[Lowfer] Time coherent scheduling [Long, Boring]

[Mike Staines]

Stewart:

Thanks for your reply.
<snip>
> This system has about 70 transmitters worldwide, and has
> functioned well for many years.  It's called LORAN :)

Thought of that 8-) but didn't want to confuse those short pulses with the
longer signaling times that I am considering (and that we are familiar
with).

<snip>

> First, if your transmitter is "on" only 10% of the time, then
> with a given PEP, remote detection (at a given confidence level)
> will take ten times as long, compared with PSK, FSK, etc., or
> five times as long as with QRSS.
I plead ignorance but I disagree anyway. I think from book theory that you
are probably correct. If were are interpreting signals as ones and zeros
that needed low S/N channels for reliable communications then you are
correct.

But we are talking about a hobby where people are happy just to see a
portion of a signal. Right frequency and all I got was a slanted line? I
just copied some of WA! Further below I give an example of how I think this
scheme would assure "hobby" level confidence of the received signal.

>Aside from the inconvenience,
> good propagation may not last long enough for a successful capture.

If we can't trust the propagation to be open for one minute out of ten (in
the examples I have been giving) then how can we expect the propagation to
stay open for the entire time it would take to copy a 3 letter CW callsign
at QRSS30?

Also, I just gave the 1/10 example off the top of my head. I think that if
we pick a baseline of how long we reasonably expect to need to integrate
then we can divide a reasonable repetition by a small number of beacons
sharing that frequency. Maybe a better example would be the 185.3 gang. If
we had WA, TAG, VD, USA and myself (mostly local and strong to each other)
all sharing 1 out of 5 minutes then I see the following advantages:

- They have each transmitted data that is twice the length of their shortest
element currently (allowing better integration within programs like Argo)

- They have completed an entire repetition in shorter time than it takes for
any of them to complete one ID cycle

- It allows operators to monitor more. John, for example, will only be
bothered by his own beacon once every five minutes leaving 4 minutes to
monitor activity on his, or any other, frequency. Currently, nearly everyone
shuts their beacons down to listen.

> A possible workaround for the above:  47 CFR 15.217(a) says
> "The total input power to the final radio frequency stage
> (exclusive of filament or heater power) shall not exceed one watt."
<snip>

I'll skip that discussion 8-) Interesting possibilities though. Bill???

> The second major problem is that efficient decoding of the ensemble
> will require specialized software.  As a minimum, you would need to
> integrate multiple pulses from a given source.  Taking full advantage
> of a pulsed system would involve considerable additional complexity.

I think that we are talking apples and oranges here. Perhaps I didn't define
my idea clearly.

Currently, I look at an argo screen and to be sure that I received XYZ I
have to see a collection of dits and dahs that translate to XYZ. Nothing
fancier than Argo.

Same thing here. If I look at my Argo screen and see a nice line that starts
at a particular tick mark and ends at the next one minute tick mark and is
reasonably contiguous during that time then I may think I copied a
particular beacon. If, at it's next transmission 5 minutes later I get that
line again *I* will have confidence that I copied whomever is scheduled for
that time. All I need is Argo, my eyes, tick marks and a PC with a
reasonably accurate clock.

Now, that is not to say (as I suggested in my post) that further processing
can not be done. I am simply stating that current state of the art is all
that is required to gain the advantages above.

> But the result could be quite fruitful, yielding propagation delay
> and phase stability information, robust rejection of birdies and
> other carrier-like interference, and reliable detection of lower
> signal levels than possible with QRSS.

Agreed! But, again, I think that you have in mind a much more elaborate
transmission and reception scheme than my post envisioned. I hope this post
has helped.

Thoughts?

> 73,
>
> Stewart KK7KA

Mike
wa1ptc