Hello, I recently successfully collected with usrp2_rx_cfile.py some WiFi data using a USRP2 with decimation=5 (which gives you about 20MHz of bandwidth). This means about 1GB of data in few seconds or so. Because of the write speed limitation of the had disk, it is basically impossible to do it using a normal HD. One straightforward solution is modify usrp2_rx_cfile so that it stores all your data in one big array and saves it in the HD at the end. These few lines describe an alternative solution using a "ramdisk" partitions of type "tmpfs" which allows you to use use any GNU Radio function without modification. You basically dump your file in your ram.
sudo mkdir /var/ramdisk sudo mount -t tmpfs none /var/ramdisk -o size=1100m cd /var/ramdisk df -H sudo usrp2_rx_cfile.py -v -s -e eth1 -f 2462.0M -g 25 -d 5 -N 250M wifi_d5_g25.bin cp ./wifi_d5.bin /home/ctae/Desktop/ sudo rm ./*; df -H; cd / sudo umount /var/ramdisk cd ~/Desktop This method seems to me to allow you to overcome the problem of the HD writing speed. Make sure however to have enough ram, in my case 2GB was enough (linux without GUI). Please let me know if a better method exists. QUESTIONS 1) For some reasons I could not use a decimation=4 (with a XCVR2450 front end) with the greatest and latest USRP2 FPGA firmware, any hint why? 2) I understand to read the collected file I can use the read_cshort_binary.m function (included in GNU Radio ), is this function the appropriate one considering that I used the option "-s" with usrp2_rx_cfile.py? 3) with the function read_cshort_binary.m, what is the best way to understand I collected meaningful wifi data? Measure the signal power in the collected signal? How? Best regards, Fabrizio _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
