[Discuss-gnuradio] 8 MHz Tx Bandwidth... What am I still missing?

[Vincenzo Pellegrini]

Hi,

what I've done so far is:

--buy a new hardisk (a 7200 rpm sata), used only for the data to be transmitted,, and XFS formatted
---check my PC's USB bus via gnuradio benchmark_usb.py, which says everything is ok up to 32MB/s (output follows)
---use short int interleaved I/Q instead of gr_complex

but still a 342958080 bytes long file, meant to last 10.717 seconds if played back at 32 MB/s (8 complex Msps)
lasts 13+ seconds while, instead it should be:

342958080 / 32e6 = 10.717 seconds

samples are damn slow to come out..this is quite frustrating as my application needs a true 8 MHz bandwidth...

scaling down to 4 MHz is instead fine.. as I really get the right 342958080 / 16e6 = 
21.435 seconds

what else should I check/modify? any hint? 

the file meant to last 10.717 secs if played back with usrp_interp = 16  is  at 
http://wwvince.interfree.it/of.dump

please, if anybody manages to send it out in not more than 11 seconds, le me know..
it would be really good news...

thanks

vincenzo

BENCHMARK_USB OUTPUT:

address@hidden gr-mystuff]# ./monitor.sh
Testing 2MB/sec... usb_throughput = 2M
ntotal    = 1000000
nright    = 986311
runlength = 947654
delta     = 52346
OK
Testing 4MB/sec... usb_throughput = 4M
ntotal    = 2000000
nright    = 1997961
runlength = 1997961
delta     = 2039
OK
Testing 8MB/sec... usb_throughput = 8M
ntotal    = 4000000
nright    = 3997979
runlength = 3997979
delta     = 2021
OK
Testing 16MB/sec... usb_throughput = 16M
ntotal    = 8000000
nright    = 7997477
runlength = 7997477
delta     = 2523
OK
Testing 32MB/sec... usb_throughput = 32M
ntotal    = 16000000
nright    = 15995879
runlength = 15991525
delta     = 8475
OK
Max USB/USRP throughput = 32MB/sec

 
-- 
Vincenzo Pellegrini