The main oscillator in the TG700 is 27MHz. This clock is used for all standard definition signal generation, and is always available. The secondary clock is synthesized from the 27 MHz oscillator, and is either 74.25 MHz or 74.175824 MHz. The 74.25 MHZ clock is used for all HDTV signal and tri-level sync generation in formats with an integer frame rate, such as 24, 30, 50, and 60 Hz. The 74.175824 MHz clock is used for the non-integer frame rates, such as 23.98, 29.97, 59.94 Hz. Only one of these clocks can be active at any given time.