Hi everyone, I got a problem in my project where I have been stuck for the past several weeks. I have searched the Gnuradio Mailing lists, I didn't find any direct answer. I’m doing the SDR project in which I use two USRPs(RFX2400) to communicate each other. I modified the benchmark example in GNU Radio to perform frequency hopping. I’m able to change frequency at transmitter side in real time according to my test, but I got hug delay with the packets sent out. What I did in the python script is something like:
## At Tx: While 1 If pktno == 100 Set freq to F1 If pktno == 200 Set freq to F2 If pktno == 300 Set freq to F3 Send_pkt() Pktno += 1 ## At Rx: Monitoring and receive all the packets sent by F2 According to frequency F2, I’m supposed to receive all the packets with pktno starts from 200 to 299, but what I got at receiver is pktno starts from around 127 to 226! What I can conclude for now is there is a big buffer for the message queue. Probably the latency is mainly introduced by USB where data entering the USB bus from PC to the USRP(FPGA). Hope I’m clear with the problem, My question is: 1. Is my thinking right? If so, how to reduce the size of USB buffer? 2. How to synchronize the (new) frequency with packet sending? Thanks in advance. Lee _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio