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FCCdata.org Now Has Skywave Contours

The technical side of broadcasting. Think IBOC is a sham? Talk about it here! How about HDTV? Post DX reports here as well.
CK-722
Posts: 599
Joined: Sun Dec 16, 2018 3:53 pm

FCCdata.org Now Has Skywave Contours

Post by CK-722 » Sun Aug 25, 2019 4:32 pm

WJR and WWJ 0.5 mV/m 50% Skywave Contours, along with 2 mV/m and 0.5 mV/m Groundwaves.

https://www.fccdata.org/?lang=en&facid=8626

https://www.fccdata.org/?lang=en&facid=9621

Zoom out for WJR Skywave Contour.

This uses the newer FCC Skywave Model Calculation using Geomagnetic Path Midpoint Latitude. Expect much less than 750 miles for Class I-As, and further distances to the South than to the North.


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Same (x, y, z), different (t)

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CK-722
Posts: 599
Joined: Sun Dec 16, 2018 3:53 pm

Re: FCCdata.org Now Has Skywave Contours

Post by CK-722 » Sun Aug 25, 2019 5:13 pm

Last edited by CK-722 on Sun Aug 25, 2019 5:18 pm, edited 2 times in total.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

Artificial Intelligence is a Child that needs a Parent to guide it through.

CK-722
Posts: 599
Joined: Sun Dec 16, 2018 3:53 pm

Re: FCCdata.org Now Has Skywave Contours

Post by CK-722 » Sun Aug 25, 2019 5:13 pm

CFCO Nighttime Skywave. Canadian Skywaves not complete.

https://www.fccdata.org/?lang=en&facid= ... tabs=77003

CHOK Skywave.

https://www.fccdata.org/?lang=en&facid= ... tabs=56553

CKLW Skywave.

https://www.fccdata.org/?lang=en&facid= ... tabs=55065

No wonder they influenced NYC Airplay!


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

Artificial Intelligence is a Child that needs a Parent to guide it through.

innate-in-you
Posts: 284
Joined: Wed Oct 31, 2018 8:54 am

Re: FCCdata.org Now Has Skywave Contours

Post by innate-in-you » Thu Sep 12, 2019 9:49 pm

I wonder what CHML looks like. It is quite a high-gain array.

WLQV (better known by their former call WJBK) would be another.
Back in the day, they blew 50kW into twelve towers (though their 5kw night signal in Grosse Pointe was not very good - Country was clearer on WSM that it was on WDEE).

But, If they had tested the the daytime parameters at night....



Rich
Posts: 74
Joined: Sun Dec 26, 2010 3:28 pm
Location: Illinois
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Re: FCCdata.org Now Has Skywave Contours

Post by Rich » Fri Sep 13, 2019 6:52 am

Thanks for update about FCCData.org.

Surprising that the 0.5 mV/m nighttime skywave contour for WWJ and I suppose other nighttime DAs appears on the map for very short distances from the transmit site where a returning skywave is virtually zero, though.



CK-722
Posts: 599
Joined: Sun Dec 16, 2018 3:53 pm

Re: FCCdata.org Now Has Skywave Contours

Post by CK-722 » Fri Sep 13, 2019 7:22 am

My recollection is that you don't get a 0.5 mV/m 50% Skywave with less than the equivalent of a Class I minimum efficiency facility, with 10 kW Class I minimum power, about 710 mV/m @ 1 mile. Then it snaps back to the 0.5 mV/m ground wave for directionals near the nulls. They are showing some skywave for many 1 kW directional stations, even nondirectional with 1/2 wavelength plus electrical height towers, so I assume this is 0.5 mV/m 10% skywave for those on this model.

From my observations, there are still some things on these maps that have to be worked out. I did find the CHML skywave by using the "interocitor" method (as you may remember in the movie "This Island Earth", the interocitor was used in a nonconventional way). The CHML skywave may have both 50% OR 10% 0.5 mV/m shown in different directions.

Here's the CHML skywave map, FWIW.

https://www.fccdata.org/?lang=en&facid= ... &tabs=3374

You may have noticed that WWJ and WXYT skywave contours were shown as going up almost to James Bay.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

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Rich
Posts: 74
Joined: Sun Dec 26, 2010 3:28 pm
Location: Illinois
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Re: FCCdata.org Now Has Skywave Contours

Post by Rich » Fri Sep 13, 2019 7:59 am

Another approach to showing nighttime contours is to revert to the groundwave contour of that station at locations where its skywave is weaker than its groundwave. Of course that doesn't mean that such signals will not have serious interference from co- and adjacent-channel stations.

The plot of the nighttime coverage for WWJ and some of its 950 kHz co-channel stations is shown this way on the coverage map below.

Image



CK-722
Posts: 599
Joined: Sun Dec 16, 2018 3:53 pm

Re: FCCdata.org Now Has Skywave Contours

Post by CK-722 » Fri Sep 13, 2019 12:27 pm

Here's the old model from the 1960 NAB Engineering Handbook.

It's on Page 1-117.

https://www.americanradiohistory.com/Ar ... tion-2.pdf


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

Artificial Intelligence is a Child that needs a Parent to guide it through.

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