DCF-77 standard is a time code format consisting of 1 pulse sent per second with the pulse’s leading-edge aligned on the second. The DCF-77 output will consist of 100ms and 200ms pulses where the pulse length of 100ms denotes a binary "0" and a length of 200ms denotes binary "1".
If you are seeing alternative pulse durations please ensure that the port is not configured for a user-defined pulse in the configuration tool.