Re: how to generate a certain band width white noise

[Kyeong Su Shin]

Hello James:

The bandwidth of the "Noise Source" block is 2pi. It's a digital signal, so the bandwidth is not in MHz, and is in range of [0, 2pi] or [0, 1] (if you normalized it).

You can calculate an equivalent analog bandwidth if you know the sampling rate of hardware sink block that is being used (ex: UHD sink, Osmocom Sink, etc). If the sampling rate is set to 4 MS/s and if a Noise Source block is connected to the hardware sink directly, then the bandwidth of the outputted noise should be (ideally) 4 MHz. If you use a resampler to interpolate the signal, it will go down. Alternatively, you can also use a low-pass filter to reduce the bandwidth (forgot to mention this in the previous e-mail, but it is probably faster and acceptible in this case).

Regards,

Kyeong Su Shin

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보낸 사람: james jordan <james.jordan.999@hotmail.com>
보낸 날짜: 2021년 3월 22일 월요일 오후 12:27
받는 사람: Kyeong Su Shin <ksshin@postech.ac.kr>; GNURadio Discussion List <discuss-gnuradio@gnu.org>
제목: Re: how to generate a certain band width white noise

 

Hi Kyeong,

thanks for your reply. what is the default bandwidth for noise source. from my understanding resampler did not modify bandwidth.

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From: Kyeong Su Shin <ksshin@postech.ac.kr>
Sent: Sunday, March 21, 2021 5:17 PM
To: james jordan <james.jordan.999@hotmail.com>; GNURadio Discussion List <discuss-gnuradio@gnu.org>
Subject: Re: how to generate a certain band width white noise

 

Hello Jordan:

Just use a "Noise Source" block and a resampler block (if needed; best be avoided) to adjust the bandwidth.  The quality of your "white noise" will depend on the resampler and the transmitter hardware, though.

Regards,

Kyeong Su Shin

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보낸 사람: james jordan <james.jordan.999@hotmail.com> 대신 Discuss-gnuradio <discuss-gnuradio-bounces+ksshin=postech.ac.kr@gnu.org>
보낸 날짜: 2021년 3월 21일 일요일 오후 12:40
받는 사람: GNURadio Discussion List <discuss-gnuradio@gnu.org>
제목: how to generate a certain band width white noise

 

Hi,

i want to use white noise to test a certain band. such as 2Mhz band width white noise. how to do this?