Re: Join a FUNcube Eval
by Kilroy, Patrick L. (GSFC-5680)
An update:
I received my FUNcube Dongle! Initial bench
test results receiving a strong PICetSat signal
(see http://simsat.net/carrollsat/) look good
so far to me.
One reluctant evaluator, however, questioned
whether the tiny unit was little more than a
toy. So, I would like to run some formal
tests on it and other receivers at the same
time under the same conditions, and then
compare results. More testing and
evaluation will follow.
In the mean time, one fine group in Texas
may have stolen my thunder. See below for an
insightful message from Ken N8KH, who uncovered
the recent NTMS test results and offered
additional helpful comments to us.
But, as an aside about Ken's pre-amplifier
recommendation, I found several amplification
stages in the FUNcube Dongle itself that are
variable and can be easily changed. I will
experiment with them before purchasing another
satellite-grade low-noise pre-amp. I also
have a nice big DCI filter for 145 MHz and
another for 435 MHz to insert between the
dongle and antenna if and when needed.
Immediately below Ken's message, please see
the related links of interest for your
convenience.
Did YOU order a FUNcube Dongle yet?
Keep trying. The next sale should be
announced on the FUNcubeDongle Web site
soon.
Cheers,
Pat
N8PK
-----Original Message-----
From: Ken Hendrickson [mailto:[email protected]]
Sent: Thursday, May 5, 2011 11:19 PM
To: pat(a)patkilroy.com
Subject: MDS & NF Tests (Including FUNcube Dongle)
The North Texas Microwave Society (NTMS) just did
some testing of minimum detectable signal (MDS)
and noise figure (NF) measurements for common IF
receivers, including the FUNcube Dongle Pro [and
the IC-910H]. (It was published tonight.)
The FUNcube performed very well. On both 435 MHz
and also 1296 MHz it was within 3 dB of the best
out there. As you know, 3 dB is just barely
measurable in the laboratory with expensive test
equipment, and only barely noticeable on the air.
Their report/slides:
http://www.NTMS.org/files/MDS_NF_Measurements_IF_Rigs_RevC.pdf
If you want to make up that 3 dB, just add a very
good pre-amp to the front end. But be careful,
and do not overload the FUNcube with too much
signal. You don't want much gain -- only the
lower noise figure and enough gain to overcome
feedline losses. Make sure to measure dynamic
range after adding the preamp, to ensure you
haven't degraded dynamic range. But to be
honest, 3 dB probably isn't worth it.
Here are some quick and easy rules of thumb:
If you want to double range, you need +6 dB.
If you cut the bandwidth in half, you will add
+3 dB of performance (at the expense of time).
So if you need 6 dB, you can cut the bandwidth
in half twice. Use slower signaling, and longer
integration times at your receiver, and you will
have your 6 dB and doubling of range.
The first step to deciding if your FUNcube will
really work in your application is to do a link
budget. Do you have antenna gain pattern
figures? Bandwidths? Power output? Perhaps
I can help you out with the link budget.
My gut level feel is that your system will work
well, but math is better than a gut feeling.
73,
Ken N8KH
PS Please send the address of the Carroll County
amateur radio club meeting on Monday night.
--------------------------
LINKS
FUNcube Dongle Pro
http://www.funcubedongle.com/
SoftRock SDR
http://www.wb5rvz.com/sdr/
http://homepages.wightcable.net/~g4zfq/Si570.htm
Power SDR
http://www.flexradio.com/Products.aspx?topic=PowerSDRv2
http://flexradiowiki.com/frsradoiowiki/index.php?title=Main_Page
http://support.flex-radio.com/Downloads.aspx
HP 83712A
http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&nid=-53690019…
MDC High-Altitude Balloon Experiments
http://simsat.net/carrollsat/
--------------------------
Sent: Wednesday, April 27, 2011 11:08 AM
Subject: Join a FUNcube Eval
Cross-posted from amsat-dc(a)amsat.org ...
Yesterday I ordered a FUNcube Dongle Pro
from Howard Long, G6LVB, and AMSAT-UK
at http://www.funcubedongle.com/ for
under $200 USD to evaluate. []
I am evaluating this SDR receiver for dual
use on the Amateur Satellites and my STEM
project of SimSat, specifically, currently,
on quality of reception of my high-altitude
balloon experiment PICetSat flight modules.
We will fly again this summer.
Part of the FUNcube Dongle Pro technical
FAQ is reproduced below, FYI.
I am looking for others who wish to also
evaluate the same receiver for whatever
one's purpose. Please let me know if you
got one or when you get one, and what
software you are trying.
Thoughts?
THANKS and 73,
Pat Kilroy, N8PK
AMSAT Area Coordinator
MDC Area
>From http://www.funcubedongle.com/ . . .
Technical FAQ
Q. What is the FUNcube Dongle Pro frequency range?
A. 64-1,700MHz, although straw poll tests on
pre-production units indicate that units can
be stretched down to 51.5MHz or so. Upper
frequency limit is beyond 2,000MHz. In testing,
we have determined that there is a gap between
about 1,100MHz and 1,270MHz where the design of
the local oscillator VCO, PLL and divider chain
in the tuner chip don't provide seemless
coverage.
Q. What can the FUNcube Dongle receive?
A. The FUNcube Dongle has no restriction on
modulation schemes: it is limited only by the
application program running on the host computer.
As long as the signal fits within about an 80kHz
bandwidth, the FUNcube Dongle is capable of
receiving the radio signal. So, for analogue
reception, as well as narrow band FM and SSB,
it is also possible to receive, for example,
sound subcarriers for TV broadcast. Similarly
for data reception, as long as a data demodulator
has been written that will accept standard
soundcard quadrature I/Q reception, that will
work too.
Q. What is the bandwidth?
A. 96kHz is the quadrature sampling rate. Once
the ADC's decimation filter skirts have been
taken into account, you have about 80kHz.
Q. What applications work with the FUNcube Dongle?
A. As well as the forthcoming FUNcube front end
application, any application that understands
a standard stereo soundcard configured for
quadrature, or I/Q, reception should work.
Examples include Linrad, Spectravue, Rocky
and M0KGK.
Q. What is the sensitivity?
A. Each unit is tested for 0.15uV for 12dB
SINAD NBFM at 145MHz and 435MHz.
Q. What operating systems are compatible?
A. Currently Windows 2000 SP4, XP 32 bit, and
Vista and Windows 7 32 and 64 bit have been
tested. The sound card element works with
Mac OSX and Ubuntu 10.10 32- and 64-bit, but
the frequency setting application has not
been ported yet.
[snip]
