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.

Cellular Connectivity: LTE with MDM9615 WiFi: 2.4 and 5 GHz with BCM4334
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  • Calista - Sunday, October 21, 2012 - link

    English is not my native language (as I'm sure you have noticed) and so the flow in the language is far from flawless. But I still believe my opinions are valid and that the review was too long-winded.
  • Teknobug - Wednesday, October 17, 2012 - link

    I live in a big city and I don't know a single person that went and got the iPhone 5, most are happy with the iPhone 4 or whatever phone they're using, I don't see what's so great about the iPhone 5 other than it being built better than the iPhone 4's double sided glass structure (I've seen people drop their's on the train or sidewalk and it shattering on both sides!).

    And what now? iPad mini? I thought Apple wasn't interested in the 6-7" tablet market, Steve Jobs said 9" is small enough. I know Apple tried a 6" tablet a decade ago but the market wasn't read for it back then.
  • name99 - Wednesday, October 17, 2012 - link

    You know what AnandTech REALLY needs now?
    A comment moderation system like Ars Technica, so that low-content comments and commenters (like the above) can be suppressed.

    Teknobug is a PERFECT example of Ars' Troll Type #1: "Son of the "I don't even own a TV" guy: "

    This is the poster who thinks other people will find it interesting that he cares nothing about their discussion or their interests, and in fact judges himself as somehow morally superior as a result. The morphology of this on Ars Technica includes people popping into threads about Windows 8 to proclaim how they will never use Windows, people popping into threads about iOS 6 to proclaim that they never have and never will buy an Apple product, and people popping into Android related threads and claiming that they will never purchase "crappy plastic phones." In these cases, the posters have failed to understand that no one really cares what their personal disposition is on something, if they have nothing to add to the discussion.
  • ratte - Wednesday, October 17, 2012 - link

    yeah, my thoughts exactly.
  • worldbfree4me - Wednesday, October 17, 2012 - link

    I finished reading the review a few moments ago. Kudos again for a very thorough review, however I do a have a few questions and points that I would like to ask and make.

    Am I wrong to say, Great Job on Apple finally catching up to the Android Pack in terms of overall performance? The GS3, HTC X debuted about 6 months ago yes?

    Have these benchmark scores from the competing phones been updated to reflect the latest OS updates from GOOG such as OS 4.1.X aka Jelly Bean?

    Clearly the LG Optimus G is a preview of the Nexus 4,complete with a modern GPU In Adreno 320 and 2GB ram. I think based on history, the Nexus 4 will again serve as a foundation for all future Androids to follow. But again, good Job on Apple finally catching up to Android with the caveat being, iOS only has to push its performance to a 4inch screen akin to a 1080p LCD monitor verses a true gamers 1440p LCD Home PC setup. Ciao
  • Zinthar - Thursday, October 18, 2012 - link

    Caught up and passed, actually (if you were actually reading the review). As far as graphics are concerned, no smartphone has yet to eclipse the 4S's 543MP2 other than, of course, the iPhone 5.

    I have no idea what you're going on about with the Adreno 320, because that only gets graphics performance up to about the level of the PowerVR SGX 543MP2. Please see Anand's preview: http://www.anandtech.com/show/6112/qualcomms-quadc...
  • yottabit - Wednesday, October 17, 2012 - link

    Anand, as a Mech-E, I think somewhere the anodization facts in this article got very wonky

    I didn't have time to read thoroughly but I saw something about the anodized layer equaling half the material thickness? The idea of having half a millimeter anodized is way off the mark

    Typically there are two types of anodizing I use: regular, and "hard coat anodize" which is much more expensive

    If the iPhone is scuffing then it's definitely using regular anodizing, and the thickness of that layer is likely much less than .001" or one thousandth of an inch. More on the order of a ten-thousandth of an inch, actually. The thickness of traditional anodizing is so negligible that in fact most engineers don't even need to compensate for it when designing parts.

    Hard-coat anodize is a much more expensive process and can only result in a few darker colors, whereas normal anodizing has a pretty wide spectrum. Hard-coat thicknesses can be substantial, in the range of .001" to .003". This usually must be compensated for in the design process. Hard coat anodize results in a much flatter looking finish than typical anodize, and is also pretty much immune to scratches of any sort.

    Aluminum oxide is actually a ceramic which is harder than steel. So having a sufficient thickness of anodize can pretty much guarantee it won't be scratched under normal operating conditions. However it's much cheaper and allows more colors to do a "regular" anodize

    When I heard about scuffgate I immediately thought one solution would be to have a hardcoat anodize, but it would probably be cost prohibitive, and would alter the appearance significantly
  • guy007 - Wednesday, October 17, 2012 - link

    A little late to the party with the review, the iPhone 6 is almost out now...
  • jameskatt - Wednesday, October 17, 2012 - link

    Anand is pessimistic about Apple's ability to keep creating its own CPUs every year. But realize that the top two smartphone manufacturers (Apple and Samsung) are CRUSHING the competition. And BOTH create their own CPUs.

    Apple has ALWAYS created custom chips for its computers - except for a few years when Steve Jobs accidentally let their chip engineers go when they switched to Intel and Intel's motherboard designs.

    Apple SAVES a lot of money by designing its own chips because it doesn't have to pay the 3rd party profit on each chip.

    Apple PREVENTS Samsung from spying on its chip designs and giving the data to its own chip division to add to its own designs. This is a HUGE win given Samsung's copycat mentality.

    Apple can now always be a step ahead of the competition by designing its own chips. Realize that others will create copies of the ARM A15. But only Apple can greatly improve on the design. Apple, for example, greatly improved the memory subsystem on its own ARM chips. This is a huge weakness on otherARM chips. Apple can now custom design the power control as well - prolonging battery life even more. Etc. etc.
  • phillyry - Sunday, October 21, 2012 - link

    Good points re: copycat and profit margin savings.

    I've always been baffled by the fact that Apple outsources their part manufacturing to the competition. I know that Samsung is a huge OEM player but they are stealing Apple's ideas. They are doing a very good job of it and now improving on those ideas and techs, which is good for the consumer but still seems completely illogical to me from Apple's perspective. Must be the 20/20 hindsight kicking in again.

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