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File sink

sumitstop
I have an application where I observe real time display of some bands. What I want to do is make a FIFO/Buffer where the data can be stored simultaneously and with a push button 'rewind' I can access the immediate past 15 sec data.

So basically I want to know how to make a such file sink, which can store just immediate past 15 sec data.

gr_file_sink keeps increasing the size while gr_head stops after taking a fixed number of samples.

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Re: File sink

Marcus Müller
Hello Sumit Kurmar,

this depends on what you want to do with your data, the data rate, and the amount of effort your willing to make.

- Easiest solution: Use the "delay" block with a delay of (sample rate) * 15s. Advantage: Yields a GNU Radio sample stream that's delayed by 15s. Drawback: This can be a _large_ amount of samples, so this might actually fail if GNU Radio is not able to allocate a shared buffer that's big enough to hold them; there are ways around that, anyways.

- Versatile solution: Write your own signal processing block. It's really a simple exercise when done in python or in C++, whatever is the language of your choice.
Just implement a ring buffer of length (sample rate)*15s by keeping an input counter that increments (mod length) whenever you copy input samples to the internal buffer, and either write a method that returns a (linear) copy of the stored data or dumps it to a file or emits it as a message or starts pushing it to the output buffer or does whatever your application needs.

Happy Hacking,
Marcus

On 09/01/2013 08:51 PM, sumitstop wrote:

> I have an application where I observe real time display of some bands. What I
> want to do is make a FIFO/Buffer where the data can be stored simultaneously
> and with a push button 'rewind' I can access the immediate past 15 sec data.
>
> So basically I want to know how to make a such file sink, which can store
> just immediate past 15 sec data.
>
> gr_file_sink keeps increasing the size while gr_head stops after taking a
> fixed number of samples.
>
>
>
>
>
> --
> View this message in context: http://gnuradio.4.n7.nabble.com/File-sink-tp43431.html
> Sent from the GnuRadio mailing list archive at Nabble.com.
>
> _______________________________________________
> Discuss-gnuradio mailing list
> [hidden email]
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio


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Re: File sink

sumitstop
Marcus.. that easiest method gave me for a temporary solution... and I am happy with it for the time being  
cheers
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