[sdiy] How to use an analog time-domain multiplexer?

cheater cheater cheater00social at gmail.com
Fri Jun 4 16:34:57 CEST 2021


Interesting!

I did some calculations earlier today and at 5m (which is the longest
patch cord I'd consider practical), the first reflection would arrive
at the receiving end after 33ns. That's way less than one on-period of
the switching. I don't really know how to figure out how many
reflections I'd be getting, though.

On Fri, Jun 4, 2021 at 4:23 PM Mike Bryant <mbryant at futurehorizons.com> wrote:
>
> Those have all had digital filters since the mid 90s.  I doubt you have one older than that.  But before that they used SAW filters which were a sort of analogue primitive version of a digital FIR filter.
>
> Either way you need to terminate the links OR pre-distort the transmit signal OR put a compensation filter on the receiver to do what you want to do.
>
>
> -----Original Message-----
> From: cheater cheater [mailto:cheater00social at gmail.com]
> Sent: 04 June 2021 15:18
> To: Mike Bryant
> Cc: Richard Wentk; synth-diy at synth-diy.org
> Subject: Re: [sdiy] How to use an analog time-domain multiplexer?
>
> Nope! It works even with the cheapest analog TVs. Like the portable, 12", color kind.
>
> On Fri, Jun 4, 2021 at 4:14 PM Mike Bryant <mbryant at futurehorizons.com> wrote:
> >
> >
> > > Explain one thing to me... how come I can send NTSC over minijack?
> > > That's not RF designed, 50-ohm terminated, or even shielded. It's just a minijack. And the ground is shared with two audio channels, none the less!
> >
> > Probably because the final generation NTSC decoder in your TV is actually an advanced digital matching filter that works like mad cancelling out reflections and other noise.
> >
> >
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