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--- guides:chipcon_cc1020_software_define_radio [2010/12/30 19:34] – [Using with AFC] laurenceb
+++ guides:chipcon_cc1020_software_define_radio [2010/12/30 19:43] (current) – active ant laurenceb
@@ Line 19: / Line 19: @@
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+===== Active antenna support =====
+ An "active antenna" with built in low noise amplifier can be used with 3.3v supply down the coax through an RF choke and decoupling capacitors. If a pull up resistor is put between portc pin 2 and 3.3v, sufficient to give around 2 volts on the pin with the pin floating, then the presence of the amplifier can be detected (and closed or open circuit ruled out). Power will then be applied at bootup. Note that avr pins cannot supply more than 20ma. The led on port c pin 0 will flash twice at bootup to indicate a detected amplifier (one 100ms flash and a short 33ms flash as opposed to the normal single 100ms flash).
 ===== Usage instructions =====