Wiring up uBlox! (Only for PRO's)
Hello again! I'm not so good making intros, so imagine you just read a long and well redacted introduction of why uBlox (the best GPS ever) is so difficult to find and interface with (Specially the SparkFun version). So let's go to the point. ;-)
If you are beginner please don't try to make this.
Fallow this pictures in order to make the wiring (hurry!):
And this is an example of how to connect it to ArduShield, but you must configure the unit first! So continue reading for instructions.
You will need to configure uBlox module using U-center, only have to do it once, the settings will remain in the EEPROM forever. Download U-center from here and install it:
http://www.ublox.com/en/evaluation-kits/u-center/u-center.html
Make sure you supply the unit with 3.3V and interface it using the FTDI cable. When you are able to see real time data with U-center, you are ready to proceed. Click here for a u-Center user guide.
Now UBX has 8 Message Class, we only use "Class 0x01" called "NAV":
Each class has "Messages ID's", we only need 3 ID's of "Class 0x01", the ones marked with blue:
Everything else must be disabled. Now that you know what we are trying to do, lets go with a more detailed instructions:
Go to Message View by pressing F9 (menu View->messages view):
1. Right Click on the NMEA Text on top of the tree and choose disable child messages
2. Choose UBX->CFG->NAV5(Navigation 5) - set it to use Airborne 8 <4G. This tells the Kalman filter to expect significant changes in direction.
Note that this setting is only good for faster moving airplanes. For a fixed position hovering heli, 'pedestrian' setting is better
3. UBX->CFG->PRT - set USART1 to 57600bps
4. Change the baudrate of U-Center to 57600bps if the connection is lost at this point
5. UBX->CFG->RATE(Rates) - change the Measurement Period to 250ms This gives a 4 Hz position update since 4 x 250ms is one second.
6. UBX->CFG->SBAS : Disable (SBAS appears to cause occasional severe altitude calcuation errors)
7. UBX->NAV (not UBX->CFG->NAV): double click on POSLLH, STATUS, VELNED. They should change from grey to black.
8. UBX->CFG->CFG : save current config, click "send" in the lower left corner to permanently save these settings to the receiver.
You are done!! Now plug the GPS to your ArduPilot and fly like a PRO ;-)
[UPDATE:]
Another great way to do it:
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Comment by tycinis on May 27, 2009 at 1:16pm -
this module is the only one with a Ublox chip ? works better than a standard EM-406A or LS20031 ?
thank for the How-to.
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Comment by Jack Crossfire on May 27, 2009 at 1:26pm -
It's a horrific marketing blunder for uBlox to only give volume pricing to the 1 module with a dorky antenna & useless wiring connector. Thanks to this decision, no-one's buying the superior uBlox-5, but going for the crummy Asian modules instead.
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Comment by Jordi Muñoz on May 27, 2009 at 1:40pm -
Tycinis,
Jack just answered your question... The Swiss made uBlox works better than the "crummy Asian modules".
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Comment by Gary Mortimer on May 27, 2009 at 2:07pm
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Is the dorky antenna vertical and better able to keep sat locks?
Cos the top sees further to the horizon than the flat others??
The wiring sucks though.
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Comment by Jordi Muñoz on May 27, 2009 at 2:13pm
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"Sarantel GeoHelix-P2
This antenna is popular among UAV designers due to it's natural rejection of other radio frequencies such as those originating from the modem or video system as well as it's improved rejection of signals reflected from the ground. U-blox recommends this antenna and features it in their reference design. Frequency and polarization are not dependent upon ground plane geometry so this antenna is sold only in the true GPS frequency of 1575Mhz. The geometry makes this antenna very inconvenient to mount, especially in an airplane. Some very non-scientific testing has been done with one of these antennas connected to a Tiny with a short length of 50 Ohm coax above a 120mm square of ungrounded aluminum foil and performance was adequate. The helical design should theoretically outperform a patch in the air, but not on the ground, so any organized comparison will be difficult. Possibly the most important aspect of this antenna is it's natural RFI filtering, which should be evaluated further. "
You can read more here:
http://paparazzi.enac.fr/wiki/GPS
They also mention that wiring may be tricky.
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Its important to have lots of antennas sticking out of your sUAS along with no hold and this way up stickers
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Comment by Todd Berk on May 27, 2009 at 5:24pm -
I'm curious, could you elaborate why ublox is "the best GPS ever"? I'm not up to date on specific GPS units.
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Comment by Todd Berk on May 27, 2009 at 5:37pm
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Comment by Jordi Muñoz on May 27, 2009 at 5:45pm
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Many reasons, the best one i guess is because the software was really designed to be used in aircraft's also, not just in cars or boats. The software is very flexible, has build-in eeprom and is very accurate compared with others.
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Comment by Jordi Muñoz on May 27, 2009 at 5:55pm
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Personally i never recommend EM-406 and Locosys (to be honest) (i have a Venus but i never try it, but the software is not designed for aircraft too, so..). But uBlox as you already noted is very difficult to find and adapt. So that the reason why EM-406 was elected (at least has binary protocol). I think Locosys is very good but the only bad point is that uses NMEA, again NMEA is no intended for aircraft's, there's no climb rate. That's why is called "National Marine Electronic Association" and not "National Aeronautics Electronics Association". But the point of ardupilot 2.2 is to give the flexibility of use any GPS you want. So you can figure out by yourself what is better for you and your goals. ;-)
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