🚀 go-pugleaf

In article <Dec.15.11.52.08.1990.12495@elbereth.rutgers.edu>
true@elbereth.rutgers.edu (Dr. Destruction) writes:
>[explains usual method of frequency inversion]
>
>My question is that it seems that the result of what I am doing could be
>achieved as follows:
>
>	1) Gate (sample) the signal at 90% of the period
>
>	2) Invert it
>
>	3) Filter sharply at 1.6k
>
>This seems to be (thinking in the time-domain here) accomplishing the same
>thing as the 10% sampling and subtraction of the baseband. The plus is that
>I wouldn't need to subtract anything now! Do you agree with this??

No, it's not subtracting the right amount of the baseband signal.

>I figured before I went and tried it I'd get a 2nd (or Nth) opinion. What
>problems can you see with this that I am not taking into account?

Yes, the gated singal is too weak.  Suppose you gate a signal with a 10% duty
cycle, and then filter it.  Then to get the signal back to its original
amplitude, you have to multiply it by the reciprocal of the duty cycle, in
this case 10.  Of course there is still a wide sinc envelope, but at least the
DC response is correct.

>Is there any reason a system such as this would be difficult to physically
>realize?

No, but it won't do what you want.

>Any feedback (no pun) will be appreciated!

How about this.  To do what you want, you should use a stream of alternating
gating pulses.  As long as the pulses have equal width and opposite amplitude,
there is no baseband feedthrough.  You can send my consulting fee now :-).