[FOSS-GPS] Mobile Robot Experimentation

[Sean Hyde]

Hey Guys,

 

I've been playing around with RTKLib for a couple months now and have run
into some issues and I was wondering if anyone had any idea on how to
improve performance.

 

---Setup---

Base Station:

NVS08C on custom PCB using the receiver to power the antenna

Antenna is Taoglas Limited AA.161.301111
(http://www.taoglas.com/images/product_images/original_images/AA.161.301111.
pdf)

Antenna is on a 12" x 24" steel plate

Connected via FTDI->USB to Rasperry Pi

Raspberry Pi runs str2str to send the data to Windows laptop running rtknavi
using wifi backhaul

 

Rover:

NVS08C on custom PCB using the receiver to power the antenna

Antenna is Taoglas Limited AA.161.301111
(http://www.taoglas.com/images/product_images/original_images/AA.161.301111.
pdf)

Antenna is on a 18" x 18" steel plate

Connected via FTDI->USB to Rasperry Pi

Raspberry Pi runs str2str to send the data to Windows laptop running rtknavi
using wifi backhaul

 

The Rover setup is on a small mobile robot with a top speed of about 3mph.
It is in a city (Pittsburgh), but the sky is relatively unobstructed.

 

I'm running rtknavi in Kinematic mode using only GPS, L1+L2, 15deg elevation
mask.  The position that I input for the base station is a 5 hour average
(though it seems to have lost some precision when I pasted it?).  I have
tried both Continuous and Fix and Hold Integer Ambiguity Res.  I'll try to
attach screen shots of rtknavi.

 

Right now, it kind of works.  I can get relatively jitter-free floats and
occasionally fixes, but these fixes don't last long and I'm not sure they
are actually globally accurate (ie: if you restart the software, you may get
a fix, but it may be several meters from your last fix).  Sometimes a fix
goes away and never seems to come back.

 

I'm wondering if you guys have any suggestions to improve these results.

Better antennas? (Which ones?)

Trying to get better placement of the base station?

Different settings in rtknavi?

Continuous vs Fix and Hold?

 

Thanks!

-Sean

 

   

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