Because in GR I can generate impaired signals approximating real world conditions, with fine control and repeatability. I can then run that through the Tayloe while experimenting with it's variables, again with fine control and repeatability. Finally I can work with DSP on the output of the Tayloe, observing the total system response.
On Sat, Aug 13, 2022 at 4:38 AM Steve Hubbard <stevezsuz...@iinet.net.au> wrote: > Hi, > > It's not clear to me why you would want to do this. As far as I can see, > the purpose of a Tayloe detector is to mix a real-valued RF signal with > a complex-valued local oscillator to arrive at an intermediate frequency > at or near zero frequency that can be sampled using a sound card. If > you're using GR the implication is that the signal has already been > sampled. > > An ideal hardware IQ mixer would be a pair of analogue multipliers with > sine local oscillators. However, this is not practical if good linearity > is required (linearity is desirable to avoid intermodulation distortion > and other nasty things). This is why switches are used. The switches > used to be diodes, and still are at higher frequencies, but at HF CMOS > analogue switches work better. With a switch based mixer you are > effectively multiplying by a square wave, which comes with the > disadvantage that odd harmonics of the square local oscillator also > convert signals and noise into the IF. This necessitates a filter in > front of the mixer to suppress these spurious responses. When IQ mixing > is required there are the added challenges of phase and amplitude > balance. Sometimes things ain't pretty in the analogue world. > > As has already been pointed out, in GR a complex multiplier is the usual > way to go. An accurate multiplier can be fed with near perfect > numerically generated sine waves with perfect amplitude and phase > balance. Besides, even if you wanted to simulate a square wave local > oscillator in DSP you'd have to approximate by only including the > harmonics up to the Nyquist frequency. > > On 13/8/22 03:08, david vanhorn wrote: > > Ive been wrestling with this for a while, and im not even seeing how > > to get started implementing a Taylor detector in gr. > > > > Is it even possible? > > -- K1FZY (WA4TPW) SK 9/29/37-4/13/15
