The iPhone 5 Review
by Anand Lal Shimpi, Brian Klug & Vivek Gowri on October 16, 2012 11:33 AM EST- Posted in
- Smartphones
- Apple
- Mobile
- iPhone 5
GNSS: Subtle Improvements
Section by Brian Klug
Like the iPhone 4S and the iPhone 4 CDMA before it, Apple has gone with the GNSS (Global Navigation Satellite System) leveraging both GPS and Russian GLONASS which lives entirely on the Qualcomm baseband. In the case of the iPhone 4S and 4 CDMA, that was onboard MDM6610 and MDM6600 respectively, both of which implemented Qualcomm’s gpsOneGen 8 with GLONASS tier. Going to on-baseband GNSS is really the way of the future, and partially the reason why so many of the WLAN, BT, and FM combos don’t include any GNSS themselves (those partners know it as well). In this scheme GNSS simply uses a dedicated port on the transceiver for downconversion, additional filtering (on RTR8600), and then processing on the baseband. The advantage of doing it all here is that often it eliminates the need for another dedicated antenna for GNSS, and also all of the assist and seed information traditionally needed to speed up getting a GPS fix already exists basically for free on the baseband. We’re talking about both a basic location seed, precision clock data, in addition to ephemeris. In effect with all this already existing on the baseband, every GPS start is like a hot start.
There was a considerable bump in both tracking accuracy and time to an assisted GPS fix from the iPhone 4 which used a monolithic GPS receiver to the 4 CDMA and 4S MDM66x0 solution. I made a video last time showing just how dramatic that difference is even in filtered applications like Maps.app. GLONASS isn’t used all the time, but rather when GPS SNR is either low or the accuracy of the resulting fix is poor, or during initial lock.
With MDM9615 now being the baseband inside iPhone 5, not a whole lot changes when it comes to GNSS. MDM9615 implements gpsOneGen 8A instead of just 8, and I dug around to figure out what all has changed in this version. In version 8A Qualcomm has lowered power consumption and increased LTE coexistence with GPS and GLONASS, but otherwise functionality remains the same. MDM9x25 will bring about gpsOneGen 8B with GLONASS, but there aren’t any details about what changes in that particular bump.
I spent a lot of time playing with the iPhone 5 GNSS to make sure there aren’t any issues, and although iOS doesn’t expose direct NMEA data, things look to be implemented perfectly. Getting good location data is now even more important given Apple’s first party turn by turn maps solution. Thankfully fix times are fast, and getting a good fix even indoors with just a roof between you and clear sky is still totally possible.
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OldAndBusted - Wednesday, October 24, 2012 - link
"I'm not an apple product owner, and never plan to be"That's actually kind of sad. That no matter what the product, you can't even consider it if it comes from Apple.
SolidusOne - Saturday, October 20, 2012 - link
How can you write page after page about geeky nuances, many of which cannot be discerned without lab equipment, and not utter a single word about the device's music player quality? This model particularly, as other reviews have said it was inferior to 4s in audio quality. ??????phillyry - Sunday, October 21, 2012 - link
Sorry but are you serious or trolling?Google search reveals nothing about this.
If you're serious then Engadget has an article for you that compares the sound quality of iPhone 5, GS3, One X, etc. with basically no appreciable difference. http://www.engadget.com/2012/10/02/iphone-vs-rival...
mshdk - Sunday, October 21, 2012 - link
What is the name of the IM app shown in the review?mohit2805 - Sunday, October 21, 2012 - link
Why Apple never goes for an inbuilt radio? why just its own ipod, when there are so many radio stations to listen to for free?Krysto - Tuesday, October 23, 2012 - link
The new Chromebook, which has a dual core 1.7 Ghz Cortex A15 CPU, reaches 668 points in Sunspider. That's compared to the 900+ for Apple's A6.darkcrayon - Wednesday, January 2, 2013 - link
Comparing a chip in a laptop to one in a smartphone.. A laptop with terrible battery life (for an ARM device) at a that. Nice work. Let us know when Apple puts an Ax chip inside of a small laptop and then let's compare performance.eanazag - Thursday, November 1, 2012 - link
I live in MN and have been using the maps app in iOS 6 on an iPhone 4 and iPad 3. I have encountered no issues with it. In fact it has been a little more accurate than the GPS I have and Google previously. I am guessing that in more urban areas there is a larger difference.I would have liked to see some more features that my GPS has, such as current speed, estimated arrival time, and remaining total miles for trip.
If I'm going to complain, wish they would have included turn-by-turn on the 4.
Coffeebean20 - Saturday, November 24, 2012 - link
Wow great review, I got my iPhone 5 free And tested it. I came up with similar results. Great review, good job :)cpu_arch - Wednesday, November 28, 2012 - link
Your block diagram of Swift is inaccurate, not because I know the block diagram of the Swift CPU, but because it fails to describe the basic out-of-order execution pipeline of any modern CPU's. Hint: instruction re-ordering is in the wrong place in your diagram.Your measurements of branch prediction microarchitecture performance are not useful. The key measurement is mispredict rate.
Also modern branch prediction is a function of branch outcome of the branch in question and prior branches, not some multiply/divide mechanism which you describe in your article.