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 <[EMAIL PROTECTED]> 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 > > _______________________________________________ > talk mailing list > [email protected] > http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk > -- Franc
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