Re: [time-nuts] Terrestrial GPS

Hi But, by their nature, not useful for timing or precision navigation. They are simply a solution to the “feed you coupons at the mall” issue. Since they run as an independent system (they have their own ID’s) the direct “pollution” issue on a GPSDO is eliminated. You still have the

Re: [time-nuts] Terrestrial GPS

Such system already exists, is called IMES, uses L1 band and is supported by standard Ublox 8 firmware. http://gpsworld.com/wirelessindoor-positioningopening-up-indoors-11603/ Leo > From: Stewart Cobb > Peter Reilley suggests a backup to GPS using terrestrial

Re: [time-nuts] Terrestrial GPS

Hi There *are* multiple different things that get tagged as “WiFi location” services. One is a passive approach. They look at what your device can “see” and guess your location. Another is an active approach. You are logged on to a WiFi system and they try to back track your location though a

Re: [time-nuts] Terrestrial GPS

Apparently the database in my area is poor. Another location I am sometimes found in is *Fremont*, almost 100 miles southeast. Fremont most frequently shows up as the "closest store" when I am looking at (for example) hardware store web sites. Jeremy N6WFO On Wed, Mar 14, 2018 at 10:15 AM Bob

Re: [time-nuts] Terrestrial GPS

I've seen wifi location reporting me almost 2000 miles east of where I am. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

Re: [time-nuts] Terrestrial GPS

Hi WiFi based location can be pretty good or it can be a real joke. It all depends on how good the database happens to be and how many stationary WiFi setups you can “see”. I’ve had it pop up with locations that are off by many miles. ISP’s feed you IP addresses via DHCP and the “on net”

Re: [time-nuts] Terrestrial GPS

Have you noticed that your mobile devices (smartphone, iPad, tablet PC, laptop PC) can often know your location when you inside a building shielding you from GPS satellites (or producing multipath confusing the GPS receiver)? Here is a quick test you can do if you have a PC with no GPS receiver

[time-nuts] Terrestrial GPS

Peter Reilley suggests a backup to GPS using terrestrial transmitters. This idea has been around since the early days of GPS. The terrestrial transmitters were called "pseudo-satellites", or "pseudolites" for short. The big problem with this idea is that the GPS signal format has a narrow dynamic