# Noob question 1 **URL:** \ **Category:** GNU Radio\ **Created:** [September 7, 2015, 10:36am UTC](https://www.ruby-forum.com/t/noob-question-1/243274 "2015-09-07T10:36:47Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\ **Post date:** [September 7, 2015, 10:36am UTC](https://www.ruby-forum.com/t/noob-question-1/243274/1 "2015-09-07T10:36:47Z")
Hello all 4 weeks ago did my first steps into Linux Ubuntu. I am trying to get the RTL-Dongel to work but still not succeded in that, Time to ask some help. There is a image with pre-installed drivers and GNU-Radio companion, [http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioLiveDVD](http://gnuradio.org/redmine/projects/gnuradio/wiki/GNURadioLiveDVD) I have downloaded that and put it on a USB stick. Works fine. In the terminal I enter rtl\_sdr -t and the RTL-dongel is found and it works. Then I start GNUradio companion, it is version 3.7.7.1. The RTL is found in the sources. But the radio has a blue output and the audio-sink a orange one. In the Help-doks it says that this is because of the datatype but I cant change that anywhere. The dongel properties-block gives “complex float 32”. Can you help me getting it to work? Only with a working system I can go further learning. Thanks Henk www.sterrenwachtleeuwarden.nl – View this message in context: [http://gnuradio.4.n7.nabble.com/Noob-question-1-tp55832.html](http://gnuradio.4.n7.nabble.com/Noob-question-1-tp55832.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![12henk12](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/1/9de053/32.png) [@12henk12](https://www.ruby-forum.com/u/12henk12)\ **Post date:** [September 7, 2015, 10:56am UTC](https://www.ruby-forum.com/t/noob-question-1/243274/2 "2015-09-07T10:56:04Z")
Hi Henk, the problem is that the RTL dongle (and any SDR peripheral) just gives you the signal as it is in the air – you will still have to demodulate it to get audio! Now, wild assumption: you want to listen to FM Radio for a start. So: - configure your audio sink to 44100 Hz sample rate - use a WBFM receiver block with a quadrature rate of N\*44100, and N as decimation, feed the output (orange!) into the audio sink - add a fractional resampler between source and WBFM receiver to match N\*44100 to a sampling rate the Dongle supports Best regards, Marcus ---
**Author:** ![12henk12](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/1/9de053/32.png) [@12henk12](https://www.ruby-forum.com/u/12henk12)\ **Post date:** [September 8, 2015, 6:42am UTC](https://www.ruby-forum.com/t/noob-question-1/243274/3 "2015-09-08T06:42:02Z")
Hooking in on the discussion here. I struggle with something similar. I know how to work gnuradio, that’s simple enough. What i want to learn more about is how to configure my own SDR using gnuradio. So what the various blocks are used for, when to use what block, etc. I have experience LISTENING to an SDR using various devices, now i want to BUILD one myself. The final objective is to learn how to decode well known signals like the various HAM radio protocols like PSK31, etc. I know that all has been done before and the easy road is to take an existing flow graph, copy it and see that it works. But to understand what is happening is a whole different story. So, without trying to hijack the thread, i am NOT looking for a gnuradio manual, i am looking for documentation on how to USE gnuradio for signal processing. Thanks for the advice, Ton. ---
**Author:** ![12henk12](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/1/9de053/32.png) [@12henk12](https://www.ruby-forum.com/u/12henk12)\ **Post date:** [September 8, 2015, 1:23pm UTC](https://www.ruby-forum.com/t/noob-question-1/243274/4 "2015-09-08T13:23:21Z")
My thoughts Ton, I just made the FM receiver Marcus advised and as discribed in tutorial 6. This week I will ask a few questions about the configuration of these blocks. Understanding is the key word for me. Thanks Henk Op 7-9-2015 om 13:38 schreef Ton Machielsen: ---
**Author:** ![12henk12](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/1/9de053/32.png) [@12henk12](https://www.ruby-forum.com/u/12henk12)\ **Post date:** [September 8, 2015, 4:31am UTC](https://www.ruby-forum.com/t/noob-question-1/243274/5 "2015-09-08T04:31:08Z")
Hi Jan Believe me, I am reading the tutorials, also the youtube lessons [![](https://img.youtube.com/vi/N9SLAnGlGQs/maxresdefault.jpg "GNU Radio Tutorials: Part 1 - GRC, Sources, Sinks, Audio & GUI Blocks") ](https://www.youtube.com/watch?v=N9SLAnGlGQs) But for me it is easier to understand basics when there is a basic working layout available. There is so much about GNURADIO out there that a noob also needs some help with the help. (lol). I am not a technician, developer or electronic engineer so the learning curve is steep. Thanks for your replay and links. When the RTL works I will post the layout here for others. Best regards Henk www.sterrenwachtleeuwarden.nl [http://www.sterrenwachtleeuwarden.nl](http://www.sterrenwachtleeuwarden.nl) Op 7-9-2015 om 10:47 schreef Jan Kr??mer: ---
**Author:** ![12henk12](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/1/9de053/32.png) [@12henk12](https://www.ruby-forum.com/u/12henk12)\ **Post date:** [September 8, 2015, 1:26pm UTC](https://www.ruby-forum.com/t/noob-question-1/243274/6 "2015-09-08T13:26:16Z")
On 09/07/2015 02:19 PM, Henk wrote: > My thoughts Ton, > I just made the FM receiver Marcus advised and as discribed in tutorial 6. > This week I will ask a few questions about the configuration of these > blocks. > Understanding is the key word for me. > > Thanks > > Henk It boils down to having an understanding of DSP, which proceeds from having an understand of signal processing in general. There are several good books, including the works of Richard Lyons, and Bill Sethares. There’s also: [www.dsprelated.com](http://www.dsprelated.com) and [www.complextoreal.com](http://www.complextoreal.com) Also, if basic RF signal-flow concepts are new to you, the first few chapters of the ARRL handbook are quite useful, even if you aren’t planning to become a ham radio operator.