[Spooks] SDR Questions By KD7JYK - SDR-IQ Example

WD8ARZ wd8arz at comcast.net
Sat Aug 9 09:06:53 EDT 2014


Hello Kurt, this is Bill WD8ARZ.

Understandable questions, and I can answer them as they apply to the 
SDR-IQ. It has had several firmware updates since it originally came out.
http://www.rfspace.com/RFSPACE/SDR-IQ.html

A variety of software will operate the SDR-IQ. A program called 
SpectraVue is provided free and a wonderful program.
http://www.rfspace.com/RFSPACE/SVDownload.html

* For those playing with the modern SDR's, do they have selectable 
bandwidth?
    Answer: Yes, most SDR's allow for variable bandwidth setting for all 
modes.
    Many allow for setting lower and upper frequency points for the 
bandwidth.

* What about looking at a wideband signal, if you set an SDR to 30 or 40 
KHz, would you see and hear that whole swath?
    Answer: Yes, most SDR receivers give you configuration options for the
    display and audio / mode separately. At some point in the bandwidth 
setting,
    audio is not provided as it will be limited to the bandwidth of the 
selected mode
    to listen in.

Specifically to the SDR-IQ
=====================
Maximum display bandwidth of 196 KHz at an incredible 0.75 HZ RBW.
Records and plays back spectrum segments up to 196 KHz wide with full 
demodulation and tuning capabilities.
Amazing Frequency coverage of 500Hz to 30 MHz. Usable down to 100 Hz.

Note: That is not an error. 500Hz and 100Hz is correct, it is NOT kilo 
hertz.

Directly interfaces with Icom, Kenwood, Elecraft and Yaesu radios for 
use as a tracking panoramic adapter. Built in serial RS-232 port. This 
port can be used to communicate with external radios. Supports AM, FM, 
NFM, WFM, LSB, USB, CW, CWR, DSB, DRM and customs demod filters / offsets.

There are many many other features, but it is probably best you explore 
those on your own. Download the manual at:
http://www.rfspace.com/RFSPACE/Support.html

One of the key features I just love that took years for other SDR models 
to pick up on, is the ability to record rf spectrum to a hard drive 
file. When you play that recorded spectrum file back it is NOT audio, it 
is just like exploring that spectrum when you are in real time tuning 
true RF, except it is a recorded file. For example. Record one hour of 
196 KHz bandwidth for the AM broadcast band. Those stations are 10 KHz 
apart. You can listen to each of those stations in turn for that one 
hour duration. It will take you twenty hours to listen to it all in real 
time playback. That includes the spectrum display. All is just as 
configurable from the recorded file as when in real time live mode. 
Change the mode, bandwidth, display rate, etc etc.

Have an elusive digital mode that your having a hard time trying to 
decode? Record the bandwidth for that signal on the frequency of 
interest, or wider if wanted. Play back that file later and tune around 
for that signal. When you find it, back up the recording the beginning 
of that signal and start playing with the bandwidth and mode settings 
for the best possible copy. Then using any external software for digital 
modes, find the type and settings needed to decode it. Play that signal 
over an over again while testing different digital software modes and 
configurations until you have cracked it.

Of course you can do the same for AM, FM, SSB etc modes. Have a weak 
signal next to a strong one and your just not making out the ID the 
speaker says? Play with the Bandwidth, Mode, RF Gain, I.F. Gain etc and 
keep playing that section and I bet you get the I.D. of that station.

I could go on and on. Your tougher task is to sort out all those 
different models and features to get the bang for the buck you want. 
Suspect you wont be disappoint in starting with the SDR-IQ for learning 
/ testing, and end up keeping it even when you try some other SDR down 
the road. You dont see an SDR-IQ on sale a lot, and most of the time 
that is due to lack of it being used by the owner.

Good luck Kurt, and please keep us informed of your progress.

73 from Bill - WD8ARZ
South Bend, Indiana

On 8/9/2014 3:27 AM, KD7JYK DM09 wrote:
> For those playing with the modern SDR's, do they have selectable bandwidth?
> Everything I am familiar with has things alongs the line of 2 KHz or so for
> AM, 1.4 for SSB, various CW bandwidths, 100-200 KHz for FMBC, 15 KHz for FM
> on 10m and so forth.  Seems with a lot of the new modulation schemes,
> something where you can manually adjust the filter by the Hz would be nice
> for cutting out noise.  What about looking at a wideband signal, if you set
> an SDR to 30 or 40 KHz, would you see and hear that whole swath?
>
> Kurt


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