[IRCA] Fw: ARLP034 Propagation de K7RA

["Art Blair" <artngwen@xxxxxxxxxx>]

----- Original Message ----- 
From: "W1AW Mailing List" <w1aw-list-request@xxxxxxxxxxxxxxxxx>
To: <artngwen@xxxxxxxxxx>
Cc: <W1AW List:>
Sent: Friday, August 17, 2007 11:39 AM
Subject: ARLP034 Propagation de K7RA


> SB PROP @ ARL $ARLP034
> ARLP034 Propagation de K7RA
> 
> ZCZC AP34
> QST de W1AW  
> Propagation Forecast Bulletin 34  ARLP034
>>From Tad Cook, K7RA
> Seattle, WA  August 17, 2007
> To all radio amateurs 
> 
> SB PROP ARL ARLP034
> ARLP034 Propagation de K7RA
> 
> We're on the road this week, and post this bulletin from
> Hillsborough County, New Hampshire.
> 
> Solar activity continues low.  The sun is currently spotless, but
> sunspots may return around August 20.  This week's average daily
> sunspot numbers were down about a point from last week's, from 12.4
> to 11.3.
> 
> Expect quiet geomagnetic conditions over the next week, according to
> a forecast from the US Air Force, which predicts planetary A index
> for August 17-23 of 8, 5, 10, 5, 5, 10 and 8.  But Geophysical
> Institute Prague has quite a different prediction for August 18.
> They predict quiet conditions for August 17, unsettled to active on
> August 18, unsettled August 19, quiet August 20-21, unsettled August
> 22, and quiet to unsettled August 23.
> 
> Jerry Reimer, KK5CA of Spring, Texas, sent in some interesting
> comments about NVIS (Near Vertical Incidence Skywave) propagation
> and antennas, and ionospheric data available on the internet.  An
> automated ionospheric sounder, or isosonde, beams energy straight up
> while sweeping the signal up in frequency, thereby determining the
> MUF or Maximum Usable Frequency of that area by measuring the
> reflected signal.  Jerry says that NVIS communication (which is used
> to communicate with stations out to about 200 miles maximum) is best
> at a frequency 50 to 80 percent below the MUF from the isosonde.  So
> if the MUF of the patch of ionosphere overhead is 10 MHz, then NVIS
> is best between 2-5 MHz.  With NVIS, users are trying to get high
> angle radiation instead of low angle, which is usually the goal with
> other modes of HF communication.  A page explaining Vertical
> Incidence Soundings is linked from
> http://www.ngdc.noaa.gov/stp/IONO/ by clicking on the Vertical
> Soundings link on the left of the page.
> 
> He also pointed out some interesting real-time maps showing
> continent-wide communication between various points at
> http://www.ips.gov.au/HF_Systems/4/1.  For instance, if
> you select Hourly HAP Charts, then select Kansas City, what you will
> see is the best frequencies for communications with Kansas City from
> across the continent at that time.  So you can look at the color
> region over any point on the map, and this is keyed to the best
> frequency for communicating with Kansas City from that point.
> 
> More about NVIS and ionospheric soundings in next week's bulletin.
> 
> If you would like to make a comment or have a tip for our readers,
> email the author at, k7ra@xxxxxxxxx
> 
> For more information concerning radio propagation, see the ARRL
> Technical Information Service at
> http://www.arrl.org/tis/info/propagation.html.  For a detailed
> explanation of the numbers used in this bulletin, see
> http://www.arrl.org/tis/info/k9la-prop.html.  An archive of past
> propagation bulletins is at http://www.arrl.org/w1aw/prop/ .
> Monthly propagation charts between four USA regions and twelve
> overseas locations are at http://www.arrl.org/qst/propcharts/.
> 
> Sunspot numbers for August 9 through 15 were 14, 14, 13, 11, 13, 14
> and 0 with a mean of 11.3.  10.7 cm flux was 67.4, 67.5, 67.6, 68.1,
> 67.7, 68.5, and 67.6, with a mean of 67.8.  Estimated planetary A
> indices were 4, 13, 12, 6, 3, 6 and 8 with a mean of 7.4.  Estimated
> mid-latitude A indices were 2, 10, 7, 5, 2, 3 and 6, with a mean of
> 5.
> NNNN
> /EX
> 
>

_______________________________________________
IRCA mailing list
IRCA@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/irca

Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers

For more information: http://www.ircaonline.org

To Post a message: irca@xxxxxxxxxxxxxxxx