Complex sentence: There are no marker symbols as in the amplitude modulated time code; in the phase modulated time code, minute framing is provided by a fixed pattern of data bits, transmitted in the last second of each minute and the first 13 seconds of the next one.
Split into simpler sentences: There are no marker symbols as in the amplitude modulated time code. In the phase modulated time code, minute framing is provided by a series of data bits of known values, transmitted in the last second of each minute and the first 13 seconds of the next one.