ARRL

ARRL Propagation Bulletin ARLP006 (2009)

SB PROP @ ARL $ARLP006
ARLP006 Propagation de K7RA

ZCZC AP06
QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7RA
Seattle, WA  February 6, 2009
To all radio amateurs 

SB PROP ARL ARLP006
ARLP006 Propagation de K7RA

K7RA is on the road this week from Charleston, South Carolina.

Still no hint of sunspots or sunspots to come.  We did see some
geomagnetic activity on February 4 from a possible coronal mass
ejection.  This raised the planetary A index to 16 that day.

Current prediction is for quiet conditions.  Geophysical Institute
Prague predicts quiet conditions for February 6-12.  NOAA and USAF
predict quiet geomagnetic conditions with planetary A index at 5,
but it jumps to 8 on February 15, then back to 5 until February
22-24, which has a predicted planetary A index of 10, 8 and 8.
While we don't see much excitement at the high end of the HF
spectrum, the quiet conditions and winter nights are great for the
lower frequencies.

There were many comments on the fascinating several decades old
letter from Ed Tilton, W1HDQ, the editor of this bulletin until
1991.  I've never learned when this bulletin began, and if Ed always
wrote it.

I remember copying it on CW from W1AW as a boy in the mid 1960s, and
it was written by W1HDQ then.  No one currently at ARRL HQ seems to
know either.

Starting out as a 12-year-old ham in the 1960s, I was always
accustomed to having some source for info from an older ham.  For
instance, if I wanted to know how experimenters set up spark
stations in the early 20th century, there were plenty of people
still around in the late 20th century who had done it themselves
when they were younger, and could lend me their first-hand
knowledge.  But now after 44 years as a ham, there aren't that many
people older than me who I can ask these sorts of questions.

Jim Muiter, N6TP of San Mateo, California commented on the W1HDQ
letter.  Jim wrote, "Ed's letter pointed out there are many layers
to ten-meter propagation and the selection of the date for the
ten-meter contest was no accident. The three hundred mile path makes
good sense. I believe the British Chain Home Radar system of Battle
of Britain fame used frequencies in that range, perhaps 30 to 50
MHz. In effect it was partially an over the horizon radar and may
have relied on tropo inadvertently."

Just after last week's bulletin, Jeff Hartley, N8II of
Shepherdstown, West Virginia wrote, "The highlight of the week was
Monday (January 26) working FW8DX on 75 meters at sunrise. 17 meters
was barely open to Europe all week long except on Monday conditions
were good enough for a brief opening on 15 meters to F/EA/sw DL from
1510-1545Z."

He continues, "I heard double hop Es on 10 meters Sunday evening
(January 25) into New Mexico and Arizona, but no QSOs as they were
fairly weak here and they had a good opening going with the SE USA
with S9 reports."

Jeff goes on to say, "By all accounts, the CQ WW 160 had the best
conditions ever; I was too tired to operate past my normal bedtime,
but did manage to work over 1000 QSOs and 51 DXCC countries with
6W/DL2MDU being a new one. Conditions were so good that many East
Coast stations worked UA9 and several caught EY8MM."

Mike Schaffer, KA3JAW of Tampa, Florida likes to hunt commercial
broadcast television DX, and reports that last winter he didn't see
any, but on January 25 he reported, "I just snagged my initial 2009
winter season television DX on channel two coming from HIJB Tele
Antillas, Santo Domingo, Dominican Republic.  I saw the station logo
(TA) several minutes before 17:00 GMT. The audio level was about
equal to the video quality in this case, but normally the audio is
loud compared to the video level.  The distance from me here in
Tampa, Florida to Santo Domingo city is 1,045 miles. Half this
distance, 523 miles, would place the Es plasma cloud near south-west
of George Town, Bahamas."

Mike copied the signal for less than 3 minutes.

Later that same day he copied WKAQ on channel 2 at 2313z from San
Juan, Puerto Rico, 1,232 miles away.  He said the sporadic-E opening
that day ran from 1530-2320z.  The next day, also on channel 2 he
copied a TV station in Managua, Nicaragua.

A new month began since the last bulletin, so we can calculate
another 3-month average of daily sunspot numbers.  This new one will
be centered on December 2008, and includes data from November 1 2008
through January 31 2009.  We were of course hoping for an uptick,
but the new average is 3.7, lower than the previous average of 4.4.

Jan 07 22.7
Feb 07 18.5 
Mar 07 11.2 
Apr 07 12.2 
May 07 15.8 
Jun 07 18.7 
Jul 07 15.4 
Aug 07 10.2 
Sep 07  5.4 
Oct 07  3.0 
Nov 07  6.9 
Dec 07  8.1 
Jan 08  8.5 
Feb 08  8.4 
Mar 08  8.4 
Apr 08  8.9 
May 08  5.0
Jun 08  3.7 
Jul 08  2.0 
Aug 08  1.1 
Sep 08  2.5 
Oct 08  4.5 
Nov 08  4.4 
Dec 08  3.7

Bill Van Alstyne, W5WVO of Rio Rancho, New Mexico had some
information and comments after this bulletin mentioned some weak
signal methods for VHF.

Bill said the web site we mentioned deals with some European
practice in Region 1.  Stations in North America, Region 2, use
different protocols.  He writes, "The Region 2 protocols are the
default settings in the WSJT software as it is downloaded from Joe
Taylor's website (http://physics.princeton.edu/pulsar/K1JT/).
Please, download the manual as well as the software."

Bill continues, "JT6M is only one of the transmission modes
contained within the WSJT suite intended for meteor scatter work.
The original MS mode, FSK441, remains the primary mode used for MS
in North America. Of course JT6M will often work, but as stated in
the web page, you need a decodable burst of at least one second
duration. While it is much more likely to get pings this long on 6
meters than on higher-frequency bands, it is likewise true that most
6-meter meteor pings are shorter than that, and hence won't contain
a full message. Using FSK441, a full message can be transmitted and
decoded in as little as 150 ms."

He goes on to say, "The trade-off between these two MS modes is
sensitivity versus time. FSK441 is faster because it takes up more
bandwidth and is therefore less sensitive; a signal at least 1 dB
above the noise floor is necessary. JT6M, on the other hand, can
decode a message as much as 12 dB or more below the noise floor! But
the signal must be present for at least one second, and more
reliable decodes are obtained when the signal is present for an even
greater length of time."

He ends with, "The best use of JT6M, in the opinion of many, is not
actually 6-meter meteor scatter, but rather very-weak-signal tropo,
ionoscatter, or sporadic-E."

For newcomers, Bill recommends the WSJT Yahoo Group at,
http://groups.yaho.com/group/WSJTgroup.  The group has a web site
at, http://www.ykc.com/wa5ufh/.

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://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/.

Instructions for starting or ending email distribution of this
bulletin are at http://www.arrl.org/w1aw.html#email.

Sunspot numbers for January 29 through February 4 were 0, 0, 0, 0,
0, 0, and 0 with a mean of 0.  10.7 cm flux was 69.3, 69.1, 69.4,
69.5, 69.1, 69.3, and 69.5 with a mean of 69.3.  Estimated planetary
A indices were 4, 4, 7, 3, 2, 4 and 16 with a mean of 5.7.
Estimated mid-latitude A indices were 3, 3, 4, 1, 0, 2 and 10 with a
mean of 3.3.
NNNN
/EX