# Is here a way to use a rtl-sdr with direct sampling mod on GNU Radio

**URL:** <https://www.ruby-forum.com/t/is-here-a-way-to-use-a-rtl-sdr-with-direct-sampling-mod-on-gnu-radio/243381>\
**Category:** GNU Radio\
**Created:** [October 4, 2015, 8:17pm UTC](https://www.ruby-forum.com/t/is-here-a-way-to-use-a-rtl-sdr-with-direct-sampling-mod-on-gnu-radio/243381 "2015-10-04T20:17:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Rafa\_F](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/958977/32.png) [@Rafa\_F](https://www.ruby-forum.com/u/Rafa_F)\
**Post date:** [October 4, 2015, 8:17pm UTC](https://www.ruby-forum.com/t/is-here-a-way-to-use-a-rtl-sdr-with-direct-sampling-mod-on-gnu-radio/243381/1 "2015-10-04T20:17:18Z")

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Hello,

I have a pre modified rtl-sdr like this  
[http://www.ebay.de/itm/like/400846220428?ul\_noapp=true&chn=ps&lpid=106](http://www.ebay.de/itm/like/400846220428?ul_noapp=true&chn=ps&lpid=106)  
which can receive vhf and shortwave directly.  
On windows shortwave listening works fine with hdsdr if I enable  
direct-sampling on Q branch in extIO.  
Now I am on Linux and I am tested gnu radio.  
GNU Radio is by building with blocks a very powerful tool. But it seems  
there is no way to receive HF except with a HF up converter.

I there any other way to receive shortwave on GNU radio?

Thanks for your answers in advance.

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**Author:** ![subroutine](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/fbc32d/32.png) [@subroutine](https://www.ruby-forum.com/u/subroutine)\
**Post date:** [February 24, 2016, 10:56pm UTC](https://www.ruby-forum.com/t/is-here-a-way-to-use-a-rtl-sdr-with-direct-sampling-mod-on-gnu-radio/243381/2 "2016-02-24T22:56:59Z")

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Hello,

the solution is to use “direct\_samp=2” in the device arguments.

Tested with both GNU Radio and GQRX (the latter has to be restarted  
after switching to direct sampling mode). I also have a modified RTL-SDR  
(PCB says it’s by BA5SBA), which looks just like the OP’s one.

Arguments for the Osmocom/RTL-SDR source block are documented here:

> **[GrOsmoSDR - gr-osmosdr - Open Source Mobile Communications](https://osmocom.org/projects/gr-osmosdr/wiki/GrOsmoSDR)**
>
> Redmine