Forum: GNU Radio USRP RX Decimation Rate

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3d593de8acbe2510722af740d8668352?d=identicon&s=25 Eng. Firas (Guest)
on 2007-04-21 21:43
(Received via mailing list)
Hi All,

I'm  a new USRP user. Kindly, I will be very appreciated if someone
could
tell me what is the decimation range of the USRP RX path? I'm really
confused. Is it linear range from [1,2,3,4,.....] ?or it is power of 2
[2,4,8,16,...]?

Thank you in advance.


Firas
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79723aa1b24981dcec2dbf7fd59403c1?d=identicon&s=25 Brian Padalino (Guest)
on 2007-04-22 00:06
(Received via mailing list)
On 4/21/07, Eng. Firas <firasmail2000@yahoo.com> wrote:
>
> Hi All,
>
> I'm  a new USRP user. Kindly, I will be very appreciated if someone could
> tell me what is the decimation range of the USRP RX path? I'm really
> confused. Is it linear range from [1,2,3,4,.....] ?or it is power of 2
> [2,4,8,16,...]?

It's linear and within 4 to 128 inclusive, according to
cic_dec_shifter.v located here:

    http://gnuradio.org/trac/browser/gnuradio/trunk/us...

Brian
3596cfe1d579c65b9babd35e8787977c?d=identicon&s=25 Matt Ettus (Guest)
on 2007-04-22 00:47
(Received via mailing list)
Brian Padalino wrote:
> It's linear and within 4 to 128 inclusive, according to
> cic_dec_shifter.v located here:
>
>
> http://gnuradio.org/trac/browser/gnuradio/trunk/us...
>

The CIC decimator does 4 through 128, but this is followed by a halfband
decimator which multiplies this by a factor of 2.  Thus, it only does
multiples of 2.  4, 6, 8, 10, 12, 14, 16, 18. 20, etc.   Up to 256
total.

Matt
3d593de8acbe2510722af740d8668352?d=identicon&s=25 Eng. Firas (Guest)
on 2007-04-22 08:32
(Received via mailing list)
Eng. Firas wrote:
>
> Firas
>


Thank you Brian, Matt.

If the CIC starts linearly from 4 to 128, and followed by decimate by 2
Half
Band Filter (HBF) Then [CIC+HBF]  should give us the following range
[8,10,12,14,...........,256], and not the range [2,4,6,8,......,256] ,
is
this correct ?


Firas
--
View this message in context:
http://www.nabble.com/USRP-RX-Decimation-Rate-tf36...
Sent from the GnuRadio mailing list archive at Nabble.com.
79723aa1b24981dcec2dbf7fd59403c1?d=identicon&s=25 Brian Padalino (Guest)
on 2007-04-22 16:18
(Received via mailing list)
On 4/22/07, Eng. Firas <firasmail2000@yahoo.com> wrote:
> Thank you Brian, Matt.
>
> If the CIC starts linearly from 4 to 128, and followed by decimate by 2 Half
> Band Filter (HBF) Then [CIC+HBF]  should give us the following range
> [8,10,12,14,...........,256], and not the range [2,4,6,8,......,256] , is
> this correct ?

Correct.

> Firas

Brian
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