Mike Collinson wrote: >Sent: 02 January 2008 9:54 PM >To: [email protected] >Subject: Re: [OSM-talk] GpsWeather: When conditions for mapping are good > >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&cou >ntry=US > >If I remember, http://sirius.chinalake.navy.mil/satpred/, is a good one, >but it is dead when I just checked it.
Yeah, I used to use the Sirius link but that's dead now I think. It's worth bearing in mind that all the manufacturers of commercial survey grade gps products maintain sat availability services. Most of these operate via a paid service or purchased software, however Trimble produce a useful free tool called "Planning" that I use when I really need to know how good its going to be out there. http://www.trimble.com/planningsoftware_ts.asp Cheers Andy > >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. > >Mike >Stockholm > > > >_______________________________________________ >talk mailing list >[email protected] >http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk
