Re: Taylor detector

[david vanhorn]

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 <stevezsuzska@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?

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K1FZY (WA4TPW) SK  9/29/37-4/13/15