fix: (issue #72) LF simulation didn't work with lo_edge_detect.v

fpga/lo_edge_detect.v

@@ -36,9 +36,11 @@ wire reader_modulation = !ssp_dout & lf_field & pck_divclk;
 
 // No logic, straight through.
 assign pwr_oe1 = 1'b0; 						// not used in LF mode 
+assign pwr_oe3 = 1'b0; 						// base antenna load = 33 Ohms
+// when modulating, add another 33 Ohms and 10k Ohms in parallel:
 assign pwr_oe2 = tag_modulation;
-assign pwr_oe3 = tag_modulation;
 assign pwr_oe4 = tag_modulation; 
+
 assign ssp_clk = cross_lo;
 assign pwr_lo = reader_modulation;
 assign pwr_hi = 1'b0;