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petehowell

petehowell

Well Known Member
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"

IMG_20150401_233829.jpg


Need to make a nice housing? I suggest the cap of a lavender bleach bottle - goes with any tasteful interior scheme. Clear heat shrink completes the look. 5V pos, Ground, and serial out lines. Circle cut from autozone rewards card and some silly-cone seals the unit. This thing screams "class".

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Performance? Thanks for asking... I programmed it for 5Hz updates and a 19200 baud data transfer rate - not bad at all. Gets a 3D sat lock in seconds. WAAS, SBAS? Check and check. Here is the "command center" software with Google Earth plug-in.

u-blox.jpg


Blue and red LEDs flashing thru purple plastic adds serious "bling" to your glareshield.....

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Meets the performance requirements set forth in the referenced TSOs???

Who knows - I'm having fun playing with it and it really seems to know its position in this world.
 
GPS Source

The drone GPSs for the most part have TTL level outputs. 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 is what I need for my intended end purpose.

RS232 GPS Source

It was delivered in a week and can be programmed thru a serial port on your computer. The software is free on the web.

Hack away guys!
 
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I've played with several cheap little imported GPS receivers to keep the time set on repeater controllers. They're really small, surprisingly cheap and seem to work quite well.
 
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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.
 
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!
 
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/sup800f-gps-antenna-module-7-dof-imu/
http://www.vectornav.com/products
http://www.microstrain.com/lord-microstrain-inertial-sensors-all-products
http://www.novatel.com/products/span-gnss-inertial-systems/span-combined-systems/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)
 
Hilarious! :D




petehowell said:
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"

IMG_20150401_233829.jpg




.....



Meets the performance requirements set forth in the referenced TSOs???

.....
Click to expand...
 
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.
 
moll780 said:
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.
Click to expand...

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 :)
 
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.


rdamazio said:
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 :)
Click to expand...
 
moll780 said:
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.
Click to expand...

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/aviation_industry/designees_delegations/designee_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)
 
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