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[Discuss-gnuradio] Questions about data type conversion in GRC. (ADC, e

From: Milo Wong
Subject: [Discuss-gnuradio] Questions about data type conversion in GRC. (ADC, encoder)
Date: Fri, 7 Aug 2009 15:13:36 -0700

Hi all,

Here I have a question regarding data type conversion in GRC. Since the output of audio source is analog signal. So, I am going to encode the analog output of audio source(float, -1 to +1 ??) to digital bit streams(byte) for digital signal Processing later on. But I found there's no ADC or encoder in GRC which could properly convert float: -1~+1 to Byte: 00~FF. Is there any way to achieve that?

Thank you,


On Thu, Aug 6, 2009 at 1:41 PM, Eric Blossom <address@hidden> wrote:
On Thu, Aug 06, 2009 at 12:39:15PM -0700, Milo Wong wrote:
> Hi,
> I was browsing the GNU radio C++ API. Here I have a couple of questions
> about the class reference of gr_sig_source_f. (Signal generator)
> 1) For the type of public member function waveform(), i.e. gr_waveform_t
> waveform () const. Where can I refer to the definition of "gr_waveform_t"?

Hi Milo,

You can find it in gnuradio-core/src/lib/gengen/gr_sig_source_waveform.h

(Given that there were only 3 includes in gr_sig_source_f, it didn't
 take long to find it...  grep would have worked too)


> Is there any description of how waveforms(sine wave) are generated?

Use the source Luke!


> 2)  I am going to generate a set of sine waves at different frequencies. If
> these sine waves are obtained from the iteration equations of harmonious
> oscillators:   v(t+dt)=v(t) - omega^2 * x(t)dt ; x(t+dt)=x(t) + v(t)dt, is
> that different from the way of sine wave generation in gnu radio. Do I need
> to create a new sine wave generation block instead of the defaut one? (x(t)
> - displacement, v(t) - velocity)
> Thank you,
> Milo

No, there's no reason to reimplement the sine generator unless
you enjoy that kind of thing.  First thing to remember is that the
block does what it says: it generates a sine wave of the specified
frequency and amplitude.

We also have blocks to generate sinusoids with frequency a function
of its input stream.  See e.g, gr_frequency_modulator_fc or gr_vco_f


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