[time-nuts] Thunderbolt GPS rollover

shalimr9 at gmail.com shalimr9 at gmail.com
Sat Jun 9 12:13:55 UTC 2012


I second that.

I normally keep the GPS on my phone turned off to save battery life, but when I turn it on to use the map service for instance, I get a fix in as fast as a couple of seconds. That makes it much more convenient than my Tom-Tom car GPS and keeping the phone's GPS turned off unless needed makes a lot of sense.

I have not tried in an area with no service (hard to do with Verizon ;)

Assisted GPS is clearly the way to go with a handheld device.

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: "Tom Van Baak" <tvb at LeapSecond.com>
Sender: time-nuts-bounces at febo.com
Date: Fri, 8 Jun 2012 22:41:32 
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Reply-To: Tom Van Baak <tvb at leapsecond.com>,
	Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] Thunderbolt GPS rollover

> Keep in mind that a vast majority of these devices are used in "unmanned"  
> installations, i.e., cellular base stations, etc.

> Another factor, competition is so tough these days that most receiver
> chip manufacturers have dropped the eeprom for cost savings. 
> Doug

The trend these days for commodity GPS chips is "assisted GPS". Mobile phones and cellular base stations both have low latency access to the entire telecom infrastructure. When you can get the time of day, day of year, approximate lat/lon or up-to-the-minute GPS ephemeris, or leap second schedules over the net within milliseconds there is no longer a compelling need for something old-fashion like EEPROM or waiting 12.5 minutes to get orbit or UTC information at 50 baud from the satellites themselves. You could call it cost savings but really it's just a clever way to vastly improve specs like time-to-first-fix for a huge segment of the GPS receiver market. For example, why would a GPS chip in a smartphone need its own eeprom?

/tvb



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