Centimeter-level precision GPS for $900

Via Hackaday:

Where most GPS receivers only look at the data coming from the GPS satellites orbiting overhead, the Piksi uses another technique, real-time kinematics (RTK), to determine the receiver’s location with exacting precision. The basic idea behind RTK is to look at the carrier frequency of the GPS signals at 1575.42 MHz. This frequency has a wavelength of 19 cm, compared to the alternating 1s and 0s of the that are transmitted at around 1 MHz, or about 300 meters between each bit. While centimeter-level precision isn’t possible with only one receiver, two of these Piksi boards – one base station and one on a vehicle, connected via radio link – can make for a very exacting high-accuracy GPS receiver.

Comments

Stefan Gofferje August 6, 2013 at 2:37am
Reading the detailed description...:

Second, an RTK GPS receiver is able to reduce the ionospheric error with the help of an additional reference receiver. The ionospheric delay varies only slowly with location, so with a nearby reference receiver, the delay is almost the same for both receivers and can largely be cancelled out. This is why an RTK GPS system uses two receivers.

And

As we explained in our technical section above you need two receivers to do RTK so the PIKSI reward on its own won't allow you to get centimeter level precision.
The RTK KIT reward is the main deal. It contains two Piksi receivers and everything else you need to do centimeter level RTK positioning.

And
RTK KIT rewards include:

2 Piksi receivers

2 Swift Navigation retractable Micro-USB cables

4 cable assemblies for connecting devices to the Piksi UART headers

2 XBee radios

2 cable assemblies for connecting the XBee radios to the Piksi receivers
Bottom-line:
Unless your UAV is a plane with, let's say, 1,5+m wingspan and you put the Piksis in the wingtips, your system only works when your UAV is in XBee range of the groundstation. Good bye multirotor-application - unless of course, you have a 1+m frame...
Alex Wheeler August 6, 2013 at 1:34am

@Monroe

Hopefully you can get some help and by starting a conversation it is a good way to start. Try asking some of the developers what they think about the GPS and witch direction to go in.
Martin August 6, 2013 at 1:25am

@Monroe,

That's really interesting.
Euan Ramsay August 6, 2013 at 1:11am

Would this 2-unit precision setup get rid of the requirement for the dreaded compassmot? :-)
Martin August 6, 2013 at 12:58am

@Monroe,

What exactly do you think would be possible with a Radiosonde?
Moderator

Ruwan August 6, 2013 at 12:35am

awesome! thanks Mark! pledged!
Don Ingram August 6, 2013 at 12:26am

That's a bit different to a real time cm level unit with 50Hz updates in a form factor which fits on a quad... The correlator block presents a massive real time parallel processing overhead best done in an FPGA.
Jesse August 5, 2013 at 11:45pm

Of course, precision is not the same thing as accuracy.
Oliver August 5, 2013 at 11:44pm

@Morli,

That 11K is how much the Kickstarter campaign has generated, not the projected price of the gear, See http://www.kickstarter.com/projects/swiftnav/piksi-the-rtk-gps-rece...
Admin

Morli August 5, 2013 at 11:27pm

$11K ?!! :(

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