[K3PZN-List] Join a FUNcube Eval

Fri May 6 16:46:16 EDT 2011

An update: 

I received my FUNcube Dongle!  Initial bench 
test results of 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 
works at Harris radio in Melbourne, FL.  Ken 
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:khendr01 at harris.com]
Sent: Thursday, May 5, 2011 11:19 PM
To: pat at 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=-536900197.536901304&pageMode=OV

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 at 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]