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[Discuss-gnuradio] Alternative Hardware [was: Re: A Humble Request.... -

From: Patrick Strasser
Subject: [Discuss-gnuradio] Alternative Hardware [was: Re: A Humble Request.... - "Open-Hardware"]
Date: Mon, 10 Jan 2011 14:23:47 +0100
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[Please! Möller, add a one line before and after you text, reading your
replies is really a pain.]
schrieb Moeller am 2011-01-09 18:07:
> On 09.01.2011 05:48, Brian Padalino wrote:
>>> Hello Mr. Ettus,
>>> Do you have any plan to reduce price for USRP1 or release PCB layout for
>>> poor students?
>> So lets figure out something that is worth while for you to do -
>> simulate something.  Simulate anything!  There is a channel simulator
>> built into GNU Radio.  Use it.  Get familiar with it.  Familiarize

> He didn't ask for a simulator, he asked for real hardware.

He did not back his request with some deeper insight why he exactly
needs this thing except for he wants it and has not enough money to buy
it. We do not know what he wants to accomplish, and how he thinks to get
there, what he already did. This would be very valuable information -
There are people around who could show alternatives that are easier to
get or cheaper/free, and some people have set up USRPs to be used by
other people. If you need off-the-air samples, some can be found already
online, or maybe someone is willing to record some special
signal for offline use on request.

Having a transmit capability is one really not replaceable capability,
but first that's quite at the end of the things to do, and second you
can easily run in problems with frequency licence regulations.

Moreover having an USRP is just half of the bill. The RF front-ends are
necessary too, and if you want one of the more advanced, you want get
far with <100$.
Compared to other systems that's still cheap, but not for free.

I agree with Brian, there is plenty of things that can be done without
(expensive) hardware.

> I saw some simpler approaches with a sound card. But that's really
> narrow band. Not very much for a spectrum analyzer.
> The SSRP approach seems to be more interesting:
> http://oscar.dcarr.org/ssrp/
> It has a 15 MS/s ADC, 40 MS/s DAC, he counts $120 for the ADC board.
> There's software to interface with Gnuradio.

Last time I asked David Carr had not time/interrest in continueing the
project. IMO the Elrasoft Interface board is ridiculous expensive. Its
merely an Cypress EZ-USB FX2 with some voltage regulators for 89$. I
think it was a good start, but there are other more promising parts
worth investigating:

* Have a look at Digilent [1] Basys and Nexsys boards. You get the same
interface chip as the USRP, which should give a good start for firmware
development, and a FPGA, switches, buttons, displays, connectors
(VGA/PS2 etc.) for about the same or less price. Academics/Students get
it cheaper.
Moreover Digilent offers a number of modules to connect, with examples
and schematics.
If you really want high sampling rates and frequencies, have a look at
the Charleston SDR [2].

* One interresting RX interface coming up these days is the
FuncubeDongle [3]. Unfortunately it's under a NDA spell, but the thingy
rocks. Hopefully the next batch will not be sold out in seconds.

* The Icom PCR1000 [4] is a commercial part with great frequency range.
ZFs at 10.7MHz and 450kHz exist, so maybe you can connect it to some
other standard hardware to do some great hacks and get RF OTA very cheap.

* If you have equipment to bring your signal down to baseband there is
nothing more promising than the SDR Widget [5][6]. They target USB Audio
usage, at 24 bits/192kHz, which should be quite sufficient for a number
of things to try. They claim to beat most of the commercial high end PC
sound interfaces in signal performance.

You see, there are quite some parts for ~100$ as alternative to USRPs.
Hardware exists, software is cheap if you have time and skill, as J.D.
Baker explained. If you do not have the skill, you still can learn ;-)



[1] https://www.digilentinc.com/
[2] http://www.amrad.org/projects/charleston_sdr/
[3] http://www.funcubedongle.com/
[4] http://shop.ebay.com/i.html?_nkw=icom+pcr
[5] http://code.google.com/p/sdr-widget/
[6] http://groups.google.com/group/sdr-widget
Engineers motto: cheap, good, fast: choose any two
Patrick Strasser <patrick dot strasser at student dot tugraz dot at>
Student of Telemati_cs_, Techn. University Graz, Austria

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