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Re: [Discuss-gnuradio] Basic analog USRP2 transmitter

From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] Basic analog USRP2 transmitter
Date: Sun, 07 Nov 2010 22:13:20 -0500
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20100907 Fedora/3.0.7-1.fc12 Thunderbird/3.0.7

On 11/07/2010 09:38 PM, alexander levedahl wrote:
This is the third time I have asked for help, each time I have tried to be civil, but I get responses back telling me to learn linux, not help with GNU-Radio/USRP2.  Or if they are help with GNURadio/USRP2, it is with GRC, which doesn't work with whatever version of Fedora I happen to have. 

My initial request for help was a couple of weeks ago and was this:

I just started using the USRP2 with GNURadio.  I have made a script that uses the gnuradio library, but it does not try and interface with the USRP2.

How do you do this?  Or alternatively is there a list of gnuradio functions that I can look at that has how to set this up?  I have tried doing a google search for this, but it turns up nothing that I have found to be helpful.


The response was for GRC, which doesn't work with whatever version of Fedora I have; however, by looking through the examples I tried to scrape together something, that didn't work.

My second request for help was this:

I have tried transmitting an analog signal from one USRP2 to another, but when I run usrp2_fft.py on the rx computer, there is no receive signal.  The analog signal is supposed to be two tones at 350 and 440 HZ transmitted at 2.6GHz.  Can anyone help me figure out what I am doing wrong?

This included the python script that I had written; I did not get any responses.

My third request:

I have tried transmitting an analog signal from one USRP2 to another, but when I run usrp2_fft.py on the rx computer, there is no receive signal.  The analog signal is supposed to be two tones at 350 and 440 HZ transmitted at 2.6GHz.  Can anyone help me figure out what I am doing wrong?

I have tried using GRC, but at the most up to date version does not work with Fedora, which is the OS that I have to use, this is for a research project with a professor at my university, and the mandate is to use Fedora, this does not look like it will change in the near future. 

Again the response was to use GRC, which does not work with the version of Fedora that I have. 

Fedora 11 is old and no longer updated. Upgrade your fedora.

As I mentioned in my initial request for help, I cannot change the version of Fedora that I have.  It is mandated by a person who at the beginning of this semester made the decision to use this specific OS and it cannot be changed because of a large amount of software that would have to be reinstalled.  This ordinarily would not be a problem, except for the fact that the software has to be installed in a specific manner depending on the specific version of the OS and the OS itself.  I do not use that software, but that is the reason I was given.  This again would not be a problem since I have a laptop that I can do whatever with, but that doesn't solve the problem for everyone else on the project, somewhere between 15 and 25 people.  And I have Fedora 13, my inclusion of the statement about Fedora 11 was to illustrate a point about how confusing the instructions are.

If you make a mistake installing software, its not a big deal, just google around, and if you need help,  ask  for help, polietly and someone will help. Complaining is not gonna fix anything.

I did ask for help; however, I did not get it, I got people telling me to use GRC, which doesn't work with whatever version of Fedora I happen to have.

Assuming you actually need to Install sdcc from source, it is no different then installing gnuradio from source. 7 simple steps here is the link from my google search "sdcc install linux"http://sdcc.sourceforge.net/doc/sdccman.html/node15.html#sub:Building-SDCC-on-Linux

And what if I don't understand 75% of phrases in these 7 "simple" steps?

I use Linux, and almost every program i use is a single click install from the software center and its free. Your comparing installing binaris in windows to installing bleeding endge source code in linux. Not a valid comparision.

Interesting, the one time I actually need to use linux, it is not a "single click install."  Someone gave a bash script that installed GNU-Radio, and that works as long as I restrict myself to using the sample scripts that come with GNU Radio, which again is not useful.

1) As with a lot of things that seems complicated at first, some basic knowledge helps simplify things greatly. I'd suggest checking out a basic linux book at your library. Perhpas some others on the list can suggest some.
2) Linux isn't that scary, and most problems you encounter can be fixed up with a bit of googling.

Or perhaps you could suggest some?  I also tried googling for help with USRP2, but got back links for a program I can't use or links that don't help.

3) GNU Radio + USRP isn't an easy thing. It requires knowledge of programming, DSP, digital communications, and maybe even some basic electronics/circuits. If you already have that knowledge, why not take a bit more time and get some linux knowledge under your belt. The two (at this point) really go hand-in-hand.

I have knowledge of DSP, programming (however, I had to start learning python), digital communications and circuits and electronics.  I do not know linux.  My objective is to learn how to use a USRP2 and I do not have the time to also learn linux.

Apples to oranges comparison.  Linux distributions have "installers" for 100s and 100s of
  of different pre-configured, ready-to-go applications, just like Windows does.  Those installers
  take care of any pre-requisites required, typically.  There are pre-packaged versions of Gnu Radio
  available for Fedora, including GRC.  Those pre-packaged versions are somewhat out-of-date
  with respect to the current development (actually, sometimes *really* out-of-date).  On Fedora,
  Using the "System->Administration->Add/Remove Software" function allows you to select
  from hundreds and hundreds of categorized software and install it over the net, generally
  utterly seamlessly.  Try going in there and typing a search term, like "gnuradio" or
  "plotting", or "scientific" or "engineering", or "radio", or "algebra", or "simulation", or
  "electronics".   Some of what you find there likely also has versions for Windows.

When I do System-Administration-Add/Remove Software and then search for grc I get grc-0.70-6.fc12, which I already have ( or at least am assuming by the checkmark next to the little open package box). 
See my comment about how packagers for various distributions cannot be *forced* to package
  newer versions of things (in this case, GRC).  No amount of complaining to *this* forum can
  change that.  You can complain to Ford all you want about a GM vehicle that happens to use
  an older part that was originally made by Ford, but really, GM are the right people to gripe at,
  not Ford.  I'll observe that even Fedora 14, which was released only last week, still bundles
  GRC 0.7, rather than a newer version.  Nothing that *this* forum can do about that.

So, the "fix" is to do an install from source, which as you've discovered, isn't "one click install".
  That's rather the nature of the beast.

It's like the difference between trading in your older and rather less functional vehicle on a
  new one, which only requires that you be able to handle sufficient amounts of cash, and
  deciding to "dive in" and repair the engine, transmission, and suspension yourself. One of
  them is going to, necessarily, require that you learn something about engines,
  transmissions, suspensions, and the appropriate tools for repairing them.
  One of them requires only a suitably-large bank account.

Let's use another analogy, because, hey, I'm full of them.  You buy a computer from Dell, which
  sports a fancy "Intel Inside" sticker.  Only you discover that they're using a CPU that's at least
  two generations out of date.  So you call up the *Intel* help desk and berate them for hours about
  how your computer is using a two-generations out-of-date CPU, and what the steaming heck is
  Intel going to do for you?  Intel will quite-rightly tell you to complain to Dell, since Intel has been
  making much-better CPUs for two years, it's not Intel's fault that Dell are using somewhat-lesser
  CPUs in the machines they sell to customers.

So you decide to upgrade your Dell machine yourself, and start bitching and griping at Intel
  and all their friends about how hard it is to upgrade a machine.  You have to know something
  about screwdrivers, and anti-static wrist bands, and heatsinks, and heatsink compound, and
  oh crap, you just cut yourself on the sheet metal.  You cuss and swear and say things like
  "you see how hard all you engineers at Intel have made my life!, you see?!!!!"

P.S. You might be able to avoid a lot of these problems if you wrote a tutorial on how to write a python script that does this instead of an infinite number of tutorials on how to write a python script that transmits 350Hz and 440Hz tones over speakers and a grc diagram that transmits the same tones over the air.

This sentence was supposed to mean that a tutorial on how to do simple transmission with USRP2 in python (and not in GRC due to issues installing it across different operating systems) would be helpful.  I am sorry that the meaning was not clear. 

I have gone back through the build guide for fedora that is located on the GNU radio website, and it does not help with upgrading GRC.  GNU radio is working fine, but GRC is not.


A volunteer group of folks will generally work on that which "turns their crank". If that means
  that some of the "useful" examples are done in GRC, rather than in "raw" Python, then so be it.
  You're free to, once you've done the necessary learning, put together examples and tutortials
  yourself and submit them to the project.  Nobody is going to stop you.

Principal Investigator
Shirleys Bay Radio Astronomy Consortium

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