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Re: APRSdata Satellite Server



> > Think of it as a tiny-web-page update to the radio's front panel, showing
> > the name of the satellite, the range and azimuth to the bird, ...
>
Henk de Groot wrote:
> Stupid question, but why does it show "range" and not the much more usefull
> elevation? I don't see any advantage in knowing the range, but elevation is
> extremely useful for knowing where to point the antenna to. Just wondering
> what is the reason of having the "range" instead...

Good question.  Range is a built-in function of the D7 and D700's, just
like Azimuth. You have no choice.  THey are computed by the radio based on
your location and the location of the satellite and always displayed.

Beyond that, there are 20 characters left for free text.  I chose to use
that to display the UPLINK and DOWNLINK frequencies and Doppler.  On the
HT, it displays like this:
+-----------+
| 1: SO35   |   Since this is transmitted to you on 144.39, and you are
| 145.825+3 |   going to QSY to work the bird, then elevation angle is
| 436.250-8 |   useless because it is changing and you wont be around
+-----------+   to see its current values.

But that is the big change I made for AO40.  SInce it is slow moving and
it does need a beam and it has broadband transponders, I swapped the
UPLINK field with the ELEVATION.  In this case ELEVATION is very useful
and UPLINK frequency is not very meaningful.  As a by product, I did
do the same thing for LEO's when they are below 5 degrees.  At that low
elevation and with a range of over 3000 km quite useless for an HT, I do
display the elevaiton angle instead of the uplink, since you can not work
it anyway...

Since Elevation angle is a function of RANGE for most of our LEO
satellites at about 600 kM altitude, it is quite easy to infer elevation.
If the range is about 1500 miles then the satellite is about 25 degrees.
if it gets to 800 km then it is 45 deg.  Close enought for a handheld.
On my mobile 19" whip, I can work them when they get within about 1000
mile range. (above 30 deg)

This "timey-web-page" is only to alert an APRS operator who is always on
144.39 that there is a bird in view... It is not intended to serve as a
tracker, since he wont remain on 144.39 for any more updates if he QSY's
to work the bird.

Hope that helps...

Bob


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