pulse code modulation

[slavica]

where do I find information about long frame and short frame synchronization for PCM? I need to know when to use which.

[Will.Spencer]

First, some background for other readers of this thread. Long Frame Syncronization and Short Frame Syncronization are two options for the clocking format used in Pulse Code Modulation (PCM).

In Long Frame Syncronization, the rising edge of the SYNC signal indicates the start of the PCM word; In Short Frame Syncronization the falling edge of the SYNC signal indicates the start of the PCM word.

In Short Frame Syncronization, the SYNC signal is always one clock cycle long. In Long Frame Syncronization, the SYNC signal must be at least two clock cycles.

Why use Short Frame Syncronization? It's faster and more efficient.

Why use Long Frame Syncronization? I do not know for certain, but I believe that it may be more reliable.

But in reality, the clocking mechanism you choose is most often dictated by the devices you are attempting to communicate with.

[Will.Spencer]

I showed this thread to a very sharp EE that I know and he recommended this document: Using ADSP-BF561 Blackfin® Processor Flag Pins to Emulate the PCM Interface.

[slavica]

Thank you very much for answering. That was very helpfull!