USRP vs alternatives

Because of the very high cost of the USRP, I’m looking for
alternatives. I found this gadget and I wondered if GNUradio is setup
to use devices like this:

http://www.amqrp.org/kits/softrock40/

It appears to have its own software, but I’d rather get it to work
with gnuradio if it’s possible to do so. Am I better of adapting the
software they provide? Am I better of trying to find the money for a
USRP? I don’t know enough to even know how to approach these
questions. It seems like everything I read in SDR turns into a very
deep rabbit hole.


If riding in an airplane is flying, then riding in a boat is swimming.
107 jumps, 43.5 minutes of freefall, 83.4 freefall miles.

I really does not have it’s own software. It’s just that most softrock
user
like to use the “rocky” software because it runs on Windows. You can’t
really do much with Rocky because it is closed source, binary only.

Many people are using other software with softrock hardware. However
I think most of that “other” software is Dttsp based rather then
gnuradio based. The
hardware is designed to be connected to a sound card and outputs
I and Q over a pair of analog outputs. So what ever software you use
it would not have to “talk” to the softrock, it would talk to your
computer’s audio subsystem. Connections to the SR are all
analog

The kit costs only $8 for the
receiver and even with it’s use of SMD is not hard to build.

On Thu, Sep 25, 2008 at 6:55 AM, Paul Miller
[email protected] wrote:

questions. It seems like everything I read in SDR turns into a very
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio

Chris Albertson
Redondo Beach, California

On Thu, Sep 25, 2008 at 12:57 PM, Chris Albertson
<[email protected]

wrote:

Many people are using other software with softrock hardware. However
I think most of that “other” software is Dttsp based rather then
gnuradio based. The
hardware is designed to be connected to a sound card and outputs
I and Q over a pair of analog outputs. So what ever software you use
it would not have to “talk” to the softrock, it would talk to your
computer’s audio subsystem. Connections to the SR are all
analog

Most of the “other” software definitely uses DttSP, either bare (on
Linux or
OS X) or inside PowerSDR (Windows). It does the job pretty well, if I
say so
myself, speaking as one of the authors, along with Bob McGwier, N4HY.
But
messing around on the inside is not for the faint-hearted and the
learning
curve is steep. The design is determined overwhelmingly by the need for
minimal latency in full-duplex, together with tight asynchronous control
of
the lowest-level parameters. It isn’t and wasn’t ever meant for
experimentation. You need to have a pretty clear idea of where you’re
going
before you ever lift the hood to change something.

If what you want is to get your fingers into the software, assemble your
own
soft radios, you definitely, positively, absolutely want to use GNU
Radio as
the software backend. That’s one of the things it’s for and it does the
job
wonderfully. Once you get the hang you can put together a new
application in
minutes. I myself am right now in the process of developing some new
features for DttSP and am prototyping them all in GNU Radio first.

A decent soundcard is a must, though.

Frank

On Thu, Sep 25, 2008 at 1:42 PM, Frank B. [email protected]
wrote:

If what you want is to get your fingers into the software, assemble your own
soft radios, you definitely, positively, absolutely want to use GNU Radio as
the software backend. That’s one of the things it’s for and it does the job
wonderfully. Once you get the hang you can put together a new application in
minutes. I myself am right now in the process of developing some new
features for DttSP and am prototyping them all in GNU Radio first.

A decent soundcard is a must, though.

I’m pretty sure GNUradio is the way I want to go then. You, and
others on this list-thread, seem to suggest the sr40 can indeed be
used with GNUradio, iff you have a decent sound card. … am I
reading that right?

I’m just trying to get my feet wet on the subject, so the $8 - $50
pricetag is easier to swallow than $700-$1400. I’m assuming there’s a
huge amount of limitations with the sr40 over the USRP, but it can be
used successfully. That’s interesting.

On Thu, Sep 25, 2008 at 1:41 PM, Stan S. [email protected]
wrote:

Ramakrishnan, VU3RDD, in March 2006, said he had made a crude first
version of a demodulator for the softrock. See
http://www.zerobeat.in/gnuradio/sr40 .

Everything about the sr40 seems “crude” but it’s interesting to note
that I wouldn’t even have to start from scratch.


If riding in an airplane is flying, then riding in a boat is swimming.
107 jumps, 43.5 minutes of freefall, 83.4 freefall miles.

On Thu, Sep 25, 2008 at 12:57 PM, Chris Albertson
[email protected]ain.invalid wrote:

computer’s audio subsystem. Connections to the SR are all
analog

GNU radio can work just fine with a sound card. I had a OFDM link
going over an audio cable before I owned USRPs. :slight_smile:

On Thu, Sep 25, 2008 at 11:18 PM, Paul Miller
[email protected] wrote:

On Thu, Sep 25, 2008 at 1:41 PM, Stan S. [email protected] wrote:

Ramakrishnan, VU3RDD, in March 2006, said he had made a crude first
version of a demodulator for the softrock. See
http://www.zerobeat.in/gnuradio/sr40 .

Everything about the sr40 seems “crude” but it’s interesting to note
that I wouldn’t even have to start from scratch.

Suggest you to not even look at that code. It is nothing more than an
SSB phasing demodulator. There is a lot more things to be done in the
recieve chain to build a decent reciever.


Ramakrishnan VU3RDD

You will need a soundcard and then you set up an stereo source. I/Q at
baseband is delivered.

There is no “softrock interface” in gnuradio because there is no
hardware to
control. It delivers a 100 kHz or so and this is centered on the
crystal
frequency on the softrock.

In gnuradio-examples/python/apps there are the Swiger hf_* applications
which could be easily modified to do the required tasks.

Bob

ARRL SDR Working Group Chair
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
NJQRP, QRP ARCI, QCWA, FRC.
“Trample the slow … Hurdle the dead”

Paul Miller wrote:

I’m just trying to get my feet wet on the subject, so the $8 - $50
pricetag is easier to swallow than $700-$1400. I’m assuming there’s a
huge amount of limitations with the sr40 over the USRP, but it can be
used successfully. That’s interesting.

These are apples-to-oranges comparisons.

The USRP is designed to digitize and present to the host software up to
8 MHz worth of bandwidth centered essentially anywhere from DC-3GHz, and
if you’re adventurous and want to reprogram the FPGA, you can do limited
processing with 60 MHz wide waveforms there. (The USRP2 extends this to
25 MHz on the host and 100 MHz wide on the FPGA). Of course you can
also do all the typical narrowband digital and analog waveform
processing you want, and the USRP also works as a transmitter.

The SoftRock-40 down-converts 48 KHz of RF spectrum at around 7 MHz
center frequency, and uses your computer’s sound card to digitize these
into samples. This is the amateur radio 40M allocation, where there is
a lot of activity in a variety of narrowband transmission modes.

Clearly, these are intended for vastly different audiences, with
differing requirements for RF capability, programming skills, and budget
constraints.

What they have in common, and what makes both such wonderful devices, is
that they make RF digital signal processing accessible to large numbers
of people. Not too long ago, this was an arcane discipline limited to
the professional RF engineering staff of industry and government
agencies. Now, along with GNU Radio, persons of the right sort of
curiosity and perseverance can learn the fundamental principles of DSP
and digital communications with a very small investment.

GNU Radio will work with either, though as a software radio toolkit,
GNU Radio requires you to write programs rather than having a lot of
canned, pre-written, fixed-function applications.

I had a question about this…

On Thu, Sep 25, 2008 at 12:57 PM, Chris Albertson
[email protected] wrote:

I really does not have it’s own software. It’s just that most softrock user
like to use the “rocky” software because it runs on Windows. You can’t
really do much with Rocky because it is closed source, binary only.

The PowerSDR software seems to both be GPL and be available on the
sr-40 website. Am I misunderstanding what the “rocky” software is?


If riding in an airplane is flying, then riding in a boat is swimming.
107 jumps, 43.5 minutes of freefall, 83.4 freefall miles.

On Tue, Sep 30, 2008 at 3:07 PM, Paul Miller
[email protected] wrote:

The PowerSDR software seems to both be GPL and be available on the
sr-40 website. Am I misunderstanding what the “rocky” software is?

http://www.dxatlas.com/Rocky/