Re: 12V Power for the Pi (was Re: [RaspberryPi-4-HamRadio] Getting back to the RPi)


Michael WA7SKG
 

And yet the previously referenced article ( https://www.amsat.org/amsat/articles/g3ruh/109.html) says:

"One is that the channel is not DC coupled. It could never be so in an FM system unless one could guarantee both transmitter and receiver were always exactly on frequency and had no drift. As this is virtually impossible to achieve, one simply AC couples the channel, i.e. gives it a response down to a few Hz, and exploits the feature of the randomised data that it has a negligible DC component."

I always thought AC coupling was often via a transformer.

That's okay, I'm a native of the State of Confusion.

I'll crawl back under my rock now.

Michael WA7SKG



Eric wrote on 12/31/19 8:31 PM:

I think I remember reading that 9600 bps requires DC coupling to the modulator.
Transformer coupling would be a problem if that is the case.
Eric
WB6TIX
On Tue, Dec 31, 2019, 20:48 Michael WA7SKG <wa7skg@... <mailto:wa7skg@...>> wrote:
"the Signalink will not work at the higher speed because it has
transformers in the audio chain."
Huh?? It is audio. Maybe a greater bandwidth due to the speed, but
audio
nonetheless. Entertainment system audio often goes over 15 kHz through
transformers. I would be interested in understanding why the Signalink
cannot do the higher speeds because it has transformers. I always like
to learn new things.
Michael WA7SKG
Bill Vodall wrote on 12/31/19 4:13 PM:
>
> The DRAWS board is designed for 9600 baud which most other sound card
> interfaces won't handle.  In particular, as handy as it is, the
> Signalink will not work at the higher speed because it has
> transformers in the audio chain.
>

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