Re: [Discuss-gnuradio] Increase sine frequency every N samples

[Josh Blum]

A few tips:

1) you dont have to lock the flow graph to change parameters (just to 
disconnect and connect blocks)

2) you simplify this problem a bit by using the 
gr_frequency_modulator_fc block. You can feed the frequency modulator a 
step function that increases every N samples.

you could probably generate the input to the modulator with a ramp 
function (sig source), a sample and hold block, and the vector source to 
control the sample and hold block

-Josh

On 02/24/2010 08:22 AM, Carlos Aviles wrote:
> Hi,
>
> I want to generate a sine wave that increases in some kHz its
> frequency every N samples it produces.
>
> I know I can change the frequency of the sine using the available
> setter method on the gr_sig_source block. My problem is how to perform
> that change exactly after N samples have been produced by the
> gr_sig_source block. I've come up with some ideas:
>
> - Make the top_block aware of the number of samples that the
> gr_sig_source has produced. When N samples are produced, the top_block
> could call Lock(), change the parameter, and then Unlock(). My problem
> here is how to make the top_block aware of that count. I could use a
> "listener block" just after the gr_sig_source and let it count the
> samples that pass through it. After N samples, it could trigger some
> signal to the top block. I don't like this approach because it seems
> too complex.
>
> - Extend the functionality of gr_sig_source to increase the frequency
> by itself. By directly extending the class that won't work because
> there is no public constructor for gr_sig_source. Is there any other
> way of doing that?
>
> - Save N samples of different sine waves into files and then generate
> a single one by concatenation. I could use then a file_source block to
> incorporate these sine waves into any flow graph. The problem is the
> size of the resulting file.
>
> I would appreciate very much any help on that.
>
> I'm using gnuradio-3.2.2 and I want to generate a 100% C++ application.
>
> Thanks,
> Carlos.
>
> PS: I haven't posted any code because I don't have any yet :)
>
>
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