How does a device receiving data tell when data transmission stops?

设备接收数据如何告诉当数据传输停止吗？

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Using a directional antenna, the device shoots data to a receiving antenna as far as 60 miles away.

利用定向天线，这种设备发射数据到远在60英里外的接收天线。

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With a tap or a wave, the cards wirelessly beam data to a receiving device on the shopkeeper's counter.

通过拍卡或者将卡挥动一下，可以用无线的方式将（付款金额）数据从卡传输到店铺柜台的接受器上。

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On the iPhone, the receiving device displays the transferred files right within the Xsync app.

WSJ: Easier File Sharing With Phones In Black and White

You don't have to crash phones together though, as all that's required is for the receiving device to accept the transfer.

ENGADGET: Hands-on with the Asha 205 and Nokia's Slam quick-sharing feature (video)

One such project is called NewsFlash, and uses high-frequency red and green light to transmit data to the built-in camera on a receiving device -- in this case Samsung's Epic 4G.

ENGADGET: NewsFlash uses high-frequency light to transmit data from iPad to smartphone, we go hands-on (video)