[FOSS-GPS] FOSS-GPS Digest, Vol 80, Issue 3

[Felipe G. Nievinski]

>
> Date: Tue, 1 Sep 2015 13:05:25 +0200
> From: Simon Treny <simon.treny at gmail.com>
> To: Open Source GPS-related discussion and support
>         <foss-gps at lists.osgeo.org>
> Subject: [FOSS-GPS] Shocks/vibrations on antenna and cycle slips
> Message-ID: <C764E181-99B8-4B0F-9FB0-858E3684456B at gmail.com>
> Content-Type: text/plain; charset=us-ascii
>
> Hello all,
>
> I'm using RTKLib to perform RTK positioning using UBlox M8T
> evaluation-kits (EVK). I have great results when the GPS antenna is
> attached on the rooftop of a car driving on a track (accuracy <10cm).
> But as soon as a I attach the EVK and the antenna on a quad bike and drive
> on a bumpy road, the accuracy becomes really bad (the distance between 2
> antennas can be off by >3 meters).
> In both cases, I have a clear view of the sky and no tree or building
> around.
>
> By looking at the recordings with RTKPlot, I've noticed that I get much
> more losses of lock when the antenna is on the quad-bike/bumpy-road rather
> than on the car/track. My guess is that the shocks caused by driving on the
> bumpy-road causes these losses of lock. I've measured with the
> accelerometer of my phone the acceleration on both the car and the
> quad-bike: on the car, the vertical acceleration never goes beyond 3g,
> while the vertical acceleration on the quad-bike can go up to 8g.
>
> I've reproduced this observation by attaching the antenna on a pole, and
> shaking the pole vertically. As soon as I shake it, many losses of lock
> occur.
> If I do the same by attaching the EVK on the pole and letting the antenna
> static on the ground, there is no loss of lock (excluding the possibility
> that it comes from the oscillator).
>
> Is this a known issue with low-cost receivers/antennas? Is there a way to
> improve the situation? Are there other low-cost receivers that support
> shocks or vibrations better than the UBlox M8T?
>
> Cheers,
> Simon
>
>
The datashet says: "Operational limits: Dynamics ≤ 4 g"...

<
https://www.u-blox.com/sites/default/files/products/documents/NEO-LEA-M8T_DataSheet_(UBX-14006196).pdf
>

-F.
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