[USRP-users] WBX Frequency Response

Simon HB9DRV simon at hb9drv.ch
Fri Jun 1 16:00:56 EDT 2012


Thanks Josh,

Using 5Ms/s sorted this problem.

Simon Brown, HB9DRV
http://dit-dit-dit.com

You are standing at the end of a road before a small brick building. Around
you is a forest.
A length of co-ax runs out of the building and down a gully.


-----Original Message-----
From: usrp-users-bounces at lists.ettus.com
[mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of Josh Blum
Sent: 01 June 2012 21:53
To: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] WBX Frequency Response



On 06/01/2012 12:35 PM, Simon HB9DRV wrote:
> Hi All,
> 
>  
> 
> After much keyboard pounding I've managed to get data from my WBX 
> (Windows 7, 64-bit, Debug mode). Please look at the screenshot below, 
> the sample rate ( using set_rx_rate() ) is 4MB. The response doesn't 
> seem flat when the sample rate is anything above 2MB. Is this to be 
> expected? I have set the RF Gain to the maximum of 38dB.
> 

MB = megabytes
Msps = megasamples per second

>  
> 
> ftp://ftp.ham-radio.ch/common/Screenshot-2012-06-01-203346.png
> 

Perhaps you are seeing the CIC filter rolloff. decimation =
100Msps/host_sample_rate. So for odd decimations, you get CIC filter and no
halfbands. Try an even decimation, you should see a flatter noise floor.

-josh

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