John - I must have been drunk when I wrote those equations. I wrote 64e10 when I meant 64e6, and put the D in a weird place. Sorry for any confusion. This makes more sense:
(16 bit/sample)*(64e6/D sample/sec)*(1/2^23 MB/bit) <= 32 MB/sec therefore, for real D >= 16*64e6/(32*2^23) = 3.81 --> D = 4 and for complex D >= 2*16*64e6/(32*2^23) = 7.63 --> D = 8 On Wed, 2006-04-05 at 17:46 -0400, Lee Patton wrote: > Hi John - > > 16/D bits/sample x 64e10 samples/sec x 1 B/8 bits x 1 MB / 2^20 B <= 32 > MB/sec > > Therefore, > > D >= 16*64e10 /(32*8*2^20) = 3.814 -> 4 > > So, if you want to transmit twice as many sample across the bus... > > D > = 2*16*64e10 /(32*8*2^20) = 7.63 -> 8 > > ...you have to halve your sampling frequency. > > Are you aware that there is a -8 option in some of the scripts that > allows you to send 8 bits instead of 16. > > Hope that helps, > - Lee > > > > ----- Original Message ----- > From: jjw <[EMAIL PROTECTED]> > Date: Wednesday, April 5, 2006 5:31 pm > Subject: [Discuss-gnuradio] Bandwidth Across USB > To: Discuss-gnuradio@gnu.org > > > > > I know this is probably an extremely stupid question, but I wanted > > to get > > some verification. I've noticed that the minimum decimation rate > > you can > > use in all of the sample programs is 4 (giving you an effective > > samplingrate of 16 MHz). If you are transmitting 1 real channel of > > data (16 bits) > > at this rate, that seems to be maxing out the USB transfer rate of > > 32 MB/s. > > Am I correct in my deduction that you need to use a decimation rate > > of at > > least 8 in order to transmit complex data (such as for FM > > demodulation)successfully across the USB? Thanks. > > > > Thanks, > > John > > -- > > View this message in context: http://www.nabble.com/Bandwidth- > > Across-USB-t1402318.html#a3773742 > > Sent from the GnuRadio forum at Nabble.com. > > > > > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > Discuss-gnuradio@gnu.org > > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
