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Author Topic: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation  (Read 1019 times)

K0OD

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Don't miss NZ5A's six page article [the cover story] in the August 2019 QST, page 38, "Optimizing Propagation on 630 and 2200 Meters" where he examines three years of observations of longwave NonDirectional Beacons (NDBs) near our two new bands.

Some Key Takeaways: Longwave signals are immensely enhanced around local sunrise, and only to a lesser extent at sunset. Conditions peak in October thru February. October is especially good. NZ5A says "plans are underway to mine deeper into the data..."

Any comments on the QST article/findings?
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KM1H

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RE: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation
« Reply #1 on: August 04, 2019, 03:25:50 PM »

Hams have been using NDB's since 600-630M was still an experimental band, myself included.

Anyone who has operated there or on 160 and 80 knows about Grayline and there are several online automatic plots about it.

My QST hasnt arrived yet so I may have more to say after Ive read it. I have no experience on 2200M but have listened to the LF Broadcast Band for many decades and have also copied SAQ on 17.2 KHz 4 times now.

Just a few of the links available:
https://en.wikipedia.org/wiki/Grimeton_Radio_Station
https://www.youtube.com/watch?v=shqi43EV07c
https://www.youtube.com/watch?v=tHOaz66DDaA


Carl
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VK6HP

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RE: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation
« Reply #3 on: August 05, 2019, 04:06:49 AM »

It's an interesting study and exploits one of the biggest advantages of NDBs: they are always on.  In principle, one can do more with an automated WSPR data taking and analysis system but the problem in this part of the world is that it's hard to be be sure what the relatively few 630 m transmitting stations on the other side of the Australian continent (and beyond) are up to on a given night.  Still, looking at some ensemble characteristics, and comparing WSPR reception at a number of, for example, VK6 stations, makes it clear than there are some interesting short-timescale temporal and moderate scale spatial characteristics that would be missed in studies such as the QST one. And, in fact, looking at the receiver bandscope also shows quite large amplitude structure on timescales shorter than the WSPR integration window. But, notwithstanding all that, I found the QST conclusions as they relate to the biggest picture to be very interesting.

One thing that I did wonder about was the nature of the (manual?) data taking.  Reading the relevant section a few times I assume that it involved the same human listening on the same equipment, with some sort of implicit signal to noise threshold.  I guess that threshold related to be being able to read the station ident, but whether there was any other s/n or signal strength information, or rough classification, logged is not clear.  The data-taking cadence is also a bit unclear and I'd have liked a few more details on the collection process before launching into the statistics.  I doubt any of these reservations upset the broadest conclusions but they may be relevant if further analysis is undertaken.

With my own recent and very limited 630 m data taken in what's "high season" for us, I can't yet see evidence of a local pre-dawn enhancement of the magnitude mentioned in the article, notwithstanding many international reports of comparable MW broadcast DX behaviour.  There's certainly a big effect around sunset, with some broadly repeatable structure.  But the QST commentary is a motivation to get more data and look harder at our local conditions, and that's a good thing.  Along with all this we hope to get some VK6 amateur MW transmitting stations on the air soon, so the reciprocal reports will also be interesting.

73, Peter.
« Last Edit: August 05, 2019, 04:12:33 AM by VK6HP »
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K0OD

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RE: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation
« Reply #4 on: August 05, 2019, 06:03:28 AM »

Number of Beacons logged by NZ5A in Texas. From his QST article:

May 4
June 11
July 21
August 16
Sept 19
October 113
Nov 41
Dec 66
January 45
February 53
March 27
April 20

My own experience monitoring European AM longwave broadcasters from Missouri suggests DX propagation peaks in December/January. My recent WSPR observations of 472 KHz saw a dramatic European peak in early January 2019. I've never noticed anything astounding about October. https://www.eham.net/ehamforum/smf/index.php/topic,123592.0.html

But note that NZ5A is merely counting the beacons he hears, many of which are surely close to him. I define good propagation in terms of extreme distance.

Is local morning vastly better than sunset? I'll have to start paying attention to that.
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KM1H

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RE: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation
« Reply #5 on: August 05, 2019, 08:36:03 AM »

Not mentioned is that NDB's are not a permanent fixture as they are going the way of commercial 2 way radio and dodo birds.....and soon petrol fueled vehicles :o

Having listened to them all these many decades I find few of my favorites still around.

I find no long term difference in Grayline hours but the length of enhancement can vary by 10-20 minutes or more at both times. Day to day differences often vary as does regular propagation.
From here in NH the evening signals are almost always low angle while in the AM there is a strong high angle component to Asia in particular.

I almost always receive on the 5 two wire (500-750') Beverages for 10 directions but have horizontal and vertical polarization TX antennas in use. Those antennas are decent performers with good directivity down to the LF BCB even tho they should be quite ineffective. I dont understand why as even the coax is decoupled by ferrite chokes and ground rods at a few places. It is CATV quad shield RG-11 to a relay hub and then ~700' of 1/2" CATV hardline.

With ~300 DXCC and 39 Zones on 160 Ive a rather good feel for the band. In addition Ive done some serious BCBDXing over the decades and expect 630M to have somewhat similar and predictable performance........and likely with a few of its own quirks. The BCB is still a great source for DX beacons since most of the planet is on 9 KHz spacing instead of our 10 KHz and it is popular even with non hams.

During my experimental trials I have been heard as far as Hawaii and Sweden with flea power on CW but that was with a good antenna....A full 1/4 wave inverted L with elevated radials off a 180' tower.

I misspoke yesterday and do have that QST. I briefly scanned that article then and didnt see anything new and tossed it on the stack of other issues.
Reading closer today I appreciate the work that went into it but question who is going to read it???
With ARRL membership at an all time low of around 20% of valid licenses, and most of those being Techs the audience is minimal.
I would suggest that Extras, Advanced, and Generals already have plenty of established detailed info sources including forums that go far deeper than propagation. EHAM is not one of them....yet anyway.

Carl
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VK6HP

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RE: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation
« Reply #6 on: August 05, 2019, 10:08:34 PM »

Regarding the longer-term operational status of NDBs, I expect that most countries will have something similar to the Australian Backup Navigation Network (BNN) plan which specifies which ground-based nav aids are being retained to cope with failures or deficiencies in the Global Navigation Satellite System (GNSS). The Australian document, with a list of retained NDBs, is available at:

http://www.airservicesaustralia.com/wp-content/uploads/BNN.pdf

Australia never had the extensive VOR network of the US or Europe and the NDBs (some quite long-range) and associated aircraft Automatic Direction Finders (ADFs) played a very important part in aircraft navigation into the 21st century.  Still, I spent quite bit of my early outback flying training believing that ADFs were only fitted to allow instructors to listen to the cricket on MW broadcast stations.  I did, however, learn visual and dead-reckoning navigation very well.  Later, with instrument flying, I came to appreciate the value of NDBs.

There are still some 630 m encouragements to be had, even with WSPR.  1 W EIRP from Hawaii partly decoded at -32 dB s/n a few nights ago in Western Australia using my 1 m active loop was a nice surprise although, in the interests of completeness, I'll add that a full decode (with a couple more dB s/n) a few nights later by a fellow VK6 located out of town and using a Beverage, claimed the cigar.

73, Peter.
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KM1H

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RE: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation
« Reply #7 on: August 06, 2019, 09:02:31 AM »

The US has already been implementing updates to that such as combining close regional and private airports with an existing larger one. A few I know of have even done that to USCG stations.

Carl
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RFRY

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Re: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation
« Reply #8 on: November 11, 2019, 02:16:18 AM »

Pardon this late posting here, but below are calculations of the nighttime skywave from a 50W, 530 kHz TIS station over a 653-mile great-circle path.

They are based on software using the FCC CDBS database and FCC methodology to estimate field intensity at the receive site.

The fields it shows probably are well below the ambient r-f noise level at most receive locations.

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W4HM

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Re: QST: NZ5A Examines NDB Reception For Clues to Ham Longwave Propagation
« Reply #9 on: November 12, 2019, 06:04:45 PM »

I learned morse code many decades ago while DXing aviation non directional beacons and marine non directional beacons.

http://g0kya.blogspot.com/2010/11/understanding-lf-and-hf-propagation.html
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