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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  • medi01 - Wednesday, October 17, 2012 - link

    Try to do it in a darker environment.
    If you still don't notice that AMOLED black is actually, cough, black and "iphone"'s black is actually gray, you probably should visit a doctor.
    Reply
  • darwiniandude - Friday, October 19, 2012 - link

    Who cares about black being 100% black when all the colour accuracy is terrible? The galaxy note looks like is has cellophane over the screen next to an iPhone, the white doesn't look white. You take a photo of a hill side and all the trees and grass is the same over saturated shade of green. It's because of this that I'd only consider the HTC one X excuse it has an accurate LCD. I've personally never found an Amoled screen so far I can put up with. Each to their own, if black is more important to you than the rest of the spectrum, then enjoy it. Reply
  • bpear96 - Thursday, October 18, 2012 - link

    Well obiously, there PPI's are almost the same, because of the size difference.
    If you had a 4.8" 1136 x 640 display, next to a 4" 1136 x 640 the 4.8" would not look nearly as good as the 4" because it would have a lower PPI (pixels per inch) since the GS3 is larger it needs a higher res display to be on par with the 4" iphone 5 display.
    Reply
  • bpear96 - Thursday, October 18, 2012 - link

    type - obviously * Reply
  • star-affinity - Tuesday, October 23, 2012 - link

    The difference (in my opinion) being that the Galaxy S III has over saturated colors which is quite bad.

    http://www.displaymate.com/Smartphone_ShootOut_2.h...
    Reply
  • GabeA - Saturday, January 05, 2013 - link

    Sorry, you're comparing a poor screen technology (PenTile subpel matrix) with a top-of-the-line LCD. The comparison is flawed because the effective resolution on text is only ~82% in either direction (something like 1050 x 590 on sharp, black text) due to the interpolated, non-RGB subpixels.

    A good comparison would absolutely involve the One X series by HTC. In fact, holding the SGS3 and the One X side by side on this page shows an obvious difference in text clarity in favor of the One X.
    Reply
  • rocketbuddha - Tuesday, October 16, 2012 - link

    Don't you know that every iPhone comes with the halo of the RDF (Reality Distortion Field) :D

    Thus things that other things have been having for months/years in other models appear antiquated/vanish once iPhone comes near ;-)
    Reply
  • doobydoo - Friday, October 19, 2012 - link

    So having the fastest hardware in any smartphone ever, the iPhone 5 was late to the party?

    Or was it the fact that it's the thinnest that you're claiming they copied from Android. Or lightest, or thinnest, or shortest, or battery life.

    I wonder when any Android phone (bar the Razr Maxx which lets face it is a brick) will catch up?
    Reply
  • A5 - Tuesday, October 16, 2012 - link

    So you want a Droid Razr HD Maxx, then? Reply
  • webmastir - Tuesday, October 16, 2012 - link

    Yep. That should be the #1 choice at the moment. Reply

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