# Polyphase Filer examples and Busport Implementation for QT GUI Frequency Sink

**URL:** <https://www.ruby-forum.com/t/polyphase-filer-examples-and-busport-implementation-for-qt-gui-frequency-sink/234128>\
**Category:** GNU Radio\
**Created:** [February 8, 2015, 8:52pm UTC](https://www.ruby-forum.com/t/polyphase-filer-examples-and-busport-implementation-for-qt-gui-frequency-sink/234128 "2015-02-08T20:52:28Z")\
**Posts on this page:** 2\
**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:** [February 8, 2015, 8:52pm UTC](https://www.ruby-forum.com/t/polyphase-filer-examples-and-busport-implementation-for-qt-gui-frequency-sink/234128/1 "2015-02-08T20:52:28Z")

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Hello:

In trying to execute the flowgraphs found in the blog post on the  
subject  
at:

> **[PFB Channelizers and Synthesizers — Rondeau Research](http://www.trondeau.com/examples/2014/1/23/pfb-channelizers-and-synthesizers.html)**
>
> Building the Filters 
> Based on the paper presented at the  Karlsruhe Institute of Technology's  Workshop on Software Radio (WSR). 
> The paper starts off by explaining how to build the prototype filters and how these lead directly to the...

I find that the Busport connections in flowgraphs such as  
fm\_reconstruction.grc and others are broken when they connect to the QT  
frequency sink block. I have been looking for information regarding the  
best way to fix these as there does not seem to be a link to the  
Bus\_connection vector in the block. I am working with GnuRadio 3.7.6.1  
under Ubuntu 12.04 LTS

Any insight or leads are welcomed.

–  
Larry Van Der J.  
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**Author:** ![larryj](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/e480ec/32.png) [@larryj](https://www.ruby-forum.com/u/larryj)\
**Post date:** [February 9, 2015, 2:32pm UTC](https://www.ruby-forum.com/t/polyphase-filer-examples-and-busport-implementation-for-qt-gui-frequency-sink/234128/2 "2015-02-09T14:32:22Z")

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On Sun, Feb 8, 2015 at 2:50 PM, Larry Van Der J. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> frequency sink block. I have been looking for information regarding the  
> best way to fix these as there does not seem to be a link to the  
> Bus\_connection vector in the block. I am working with GnuRadio 3.7.6.1  
> under Ubuntu 12.04 LTS
> 
> Any insight or leads are welcomed.
> 
> –  
> Larry Van Der J.

Hi Larry,

Unfortunately, this is a pretty nasty problem. I’m not sure where it  
came  
from, but it’s likely due to some update in GRC (a while ago) that  
caused a  
slight change in formatting or parsing. The result is that the GRC files  
for this example have to be pretty much redone from scratch as far as I  
can  
tell. I’m not sure when I’ll be able to get to this, either.

Tom