ION presentation - "Session A5b: Applications of Multi-GNSS Measurements from Smartphones"

[Sean Barbeau]

Hi all,

Just wanted to share this as it's relevant to recent discussions about what smartphones are capable of RE: RTK:

https://www.ion.org/ptti/abstracts.cfm?paperID=13055

"The recent development of Global Navigation Satellite System (GNSS) chipsets, makes cm-level real-time kinematic (RTK) positioning possible with Android-based smartphones. In this contribution we investigate the single-baseline RTK performance when using a baseline consisting of two smartphones, i.e. no geodetic base station infrastructure is necessary. We will evaluate the performance of some of the recent smartphone models, including Google Pixel5, Pixel6 Pro, Pixel7 Pro, and Samsung Galaxy S22, respectively. The assessments are conducted in Mountain View, California (USA), and some of the smartphones can track dual-frequency code division multiple access (CDMA) signals of L1 + L5 Global Positioning System (GPS), E1 + E5a Galileo, L1 + L5 Quasi-Zenith Satellite System (QZSS) and B1 + B2 BeiDou Navigation Satellite System (BDS) code and carrier-phase observations. We will demonstrate that one can now achieve cm-level positioning and near hundred percent RTK integer least-squares success rates for some of the smartphone models, while stationary, even with the use of the internal smartphone antennas. This will be shown true for both the ’single-epoch’ model whereby all the estimated parameters are unlinked in time, as well as for the ’multi-epoch’ model where the ambiguities are treated as time-constant parameters through a dynamic model in a Kalman filter."

I'm not sure if there is a paper/presentation available.

Sean

[Jim bell]

Aha!  Just as I suspected!  This talk of 'bad antennas' has come to...THIS!!!!

I can say this with some level of expertise, I have been a ham since 1986, and not only that, extensively familiar with electronics in radio and the use of antennas. 

But those antennas were not so bad, after all!   Sure, they're not ideal!  But  semiconductor and RF (radio-frequency) technologies have gotten really, really good in the last 35 years, since Magellan came out with their SINGLE RECEIVER GPS devices.  Back when receiving four satellites was a challenge.  

As RF devices, there were some exotic materials like gallium arsenide even back around 1990. But RF technology has dramatically improved over time.  

In the past, I have pointed it out that smartphones could be checked for potential performance by first using a good antenna, amplifying the signal, and then exposing the smartphone to that signal, varying it. I believe that this would essentially eliminate the arguable bad and antenna problem at least for purposes of analyzing the potential performance.

I get 34 (or more?) satellites USED with my dual-frequency-capable OnePlus Nord2 5g and a mostly-open sky.   And an estimated accuracy of "1.2 meters" as calculated by GPSTest.    

Radio communication, and especially digital communication, has been described as a cliff: if the signal goes somewhat away, you can "fall off the cliff". 

 But if you are far away from that cliff, things can look much better.  I think that industry simply did not try to push smartphone technology where it would lead us.

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