[Elecraft] (phase signals RE: SDR IQ/IF Questions

[Wes Stewart]

Just a couple of extra thoughts.

I use an SDR-IQ as a panadapter on the i-f output of my K3 and it works (*almost) flawlessly.  

(*I have never found anything with a microprocessor in it to work completely flawlessly).

So the SDR-IQ can be used both as a standalone receiver with decent demodulation capability with the supplied SpectraVue software and/or as an excellent panadapter with the same software.  This has a good (i.e simple) GUI and serves the purpose well.

SDR-Radio is another program that supports the SDR-IQ but it is way too complicated and changes sometimes several times a day.  Not ready for prime time in my view. (Flame suit on)

The LP-Pan works well with a decent soundcard, but suffers from the use of PowerSDR software, which is simply awful in my opinion, and lots of cabling.

I have seen a prototype P3 in action, but don't have extensive knowledge of it, other than to note that the screen is too small for my taste and located in the wrong place.  The proposed VGA output will solve the screen size problem, but unless I'm mistaken, precludes the use of the same display for several programs.

My current setup has a laptop usually with a web browser displayed and N1MM (if contesting) or DXBase (if DXing), MMTTY and the panadapter window all on a second monitor.  For my purpose this is the most functional option.

Wes  N7WS

--- On Wed, 4/6/11, George A. Thornton <gthornton at thorntonmostullaw.com> wrote:

> IQ data is a method for describing
> the characteristics of a wave.  IQ
> uses amplitude and phase angle to describe the wave, see
> for example 
> 
>  http://zone.ni.com/devzone/cda/tut/p/id/3013
> 
> The K3 takes an RF signal from an antenna, filters and
> modulates it.  At
> some point the filtered, modulated signal is made available
> to an IF out
> port where it can be used conveniently by various testing
> and measuring
> devices.
> 
> A panadapter takes the IF signal and converts it into IQ
> signals.  These
> IQ signals can then be used to visually represent
> characteristics of the
> signal on a chart or screen.  The LP-pan converts the
> I and Q signals to
> audio for input into a computer using a sound card. 
> The P3 panadapter
> directly charts the IQ data onto the built in screen.
> 
> The SDR-IQ is a standalone software designed
> receiver.  It is designed
> to hook directly into an antenna source and can be used
> with software to
> directly display data about the signal.  I do not
> believe it is designed
> to work with modulated IF output from a quality receiver,
> but I could be
> wrong.
> 
> The SDR-IQ can be used as a standalone panadapter through a
> computer,
> getting its signal direct from the antenna, completely
> bypassing the
> transceiver altogether.  According to its own manual
> it does not have
> much filtering and it can get overwhelmed by other RF
> sources.  
> 
> The price for the LP-Pan and sound card is less than the
> price for the
> SDR-IQ.  The P3 costs only a small amount more than
> the SDR-IQ.
> 
> The P3 and LP-Pan were compared in a recent QST
> article.  According to
> the testers, the two approaches are roughly equal in their
> ability to
> decode and display weak signals.  
> 
> The LP-Pan has the advantage of allowing the use of a large
> computer
> screen for a panadapter. The disadvantage is that it is
> complex to set
> up, requires use of buggy computers and software with
> driver
> compatibility issues and has a lot of loose wiring.  
> 
> The P3 is a plug and play solution that is reliable and
> easy to use. The
> P3 is more closely integrated with the K3.  IN the
> future the P3 is
> going to allow direct connection to a computer monitor and
> keyboard.
> 
> Given all the factors, I do not think the SDR-IQ solution
> is the best
> choice here.