[time-nuts] antennas was Re: Common-View GPS Network
Jim Lux
jimlux at earthlink.net
Thu Apr 18 17:20:56 EDT 2013
On 4/18/13 1:40 PM, bg at lysator.liu.se wrote:
> All of the "high quality" GNSS receiver manufacturers have their own
> version of correlator that try to mitigate multipath. See for example
> this Ashtech-document (for a ca 10 year old L1 only receiver (DG14/16)).
>
> ftp://ftp.ashtech.com/OEM,%20Sensor%20&%20ADU/DG16%20&%20DG14/Reference%20Material/Correlator.doc
>
I'm sure..
I wonder, though, if you have a GPS receiver for which you do not know
how it works internally, can one come up with a guideline for how much
multipath suppression you want.
At some level, all those fancy algorithms are trying to build an
adaptive equalizer and/or filter for the multipath, helped by the
knowledge that the "true" path is the shortest one.
In theory, one should be able to deconvolve arbitrary multipath (if you
collect all signals from all directions of the sky, etc.), but I think
the idea of the chokering (and other clever antenna designs) is to
reduce the work for the back end processing.
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