|Subject:||Re: [Discuss-gnuradio] Estimating SNR|
|Date:||Thu, 12 May 2016 13:11:24 +0200|
|User-agent:||Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0|
please stay on-list with your replies!
On 12.05.2016 12:48, Raja Muneeba wrote:
I think so! You should start to model your noise. Is your noise model "white"? If it is, what does it say about the power of noise contained in different, equally wide bandwidths?
Full scale! This is DSP, there's no physical units to the numbers you handle. So, if you feed in a constant 1 into your fft plot, you'll see a specific value.
That doesn't have to do anything with each other:
Sampling rate is just a number that the signal source uses together with the signal frequency to calculate how many *samples* long a full period will be – there's no "real world" time in this kind of DSP, just samples. So a signal source with f_sample=1 and f_signal = 0.2 will have exactly the same output as a signal source with f_sample = 5e6 and f_signal = 1e6.
Now, you don't sample at 2.48GHz directly – your USRP is an upconverter that allows you to get complex baseband equivalent to what happens in a real passband at RF frequencies.
The idea of complex baseband is very important here – GNU Radio has a suggested reading wiki page, but seeing that you're probably a student at the Aalto university, I'd just ask for the scriptum or recommended book of the basic digital communications lecture in electrical engineering, and read up till you reach the baseband receiver. Such a lecture was where I learned those principles!
So, now the sampling rate you chose for your USRP sink or source does have a real-world effect: it actually sets the rate at which samples are converted to/from analog values. And hence, the sampling rate you use with the hardware directly sets the Nyquist rate, and hence, your signals' bandwidth.
That are in any case values that the SBX and the N210 support.
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