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Re: [Discuss-gnuradio] FSK modulation

From: Pascal Matthieu
Subject: Re: [Discuss-gnuradio] FSK modulation
Date: Fri, 29 Apr 2011 13:51:37 -0700 (PDT)

Hi Marcus,

    yes I read a while ago and I will use code from FM.

   GNURadio is a very interesting software development toolkit. It's very usefull when trying to make some research, to try out many interesting things, but if you intend to make something that will be installed on certain computers in hundreds of different locations, you can't tell that they should install GNURadio, and install Python and Install I don't know how many dependencies, and an application will run some python code that will glue together some functions written in C++ and so on; you have to give a single executable, that will interact with some DLL files like the UHD to get data from different SDR platforms (the USRP in my case or maybe other Ettus devices).

  In Visual Studio I can make a professional GUI. As you said, yes I can use UHD to program USRP's FPGA, to get I/Q data and after that I could make my own software (containing GNURadio source code) to be able to do many interesting things. Anyway if GNURadio is compiled (gnuradio-core.dll) I could call functions directly from this DLL (I saw how functions are exported), anyway I don't know if functions use anything from boost and other libraries. So the idea is to be able to make own GUI in Visual Studio not python, to use functions from these libraries (UHD, gnuradio-core and others that might help) to make a fully functional software without the need to install Python; I will use some custom scripting language to set different parameters and specify some other libraries to modulate/demodulate or respectively encode/decode data. 

  The only thing to make my custom software is to find out how to use and how to call different functions from compiled DLL files and for this I will use example source codes.

  So as a final word GNURadio together with UHD are very valuable, what I don't like is python, and the idea that I would have to run some extra program to glue together C++ blocks, I like native code :). Anyway at the beginning I will use these tools to learn, and to make the project, after that I will move everything to my software. I was only interested if what I described at point nr. 2 is correct, with the received data, and the logic.

Thanks you Marcus for your answers. Have a nice day.


From: Marcus D. Leech <address@hidden>
To: address@hidden
Sent: Friday, April 29, 2011 9:18 PM
Subject: Re: [Discuss-gnuradio] FSK modulation

On 29/04/2011 2:05 PM, Pascal Matthieu wrote:

    I would like to ask a few questions regarding USRP, UHD and GNU Radio. I have 2 USRP devices and one module I bought that's able transmitt and receive on 433.92 MHz. I installed UHD on 2 computers (both with Win XP OS), connected to each one a USRP1 that has a WBX daughterboard and a Log Periodic type antenna by Kent Electronics that's on Ettus order page. Both USRP's are recognized. 

1. I would like to send some data packets that will have FSK and GFSK modulation. With one USRP I will receive data coming from the module and data coming from the second USRP. Each packet will have some data in it to be identified, so that I could log it. As I am a newbie I would like to ask if there are any test examples for GRC or simply Python to modify it to meet my requirements. Honestly I don't know where to start. There are blocks for AM, FM, DPSK, GMSK, QAM and others, each one heaving a MOD and DEMOD block but no blocks for FSK.
One thing to observe is that FM and FSK are essentially the same thing, with FM having a "continuous" modulation input, and FSK having
  a "discrete" (1s and 0s) input.
rors and data is not usable. Is it correct how I'm thinking the problem or I should tink in a different way. 

3. My first steps will be to try some source code in Python but after that I plan to make my own interface to control these devices (the second USRP and the module). I don't really know how to get the I/Q data from USRP, how to set different parameters like center frequency and others. There's any partial or full documentation related to this. If I could use the Visual Studio I would be able to make some GUI. If there's no souce code written for FSK maybe based on other codes written for other modulation types, I will make one, but ther's little chance for that to work, anyway I will have to know how to get I/Q data from USRP, how to write .rbf file to FPGA, and others.

Use the source, Luke.  All of the source code for Gnu Radio, UHD, and the FPGA code is all there.  If you want to build your own interface
  to the hardware, all the information is there, in the form of the source code, to do so.  But I have to ask--why?  Unless you have some
  very-stringent requirements, it doesn't sound like what you want to do can't be accomplished with UHD+Gnu Radio.  In terms of interesting
  intellectual exercises, I can think of others that would be more productive than re-inventing Gnu Radio and UHD.

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