Requested decimation is odd

Hi all,

I am using USRP N200 with LFRX daughter board. The newest version of
images
has been loaded.

The sampling rate is set as 4 MHz. There is constantly a UHD warning:

The requested decimation is odd; the user should expect CIC rolloff.

Select an even decimation to ensure that a halfband filter is enabled.

How do I change the decimation value?

And what value should I set it?

Thanks!

Ting Wu

How do I change the decimation value?

And what value should I set it?

Thanks!

Ting Wu

100e6 / 4e6 = 25

Which is odd value which changes the “line up” of filtering in the FPGA.

Select a sample rate that results in an even decimation value, unless
you can live with the edge roll-off for an odd value.

Thank you for your response!

We need to use the sampling rate of 4 MHz. How can I deal with this
problem?

Actually we have been running the same application on several USRPs
(N200
and N210), and there was no such warning.

Any suggestions?

Ting Wu

From: Marcus D. Leech [mailto:[email protected]]
Sent: Monday, November 12, 2012 11:29 AM
To: Ting Wu
Cc: [email protected]
Subject: Re: [Discuss-gnuradio] Requested decimation is odd

Hi all,

I am using USRP N200 with LFRX daughter board. The newest version of
images
has been loaded.

The sampling rate is set as 4 MHz. There is constantly a UHD warning:

The requested decimation is odd; the user should expect CIC rolloff.

Select an even decimation to ensure that a halfband filter is enabled.

How do I change the decimation value?

And what value should I set it?

Thanks!

Ting Wu

100e6 / 4e6 = 25

Which is odd value which changes the “line up” of filtering in the FPGA.

Select a sample rate that results in an even decimation value, unless
you
can live with the edge roll-off for an odd value.

On 11/11/12 09:42 PM, Ting Wu wrote:

*From:*Marcus D. Leech [mailto:[email protected]]


Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
The warning is new. But nothing else has changed. If your application
has been running fine, it will continue
to run fine.

I see.

Thanks a lot!

Ting Wu

From: Marcus D. Leech [mailto:[email protected]]
Sent: Monday, November 12, 2012 12:05 PM
To: Ting Wu
Cc: [email protected]
Subject: Re: [Discuss-gnuradio] Requested decimation is odd

On 11/11/12 09:42 PM, Ting Wu wrote:

Thank you for your response!

We need to use the sampling rate of 4 MHz. How can I deal with this
problem?

Actually we have been running the same application on several USRPs
(N200
and N210), and there was no such warning.

Any suggestions?

Ting Wu

From: Marcus D. Leech [mailto:[email protected]]
Sent: Monday, November 12, 2012 11:29 AM
To: Ting Wu
Cc: [email protected]
Subject: Re: [Discuss-gnuradio] Requested decimation is odd

Hi all,

I am using USRP N200 with LFRX daughter board. The newest version of
images
has been loaded.

The sampling rate is set as 4 MHz. There is constantly a UHD warning:

The requested decimation is odd; the user should expect CIC rolloff.

Select an even decimation to ensure that a halfband filter is enabled.

How do I change the decimation value?

And what value should I set it?

Thanks!

Ting Wu

100e6 / 4e6 = 25

Which is odd value which changes the “line up” of filtering in the FPGA.

Select a sample rate that results in an even decimation value, unless
you
can live with the edge roll-off for an odd value.


Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

The warning is new. But nothing else has changed. If your application
has
been running fine, it will continue
to run fine.