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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  • grkhetan - Wednesday, October 17, 2012 - link

    Multiple display reviews conclude that the iPhone 5 has the best display in a smartphone (And much better than a Samsung Galaxy S 3)

    http://www.displaymate.com/Smartphone_ShootOut_2.h...

    http://www.anandtech.com/show/6334/iphone-5-screen...
    Reply
  • rarson - Thursday, October 18, 2012 - link

    Your second link doesn't compare it to anything but the iPhone 4. Your first link ONLY compares it to the S3. Neither link supports your statement ("best display in a smartphone"). Reply
  • doobydoo - Friday, October 19, 2012 - link

    A quote from his second link:

    'To put this in perspective, in the past few years I've reviewed probably 30-40 different displays, from PC monitors to TVs to projectors. Not a single one, out of the box, can put up the Gretag Macbeth dE numbers that the iPhone can, and perhaps one projector (which listed for $20,000) can approach the grayscale and color accuracy out of the box.'
    Reply
  • steven75 - Wednesday, October 17, 2012 - link

    Those pesky facts are annoying! Reply
  • Obsoleet - Tuesday, October 16, 2012 - link

    No, it's not. There's many reasons the GS3 is the better choice based on the software and hardware, mainly that the MaxxHD only matches a 5 month old phone in hardware specs and tosses on a bigger battery as the only clear win (but you get stuck with a Motorola phone vs most people's preferred choice Samsung).
    But the killer reason is that the charger is on the left hand side.

    For many of us lefties, that is a deal breaker. As a right handed user, you don't realize this. I want the ports on the top or bottom, and I just ordered a GS3 because of this being a tipping point.

    The original Maxx had the ports on the top! Motorola is clueless.
    Never again.
    Reply
  • Ckaka1993 - Thursday, December 06, 2012 - link

    Ppi does make a difference. Go see the videos of droid dna(has 440) ppi and you can make out the difference. iPhone 5 doesnt have true 720p but that doesn't matter cause it's quite close to 720p. Anyways iphone5 is behind so many smartphones at present. Nokia lumia 920 is a treat to watch with its 332 ppi pure motion hd+ display and high refresh rate, u can make out the difference. But nexus 4 is the smartphone which gives u the best worth for money at ony 350usd it is freaking awesome Reply
  • makken - Tuesday, October 16, 2012 - link

    The Physical Comparison table lists the iPhone 5's resolution at 1136 x 960, instead of 1136 x 640. Threw me off for a second there =P Reply
  • Brian Klug - Tuesday, October 16, 2012 - link

    Oops, fixing. There's always something in the table that needs fixing it seems :P

    -Brian
    Reply
  • DukeN - Tuesday, October 16, 2012 - link

    And always favorably on the Apple side.

    Maybe you took a picture of the pixel count with the iPhone's camera...
    Reply
  • Alucard291 - Tuesday, October 16, 2012 - link

    I know I love how their own benchmarks show how the battery life is worse in just about everything than the 4s and yet and yet "its better" >.> Reply

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