|
| From: | Jiji Varghese |
| Subject: | Re: [Discuss-gnuradio] Confusion about Sample rate |
| Date: | Sat, 1 Jun 2019 21:05:40 +0530 |
Thank you for the responses.
I was planning to use USRP B200 which allows a BW of 56MHz.
Yes. I just want to sense the WIFI spectrum. I came across various sensing techniques like energy sensing, cyclostationarity, covariance based etc. Hope I am right. But I didn't get how performance tradeoffs affect sample rate?
J. Varghese
On 12:09PM, Sat 01-Jun-2019 Marcus D. Leech <patchvonbraun@gmail.com wrote:
>
> >
> On 06/01/2019 02:03 AM, Kyeong Su Shin wrote:
>
> >>
>> To whom it may concern:
>>
>> While I mostly concur with Marcus's response, I would like to note that maybe you can get away with a lower sampling rate (lower than the Nyquist rate) since you are working on spectrum sensing (not on decoding the full WiFi signal).
>>
>> Actual sampling rate needed by your application will depend on the spectrum sensing algorithm and various performance factors that you want to use.
>>
>> Regards,
>> Kyeong Su Shin
>
> Agreed. I had missed the "for spectrum sensing" part. There are a number of algorithms possible, with various performance trade-offs
> possible.
>
>
>
> >> ________________________________
>> 보낸 사람: Marcus D. Leech <patchvonbraun@gmail.com> 대신 Discuss-gnuradio <discuss-gnuradio-bounces+ksshin=postech.ac.kr@gnu.org>
>> 보낸 날짜: 2019년 6월 1일 토요일 오후 12:28:49
>> 받는 사람: discuss-gnuradio@gnu.org
>> 제목: Re: [Discuss-gnuradio] Confusion about Sample rate
>>
>> On 05/31/2019 11:21 PM, Jiji Varghese wrote:
>
> >>>
>>> I am trying to store WiFi signals samples in a file using file sink block, using GNU radio, for spectrum sensing. I know that a single WiFi channel has a bandwidth of 20-22 MHz. So should I use the sample rate in GNU radio block to 40e6 - 44e6 or can I use a lower value? Can I use 1e6 as sampling rate?
>>> What is the lower bound for the sample rate in GNU block?
>>>
>>> I am confused about giving the sample rate.
>>>
>>> J. Varghese
>>>
>> A couple of different issues here:
>>
>> GnuRadio *generally* deals with *complex samples*. Complex sampling satisfies the Nyquist Sampling Criterion in a way that allows you to
>> run those samples at a rate == bandwidth (more or less).
>>
>> Gnu Radio doesn't care, per se, about sample rates, and will pass your request on to the underlying *HARDWARE*. The hardware will, most
>> definitely have limits and policies with respect to sample rate, and to answer the question "what sample rates are allowed" you need to refer
>> to the hardware you're using.
>>
>> If you don't understand what the Nyquist Sampling Criterion is, you should definitely spend some time researching that, and how it relates
>> to the kinds of things you might be wanting to do with samples, and why 1e6 is not an appropriate sampling rate for a signal with an
>> information bandwidth of 22MHz.
>>
>>
>>
>>
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>> Discuss-gnuradio@gnu.org
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>
>
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