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

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
>>>
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>>> 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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