Re: New J-10 Thread III
Why do phone tend to work better when brought into China? I can only speculate the following reasons:
1. The towers transmit more power.
That would only increase interference against each other without taking account of distance.
As a matter of fact, because of higher density of towers in a Chinese city as well as a higher density of handsets, which can place handsets closer to the tower, transmit power should be weaker to reduce noise and interference and lesser distance reduces the need for a higher transmit power. The closer, less power, the farther, more power.
2. Each andset's wireless chip has the potential to transmit more power, but they are limited by law outside China to transmit as much.
Wrong. Transmit power is part of the protocol. Screw with the amplitude and you screw the entire thing. GSM handsets make 1-2 watts when they transmit depending on distance, and its the same through out the world given any of the four GSM bands (1900 should require more power than 850/900). EV-DO, which also exist in China, transmit only at 0.6 watts, and that's true wherever they are. Handsets continually adjust their power depending on their range with the station.
Take for example the 500mW tx power (yes it's tx power, not input power) wifi dongle. The atheros chipset used on the dongle is limited by the device driver to how much power it can transmit depending on which country the device is in. This is documented by many people who write device drivers for those chips. There are not-so-legal ways to get around it though.
Seems to me that this sounds like maximum transmit power specified by the chip. It says nothing about transmit power regulations in China.
Increasing tx power does make interference more severe, but keep in mind they are "designed" to transmit at that high of a level by the chip designers. Therefore they would need to be tested in different power levels before the wireless chip becomes a final product. I am not talking about out-of-spec increase in tx power. The higher numbers are still within the spec of the chips and therefore should work better than lower tx power.
Not without knowing the actual regulations in China.
And no. The higher power is there to cover all bases globally and for every potential use of the chip.
There are proper and desired power transmit settings which differ with distance. The closer the two radios are, the weaker the combined transmit power to deal with the noise and interferance issue. As the two radios become farther in distance, the greater the combined transmit power between the two radios, but the degree of attenuation of the transmission power as distance increase, means the actual power drops to the same level as they are with a closer distance. This maintains the overall combined transmit power of the network at the same level.
Given the same distance, the WLAN's total combined transmit power should not be any different in the US or China. Having greater transmit power in the router or dongle only means the devices will have greater potential range, and that extended power is only used when the longer range option is used.
You have not specified what kind of Alteros chipset, or whether the dongle operates at 802.11a/g or -h, what frequency (2.4ghz or 5) and what channels. In the US, certain channels at 5 GHz, are limited to 40mw, in other channels up to 200mw. 5GHz needs more transmit power than 2.4GHz.
As to the electronic parts used for their space program. Again, I'd be surprised to see if they use anything newer than the mil-1553B bus standard. When I say they haven't got the parts reliability down, I was talking about the "cutting edge" commercial implementations. Not the 70s technology that's still used for manned space.
Mil 1553B is a serial bus standard. That's like a serial port. That has nothing to do with the main bus architecture of the components and its not necessary at all or used with civilian technologies. You're referring to a standard that lets say, allows a common interface to a missile to the fire control system.
70's technology? You got to be joking. Transmitters used in space has to be made of Gallium Arsenide or generally means they use AESA or GaAs MMICs. GaAs is cosmic ray hardened. That last moon probe of theirs managed to SAR mapped the entire moon in strict detial, including a degree of penetration of the moon's surface to account for different surface densities and hardness (for potential landing sites).
As for the airplanes, do you think the datalink carried on the new J-10B's vertical tail has a heater of its own? It gets pretty cold up there. These parts do need to qualify to run at -55C to 125C temp. range reliably. I doubt any of that 3/4G technology can be easily qualified.
The datalink is carried on the plane's spine, not the tail.
And sorry, 3/4G equipment does require that they have to withstand a wide range of temperatures because they are after all installed in a very wide variety of environments.
As for China's "cutting edge" applications, these systems, by ZTE and Huawei, goes often to countries that has more severe weather and climate conditions, in the Third World, in the Middle East, Africa, South America even to cold countries like Norway.
At one point, ZTE was installing 40% of the CDMA/EVDO of the world's contracts to that protocol. Huawei isn't the 4th/5th largest telecom company now (over 23 billion on sales) just doing contracts in China. It is already a company that is doing global contracts from Canada to Australia.
