ABS wheel speed sensor - measuring vehicle speed

Hey guys,

Instead of trying a hardware configuration, i just bought a coax cable so normally there is no more noise on my signal. However, when i use interrupts (see code above, anyone who notices any mistakes please let me know!) i still don't get a correct pulsecounter. Sometimes it counts a couple of pulses (most i had was 8, but it should be a lot more), most of the time it doesn't respond at all. Does anyone have any suggestions?

Appreciate it!