how to implement sequence with timing relationship about an known delay time

[nevermind]

Hi:
my purpose is to monitor a signal behavior which is used for coverage.
there is a signal, let's call it A, low active, only a pulse. I need to monitor this scenario:
if delay time between two continuous A falling edge < 100ns, I need to trigger an event.

I use

cover property
@(posedge clk) $fell(A) |=> ##[1:10] $fell(A)
-> trigger_event;
actually signal A's behavior is async with clk, but I only know this definition with a clock, so i have to create a fake clk and adjust its period, that's not good for use.
it there any method for me to describe this kinds of protocol? how to define an implication sequence within a known time? like sys.any in e

Thanks.P

[dave_59]

You probably want a $period timing check.


logic notify;
specify
$period(negedge A, 100ns, notify);
endspecify