Re: [Discuss-gnuradio] How do you measure the channel impulse response?

[sirjanselot]

Yes with 40 dB attenuation.  

Somehow I didn't see your post.  



Marcus D. Leech wrote:
> 
> On 10/06/2010 11:41 AM, sirjanselot wrote:
>> I meant TXA to RXB.  
>>
>> sirjanselot wrote:
>>   
>>> Thank you for your response.
>>>
>>> I've tried gr sounder but from the looks of it, it is only accurate when
>>> you use the LFRX/TX or the RFX boards.
>>>
>>> I have a WBX transciever and when I tried it on my first shot measuring
>>> the channel coefficients by directly connecting the output of my TXA to
>>> my
>>> RXA, the length of the channel was 32760 coefficients!!!!
>>>     
> When you say "directly', you mean through a minimum 30dB attenuator,
> correct?  The output power of
>   the transmitter can easily damage the LNA in the receiver if directly
> connected, and at the
>   very least, will cause serious clipping.
> 
> 
>>> I haven't been able to figure out how to read the output.dat of the
>>> gr-sounder yet but this is what is showing me on debugging mode.
>>>
>>> It also keeps giving me this warning message:
>>> gr_buffer::allocate_buffer:
>>> warning: tried to allocate
>>>    4 items of size 32760. Due to alignment requirements
>>>    512 were allocated.  If this isn't OK, consider padding
>>>    your structure to a power-of-two bytes.
>>>    On this platform, our allocation granularity is 4096 bytes.
>>>
>>> Any thoughts?
>>>
>>> Thank you.
>>>
>>>
>>> Martin Braun-4 wrote:
>>>     
>>>> On Tue, Oct 05, 2010 at 11:43:53AM -0700, sirjanselot wrote:
>>>>       
>>>>> Hello,
>>>>>
>>>>> I'm trying to figure out how to measure the impulse response of a
>>>>> channel
>>>>> its coefficients.  
>>>>>         
>>>> Hello sirjanselot,
>>>>
>>>> the channel sounder which is part of GNU Radio works, but has no
>>>> synchronisation or anything--so you have no direct means of averaging
>>>> taps. Perhaps you can give it a bash, though.
>>>>
>>>> Cheers,
>>>> MB
>>>>
>>>> -- 
>>>> Karlsruhe Institute of Technology (KIT)
>>>> Communications Engineering Lab (CEL)
>>>>
>>>> Dipl.-Ing. Martin Braun
>>>> Research Associate
>>>>
>>>> Kaiserstraße 12
>>>> Building 05.01
>>>> 76131 Karlsruhe
>>>>
>>>> Phone: +49 721 608-3790
>>>> Fax: +49 721 608-6071
>>>> www.cel.kit.edu
>>>>
>>>> KIT -- University of the State of Baden-Württemberg and
>>>> National Laboratory of the Helmholtz Association
>>>>
>>>>
>>>>  
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>>>>
>>>>
>>>>       
>>>
>>>     
>>   
> 
> 
> -- 
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
> 
> 
> 
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