Hi Dingfu,

This is one high speed serial transmission issue. The channel is very important for this system. Ti claim that it can support up to 15m cable is based on the channel loss, impedance etc. So please check your cable loss, connector loss, PCB trace etc., these seriiously impact the link bit error. 

regards,

Steven

Thanks for your reply, Steven

Actually, the DS90UB947 EVM and DS90UB948 EVM are used in this system and the cable is a normal STP.  it is the cable which most likely to cause this issue per your analysis. 

Is there test method to check if this cable meets the requirement? or in what situation the transmission can be up to 15m, like the cable resistance should be lower than XXX/m?

Really appreciate your support!

B&R

2020/8/20

based on high speed serial link analysis, the cable is one of key transmission channel's parts. As mentioned, pls check the cable s parameters such as return lossand the impedance.  also what is the pclk in your test?

Regards,

Steven

Got it. The pclk is around 26MHz.

B&R