[TenTec] Slightly OT: SSB vs AM (Warning!: Heavy Sarcasm)

[al_lorona at agilent.com]

> SSB still wins in the bandwidth verses fidelity category.
> 
> Carl Moreschi N4PY
> Franklinton, NC


Shhh, Carl, you used a bad word: fidelity. You see, almost nobody is even considering fidelity in any of these discussions. Only bandwidth. As hams, we're not suppposed to be concerned about fidelity... I mean, who do we think we are, broadcast radio stations? We'll leave the really good audio to the pros. We're mere amateurs, remember? Who ever heard of 'fidelity' in a 3 kHz bandwidth, anyway?!

Seriously, there are a lot of very cool digital modulation schemes out there, but pretty much all of them sacrifice fidelity (and sometimes even some intelligibility) for gains in something else: occupied bandwidth, for example. 

For those still with us, here is some homework: have you seen the new amateur radio promotion video, available from the League's web site, called Amateur Radio Today? This is the one narrated by Walter Cronkite. If you haven't done so, download it and watch it. At about the 5:00 minute mark, there is a clip from an actual ARISS contact with a school. Listen closely to the live audio from the space station.

It is quite intelligible. Communications quality, I'd say. And I'm sure whatever scheme NASA uses, it uses no more bandwidth than absolutely necessary.

(This is exactly how live NASA downlink audio sounds, by the way. I live near JPL and they re-broadcast space shuttle audio on their 147.15 repeater during all of the shuttle missions. I can't listen for more than 15 minutes at a time. It reminds me of fingernails on a chalkboard.)

I intend for this to be my last post on the subject, lest I chase yet more people off of the reflector, which is the last thing I want to do. I've already belabored my point. Thank you. For the bandwidth.

Al W6LX