foreach my $time ( sort {$a <=> $b} keys %{$Signal_ref})
{
   print"my signal: $Signal_ref->{$time} at t = $time \n";  # first test
 	
   if (defined $Signal_ref->{$time})
   {
     my $SigValue{$time} = $Signal_ref->{$time}{'signal_1'};
     print"my values: $SigValue{$time} \n";
   }

}