from
https://github.com/iceman1001/proxmark3/commit/
e1778858ddc53a6a82e8ee24f02e6b673687f69a
and http://www.proxmark.org/forum/viewtopic.php?pid=26733#p26733
sim mode should not have the reader field on.
 
        
        // Set up simulator mode, frequency divisor which will drive the FPGA
        // and analog mux selection.
-       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_READER_FIELD);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
        FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
        SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
        RELAY_OFF();
 
 // Set up simulator mode, frequency divisor which will drive the FPGA
 // and analog mux selection.
        FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
-       FpgaWriteConfWord(
-       FPGA_MAJOR_MODE_LF_EDGE_DETECT | FPGA_LF_EDGE_DETECT_READER_FIELD);
+       FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_EDGE_DETECT);
        FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
        SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
        RELAY_OFF();