Clock Synchronization Problem

After testing the whole circuit and it is working as expected by using the same clock for both transmitter and receiver. But the biggest problem is that when I separate the two pieces apart and using different separate clock the problem occurred because the two clocks were not in sync both transmitter and receiver. But the system still transmitting and receiving data perfectly fine, when they are in sync I can hear the music when they are not I've got this jitter noise. Found out that the problem was the frame clock since the frame clock trigger the PCM transmitter and receiver. Therefore, the frame clock must be absolutely in sync. Since the PCM receiver need to know when the information is being sent and this can be achieve by using structure called frame. The beginning of the frame consists of repeated copies of a special bit pattern called a frame marker. So the frame markers are repeated several times to allow time for bit synchronization to be achieved before the arrival of the information bits. And then the frame markers are followed by a stare of message marker which is another special bit pattern, to mark the start of the information bits. Therefore, in order to solve this problem I need to do a lot research on how to recovery the frame clock from the transmitter so both transmitter and receiver clock are in sync.

Combining all Circuit and Testing

At this state all individual circuit were working and now it's time to connect them all together and testing them out. When connect all the circuit it is necessary to pay extra attention because if some connection between the pin or chips are not properly grounded will have a problem during operation. Based on my experience it is better to do it step by step and follow the schematic. And also check all connection as it goes. When it's all being connected then used since wave to check each chip's input and output so we know it is behaved as expected. When all the chip working as expected then we can use mp3 music player to send a music into the ADC, for this project we used iphone to play music then feed it into PCM encoder and then the output of the encoder will output digital data which then send into LED driver to transmit through fiber cable. And at the other end the receiver photodiode will receive the data been transmitted and then send it to PCM decoder and it will convert it back to analog signal. And then to play the music I'm going to use my computer to play back so the analog output of the PCM decoder will connect to audio interface and then the interface will connect to my computer and output the music. During this process I've encountered lot of problem such as wrong connection of the clock, LED driver (wrong calculation of resistor), lot of noise from LED transmitter and photodiode receiver and so on. The worse thing is identify the problem when the problem is identified then it can be easily solve but sometime a little bit difficult.