# Error executing usrp2\_wfm\_rcv.py

**URL:** <https://www.ruby-forum.com/t/error-executing-usrp2-wfm-rcv-py/207982>\
**Category:** GNU Radio\
**Created:** [June 7, 2011, 4:14pm UTC](https://www.ruby-forum.com/t/error-executing-usrp2-wfm-rcv-py/207982 "2011-06-07T16:14:59Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\
**Post date:** [June 7, 2011, 4:14pm UTC](https://www.ruby-forum.com/t/error-executing-usrp2-wfm-rcv-py/207982/1 "2011-06-07T16:14:59Z")

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Hello.

Can this variable “step\_size” have an arbitrary value? I tried several  
times  
and I always get this message:

(python:3293): Gtk-CRITICAL \*\*: IA\_\_gtk\_range\_set\_range: assertion `min  
\<  
max’ failed

and nothing at the USRP2 output (around -400 dB)

By the way, I am using BasicRX.

Thanks!

Eduardo.

2011/6/6 Nick F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)

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**Author:** ![eduardoflores](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/41988e/32.png) [@eduardoflores](https://www.ruby-forum.com/u/eduardoflores)\
**Post date:** [June 7, 2011, 4:39pm UTC](https://www.ruby-forum.com/t/error-executing-usrp2-wfm-rcv-py/207982/2 "2011-06-07T16:39:07Z")

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On 07/06/2011 9:58 AM, Eduardo Lloret F. wrote:

> and nothing at the USRP2 output (around -400 dB)
> 
> By the way, I am using BasicRX.

OK, found the problem. The problem is that for a BASIC\_RX, the  
available settable gain range is [0,0], since it has no settable gain  
elements.  
Which means the slider won’t work properly. Perhaps one could put  
in a conditional prior to creation of the slider that checks for [0,0].  
And doesn’t create the slider at all if there is no usable gain  
range.

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<div class="post-metadata">

**Author:** ![eduardoflores](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/41988e/32.png) [@eduardoflores](https://www.ruby-forum.com/u/eduardoflores)\
**Post date:** [June 7, 2011, 5:01pm UTC](https://www.ruby-forum.com/t/error-executing-usrp2-wfm-rcv-py/207982/3 "2011-06-07T17:01:25Z")

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On 07/06/2011 9:58 AM, Eduardo Lloret F. wrote:

> and nothing at the USRP2 output (around -400 dB)
> 
> By the way, I am using BasicRX.

The step size can be small, but in this case, the GTK package is  
complaining that the “MIN” and “MAX” values on the slider are reversed,  
or don’t conform to the required “MIN \< MAX” requirement.