Hello everyone, I am trying to implement a simple FSK system to measure bit error rate (BER), and packet loss rate (PLR) using:
1-Linux 2-USRP motherboard 3-RFX2400 daughter card I want to implement an echo back system where one Transceiver (say Master) will transmit a small frame (let say 48 byte, and important thing is that I neccessarily need small payload) to other transceiver (say Slave). The Salve returns the frame immediatelly without any processing to Master and Master measures BER and PLR. The problem which I am facing is that I am unable to transmitt such small packets. I have noticed that if I have a large file with let say few Kbytes contents then it is transmitted (partially, the end of file is always missing...I guess it is stuck somewhere in buffer????) but if I have such small packets as I metioned earlier then most of the time the packets are lost. If the packet is received then it is totally corrupt (say almost 100% BER) unlike large files which are received in very good quality (But important and notable point is that even the large files are 100% courrupt at the end). This makes me wonder why last few hundered bytes are always courrupt??? (for small file the whole file lies in that category of last few hundered bytes) I have tried a lot but unable to solve the problem! Now can any one help me to understand what can be the problem? Is it somewhere in the buffers? Is it some sort of synchronization problem??? and which buffers (of USRP/RFX2400/GNURadio) are involved in such flowgraph. The flow graph with actual names of blocks used by me is given below (I have attached complete code if some one want to have a look): Transmit path flowgraph: gr.file_source -> gr.simple_framer -> gr.bytes_to_syms -> gr.interp_fir_filter_fff -> gr.frequency_modulator_fc -> gr.multiply_const_cc -> usrp.source_c Receive path flowgraph: usrp.source_c -> gr.fir_filter_ccf -> gr.quadrature_demod_cf -> simple_correlator -> gr.file_sink Best Regards Kaleem Ahmad http://www.nabble.com/file/p19415046/fsk_rx.py fsk_rx.py http://www.nabble.com/file/p19415046/fsk_tx.py fsk_tx.py -- View this message in context: http://www.nabble.com/RFX2400%2BUSRP-buffers-tp19415046p19415046.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
