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ARRL Propagation Bulletin ARLP006 (2006)

ARLP006 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7RA
Seattle, WA  February 10, 2006
To all radio amateurs 

ARLP006 Propagation de K7RA

Our sun is very quiet. The daily sunspot reading was 0 each day from
January 29 through February 7. The last time we saw ten consecutive
days with a sunspot number of 0 was way back on the other side of
the solar cycle, from December 24, 1996 to January 3, 1997. Prior to
that, from September 13, 1996 through October 20 1996 were 38 days
with a sunspot number of 0. Perhaps a year from now we'll again see
a whole month with 0 sunspots.

Compared with last week, the average sunspot number declined over 7
points to 1.7. Average daily solar flux was down over 4 points to

Sunspot numbers and solar flux should rise over the next few days,
but not by much. Geomagnetic conditions also look quiet, with the
next period of high geomagnetic activity set for February 22. This
is based upon the previous rotation of the sun.

A fascinating email arrived this week from Larry Putman, WB3ANQ of
Pasadena, Maryland. He described working VK6DI in Western Australia
on 30 meters using very slow-speed CW, running only 961 microwatts.
That is under 1 milliwatt, over an 11,558 mile path. Larry used an
old Hewlett-Packard HP-3336 signal generator as a transmitter
feeding a 30 meter half-wave inverted vee dipole. To achieve the low
output power and measure it precisely, he used a precision
attenuator and measured the signal with an HP-3586C Selective Level

But Larry didn't depend on the station at the far end to copy by
ear. The CW was sent in QRSS mode, which has a very slow rate of as
little as one word per minute or less for weak signal work. The CW
was pulled out of the noise by feeding the audio into a computer
sound card, and detecting with ARGO software.

You can see info on this mode of communication at,, and Larry's operation is
detailed on his web site at,

You can see the web page of VK6DI on the receiving end at,

Details on ARGO software are at,, and
see the efforts of a group called the QRSS Knights at,

Also check out ON7YD's page on extreme narrow band techniques at,

This mode is also used on longwave VLF operations, and you can see
information on this at,

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation and an explanation
of the numbers used in this bulletin see the ARRL Technical
Information Service propagation page at, An archive of past
propagation bulletins is found at,

Sunspot numbers for February 2 through 8 were 0, 0, 0, 0, 0, 0 and
12 with a mean of 1.7. 10.7 cm flux was 77.3, 78.7, 77, 76.3, 74.9,
74, and 74, with a mean of 76. Estimated planetary A indices were 3,
4, 4, 3, 12, 4 and 3 with a mean of 4.7. Estimated mid-latitude A
indices were 1, 3, 3, 3, 11, 4 and 2, with a mean of 3.9.


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