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[aprssig] RE: 6 meter APRS or meteorscater?

Robert Bruninga bruninga at usna.edu
Wed Jan 23 22:54:38 UTC 2008


> What data mode was used in the examples below?  
> I see one mention of "PSK" and never any mention 
> of 1200 baud AFSK  AX25. 

Good point.  I think it was PSK.

> I'm still skeptical of how a 600 millisecond packet 
> is going to work in a system with 300 millisecond openings.

Will have to wait for the 1 second ones..

> How about having a super short MIC-E packet 
> with no path for a "PING" packet to look for 
> minimal openings?   I can be generating those 
> on a regular basis by the end of the month.

Yes, I hope for experimenting to get several of us generating 15
seconds of continuous Mic-E short packets per minute (during our
quadrant).  And see what we get.

> To confirm, you are now thinking of 50.62 yes?  

That or 50.63.  I just don't know which is right.  I remember I
chose 50.62 out of the air back in the 80's, (on a 20 KHz
raster) but then other band plans have shown 50.63.  I don't
know how to resolve the difference.  Sine I have not used the
band, I am not in the position to make an informed decision.  I
am open to inputs.

> We'll have at least a half stations on there in 
> the PNW by spring.

Great.  That will give the midwest something to shoot for.  But
its too far for us.  But my rig is up and connected to my long
wire pointed at Florida, but I don't have a TNC hooked up yet.
Currently molnitoring 52.525 and just listening by ear.

Bob WB4APR

> > Here is our project:
> > http://www.ew.usna.edu/~bruninga/meteors.html
> >
> > Oh, also found that the daily reliability is worst at 8PM
and
> > best at 8 AM by a factor of 3 or so.  And annual reliability
is
> > worst in February and best in the summer by a factor of 4 or
so.
> > But the message still gets through.
> >
> > Here are some data points I got out of some old reports.
Notice
> > the 4th example when 4 receivers were added!
> >
> > * 600 mi, 2 kbd, 200W, 1 RX, 10+10dB antennas, worst case
wait
> > time was between 1.3 to 3.3 minutes for a 150 byte message
at 38
> > MHz.
> >
> > * 500 mi, 2 kbd, 400W, 1 RX, 10+10dB antennas, worst case
wait
> > time was between 1 to 4 minutes for a 50 byte message at 38
MHz.
> >
> > * 1000 mi, 2 kbd, 400W, 1 RX, 10+10dB antennas, worst case
wait
> > time was between 2 to 8 minutes for a 50 byte message at 38
MHz.
> >
> > * 600 mi, 2 kbd, 2Kw, 4 RX, 2+10dB antennas, wait times 3 to
10
> > seconds for 130 bytes at 38 MHz
> >
> > * 400-900 mi, 2kw, 8+14 dBi, 15 to 48 secs for 130 bytes at
38
> > MHz
> >
> > * 600-1200, 750W, 2Kbd, Dipole +13 dBi, 2 to 5 minutes for
June
> > 46 MHz, PSK, -126 dBm for 15 bytes.
> 
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