CHAPTER 3: INSTALLATION WIRINGB30 BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL 3-353Ensure that the dust covers are installed when the fiber is not in use. Dirty or scratched connectors can lead to high losseson a fiber link.3.3.10 IRIG-BThere is a round IRIG-B connector at the back of the CPU module, marked "IN". Use is optional.IRIG-B is a standard time code format that allows stamping of events to be synchronized among connected devices. TheIRIG-B code allows time accuracies of up to 100 ns. The GE MultiSync 100 1588 GPS Clock as well as third-party equipmentare available for generating the IRIG-B signal. This equipment can use a global positioning system (GPS) satellite system toobtain the time reference so that devices at different geographic locations can be synchronized. The IRIG time codeformats are serial, pulse width-modulated codes that can be either DC level shifted or amplitude modulated (AM). UsingIRIG-B input, the B30 operates an internal oscillator with 1 μs resolution and accuracy.Figure 3-33: Options for IRIG-B connectionUsing an amplitude-modulated receiver causes errors up to 1 ms in event time stamping.
