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[aprssig] Satellite positions: FREQUENCY

Greg Dolkas ko6th.greg at gmail.com
Wed Oct 19 06:16:24 UTC 2011


Adding my $.02...

YES to what Bob describes here, especially the idea of using the DX Cluster
format for future passes.  Those slots have yet to have anything drop into
them in the many years I have owned my D7, and this is a great use.

Please, Bob knows what he is talking about with the future pass stuff.
Anything more than an hour away will have to get converted to a specific
time anyway, and written down, otherwise it will get forgotten or
mis-remembered.  Much better to do the math before sending the message.  So,
prediction more than an hour away needs to be "AOS at hh:mm".  Less than an
hour needs to be "AOS in 25min" (with AT and IN important key words).
During a pass, "LOS in 12min".  Don't bother with seconds; if you're out and
about with your HT, they are useless.  (Even at home with the beam antennas
and computer control of everything, they're nearly useless.)  I'm not sure
how it would fit, but knowing the date as well as the time would be good,
given that a suggested near-GEO satellite could have passes lasting more
than a day, and not repeating for more than a day.  Hmmm, LOS in 507min is
kind of meaningless too.  Maybe LOS in 8h27m if it's longer than an hour
away?

Don't forget about the max elevation for the pass.  That is the first thing
I look at for evaluating whether it's worth trying for the pass, especially
if the Az of that max elevation is also given.  "10 degree pass behind that
big hill over there to the East..."  Yeah, skip it.

I like the idea of asking what satellites are coming up next, but prefer
that to be the default if the message is empty.  Otherwise, the message
would have a command and a satellite name, say "PASS satellite,
satellite...", leaving open other commands, perhaps for MODE, FREQ, or other
things that can be predicted based on the satellite, time of day, and your
location.

Greg  KO6TH



On Tue, Oct 18, 2011 at 9:43 AM, Bob Bruninga <bruninga at usna.edu> wrote:

> > Would it be possible to send a message to a generic
> > "sat" or "space" to find out the nearest target?
>
> I'd like the name maybe "SATS"
>
> > Then once the name is known, the user could then send
> > another msg to find out detailed info.
>
> A message to SATS with "?" would return a list of the next 3 satellites in
> the format:
>
> ISS in 20m, AO27 in 145m, AO51 in 405m, SO50 in 540m
>
> Arranged first to last, no more than 4 (because the D7, the most popular
> Satellite HT ever, can only display 45 characters.  But again, I do not
> like
> this delta-time format because once it is received, it is USELESS unless
> you
> remember when it was received, do all the mental math then, and then
> REMEMBER those future times.  This is why I do not like mintues-to-go
> beyond
> 99 miniutes.
>
> Also this SATS engine should not include ANY satellites than cannot be
> worked with an FM radio.  It is a waste of bandwidth.  But if someone has
> an
> SSB radio, they could ask for "?SSB" and get the next WORKIGN 4 satellites
> of any type.
>
> Of course, the way we did this back when APRSdat and DIGI_NED were king was
> to send the response in DX CLUSTER format so that it would go to the 10
> normally unused DX CLUSTER PAGES in the D7 and D700 radios and not clutter
> up the message space.  But again, we preferred the format:
>
> ISS 1045z, AO51 1213z, AO27 1425z, SO50 1920z
>
> Because once received, it was there in the LIST all day for you to refer to
> and know when they were doming up without any mental math of remembering
> from when the quesry was made.
>
> Bob, WB4APR
>
>
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