4 ms·

Is it illegal to use directional antennas in China? If not, do businesses just get a place with a view to Taipei and route all non-chinese IP requests that way?

walrus01 10y ago
that is way, way too far for any sort of reliable point to point microwave, even with a lot of elevation above MSL on both ends. also the chinese version of the FCC will come along with their partyvan. when you are dealing with a government where non-licensed non-compliant ISP type things will be shut down at OSI layer 1 by armed men with carbines, you have other problems.
- phantom784 10y ago
  Legality and party vans aside, the concept might work from Shenzhen to Hong Kong.
dredmorbius 10y ago
I'd suggest you run some calculations of mast heights and curvature-of-Earth for various LoS distances. Then consider possible alternatives.
z2 10y ago
Not sure if you were being serious, but along these lines, I stayed in a Shenzhen hotel late last year that strangely provided unfiltered internet. Of course it wasn't advertised as such, but Google worked (redirected to google.com.hk). Given the hotel was right on the border with Hong Kong, one could only speculate how this worked and which option was easier: always-on VPN or antenna :)
- paulsutter 10y ago
  My AT&T roaming in China was unfiltered too.
  - omginternets 10y ago
    How could you tell?
  - mistermumble 10y ago
    I was in Beijing two weeks ago, with 3 phones (AT&T, Sprint and T-Mobile). I could not get Gmail on any of them. No Facebook, Twitter, Google search, Google translate, etc. I had to fall back to Yahoo Mail (and WeChat and QQ). In Shenzhen, there was a moment in the hotel where Google worked for about 10 minutes. I was elated but then disappointed when that brief window of openness ended.
- xkcd-sucks 10y ago
  I've had consistent, unrestricted access to google/facebook/videos from 1989, all over China, using a tmobile sim card registered in another country. A financial services "startup" in sz manages to run a VPN with some sort of official permission. Not sure what sort of connections made this possible...
  - uola 10y ago
    Yes, roaming works. Preferably you use a HK sim. At least foreign companies can buy a connection to a foreign IX that doesn't go through the firewall. You can pickup HK 4G in SZ without roaming. International traffic from China sucks in general, not only because of the firewall. You can buy better international connectivity in some cases.
refurb 10y ago
Distance over the horizon can be estimated using d = 3.57 x (h)^1/2. Distance in km, height in meters. Width of the Taiwan Strait = 180 km (coast to coast) Height of antenna required for direct line of sight = 2,542 m or ~8,400 ft. This would be one antenna on a tower and one on the ground. Tallest antenna in the world is on top of the Burj Khalifa skyscraper at 2,722 ft. If you split the difference (so each antenna just sees the other at sea level), the tower would need to be 635m tall or 2,088 ft. So if you put a Burj Khalifa tower on each coast you could make it work.
- gruez 10y ago
  Or you can cross the relatively shorter distance between Shenzhen and hongkong
  - jasonjei 10y ago
    That's definitely much easier. Crossing Shenzhen to Hong Kong is literally getting off the Shenzhen subway, crossing a bridge, and entering Hong Kong immigration and MTR.

walrus01 10y ago

that is way, way too far for any sort of reliable point to point microwave, even with a lot of elevation above MSL on both ends. also the chinese version of the FCC will come along with their partyvan. when you are dealing with a government where non-licensed non-compliant ISP type things will be shut down at OSI layer 1 by armed men with carbines, you have other problems.

phantom784 10y ago
Legality and party vans aside, the concept might work from Shenzhen to Hong Kong.

dredmorbius 10y ago

I'd suggest you run some calculations of mast heights and curvature-of-Earth for various LoS distances. Then consider possible alternatives.

z2 10y ago

Not sure if you were being serious, but along these lines, I stayed in a Shenzhen hotel late last year that strangely provided unfiltered internet. Of course it wasn't advertised as such, but Google worked (redirected to google.com.hk). Given the hotel was right on the border with Hong Kong, one could only speculate how this worked and which option was easier: always-on VPN or antenna :)

paulsutter 10y ago
My AT&T roaming in China was unfiltered too.
- omginternets 10y ago
  How could you tell?
- mistermumble 10y ago
  I was in Beijing two weeks ago, with 3 phones (AT&T, Sprint and T-Mobile). I could not get Gmail on any of them. No Facebook, Twitter, Google search, Google translate, etc. I had to fall back to Yahoo Mail (and WeChat and QQ). In Shenzhen, there was a moment in the hotel where Google worked for about 10 minutes. I was elated but then disappointed when that brief window of openness ended.
xkcd-sucks 10y ago
I've had consistent, unrestricted access to google/facebook/videos from 1989, all over China, using a tmobile sim card registered in another country. A financial services "startup" in sz manages to run a VPN with some sort of official permission. Not sure what sort of connections made this possible...
- uola 10y ago
  Yes, roaming works. Preferably you use a HK sim. At least foreign companies can buy a connection to a foreign IX that doesn't go through the firewall. You can pickup HK 4G in SZ without roaming. International traffic from China sucks in general, not only because of the firewall. You can buy better international connectivity in some cases.

refurb 10y ago

Distance over the horizon can be estimated using d = 3.57 x (h)^1/2. Distance in km, height in meters. Width of the Taiwan Strait = 180 km (coast to coast) Height of antenna required for direct line of sight = 2,542 m or ~8,400 ft. This would be one antenna on a tower and one on the ground. Tallest antenna in the world is on top of the Burj Khalifa skyscraper at 2,722 ft. If you split the difference (so each antenna just sees the other at sea level), the tower would need to be 635m tall or 2,088 ft. So if you put a Burj Khalifa tower on each coast you could make it work.

gruez 10y ago
Or you can cross the relatively shorter distance between Shenzhen and hongkong
- jasonjei 10y ago
  That's definitely much easier. Crossing Shenzhen to Hong Kong is literally getting off the Shenzhen subway, crossing a bridge, and entering Hong Kong immigration and MTR.