# GnuRadio File sink Operation, Need help

**URL:** <https://www.ruby-forum.com/t/gnuradio-file-sink-operation-need-help/231911>\
**Category:** GNU Radio\
**Created:** [September 5, 2014, 5:08pm UTC](https://www.ruby-forum.com/t/gnuradio-file-sink-operation-need-help/231911 "2014-09-05T17:08:12Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [September 5, 2014, 5:08pm UTC](https://www.ruby-forum.com/t/gnuradio-file-sink-operation-need-help/231911/1 "2014-09-05T17:08:12Z")

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Discuss-gnuradio mailing list  
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[https://lists.gnu.org/mailman/listinfo/discuss-gnuradio](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio)

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**Author:** ![Sumit\_Saluja](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e0b2c6/32.png) [@Sumit\_Saluja](https://www.ruby-forum.com/u/Sumit_Saluja)\
**Post date:** [September 5, 2014, 5:11pm UTC](https://www.ruby-forum.com/t/gnuradio-file-sink-operation-need-help/231911/2 "2014-09-05T17:11:57Z")

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There’s the metadata file sink. You could insert date/time tags.

Or, if the rates are quite low (a few Hz at most), you could use a  
probe, and have a poller function that grabs data from the probe, and

formats it all pretty like. That’s how simple\_ra writes its data log  
files…

On 2014-09-05 11:06, Sumit Saluja wrote:

> Physics Department
> 
> Princeton, NJ 08540
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> Phone-(609)258-7916\_\_
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**Author:** ![Sumit\_Saluja](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e0b2c6/32.png) [@Sumit\_Saluja](https://www.ruby-forum.com/u/Sumit_Saluja)\
**Post date:** [September 5, 2014, 5:13pm UTC](https://www.ruby-forum.com/t/gnuradio-file-sink-operation-need-help/231911/3 "2014-09-05T17:13:49Z")

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**Author:** ![Sumit\_Saluja](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e0b2c6/32.png) [@Sumit\_Saluja](https://www.ruby-forum.com/u/Sumit_Saluja)\
**Post date:** [September 5, 2014, 5:21pm UTC](https://www.ruby-forum.com/t/gnuradio-file-sink-operation-need-help/231911/4 "2014-09-05T17:21:53Z")

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Hi Sumit,

that’s kind of redundant – you know the start time and you know the  
constant sampling rate, so you know the time of each sample in your  
file. Anyway, the metadata sink saves every tag you specify, so just  
write a block that calculates the time to a given sample number, and  
occasionally adds a tag to the stream.

Greetings,  
Marcus

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**Author:** ![Sumit\_Saluja](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e0b2c6/32.png) [@Sumit\_Saluja](https://www.ruby-forum.com/u/Sumit_Saluja)\
**Post date:** [September 5, 2014, 5:24pm UTC](https://www.ruby-forum.com/t/gnuradio-file-sink-operation-need-help/231911/5 "2014-09-05T17:24:22Z")

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This then turns into a discussion about tagging during flow-graph  
operation. A subject I’m not that familiar with, so perhaps someone

else can insert their $0.02.

On 2014-09-05 11:12, Sumit Saluja wrote:

> SUBJECT: Re: [Discuss-gnuradio] GnuRadio File sink Operation, Need help
> 
> > Princeton, NJ 08540
> > 
> > Phone-(609)258-7916
> > 
> > * * *
> > 
> > Discuss-gnuradio mailing list
> > 
> > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)
> > 
> > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) [1]

Links:

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**Author:** ![Sumit\_Saluja](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/e0b2c6/32.png) [@Sumit\_Saluja](https://www.ruby-forum.com/u/Sumit_Saluja)\
**Post date:** [September 5, 2014, 6:28pm UTC](https://www.ruby-forum.com/t/gnuradio-file-sink-operation-need-help/231911/6 "2014-09-05T18:28:06Z")

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I’ll flip you $0.01; I found the new tutorials to be really helpful, and  
this  
one specifically shows how to write a block that inserts stream tags  
(the  
preceding tutorial shows how to write a block):

[http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided\_Tutorial\_Programming\_Topics](http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorial_Programming_Topics)

Although adding system time to every Nth sample may be pointless on a  
high  
rate stream, it may be useful for low rate stuff.

Lou  
KD4HSO

mleech wrote

> This then turns into a discussion about tagging during flow-graph  
> operation. A subject I’m not that familiar with, so perhaps someone
> 
> else can insert their $0.02.

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