[OSM-talk] GpsWeather: When conditions for mapping are good

[Franc Carter]

I have found an external antenna  also dramatically improved things (for a
car),
my working assumption is that it is because the external antenna gets an
uninterrupted view of more of the sky - i.e not blocked by the roof of the
car

On Jan 3, 2008 9:16 AM, Jo <ml at winfix.it> wrote:

> Mike Collinson schreef:
> > At 10:11 PM 2/01/2008, ivom wrote:
> >
> >> Folks!
> >>
> >> >From time to time, I am suffering from the limited reception
> capabilities
> >> of my Garmin Etrex Venture Cx. I guess this is a recognizable state of
> >> being, during a mapping session in urban canyons, walking around with
> an
> >> accuracy of 17 meters or more...
> >>
> >> I am looking for some sort of indication telling me, at which
> time-of-day
> >> there would be excellent conditions for creating tracks in a dense city
> >> area. Has anybody come about such a service on the web yet?
> >>
> >> Currently I am not planning to upgrade on the hardware side, but do not
> >> hesitate to suggest different makes, models or add-ons, which would
> suffer
> >> less from this urban canyon problem.
> >>
> >> Kind regards,
> >> IvoM
> >>
> >
> > IvoM,
> >
> > I think what you may be after is being able to predict date/times when
> a) there is a good number of satellites in the sky around you so that your
> GPS device can get as many readings as possible and choose the best, b) the
> satellites are well distributed over the sky to help the mathematical
> calculation of the GPS device and so that they are not all blocked by a tall
> building at the same time.
> >
> > If so, try typing into Google: GPS Satellite predictor
> >
> > I came up with
> >
> >
> https://stellarsupport.deere.com/stellar/SatellitePredictor?language=en&country=US
> >
> > If I remember, http://sirius.chinalake.navy.mil/satpred/, is a good one,
> but it is dead when I just checked it.
> >
> > Unfortunately,  even that probably won't  help that much with urban
> canyoning - you'll probably have to do several runs and then tie it in with
> Yahoo imagery if you are lucky enough to have it for your area.  One tip,
> I've got my best results having my GPS device mounted in a bicycle
> saddle-bag - it provides a much more stable platform than walking.  And if
> you are walking and your device loses satellite connection, put it on a
> metal surface - a man-hole cover,  traffic-signal controllers, even large
> waste-paper bins. It seems to act as a ground-plane which improves the
> antenna gain.
> I have an external antenna, which has a magnet. When I stick it to the
> frame of the bus or even the toddler's stroller/buggy, reception
> increases dramatically. Could this be the same effect, or did I simply
> increase the size of the antenna?
>
> Polyglot
>
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-- 
Franc
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