In a separate question on Travel.SE I asked why my phone's GPS didn't seem to work in Beijing, China. Turns out that it was simply an "urban canyon" problem, and that the GPS did in fact work when I moved to higher and/or more open areas. What I'm wondering, is why is my phone capable of receiving GPS satellite signal in New York City, a much more dense city than Beijing especially in terms of skyscraper density downtown, but not so in Beijing? It seems if anything that it should be the other way around, or that I shouldn't be able to receive signal in either city.
Please note: I am not asking about location services on the phone, which can be influenced by things such as nearby WiFi networks and certain service carriers. I am specifically asking about GPS satellite reception coverage.
Clarification:
Outside of downtown Beijing my phone is able to receive GPS signal just fine. This question is not an issue of the GPS receiver on my phone altering the signal or any type of Chinese law. I know that the GPS receiver works perfectly. I'm simply confused as to why downtown Beijing has particular problems compared to a denser city such as downtown NYC.
Best Answer
There are a variety of reasons why your phone is giving imprecise coordinates when in china, and we can't straight away blame multi-path errors in the Urban canopy for those errors.
I feel that you should also know the following before jumping to conclusions.
1) Firstly, As a foreigner, it is illegal to use a GPS device in China
2) Many manufacturers introduce a deliberate error in the GPS location when in china.
3) It is known that Companies like Apple have a predictable error in the GPS location recorded in China.
I feel that it is reasonable to assume that the error that you see, has a far greater chance of being a result of China's Laws, rather than any technical issue.
Further reading: