Hi guys,
On the subject of multiple amplifiers driven in phase, a few thoughts
have come to mind.
A few conditions:
I am using the US 1.5kw PEP limit and part 97 for some of these conclusions.
Please note that I did use signal and transmitter fairly interchangeably,
and therein 'lies the rub'. That is most probably the crux of the argument.
I am concluding that they are the same, and that there is nothing saying
we can't xmit two signals on the same frequency.
I am aware that liscencing varys from place to place, some having no power
limit. If you build it and pay the electric bill (and might I add; survive thei
RF field!) you can run it.
After considerable *casual* inspection of Part 97, I interpret;
A. Transmitting more than one signal is legal.
B. Transmitting more than one signal on the same frequency
is not interference in the legal sense, as the station operator
desires to experiment with 'free space RF mixing' or somesuch.
C. When transmissions are content and phase-identical, a
special case of multiple signal transmissions results in total, or
near-total constructive interference (interference in the scientific
sense).
D. Each signal is discrete, even though the desired effect
is for combination, as such combination occurs 'outside'. Since
AT NO TIME is A transmitter power greater than 1.5kw PEP. It passes
the part 97 legality test. (this is only my point of view).
E. Identification may still be facilitated for each of the
discrete transmissions, as even with constructive interference, the
condition of "...clearly making the source...known..." is still kept.
Note: this might preclude >10minute simultaneous transmissions in
cases where constructive interference did not clearly make the source
known, but then it would probably be difficult to make many QSOs!
These last parts would apply to everyone, regardless of QTH, but would depend
on the contest, and how the rules are worded (some say signal, signals, whereas
others speak of transmitters). This is where I think Martti would be tripped up.
F. By utilizing the DSCI ('discrete signal constructive
interference') philosophy to argue legality, one would have to extend
the same philosophy when applying the contest rules. (BTW: DSTCI or
DSNTCI seem unwieldy, even if they are more concise... then again
they could be combined into DSTONTCI !!)
G. "...allowed only one transmitted signal at any given time."
(either on any, or the same band) would make a DSCI station invalid.
It seems to DQ you in most contests, except maybe ARRL SOA, there you
hafta assume that Single Operator Assisted has no connection to plain
Single Op (wheras categories like QRP say they are "Single Operator",
and then add further conditions.).
I think that is a stretch, but the league might want to clear that
up even for the 'xmit on 40 and 80 simultaneous' crowd.
The same stretch would need to pass the scrutiny of the CQ gang for
QRP and SOA as well, and again I don't think it would. The way the
rules are laid out here should probably be clarified. Even though I
know that there is no single band assisted categories, it isn't clear
the way the rules are printed in CQ. (Mild digression! Maybe print
the 'real rules' with examples in a flyer and a condensed version
for the masses??)
In summation, my take on DSCI is that it is OK for experimentation, but
that most contests prohibit it.. regardless of the power numbers applied.
I am very curious as to what others think! E-mail appreciated!
73 de Luigi AA1AA
jlgiasi@hcx5.ummed.edu
jlgiasi@umassmed.ummed.edu
Standard Copyleft and keep my name on it!
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