Rohde schwarz hm8123 3593 0545k02 digital frequency counter rohde schwarz 3593 0545k02 p the rohde amp schwarz hm8123 3593 0545k02 is a digital frequency counter which features three high sensitivity inputs and allows the measurement of signals in the frequency range between dc and 3ghz p p the hm8123 is ideally suited for test installations in production and automated tests in laboratories it supports both rs 232 and usb or an optional gpib ieee 488 interface and can be easily