Ooops,

[Jared Harvey]

Hello hamnerds,

Seems I hit a key and sent that last message
before it was completed. Here it is again, but
completed. Sorry about the last e-mail.

Looks like that $11 receiver is a bit hard to
obtain, seems everywhere is sold out. So I thought
I'd see if anyone might be interested in a
different approach. I have 4 or 5 of these
microtune 4707 cable front end tuners. They tune
an 8MHz bandwidth, for a large range for the
center frequency 48 MHz to 862 MHz. Here's the
datasheet.

http://www.tapr.org/pdf/4707-PH5-3x0456.pdf

I was working to use it with the SSRP from David
Carr a while back, but lost track of the project
when I pickup a hammer to build my house.

http://oscar.dcarr.org/ssrp/hardware/LTC1746/LTC1746.php

I also have this as the PC's USB interface, which
can get you receive from 0 to 20MHz. Such it can
nearly receive dc to 862MHz, with one blank area
between 20MHz and 48MHz.

http://oscar.dcarr.org/ssrp/hardware/usb/usb.php

I should have all the hardware required to make
this a functional device, but got a bit lost in
the software. Back when I worked on it last, using
GNURadio was much harder task. However GRC makes
the use of GNURadio much easier these days. Key
software steps include, writing some code for the
I2C tuner interface, and tweaking the code that
David used for his version, such that the I2C
commands can be passed to the tuner via USB.

If someone is interested, I'd be willing to help
them figure out how to make this into a radio
receiver. You'll need a computer that's fairly
recent, say less than 5 years old, other than
that, it should all be here and ready usable.

Best regards.

.. ..-. / -.-- --- ..- / .-. . .- -.. / - .... .. ...
.-.. . - ... / .... .- ...- . / .- / -... . . .-.

Jared Harvey Operator KB1GTT

e-mail ma...@jaredharvey.com
Web page http://jaredharvey.com

[AI2Q]

It was good to see you at the NERDS Tech Talk last night, and thanks for the
follow-up on the GNUradio SDR. I, for one, would be very interested in this,
however I am at a loss when it comes to software. Personally, I would be
able to assist with component procurement, hardware integration, PCB
fabrication and component soldering, testing, etc.

If others in the NERDS community are interested, perhaps we can proceed at
our meetings.

If you could define the various steps needed to move this along, that would
be good. I am a bit confused when I study the references you gave. Much of
it seems somewhat disconnected, with assumptions apparently made that target
those who might have been involved in this project for a long time. That is,
where is the entry point for a beginner?

I know guys like NV1T have software development expertise, and others have
extensive RF experience, so I'm sure we could get this kind of SDR project
going.

Vy 73, AI2Q, Alex

[Jared Harvey]

Hello AI2Q,

A> If others in the NERDS community are
A> interested, perhaps we can proceed at our
A> meetings.

I think you know someone with a SoftRock, perhaps
that would be a good demo ;)

About the SSRP, yes it's a bit hard to see the
trees from the weeds, as it's basically that
fellows project. Here's the basic flow of the SSRP
setup I have from start to finish.

An 8MHz wide bandwidth is captured from an Antenna
and mixed down to a 0Hz to 8MHz. This is done via
Microtune 4707 cable tuner. The Microtune has the
typical mixing and filtering found in most radios,
such that you can tune the center frequency of the
receiver and it will mix down to a base signal
that can then be used by something else. For many
radios, the base band signals would drive an audio
path such that you hear audio on a speaker.
However in this case, it's A TV Cable tuner, so
what comes out is 8MHz wide, not 20KHz wide.
Instead of a radio with a knob for tuning the
center frequency, the frequency can be changed via
I2C digital communications. Such that you can
choose nearly any 8MHz wide band, as low as 48MHz
and up to 862MHz.

This base band 8MHz signal can then be converted
from analog to digital via ADC chip that captures
data from 0Hz to 20MHz, which easily captures the
8MHz signal coming from the cable tuner. If you
bypass the cable tuner, the ADC can directly
decode signals up to 20MHz.

This digital data from the ADC is then brought
into a USB converter chip, where the signal is
converted and piped to a modern/fast processor.

At this point, GNURadio, and GRC take over. GRC
allows you to draw a flow diagram where you draw
can draw about any signal flow you want.

One example that could be done in software is to
demodulate an AM signal and pipe it to a sound
card or headphone jack. To make an AM radio
receiver, you can drag and drop (or load) blocks
like those shown at the beginning of this video.

http://www.youtube.com/watch?v=317Iu6HRA0w

The example shows the full flow diagram that then
creates the user interface and AM decoder. The
fellow keeps changing stations by moving the 0
mark on the FFT display to a peak.

Another possibility is to draw or load a flow
graph that takes the USB data stream and decodes
side band radio like in this video.

http://www.youtube.com/watch?v=U0Jt9f7LSYc

That was the same hardware, the only change was a
different program. You can make what ever you want
by simply snapping different blocks together to
create different features. If you want PSK, you
simply change the blocks around. If you want a CW
skimmer, same thing, change the blocks around. The
sky is the limit on what can decode.

After you get this USB stream of bits, you can
make the receiver into almost anything you want,
all you have to do is change the software to
decode what ever you might be looking for.

I hope that helps show the basic outline of how
the SSRP would work. I have all the parts
connected that get that USB stream physically
there, however there are a couple software steps
that need to happen before my pieces of hardware
can actually operate.

[AI2Q]

 

Thanks for passing this along, Jared.  The ability to graphically program to reconfigure the GNU radio is the essence of SDR.

 

It reminds me of National Instruments's company's LabVIEW graphical programming environment for industrial and scientific non-radio applications. In NI LabVIEW you connect blocks graphically and the system compiles the object code from that easy-to-use human interface that Ni has created.

 

Also, check out the SDR in this month's issue of QEX here:  http://www.arrl.org/files/file/QEX_Next_Issue/Mar-Apr_2012/Hightower.pdf  

 

This circuit resides on a 2 x 3-in. board and includes the requisite data conversion and filtering, as well as the communications to/from the PC. For the latter, it uses a Cypress semiconductor PSoC

that packs a built-in USB port. Nothing could be simpler.

 

The program files for the PSoC micro, and the Windows driver files can be downloaded from the ARRL QEX files at www.arrl.org/qexfiles. Look for the file 3x12_Hightower.zip.

 

 

I wonder if ARRL or the author could supply either the PCB files or perhaps even kits?  It would make a fabulous NERDS club project.

 

Vy 73, AI2Q, Alex

 

[Jared Harvey]

Hello NERDS,

I just got this SDR radio receiver

http://www.ebay.com/itm/Digital-TV-Tuner-DVB-T-MPEG4-Digital-TVSD-Realtek-RTL2832U-Elonics-E4000-P250-/220992182158?pt=US_Video_Capture_TV_Tuner_Cards&hash=item337429178e

Should work with the software noted on this page.

http://sdr.osmocom.org/trac/wiki/rtl-sdr

Basically I read an article, then got the $20
device, now I need to figure out what to do next.
Perhaps other NERDS would like to help me figure
out how to make this guy go :)

[AI2Q]

Once baseband I/Q signals are derived, how are they digitized?

Vy 73, AI2Q, Alex


----- Original Message -----
From: "Jared Harvey" <ma...@jaredharvey.com>

[Jared Harvey]

Hello AI2Q,

A> Once baseband I/Q signals are derived, how are
A> they digitized?

It appears it's an 8 bit ADC, min sample rate is
apparently 900 ksps and max is 3.2Msps, nominal
1Msps. A data sheet would be nice, this page seems
to fill in some technical details.

http://wiki.spench.net/wiki/RTL2832U

According to this page.

http://superkuh.com/gnuradio.html

This is the schematic for the E4000 I got.

http://superkuh.com/gnuradio/e4000_refsch_rev4.pdf

[AI2Q]

Looks like dual I/Q outputs. Very cool, especially as there is software
available to process it.

== Alex

----- Original Message -----
From: "Jared Harvey" <ma...@jaredharvey.com>
To: <hamn...@googlegroups.com>