samples per symbol this sample clock is coupled to the adc 30 when a new channel is tuned symbol synchronization must be acquired this process will be described in more detail below once acquired symbol synchronization must then be maintained or tracked the hdtv television signal is transmitted as successive frames each frame containing two fields each field containing 313 segments each segment containing 832 symbols each field begins with a field synchronization segment and each segment including the field synchronization segments begins with a four symbol synchronization sequence all of which have the same fixed value network 60 detects the repetitive sync components at the start of each segment in the received data segment synchronization signals are supplied not shown to simplify the figure to other processing blocks the time locations of the segment synchronization signals are also detected and used to maintain a properly phased 21 52 mhz sample clock which is used to control the data stream symbol sampling by the adc 30 all in a known manner once circuit 60 acquires a lock on the channel so that the receiver clock is synchronized with the transmitter clock the vsb receiver is tuned to the appropriate channel and can function in an appropriate manner the output of the digital demodulator and carrier recovery circuit 40 is applied to.