Re: Digital modulation 'constellation modulator' output.

[Khalilur Rahman]

Hello Fabian,

I hope you are doing great!

'' from Gnu Radio in PC digital modulation is done, the generated signal sink through Red Pitaya(FPGA). We are only concerned about processing the baseband signal by Gnu radio with Red Pitaya. From GitHub we found one SDR project. The 'sink' for red pitaya is also available on that project, so we don't need to make one. Now we are confused as the analog signal sink to Red pitaya how does it processing it? I mean the signal as an input to red pitayas CPU should be digital. ''

Thank you

Best regard 

Khalil

On Sat, 13 Jun 2020 at 11:29, Fabian Schwartau <fabian@opencode.eu> wrote:

Hey Khalil,

first of all: every signal is digital within the computer. What you
probably mean is what this signal represents. The output of a modulator
usually represents an anlog signal. It is of type float (or complex
float) and each sample represents for example a voltage. I don't
understand what you are supposed to do with that signal after that. When
you say you need to "sink this signal though an embedded processor" you
mean an external physical device? If that is the case you need some sort
of sink in GNU Radio, like an audio sink, which will convert you digital
signal into an analog audio signal (DAC).
If you want to process the signal further, e.g. by filtering it, you can
do that in GNU Radio.
Hope that helps,
Fabian

Am 13.06.20 um 10:40 schrieb Khalilur Rahman:
> Hello Guys,
> I was studying the digital modulation in regards to GNU Radio. I have
> one confusion which I really need to get over with.
>
> Let say, I am using BPSK modulation for processing low-frequency
> baseband  I- signal. After the digital modulation, the output I-signal
> is digital or analog type? Yes, as baseband signal it is
> obviously analog. I mean the output type of constellation modulator. If
> I put a time sink it will show as an analog signal but my study partner
> said it is digital. Same with QPSK or QAM. I know this is very basics
> but I did not find any answer.
> We need to generate baseband from GNU Radio and sink this signal through
> an embedded processor for further signal processing. If the
> constellation modulator gives an analog signal then we have to first
> convert signal through ADC. We are very much new on GNU Radio.
>
> Thank you in advance.
>
> Best regards 
> Khalil