However, I don’t know of any tablets that can use them. Similar systems are being implemented elsewhere, such as EGNOS, the European Geostationary Navigation Overlay Service, and India’s Gagan (GPS Aided Geo Augmented Navigation). In passing, further improvements in GPS come from America’s WAAS (Wide Area Augmentation System), which provides a network of ground-based reference stations. (This does not require Simultaneous GPS or S-GPS, which just means the device can receive GPS and voice data at the same time.) It already knows that, especially if it has been supplied with orbital satellite data over the mobile phone network. This system is usually called Assisted GPS (A-GPS, AGPS or sometimes aGPS).Īssisted GPS greatly reduces the critical time-to-first-fix, because the device doesn’t have to scour the sky to figure out where it is. Add a bit of real GPS and the results are even better. Indeed, it works without a proper aerial and no view of the sky. Today, the location system in smartphones and tablets works pretty well using triangulation from cellphone towers, input from in-range Wi-Fi, and tracking from your last known position.

This muddied the distinction between any old location system and the real satellite-based GPS. Instead, they used triangulation (actually, multilateration) between nearby cell-phone towers or base stations. This led to the development of “GPS” systems that didn’t use the US government’s satellite-based Global Positioning System (GPS). When smartphones started to become widely used, the US government was concerned that there was no way of locating users who called the emergency services (911 in the US, 999 in the UK). What you get in a smartphone or tablet is a very low power GPS that needs a lot of help from the mobile phone network. Real GPS chips cost money and consume too much power. But even if it has “real” GPS – usually a combo chip, not a dedicated GPS chip - it’s not going to be as good as devices sold by companies such as Garmin, TomTom and so on.

Unfortunately, it’s usually impossible to tell from the product specs whether a smartphone or tablet GPS works offline, and if so, whether it’s any good.

However, you should try asking other sailors in person or in sailing-oriented forums, or ask for advice in the GPS Review Forums. Perhaps some Ask Jack readers have done this experiment and can recommend tablets that work well.

Blacksmith3d 6 tablet navigation