Any detail spec about the built in GPS and GLONASS chipset in iPad Air

Hello,

I'm current investigating some external GPS solutions with better than normal accuracy for iPad working under both offline and online condition. As from iPad mini, iPad Air it already supports AGPS and GLONASS, now I'm wondering if it's still necessary to get an external GPS receiver. It would be very helpful if more detail about the actual GPS and GLONASS chipset used in iPad in order to compare apple to apple. For example, how would the chipset in iPad Air compare to one of the external GPS receiver on the market with the following spec? Thanks

<Bad Elf>

• 2.5m (9 ft) positional accuracy with MTK chipset
• 66 channel GPS & GLONASS Receiver
• WAAS compatible, SBAS/EGNOS/MSAS support
• Up to 10MHz sample rate

regards,

Jack