# Exposing packet informatoin

**URL:** <https://www.ruby-forum.com/t/exposing-packet-informatoin/232051>\
**Category:** GNU Radio\
**Created:** [September 15, 2014, 9:42pm UTC](https://www.ruby-forum.com/t/exposing-packet-informatoin/232051 "2014-09-15T21:42:12Z")\
**Posts on this page:** 3\
**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 15, 2014, 9:42pm UTC](https://www.ruby-forum.com/t/exposing-packet-informatoin/232051/1 "2014-09-15T21:42:12Z")

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I wrote a VITA-49 deserializer block. How can I expose information like  
the sample rate extracted from the header to the other blocks in the  
system?

//\ark.

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**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\
**Post date:** [September 15, 2014, 10:27pm UTC](https://www.ruby-forum.com/t/exposing-packet-informatoin/232051/2 "2014-09-15T22:27:20Z")

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Hi ?arc,

This depends on the other blocks you’re looking at!  
The gr-uhd USRP source uses stream tags to enrich the sample stream with  
such information as rx\_freq and rx\_time, but the other blocks need to  
care about these tags, or they won’t change their behaviour.

Greetings,  
Marcus

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**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\
**Post date:** [September 16, 2014, 5:31pm UTC](https://www.ruby-forum.com/t/exposing-packet-informatoin/232051/3 "2014-09-16T17:31:00Z")

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That is what you would use stream tags for.

Cheers,  
M