Sub-GHz Radio Goes the Distance

　　隨著2.4 GHz ISM頻段變得更加擁擠，亞兆赫868兆赫頻段已經開始得到很多關注-提供更大的范圍和更少的干擾。同樣的論點，適用于868兆赫，甚至更引人注目，在一半的頻率。Silicon Labs ezr-ledk2w雙向鏈接的演示套件使得它在較低的頻段范圍的測試設計容易。

　　建立在Silicon Labs的ezradio?si4455收發器，該套件包含兩個電池供電的射頻收發器板（rfstick）和編程的toolstick底座適配器。該試劑盒有三個版本：434 MHz的運行ezr-ledk2w-434，868 MHz和915 MHz ezr-ledk2w-868，ezr-ledk2w-915。本文包括對434 MHz工具包的一次實際檢查，并進行范圍測試，以檢查不同距離的分組錯誤率。

　　Silicon Labs si4455 ezradio雙向鏈接的演示工具（參見圖1）包含兩個完整的收發器電路板印制的定向天線，編程板兩toolstick底座適配器，兩USB擴展器電纜，四節AAA電池。該板預編程的范圍測試演示，讓你很快看到多遠，你可以傳輸數據在亞GHz頻率相比，Wi - Fi的或藍牙在2.4千兆赫的銷售。使用該套件的434 GHz版本的差異-甚至允許內置的定向天線-是戲劇性的。

　　The transceiver boards are divided into two sections that can be easily split apart. Silicon Labs even encourages you to split them apart and use the transceiver module directly in your own designs. To do so， you need to remove a “zero-ohm resistor” that then bypasses the PCB antenna and routes the output of the PA to an F-connector for use with an external antenna.

　　The transceiver portion of the board is built around Silicon Labs’ “next-generation EZRadio” chip， the Si4455 （see Figure 2）。 The chip is a complete sub-GHz RF transceiver including a PA and SPI MCU interface. The Si4455 covers all the major sub-GHz bands from 283 to 960 MHz. In TX mode， the chip draws 18 mA from a 1.8 to 3.6 V supply at +10 dBm output （+13 dBm max）。 It can transmit using FSK， GFSK， and OOK modulation with a maximum data rate of 500 kbps.