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04-02-2015, 12:28 PM
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Join Date: Sep 2013
Location: Ooltewah, TN.
Posts: 580
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Once I saw the PPS outout on the board, I was hooked. I ended up buying one and using the cheapest shipping option. Came out to be about 30 bucks.
I think this thing will be perfect as a Stratum 0 time source for my pfSense server. It will end up being the GPS clock for the NTP server at my house.
May pick up a second one and use it to tinker with APRS.
__________________
Lynn Dixon
RV-7 Slider -
Tail kit Completed - March 2017
Wing Kit Started - June 2017
My Build Log: http://www.theskunkwerx.com
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04-02-2015, 12:35 PM
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Join Date: Jan 2005
Location: MN
Posts: 2,269
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Quote:
Originally Posted by CubedRoot
Very cool little unit. Are you going to use it for APRS?
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APRS or ADS-B Some A-thing or another.........
the PPS is accurate to something like 30 nanosecs - crazy.
__________________
Cheers,
Pete
Amateur Plane - RV-9A N789PH - 2350+ Hrs
Amateur Radio - KD0CVN
Doggies Delivered - 25+
St. Paul, MN
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04-02-2015, 04:24 PM
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Join Date: Feb 2008
Location: Los Angeles, CA
Posts: 146
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Nice to see more hackers around. I've been using one that will track above the ~50,000 foot limit for balloon launches. Obviously not a requirement for RV's but these little gizmos keep getting cheaper and more feature rich!
Bring it!
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RV-x Planning stage
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04-02-2015, 05:24 PM
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Join Date: Aug 2007
Location: Topeka
Posts: 323
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Quote:
Originally Posted by petehowell
This one is nice in that it has a max3232 TTL to RS232 converter chip and a 5V to 3.3V regulator on board. RS232...
RS232 GPS Source
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Kind of what I was thinking.
__________________
Steve Stucky
Topeka, Ks
N282S - VariEze 500+ hrs
N283S - RV-7 1400+ hrs
KC-135 A/D/E Boomer (Ret.)
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04-04-2015, 06:58 PM
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Join Date: Dec 2013
Location: Santa Clara, CA
Posts: 250
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I've been researching sensors like this for a bit, since I'm still considering building my own avionics.
My findings so far are that you get what you pay for, so there are very cheap and tiny hobby-grade sensors (tens to hundred of dollars), there are commercial-grade sensors (some still tiny like the 3DM-GX4-45) (thousands to tens of thousands of dollars), and then there are military-grade/airliner-grade sensors ("if you have to ask the price you can't afford it" dollars). The nice thing about a lot of them is that they include not just a GPS, but also an inertial measurement unit, and then can merge the information the two to give you very, very accurate readings. The keyword there is the Kalman Filter, which essentially does the merging.
Here are some links, hope they're useful:
http://navspark.mybigcommerce.com/su...ule-7-dof-imu/
http://www.vectornav.com/products
http://www.microstrain.com/lord-micr...s-all-products
http://www.novatel.com/products/span...tems/span-cpt/
http://www.sbg-systems.com/products/overview
http://www.septentrio.com/products
http://www.advancednavigation.com.au/products-showcase
There are some catches - most of the GPS/IMU sensors need to be able to figure out their magnetic heading (yaw) before they'll spit out a precise position. Some sensors (again the GX4-45 is an example) come with a magnetometer for that, but then you have to be very careful where you install it so the magnetometer can get a good enough reading. Others will rely on movement to detect your heading, and others allow installing two GPS antennas (either plugged to the same unit or two units) to get a differential position from the two to figure out which way you're facing.
While playing with these sensors it also became apparent that some of them are so sensitive that you have to filter out the rotation of the Earth from its reading  (and some of them will do that for you)
__________________
Rodrigo Damazio Bovendorp
San Jose, CA
RV-10 builder #41623
Build log at http://www.airplane.build/
VAF dues paid
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04-04-2015, 08:09 PM
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Join Date: Oct 2008
Location: Utah
Posts: 8,151
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Hilarious!
Quote:
Originally Posted by petehowell
Need to know where you are in life? Need to know where you are going? Need a project to keep you from finishing your taxes? Worried you have lost your edge in geek cred?
Here you go. A really small GPS, a really small price, and some serious performance.
Swiss GPS, so you know it is precise........ Blue LED means "cool"
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Meets the performance requirements set forth in the referenced TSOs???
.....
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04-06-2015, 08:10 AM
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Join Date: Aug 2011
Location: Austin TX
Posts: 347
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seems like it would be totally possible to build a home grown ads-b out/in solution; some antenna's, couple of these gps sensors and a transponder.
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--2008 RV-9A
Austin TX
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04-06-2015, 12:51 PM
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Join Date: Dec 2013
Location: Santa Clara, CA
Posts: 250
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Quote:
Originally Posted by moll780
seems like it would be totally possible to build a home grown ads-b out/in solution; some antenna's, couple of these gps sensors and a transponder.
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While the FAA no longer requires experimental ADS-B to be certified, they still require that it's "built to the same standards", so while it's definitely possible, DO-254 and DO-178C are very, very annoying standards to follow. Of course, all it takes is convincing one FAA DER 
__________________
Rodrigo Damazio Bovendorp
San Jose, CA
RV-10 builder #41623
Build log at http://www.airplane.build/
VAF dues paid
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04-06-2015, 12:58 PM
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Join Date: Aug 2011
Location: Austin TX
Posts: 347
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why would one have to convince a DAR, or for that matter even get a DAR involved?
seems like it would be like adding a radio, swapping an antenna or garmin 696 for 796 or installing APRS.
just do it and fly and ATC sees an aircraft in compliance.
get it installed, make it safe and make it work.
Quote:
Originally Posted by rdamazio
While the FAA no longer requires experimental ADS-B to be certified, they still require that it's "built to the same standards", so while it's definitely possible, DO-254 and DO-178C are very, very annoying standards to follow. Of course, all it takes is convincing one FAA DER 
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__________________
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--2008 RV-9A
Austin TX
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04-06-2015, 06:02 PM
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Join Date: Dec 2013
Location: Santa Clara, CA
Posts: 250
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Quote:
Originally Posted by moll780
why would one have to convince a DAR, or for that matter even get a DAR involved?
seems like it would be like adding a radio, swapping an antenna or garmin 696 for 796 or installing APRS.
just do it and fly and ATC sees an aircraft in compliance.
get it installed, make it safe and make it work.
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Hmmm you may be right.
I was talking about DER, not DAR btw - the DER is the Designated Engineering Representative, who does the certification process for equipment:
https://www.faa.gov/other_visit/avia...nee_types/der/
But you may be right that you don't need a DER to look at it if it's experimental even if it's talking to certified ATC equipment. Unfortunately, even without them looking at it, the process of "building to the same standards" is still very annoying.
I wonder if you'd still need FCC certification though?
(I think the idea is awesome btw, wish I had the RF design skill to design/build the actual transmitter)
__________________
Rodrigo Damazio Bovendorp
San Jose, CA
RV-10 builder #41623
Build log at http://www.airplane.build/
VAF dues paid
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