From: "an old friend" on Fri 29 Jul 2005 18:02


wrote:
From: K0HB on Jul 29, 12:46 pm
"an old friend" wrote

gee I need more than the word of the people who developed it

The people who developed it did not call it an encryption method. (For the
simple reason that no cryptology is involved.)

Tsk, tsk, TSK! You FORGOT to mention the "papers" on the ARRL
website describing Peter Martinez' PSK31. [that's not like you]

You are skirting a very grey line on "cryptology." PSK31 is
NOT about "intentional obscuration of the meaning of a
communications," the boilerplate statement in Part 97 on
what can be sent or not sent by radio amateurs.

On the other hand, PSK31 is sufficiently UNLIKE conventional
TTY codings that it cannot be decoded by any TTY machinery
or even Hellschreiber.

and most artical I have read deal quickly with showing the PSK 31 which
Is a modulation different than most and an encoding of the character
different than most, that everyond kept talking about why is wasn't an
ilgeal code

That's in regard to the FCC regulations on permissible codings.
IF A CODING HAS BEEN PUBLISHED (and supposedly well-enough
known) then it is okay to use by radio amateurs. That ties
into the basic warning of amateur radio communications shall
not be intended to obscure the true meaning (as with 'secret'
codes).


Too many have the emotional labeling of "cryptology" in regards
to secrets and spies. In checking out Webster's New World
Dictionary, Prentice-Hall 1989, it defines "cryptography" as
"the art of writing or deciphering messages in code." Tsk, that
would apply to morse codes, wouldn't it? :-)

indeed it does as has been pointed out to hands in this or other
threads to Hans

I'm of the understanding that Hans DOES understand it, but is
trying some wordplay. "Cryptic" as in "cryptology" or
"cryptography" carries with it some emotional baggage for
many in being related to espionage activities. "Morse code"
of course is absolutely not (in more emotional baggage of
morsemen) any "code" of any kind...ahem...yet morse code is
IS a CODE of aperiodic on-off states representing the English
alphabet, numerals, and some punctuation marks.

That morse code is an "international language" is more
nonsense by morsemen. The CCITT and later ITU-R simply
STANDARDIZED the "International Morse Code" as being
the standard for radio amateurs. Has NO relation to
a "language" other than being a representation of the
English language characters.


a point or 2 about Morse as it compares to PSK 31

When someone says PSK 31 they mean the modulation and the character set
much like Morse Code you have the modulation which is assumed to be
OOKed CW, but doesn't have to realy (we have MCW sounds of dit and dah
on FM voice, or maybe alsoused to ID anautoumatic SSB to for all I
know)and the letter set

Peter Martinez' innovation (he is G3PLX) uses PHASE modulation
which can be picked up with an FM demodulator. Peter goes
one step further in the character coding...that of - in effect -
altering the modulation spectrum by the CHOICE of bits and
bit lengths. [there's a very long explanation of the effect
on spectral content which can't be done in here without
some pictures or whiteboard sketching]

Phase modulation has some definite advantages insofar as
very low received signal levels are concerned. [again, that
gets to a complex explanation involving some statistics
knowledge] It CAN actually work BETTER than on-off-keyed
CW at very low signal levels, aided by only a simple
hardware expansion of the detector system in a receiver.
Conservative traditionalist radio amateurs are horrified
at such upstart ideas (only four decades or so old) and
will have NONE of that!

As long as a message/communications is being sent, the
transmitter MUST be on for PM or FM. The carrier is always
present. Again, the conservative traditionalists argue that
this is "inefficient" and other ill-informed horse pucky,
not counting on the added electronic stress on the power
supply or final amplifier or the resulting shock to the
primary power source. [I've seen some truly marvelous
rationalizations on that, little more than nonsensical
imaginings of those that haven't learned enough of FM and PM]

One could send Morse by FSK keying makeing it sound more like RTTY than
anything any ham would reconize and Morse, but one always means int eh
ARS the very specail mode/letter set

FSK and PSK "sound" almost identical. Their modulation
spectra are VERY close, almost exact if only magnitude of
the spectral components are considered (the difference is
in the phase of their sidebands relative to the carrier
phase and modulation phase). With a binary (two-state)
modulation signal, PSK is a tiny bit easier to implement
on a transmitter than FSK.

But, on regulatory matters, the FCC is quite firm on the
"public knowledge" aspect of ANY coding. For OOK CW, they
reference the CCITT/ITU-T standard on commercial telegraphy
as the International Morse Code. For RTTY they reference
the 5-level so-called Baudot code and the 7-level-plus-
parity ASCII code. PSK31 was allowed for use (followed
up by specific communications from the FCC) when it was new
due to extensive publication in Europe for years before
it was published in QST.

On Spread Spectrum techniques, there's still a gray area in
the regulations. FCC regulations have allowed a greater
range in the pseudo-random sequences for direct-sequence
spreading (than the original regs) but they still require
some form of "recording" of EVERY transmission for "later"
use! [that's the interpretation of that very general
regulation on SS] On the other hand, there's a difficulty
in obtaining the EXACT nature of just about EVERY commercial
SS sequence in commercial use...from keyless auto entry
fob transmitters to garage door openers to LANs and WLANs*
to remote electrical meter useage transmitters. Millions
of commercial SS sequences being sent but there are NO
regulatios imposed on THEIR transmission recordings!

* I'm classifying all those "cordless" devices from 'phones
to remote TV monitors to home networking gadgets in the WLAN
category...that's a few million or so more devices.