You missed my point - maybe deliberately you pedant!
You can argue by that reasoning that the entire Internet is analog as it is so
at the physical layer. That layer is a means to an end. By regulating by
content type in the case of "image", the FCC is attempting to control the means
by regulating the end in a way that made sense and was effective in the
technology world of 1950.
But by a set of (hypothetical) regulations that makes transmitting a .jpg at
the current 300 baud limit illegal while transmitting the text of "War and
Peace" at 9600 baud OK is a distinction that makes no sense.
Once you employ digital encoding, then bandwidth is correlated to symbol rate.
Trying to control bandwidth usage by regulating content in that scenario is
pointless.
Al
AB2ZY
________________________________________
From: Kok Chen <w7ay@comcast.net>
Sent: Wednesday, August 17, 2016 12:59 PM
To: RTTY Reflector
Cc: Al Kozakiewicz
Subject: Re: [RTTY] If you care about CW and RTTY - time is of
the essence
> On Aug 17, 2016, at 7:20 AM, Al Kozakiewicz <akozak@hourglass.com> wrote:
>
> In an all analog world, it makes some sense to regulate transmissions based
> on content. In a digital world, it does not. There is no syntactic difference
> between text, image, an Excel file or any other non-streaming data source.
> It is all data.
Please allow me to play the pedant for a moment, then follow with less
off-topic comments below.
What we have on HF *is* an all analog world. This is why we need modems that
allow us to take discrete data and convert them to analog waveforms which then
make use of the “analog” mechanism of data transfer.
One exception is perhaps Henning Harmuth’s work on directly transmitting
“square waves.” The basis of his “waveforms” are based on the Walsh functions
instead of sinusoids.
Harmuth's “spectrum” consists of coefficients of the Hadamard transforms,
rather than the Fourier transforms that we usually associate with a “spectrum.”
(In mathematics, a spectrum is a pretty general animal.)
Harmuth’s “carrier,” being a Walsh function, would spread from DC to infinity
in the Fourier space. By the same token, a sinusoidal carrier would spread
from DC to infinity in the Hadamard transform space. The two will never
coexist peacefully, and Harmuth has said as much.
This part of Harmuth’s work was published in an Academic Press book in the
series “Advances in Electronics and Electron Physics,” Supplement 14,
“Nonsinusoidal Wavesform Radar and Radio Communications,” ISBN 0-12-014575-8,
and even included chapters on antennas for this type of waveforms.
That being said, what we have in the all-modem (a.k.a. digital) world has
equally bad consequences when you mix narrow and wide band signals.
The extreme example are spread spectrum (Hedy Lamarr’s invention, bless her
soul) and something like RTTY or CW, and is a reason why spread spectrum is
still not allowed for amateurs below 29 MHz.
At least in the case of spread spectrum and CW or RTTY, the damages are lowered
performance, and not complete incompatibility — spread spectrum will appear to
a CW or RTTY op as a raised noise floor, and narrow CW will appear to a spread
spectrum signal as errors that are correctable by FEC.
It is actually a less extreme case where the problem is possibly greater.
A wideband digital signal is not spread evenly in the spectrum (they won’t dare
claim to be spread spectrum for fear of being banned by the FCC) to simply
appear as a raised noise floor to a narrow band RTTY signal. The wideband
signal has spectrum structures that will (not “may”) cause harm to RTTY,
especially since RTTY has no error correction. Take it from someone who has
occasionally dabbled in RTTY modem techniques, a wide “digital" signal will
cause harm to RTTY, and vice versa, if the two are allowed to intermingle.
Sure we can add FEC to RTTY, but we are a *hobby*, folks. We (the royal “we,"
since I haven’t even used keyboard CW in a decade :-) still use CW, and that is
as inefficient a mode to transfer discrete information (OOK) as you can get.
Many aspects of amateur radio is not about efficiency (which ARRL lawyers
appear to keep harping on) but about enjoyment and love of operating.
Now show me an HF email user who enjoys “operating.”
73
Chen, W7AY
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