1 GHz無線智能電表接口的設計

　　智能電表是創建智能家居的核心。能夠衡量家庭的總體電力使用情況并將數據反饋給公用事業是管理公用電網負荷并最終減少用戶賬單的關鍵因素。

　　增加無線連接到電表是相對簡單的最新的射頻模塊。這些提供了所有在特定地理區域認證的rf連接。然而，這些模塊需要連接到儀表上直接獲取數據，或者連接到電流消耗的傳感器。這可以用低成本的8位微控制器相對容易地完成。

　　使用不受管制的子1 GHz頻段具有智能儀表設計的許多優點。較低的頻率進行較低的數據傳輸速率更長的距離，給系統設計者顯著的優勢。智能電表只需要每天發送少量數據，因此數據速率很低。這允許使用更長的距離，與諸如ZigBee這樣的協議在2.4 GHz時可以攜帶更多數據是非常不同的。使用子1 GHz頻帶也避免了來自2.4 GHz源的潛在干擾，例如Wi-Fi、藍牙和微波爐，這進一步降低了建立可靠無線鏈路所需的功率。

　　The latest RF chips from Texas Instruments have been demonstrated to carry low rates of data （a few kbyte/s） over distances of up to 10 km at these lower frequencies. This has two advantages： more devices can be connected to a single hub or concentrator， or the power consumption of the RF transceiver can be reduced dramatically. This allows the system architect to optimize the balance of power consumption and reach. For example， several streets of houses could be connected via a sub-1 GHz link to a concentrator in the street， avoiding the need for broadband hubs in every home.

　　Modules support different wireless network topologies such as point-to-point， point-to-multipoint， peer-to-peer， and mesh networks depending on the system architecture. Mesh networks allow neighboring units to link together and carry data， greatly extending the reach. This hits the data rate， but for a smart meter network， the reach is far more important to saving costs than the data rate and there is plenty of headroom to support mesh networking.