Just saw an earlier post regarding GPS and other systems. I would like to share what I knew/heard about that topic. Seriously, nothing fancy or deep, just some common sense.

GPS was considered high tech in the 70\'s. One can imagine what it becomes now, right, another commodity. The concept was smart, and it was unique - using different satellites to determine the position of certain object. As many know, you need at least 4 satellites to track an accurate 3-dimension position of an object at any given moment, and you need 24 satellites to cover globally. Given complicated surface, ie forest or high building etc, the more satellites the better. The implementation of GPS isn\'t fancy either, shooting satellite up and keeping it in control is the most difficult part. Of course, it requires huge amount of money and resources to build such system. No wonder US was the fist one implemented it, and UdSSR was the second to follow suit and come up with their own branded counterpart - Glonass.

In the early 90\'s, both GPS and Glonass were fully implemented and in full service mode, not just for military but also civil application. US has decided to insert artificial error into GPS signals served for civil application. With the capability of serving accurate position info as close as within 1 meter, location info provided to civilians with that artificial bandage comes with error of 100 meter. At that time, Russia stepped up by offering service from Glonass, and promised that they would never add artificial error to end users.

There were lots of discussion in Europe at that time, many preferred Glonass over GPS, for a. it\'s closer b. no artificial error, although there were very few manufacturers providing receivers for Glonass system. Lots of manufacturers saw the opportunity, and started to produce receivers to receive/handle both signals, and claim to make best out of both worlds. I did a very small Studienarbeit (study paper) about it. It wasn\'t a thesis, just a copy/paste/translation simple paper, for the sake of writing a paper, which no one wants to read about, including myself:)

I believe it was around 2000, US decided to dump that artificial error crap. Overnight, Glonass was knocked out of the market. Of course, Russia military is still using that. It was a smart move by US, because when it comes to war time, they can still add back that artificial error/noise back to it, selectively, to prevent unfriendly countries taking advantage of it.

Most of the countries, at the time, were either friends of US or Russia. Those sorry countries didn\'t have the luxury to worry about whose satellite signal to use. China didn\'t have any friend, and it cannot trust US nor Russia. China did the right thing, to implement its own system - 北斗。

It was a wise move of China to start on a smaller scale - covering own territory and neighboring areas. That\'s a very good example of starting a mission with a well-studied strategy and clear goal, long term plan, and streamlined and organized execution. There is no shame of using matured technology, and it should be recommended as a matter of fact. However, it\'s shameless to claim existing mature technique as own ground-breaking new invention.

GPS/Glonass and later on, with European\'s own Galileo system, due to their wide coverage, it\'s safer/cheaper and more reliable to have all the satellites moving in one direction. Bi-directional implementation of 北斗 was a smart implementation, given limited coverage, because China wants those designated areas are at least covered all the time.

As matured technology, there is no need to further develop GPS or Glonass, as a system. 北斗 has a lot catch-up to do, not technology-wise, but just implementation to cover globally. To claim GPS has no room to grow, but 北斗 has brighter future, is like claiming that China\'s LCD TV manufacturers have a lot more room to grow than those counter parties in Japan, Korea, and Europe, it\'s laughable. Duh, they are moving towards more advanced technology, while the old one becomes commodity.

I like this forum for various reasons. That fondness makes it hard for me to just ignore utter-nonsense and bunch of bull crap spewed into the board. There are great things happening in China, but over-exaggerating achievements and even lying about improvement to an extend, that it totally blows things out of proportion, is doing a disservice of promoting China and its development.