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Re: [Discuss-gnuradio] Bandwidth Across USB
From: |
Lee Patton |
Subject: |
Re: [Discuss-gnuradio] Bandwidth Across USB |
Date: |
Wed, 05 Apr 2006 17:46:59 -0400 |
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 <address@hidden>
Date: Wednesday, April 5, 2006 5:31 pm
Subject: [Discuss-gnuradio] Bandwidth Across USB
To: address@hidden
>
> 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.
>
>
>
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