Data encoding techniques used in Altera FPGAs

[Altera_Forum]

Hi all, 

I am looking for the information regarding the encoding techniques used in Altera. More specifically, I do not how the signals are encoded before being sent out over the media (like SMA cables). If the encoding techniques are NRZ, RZ, Manchester,...If anyone knows the related materials about this, please share with me. And I also do not know whether the techniques are different for different devices. I am using Stratix IV GT.  Thanks a lot.

[Altera_Forum]

You can write your own core, so you can encode any data however you want.

[Altera_Forum]

--- Quote Start ---  You can write your own core, so you can encode any data however you want.  --- Quote End ---    Thanks for your comment. Actually, my purpose when posting this thread is like this. I have a design running in FPGA (stratix IV GT) that sends data to a transceiver SMA connector on the development board. I connect the cable from this connector to an Oscilloscope to observe the output signal. If I choose to send a known bit sequence, what do I expect to see in the scope? This leads me to believe that the signal observed on scope depends on what data encoding technique used to encode the data (bit sequence).  And I am not sure, but think that this is done by physical layer protocol (PMD sublayer). In my case, I use Ethernet protocol with 10GBase-r IP core as physical block (PCS+PMA). So, I just think that maybe this is a built in hardware functionality (transceiver technology). That is why I want to get some advice from this thread post. But your answer comment tells me that this is something we can decide by coding. Please put some more details or correct my understanding.

[Altera_Forum]

The question is too general for a simple answer, I fear. There's is a 500 pages handbook part about the Stratix IV Gigabit Transceivers, did you get at least an overview what it's talking about? 

 At the byte and bit coding level, you find some basic elements, e.g. 8B/10B encoding, that are more less common to all fast serial protocols. In so far, most serial data streams look almost similar when watched on an oscilloscope, apart from a varying data rate.  This applies at least to binary data links that don't use modulation. Some interface standards, e.g. several fast Ethernet variants use modulation and need dedicated hardware.   Regards, Frank

[Altera_Forum]

In so far, most serial data streams look almost similar when watched on an oscilloscope, apart from a varying data rate. This applies at least to binary data links that don't use modulation. 

 Thanks FvM. Serial data streams look similar in the scope, so how do they look like? Actually, because it looks like I just see some noise on the scope rather than my output signal coming out from transceiver connectors, I cannot imagine the signal is a sine wave or something else.  PS: I have read the handbook of stratix IV, and just got an overview idea. I did not remember that the data encoding is mentioned there. But, I will check again.  Thanks

[Altera_Forum]

TO_BE_DONE

[Altera_Forum]

Thanks Altera Guries indeed. I will investigate more by checking the scope and reading PHY IP spec documents.

[Altera_Forum]

Without referring to details, the waveforms looks like a regular GBit datastream, probably not very good triggered. You should know if the bit rate visible in the screenshots is corresponding to the design parameters. 

 More generally speaking, I see some lack of knowledge about high speed digital systems. Nothing that can be overcome in a brief forum discussion.