Re: LF: Re: DSP Question I/Q inputs?

[Wolf DL4YHF <dl4yhf@freenet.de>]

Hi Warren,

Just returned from a QRL trip to Bavaria so sorry for the delay.

Not much to add to what Alberto said.. it's nice to have I/Q output from 
the frontend of an image-cancelling DC receiver, and to effectively 
double the bandwidth of the soundcard input (for example, observe a 96 
kHz wide spectrum band if the soundcard supports a true sample rate of 
96 kSamples per second). But for LF... well ..
To decode a PSK(31) signal from such a receiver, you could use SpecLab 
with I/Q inputs (stereo mode), use the mixer/multiplier block in "I/Q" 
mode to convert the signal back into a single-channel audio signal (can 
be done but tricky to set up; please ask if you need further 
instructions).  The PSK decoder (aka "digimode terminal") must be 
connected to label L5 in the circuit diagram, after combining the 
downconverted I- and Q channels.
Cheers,
 Wolf .