Homemade avionics

The first link is very interesting!  Schematics for a whole range of interesting homebuilt aircraft instruments.  Is this your own web page?  Whoever did this deserves some kudos!

That is awesome!  Those avionics look light as well.  I've been searching for something like this for a while. Thanks!

Jon

Dear Reggie,

That page is not my own. I am not connected with author of that site.

I am surfing in Internet and blogs for bright ideas.

Regards,

Alexander.

Has anyone thought about home building a UAT? I've been digging around, and it seems like it ought to be done for under $100 (BOM). Certification, and all would probably be a consideration, but assuming that the FAA is gonna force all US aircraft to have one, and foreign sales would be icing on that cake.

It is really a simple design, FM transmitter running about 1MB/s data rate. Many manufacturers will build chips in the 800-1000MHz range (IE Maxim MAX2365 transmitter). The last couple pages of this PPT (http://www.icao.int/anb/panels/acp/wg/M/Seminar/presentations/SP23_UAT%20Briefing%201111703_1USA.ppt) lays out the format of the message, both receive and transmit.

The one challenge might be to build a big enough linear amplifier. I think it only needs to get to 10W, which is a bit, but not out of line. 

My gut feel is with enough cooperation, we could get 'em built for under $200 including all certification costs.

 I don't know about amateur built transmitters at that power output. I have a feeling both the FAA and FCC would have something to say about that. You mention getting it certified, and that can be a heck of a process. I'll defer to others with more knowledge of this feasibility.

On the other hand...

ADS-B *in* capability is very much within the grasp of the hobbyist. I've been looking at 1090ES recently as there seems to be a more active hobbyist community listening in on those transmissions. The basics of it are a low noise amplifier, 1-2 filters (1090 MHz SAW filters are available from several places), and most often a logarithmic amplifier as an amp/detector. The output can be sampled with an analog-to-digital converter or a comparator driving logic level inputs into a microcontroller which then does the very simple decoding. I assume a 978 MHz (UAT) receiver would be more or less the same. From there, it can be as easy as plugging it into a laptop for display.

Some websites of interest:

http://www.lll.lu/~edward/edward/adsb/Very%20Simple%20ADSB%20receiver.html

http://miniadsb.web99.de/    (these guys sell a kit of a complete RF front end for 1090ES reception)

http://rxcontrol.free.fr/PicADSB/index.html

http://www.qsl.net/dl4mea/picadsb/picadsb.htm

And finally, the holy grail for information about both UAT and 1090ES, hidden under the guise of boring, bureaucratic technical meetings. See working group 3 and 5 and click their most recent meetings. Draft versions of DO-260B (1090ES ADS-B standard) and DO-282B (UAT standard) are available. They are the most recent draft versions, but I can't imagine much of the technical information changed before publication. For what it's worth, these documents go for $500-$700.

http://adsb.tc.faa.gov/ADS-B.htm

-Tony

Good info, thanks.

I know the FAA will get excited about homebuilt stuff on 978MHz, it might have to be a formal project, with some investment. Like I say, with maybe 20-50K airplanes needing these things, it might not be too hard to come up with the $$ to make it happen. Garmin charging $7-9K for one is so far out of line.

1090ES is non-started for most of GA (except jets) since it requires flying above 18,000ft.

The UAT is what we need.

I found the ICAO document 9861-AN/460 which lay out the message formats, and discussions about UAT transeiver design antennas, error recovery, and other considerations.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.118.6485&rep=rep1&type=pdf 

Just joining the RTCA as an individual costs about $600, and you get the documents for free (soft copy).