR uses a USB port to communicate, why couldn't the routines running on the pi be run inside android, and avoid the extra hardware? Is it just too much overhead for one device to handle ADSB tasks in addition to mapping?

Charlie
 
Hi Charlie.

No worries on "the learning curve".

We can dismiss building it with iOS since there is no direct way to get to the necessary internal protocols and no access to the SDR via USB. That leaves Android. ForeFlight does not run on Android.
 
Last edited:
Do you have, by chance, the TSO sensitivity specs for UAT receivers? I'm curious to quantify the difference between the published specs on an RTL-SDR dongle vs that.

I don't know about other brands, but the Dynon ADS-B receiver is about 15dB better than the TSO requires, and it does this in the presence of a +17dBm 1090 transponder pulse.
 
Back
Top