property p_NOP_2_RX_CAL;
  @(posedge clk)
  (cal_frame_mode==3'b001) |-> ##2 $past(cal_frame_mode)==3'b000;
endproperty

assert_nop2cal : assert property(p_NOP_2_RX_CAL);

(cal_frame_mode==3'b001) |-> ##2 $past(cal_frame_mode)==3'b000;

(cal_frame_mode==3'b001) |-> ##1 cal_frame_mode==3'b000;

$changed(cal_frame_mode) && (cal_frame_mode==3'b001) |-> $past(cal_frame_mode)==3'b000;