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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A5 - Tuesday, October 16, 2012 - link
I don't think there's a good way to measure storage performance on the iPhone. Also not really sure why it matters.repoman27 - Tuesday, October 16, 2012 - link
I timed how long it took to transfer my music library, and clocked 11.1 MB/s writing to the user area of a 64GB model. So no significant change from previous iPhones, and still pretty typical for a smartphone. I'd be interested to get some gauge of the read speeds.And @A5, storage performance affects boot and application load times as well as sync and backup. With a 64GB model, syncing can take quite a while.
name99 - Wednesday, October 17, 2012 - link
Transferring the music library is a LOUSY choice for speed measurement because (depending on your iTunes settings) you may be transcoding all your music to a lower bit rate to fit more on the iPhone; so you are gated by the transcoding performance, not the flash write speeds. I transcode my music (most in Apple lossless on my iMac) to 192kbps AAC for my iDevices, and on my ancient iMac it is the transcoding that throttles performance.A much better situation to look at is transferring large movies. On my devices
- iPhone 4 writes at about 18MB/s
- iPad3 writes at about 22MB/s
Over the last 6 months Anand occasionally has published flash numbers for Android phones and they're generally around half these Apple numbers.
repoman27 - Wednesday, October 17, 2012 - link
Believe you me, I don't allow iTunes to transcode anything, except to ALAC on occasion. But yes, that number I gave was on the low side, but probably more due to it being thousands of files as opposed to one large sequential write.I just transferred a large video file back and forth directly to and from the user storage area of one of my apps, and came up with numbers that are more in line with yours. 23.84 MB/s avg read and 20.05 avg write.
Most MLC NAND modules capable of 20 MB/s writes should be able to do at least 40 MB/s on sequential reads, which leads me to believe that we're still gated to around 25 MB/s by the NAND interface here, which is kinda bogus.
Spunjji - Friday, October 19, 2012 - link
name99, that is not a "better situation" because the performance figures you quote only apply to large block file transfers. It's no more real-world than the figures repoman quoted, which are not "LOUSY". Both are valid, so ideally a proper test should mix both types of data.Furthermore, the idea that your admittedly ancient iMac being crap at transcoding MP3s somehow invalidates somebody else's testing is ridiculous as well. With any decent system that would only be the case if you were shifting data to a device a *lot* faster than any smartphone NAND.
So, you may need to rethink your "victory" a little more.
KPOM - Wednesday, October 17, 2012 - link
I've had my iPhone since 9/22 and there is not a single scuff on it. My guess is that in the rush, some units got through QC, but the phone itself isn't any more prone to scratching in normal use than other phones. Meanwhile, Apple being Apple, they have held up production to improve QC even if it means fewer sales in the short run.rarson - Wednesday, October 17, 2012 - link
You've had it less than a month. There shouldn't be any scuffs on it."Apple being Apple"
Ha! That's a good one!
Spunjji - Friday, October 19, 2012 - link
Trololololol"Mine is fine so everyone else is lying". <- Possibly my favourite bogus argument ever. Apple the generous indeed...
doobydoo - Saturday, October 20, 2012 - link
Because it's so much more compelling than the 'Mine is scratched so everyone elses must be'?lukarak - Wednesday, October 17, 2012 - link
But it doesn't rust. It scratches if it comes in contact with something harder. Just as a car does. Would you buy a car that gets a scratched bumper when you hit a wall? Well, maybe you wouldn't but people do. Regularly.This iPhone is no different than every other iPad, MBP or MBA or the first Al MB. Or any other device constructed from aluminium. They scratch if they are brushed against something. It's just normal.