SB PROP @ ARL $ARLP043   
   ARLP043 Propagation de K7RA   
      
   ZCZC AP43   
   QST de W1AW     
   Propagation Forecast Bulletin 43  ARLP043   
   From Tad Cook, K7RA   
   Seattle, WA  October 29, 2010   
   To all radio amateurs    
      
   SB PROP ARL ARLP043   
   ARLP043 Propagation de K7RA   
      
   The daily sunspot number went all the way to 74 this week (on   
   Tuesday, October 26), but the average sunspot number was down over   
   five points from the previous week, to 50.3.   
      
   Several sunspot groups contributed this week.  1113 first appeared   
   October 13, and was visible through October 26.  1115 emerged on   
   October 15, and ran through October 27, its last day.  1117 emerged   
   October 19, and was still growing yesterday, October 28.  But 1117   
   is now approaching the western horizon, and is less and less   
   geoeffective.   
      
   The latest prediction is for solar flux of 85 through October 31, 82   
   on November 1 and 78 on November 2-5, then 80 on November 6-11, and   
   rising after that.  Predicted planetary A index for October 29   
   through November 1 is 5, 8, 5 and 7, then back to 5 on November   
   2-17.  Geophysical Institute Prague sees quiet to unsettled   
   conditions October 29-30, quiet October 31 through November 1,   
   November 2-3 unsettled, and November 4 quiet to unsettled.   
      
   Conditions shouldn't be bad this weekend for the CQ World Wide SSB   
   DX Contest.  Geomagnetic conditions should be relatively quiet, and   
   we've had a little sunspot activity of late.  But with sunspot group   
   1117 disappearing, unless a new one emerges, the sunspot number   
   could drop back to zero.   
      
   A look at the STEREO mission at http://stereo.gsfc.nasa.gov/ shows   
   some possible activity just over the eastern horizon.  There is also   
   a very bright area, indicating magnetic activity straddling the   
   unseen sector, which keeps getting smaller. Coverage should reach   
   96% around 1014 UTC on November 1, 97% at 0014 UTC on November 22,   
   98% coverage at 0014 UTC on December 14, and 99% at 1700 UTC on   
   January 7, 2011.   
      
   Check http://snipurl.com/1dauya for a dramatic Sun photo taken on   
   October 20 by amateur astronomer Alan Friedman with a small   
   telescope.  Thanks to "Phil Plait's Bad Astronomy Blog" at   
   http://blogs.discovermagazine.com/badastronomy/ for this.   
      
   Rich Dowty, W7EET reminds us of the DX Sherlock maps for propagation   
   on 28 MHz and higher.  See http://www.vhfdx.info/spots/map.php and   
   dial in your favorite band and region.   
      
   Stu Phillips, K6TU had some comments regarding remarks I had in last   
   week's Propagation Forecast Bulletin ARLP042 regarding WSPR real   
   time data and how it might be used for evaluating propagation paths   
   for other modes, such as SSB and CW.   
      
   He writes, "For every WSPR spot (which you can see in the database   
   at the WSPRnet.org website), there is a power level in dBm and a   
   signal to noise ratio reported by the receiving station.   
      
   "Although the antenna used by the transmitting station isn't known,   
   you can get a pretty good idea of the path and what it would take in   
   terms of increased ERP to successfully conclude either a CW or a SSB   
   contact.  I've also found pretty good correlation between   
   propagation predictions using VOACAP that when adjusted for   
   bandwidth (WSPR calculates SNR assuming a 2.5 kHz effective   
   bandwidth) and power levels, correspond pretty closely with the SNR   
   levels reported by WSPR.   
      
   "So pick you reference point - for example, if you need 12 dB SNR in   
   a 200 Hz bandwidth to complete a CW contact, you can scale the WSPR   
   report by adding 10 dB for the bandwidth delta and then scale   
   appropriately for power/ERP delta.  Most WSPR transmissions on the   
   HF bands are 5 watts or less - so even a "standard" ham transmitter   
   at the 100 watt level is a further uplift of 13 dB even without ERP   
   boost from a decent antenna."   
      
   We'll have more information next week from K6TU regarding WSPR and   
   propagation.   
      
   If you would like to make a comment or have a tip for our readers,   
   email the author at, k7ra@arrl.net.   
      
   For more information concerning radio propagation, see the ARRL   
   Technical Information Service web page at   
   http://arrl.org/propagation-of-rf-signals. For an explanation of the   
   numbers used in this bulletin, see   
   http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past   
   propagation bulletins is at   
   http://arrl.org/w1aw-bulletins-archive-propagation.  Find more good   
   information and tutorials on propagation at   
   http://mysite.ncnetwork.net/k9la/index.html.   
      
   Monthly propagation charts between four USA regions and twelve   
   overseas locations are at http://arrl.org/propagation.   
      
   Instructions for starting or ending email distribution of ARRL   
   bulletins are at http://arrl.org/bulletins.   
      
   Sunspot numbers for October 21 through 27 were 34, 34, 43, 57, 57,   
   74, and 53, with a mean of 50.3. 10.7 cm flux was 83.5, 82.2, 84.3,   
   82.1, 86.2, 86.1 and 87.6 with a mean of 84.6. Estimated planetary A   
   indices were 3, 6, 23, 14, 6, 8 and 4 with a mean of 9.1. Estimated   
   mid-latitude A indices were 1, 4, 16, 10, 4, 6 and 3 with a mean of   
   6.3.   
   NNNN   
   /EX   
      
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