Working On A Faster GPS Fix

As I’ve mentioned repeatedly, I consider a GPS solution for the Treo to be one of the single best accesories that you can add to your kit. 

I recently voted the Treo GPS my favourite accessory of the year and I wouldn’t dream of travelling anywhere without one as it’s saved me from getting utterly lost on numerous occasions (see Ahead of Time With My Treo 650 GPS and Traveling with a Treo 650 GPS In My Pocket).

However, there is always room for improvement... 

Treonauts who are already GPS-enabled have like me more often than not raved about their experiences.  There is nevertheless arguably one tiny little issue that has thus far remained unsolved.

Namely, when first starting your GPS unit it may take up to a few minutes for it to acquire one or more satellites for precise GPS location data and so you’ll be waiting until the “No Valid GPS Signal” message clears before you can start driving away.  At most the wait should not be more than 1 or 2  minutes under normal conditions but might be longer in urban canyons, under dense foliage or other weak-signal conditions.

SiRF, the company which provides the GPS chipset for both of my favourite solutions the TomTom Navigator 5 Bundle and Palm GPS Navigator, recently announced the introduction of a new service called SiRFInstantFix which “provides consumers with the ability to turn on the their SiRF-based navigation devices and achieve the first fix in as fast as eight seconds to begin navigating faster than ever before”.

According to the company:

“SiRFInstantFix eliminates the initial time-consuming task of obtaining precise GPS satellite location data - ephemerides - from the satellites themselves.  Instead, the SiRFInstantFix server uses a sophisticated set of proprietary algorithms to predict seven days of ephemerides and distills them down to a small file which SiRF-based navigation systems can use to pinpoint every GPS satellite.  Using SiRFInstantFix, today's high-performance GPS receivers can not only start tracking satellites and navigating more quickly, they can do it using signals much weaker than those needed to obtain ephemeris data the traditional way, removing the barrier that often stands in the way of successfully navigating under very weak signal conditions.

While in theory the determination of location using GPS satellites is a simple process of triangulation, the reality is more complex.  First, the GPS receiver needs to know where each GPS satellite is with a very high degree of accuracy.  Each satellite broadcasts its precise location once every 30 seconds, and the receiver must collect this data from every satellite it needs for a fix.  If anything interrupts the signal while receiving this data, such as driving by a building or under a tree that momentarily blocks the signal, the receiver has to wait another 30 seconds until the information is broadcast again.  In real-world conditions of urban canyons and dense foliage, where the GPS receiver is usually moving, it can often take several minutes to obtain all the ephemerides the receiver needs to perform its calculations and obtain a fix, resulting in a long period with a great deal of location uncertainty before navigation can begin.  In some environments where the signal levels are very weak, the receivers may never be able to download this data reliably.  Using weekly synchronization to SiRFInstantFix servers and downloading a small file, users can get much faster and more reliable fixes in most of the environments.”

After speaking with a SiRF representative I learned that currently only SiRF Star III chipsets (found on the TomTom Navigator 5 Bundle) with version 3.2 software installed are capable of managing InstantFix data while SiRF Star II chipsets (found on the Palm GPS Navigator) will be ready within six months.

Unfortunately, this doesn’t mean that Treonauts will be able to use InstantFix tomorrow since this will first require an update to the TomTom Navigator software which would periodically fetch the InstantFix data from SiRF’s servers (via a wireless data connection for example).  I was unable to reach TomTom for comments as to when or if such an update might be released but I will speak with them in about 10 days at the 3GSM World Congress in Barcelona.

I’ll be extremely glad the day that I can have ‘Instant On’ GPS navigation but in the meantime I for one am not complaining about my already excellent existing solution – I absolutely love it.

Treonauts always look for things to fix…