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From: Laurence KL7 L <hellozerohellozero@hotmail.com>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Date: Thu, 2 Jan 2014 15:20:00 -0900
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Subject: LF: Coast to Coast on 74kHz ground wave ?
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Hi Chaps - I saw the discussion on the modes and losses and wanted to add a=
 bit -=20
=20
When looking at WWVB 60Khz  (close to 74?) contours for daytime I notice mo=
re of a Vertical peanut shape in the fiedlstrength favoring North South=2C =
with highest losses over Mountaineous terrain and likely the lowest ground =
conductivity=2C say between 0.5 and 2 milliseimens - something we see (in g=
eneral) afforded by ground to the West of Ft Collins (especially NW) and to=
 the Eastern mountain ranges=2C and its not too Bright on most bearings fro=
m here in Alaska as we have a lot of the pointy high snow covered thingies =
up here too.  I see they plonked WWVB there due to having local high Alkali=
nity of the soil - high conductance.
=20
 Whether given the height of the mountains even at 60kHz we loose a bit mor=
e than flat Earth Id say a whopping Yes=2C that and some of the oddities th=
at ground waves going over glaciers can have all add up to further attenuat=
ion.
=20
Have a looksee at http://www.fcc.gov/encyclopedia/m3-map-effective-ground-c=
onductivity-united-states-wall-sized-map-am-broadcast-stations
=20
If I look at how /4 gets up here - it would in reality have to be a fairly =
high angle reflection=2C as Im close in to the Chugach and Talkeetna Mounta=
ins and those mountain ranges extends hundered of miles on the /4 bearing. =
- I see no signal at all (ok I wasnt using OPds) and even with a reasonable=
 antennae and good s/n its a sky wave opening only - well=2C at any reasona=
bly power that we can generate. Whereas he was strong in CA last night he w=
as only just detectable up here - though I blame the Auroral ovaly stuff to=
o for that.
=20
Interestingly enough and with the limited amount of data - if Bob was to ge=
nerate another 3dB he would have probably been visisble at dot 60 every nig=
ht to date over the 5000Kms path or so =2C ie a lot less variation on a day=
 to day than I see at 137.
=20
On groundwave on 137 I did some reasonable tests and with my 3W ERP (ish) i=
n the main loop on a quiet iono day in Autumn maintaining a CW just read le=
vel of some 1000Kms down to Corpus Christi from the OKie/Kansas Border and =
 but out West  was considerably poorer - we had poor conductivity to the We=
st of us for a while....
=20
I saw with interest on the NIST web site the scalloped nature of signal rec=
eption at night  at 60KHz at some times of the night.
=20
http://tf.nist.gov/images/radiostations/wwvb-large/0800utc.jpg
=20
Cheers from a soggy snowyish Anchorage.
=20
=20
=20
=20
 		 	   		  =

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<body class=3D'hmmessage'><div dir=3D'ltr'>Hi Chaps - I&nbsp=3Bsaw the disc=
ussion on the modes and losses and wanted to add a bit - <BR>&nbsp=3B<BR>Wh=
en looking at WWVB 60Khz&nbsp=3B (close to 74?) contours for daytime I noti=
ce more of a Vertical peanut shape in the fiedlstrength favoring North Sout=
h=2C with highest losses over Mountaineous terrain and likely the lowest gr=
ound conductivity=2C say between 0.5 and 2 milliseimens - something we see =
(in general) afforded by ground to the West of Ft Collins (especially NW) a=
nd to the Eastern mountain ranges=2C and its not too Bright on most bearing=
s from here in Alaska as we have a lot of the pointy high snow covered thin=
gies up here too.&nbsp=3B I see they plonked WWVB there due to having local=
 high Alkalinity of the soil - high conductance.<BR>&nbsp=3B<BR>&nbsp=3BWhe=
ther given the height of the mountains even at 60kHz we loose a bit more th=
an flat Earth Id say a whopping Yes=2C that and some of the oddities that g=
round waves going over glaciers can have all add up to further attenuation.=
<BR>&nbsp=3B<BR>Have a looksee at <a href=3D"http://www.fcc.gov/encyclopedi=
a/m3-map-effective-ground-conductivity-united-states-wall-sized-map-am-broa=
dcast-stations">http://www.fcc.gov/encyclopedia/m3-map-effective-ground-con=
ductivity-united-states-wall-sized-map-am-broadcast-stations</a><BR>&nbsp=
=3B<BR>If I look at how /4 gets up here - it would in reality have to be a =
fairly high angle reflection=2C as Im close in to the Chugach and Talkeetna=
 Mountains and those mountain ranges extends hundered of miles on the /4&nb=
sp=3Bbearing.&nbsp=3B- I see no signal at all (ok I wasnt using OPds) and e=
ven with&nbsp=3Ba reasonable antennae and good s/n its a sky wave opening o=
nly - well=2C at any reasonably power that we can generate. Whereas he was =
strong in CA last night he was only just detectable up here - though I blam=
e the Auroral ovaly stuff too for that.<BR>&nbsp=3B<BR>Interestingly enough=
 and with the limited amount of data - if Bob was to generate another 3dB h=
e would have probably been visisble at dot 60 every night to date over the =
5000Kms path or so =2C ie a lot less variation on a day to day than I see a=
t 137.<BR>&nbsp=3B<BR>On groundwave on 137 I did some reasonable tests and =
with my 3W ERP (ish) in the main loop on a quiet iono day in Autumn maintai=
ning a CW just read level of some 1000Kms down to Corpus Christi from the O=
Kie/Kansas Border and&nbsp=3B but out West&nbsp=3B was considerably poorer =
- we had poor conductivity to the West of us for a while....<BR>&nbsp=3B<BR=
>I saw with interest on the NIST web site the scalloped nature of signal re=
ception at night&nbsp=3B at 60KHz at some times of the night.<BR>&nbsp=3B<B=
R><a href=3D"http://tf.nist.gov/images/radiostations/wwvb-large/0800utc.jpg=
">http://tf.nist.gov/images/radiostations/wwvb-large/0800utc.jpg</a><BR>&nb=
sp=3B<BR>Cheers from a soggy snowyish Anchorage.<BR>&nbsp=3B<BR>&nbsp=3B<BR=
>&nbsp=3B<BR>&nbsp=3B<BR> 		 	   		  </div></body>
</html>=

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