Question about USRP Packet TX/RX example ?

[HustLiliAn]

Hi , everyone, I have some problems about the NI-USRP packet TX/RX example. At the Receive side, there is a parameter called Acquisition time, which determine the process samples once a time. so if a packet was cut off, the packet would loss, whether I am right?  From the example, we found there always some packets lost even we connect the TX, RX by a cable. So what is the method to solve the problem?  In my opinion , whether can I process only a sample with the matchfilter one a time, whether the cpu can detect the packets immediately and correctly?  Thanks

[Anthony_F]

Hello Hust,

You are correct, there is an inherent synchronization problem because the receiver is not sharing any clocking information from the transmitter. 

I believe that this was overcome (I might be thinking of the 6x6 MIMO demo) by creating a small circular buffer that is capturing "pre trigger samples" much like a digitzer. One a certain power level is reached, we say that our reference condition has been met.  A certain amount of samples from the circular buffer is combined with a certain number of samples after the reference condition.

[HustLiliAn]

Hi, Anthony

 Thank for reply. It is very important for me.

 I am still have some questions about the circular buffer and pre trigger samples,  if the transmitter send the packets quickeyly , whether the receiver can process the samples in time based on your recommend way? 

ps: How should I find the trigger condition, can you give some simple example?  Thank you very much!