Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

Keskustelua antenneista, radioista, yms. radioamatööritekniikasta

Aurora Scatter - Revontulten tanssi dopplertutkan nauhoilla

ViestiKirjoittaja OH7HJ » 20.04.2018 20:16

Tässä leimahtelevien revontulten 'lieskat' saavat muodon radiokaikuina. Harrastajavoimin toteutettu revontulitutka kertoo revontulipurkausten suuntien vaihtelut muuttuvina väreinä Spectrum Lab -softan Radio Direction Finding (RDF) -toiminnon avulla.

Tutkaotoksessa oikealla ovat 'raakanauhat' kahdelta eri antennilta, joista spektrisofta laskee keskellä näkyvälle nauhalle suunnat väreinä. Vasemmanpuoleisin nauha on tarkoitettu nopeiden ilmiöiden seurantaan.

Revontulipurkausten luonnollisten liikkeiden mukana niiden kohinana kuuluvat ja 'lumisateena' spektrinauhoilla näkyvät kaiut liikkuvat dopplersiirtymän johdosta nauhoilla oikealle ja vasemmalle. Seassa näkyvät ohuet kaaret ovat lentokoneiden dopplerkaikuja ja pystysuorat viivat TV-lähetteitä. Aikaleimat nauhojen reunoissa ovat Suomen aikaa.


In English: Flaming Northern Lights on radar spectrum strips. The passive 'Aurora Radar' is built by radio hobbyists. It shows directions of high sky Aurora discharge flares as changing colors.

Two separate receiving aerials are used to get the directions of radio waves bouncing back from Northern Lights (Aurora Borealis) discharge front. The 'snowfall' like noise clouds on radar strips are radio waves scattering from the aurora discharge flares that are constantly igniting, moving and fading on the 'Aurora Oval', a discharge front around Earth poles.


Links:

Uusimmat kuvat monipaikkatutkasivulla - Updating multi-static radar online demo page: https://maanpuolustus.net/pages/tutka/
Aurora Scatter on RDF Strips - Revontulipurkaus: viewtopic.php?f=21&t=295&start=190#p2519
Birth of Aurora Discharge on Fast RDF Strips: viewtopic.php?f=21&t=295&start=190#p2520


T: - Juha
Liitteet
2018-04-20-2233 FT - RDF - St. Petersburg TV D4H - Y6H 120 - Aurora flares fading (c) OH7HJ.JPG
2018-04-20-2233 FT - RDF - St. Petersburg TV D4H - Y6H 120 - Aurora flares fading (c) OH7HJ.JPG (329.21 KiB) Katsottu 82 kertaa
2018-04-20-2206 FT - RDF - St. Petersburg TV D4H - Y6H 120 - Aurora flares fading (c) OH7HJ.JPG
2018-04-20-2206 FT - RDF - St. Petersburg TV D4H - Y6H 120 - Aurora flares fading (c) OH7HJ.JPG (339.19 KiB) Katsottu 83 kertaa
2018-04-20-1954 FT - RDF - St. Petersburg TV D4H - Y6H 120 - Aurora (c) OH7HJ.JPG
2018-04-20-1954 FT - RDF - St. Petersburg TV D4H - Y6H 120 - Aurora (c) OH7HJ.JPG (303.92 KiB) Katsottu 84 kertaa
OH7HJ
 
Viestit: 410
Liittynyt: 22.02.2009 12:38

Natural Spread Noise Spectrum Radio Scatters

ViestiKirjoittaja OH7HJ » 27.04.2018 14:30

By the article "Limits on radio emission from meteors using the MWA" it looks like formal science is opening its eyes to the spread noise spectrum natural scatters that amateurs have been spotting and explaining for years?

... "broadband radio emission has been observed accompanying bright meteors" ...
"The broadband spectra between 20 and 60 MHz were captured" ...
... "with a usable bandwidth of 75 kHz tunable to any centre frequency between 10 and 88 MHz. These two events lasted for 75 and 100s, respectively, at 37.9 and 29.9 MHz" ...


The pics on paper are not similar spectrum analyzer strips familiar for us with high sky scatter spotting but these quotations suggest that there is something similar on low VHF that they are observing. There is something related to explaining birth of the spread noise spectrum scatters that the article authors appear to miss.


Spread Spectrums by Electric Discharges

Electrostatic experimenters know that scattered radio wave spectrum spread is a characteristic mark of radio waves scattered from air ions accelerated by electrostatic discharge. A high voltage discharge in low pressure gas creates ionization or plasma which modulates scattering radio waves by a noise spectrum.

One may suppose that high atmosphere spread spectrum scatters are created by natural atmosheric electricity discharges. Usual causes of short electric discharge scatters (EDS) appear to be high sky lightning discharges that seem to be triggered either spontaneously or by ionized meteor trails.

Long lasting spread spectrum scatters on 50 MHz appear to be related to such natural electric events as thunderstorm Es and Aurora discharges, for example.

Attached are examples of short and long spread noise spectrum natural scatters on RDF spectrum strips at R1 channel Nyandoma TV and Syktyvkar TV Tx frequencies:
RDF MS Syktyvkar TV D4H - Y6H 080 (c) OH7HJ - 2018-04-27 - Long Spread Noise Spectrum ED Scatters.jpg
RDF MS Nyandoma TV D4H - Y6H 090 (c) OH7HJ - 2018-04-24-25 - Short Spread Noise Spectrum ED Scatters.jpg



Regards,

- Juha OH7HJ


Article Link:

Limits on radio emission from meteors using the MWA, 20 April 2018 - https://arxiv.org/pdf/1804.07060.pdf


Related Links:

50 MHz Spread Spectrum Noise Scatter Observations:


Aurora precursors on RDF strips - viewtopic.php?f=21&t=295&p=2518&hilit=Spread+Spectrum#p2518
Meteor Scatter 'Head Echo' Dopplers - 7. - viewtopic.php?f=21&t=295&p=2511&hilit=Spread+Spectrum#p2511
Meteor Scatter 'Head Echo' Dopplers - 6. - viewtopic.php?f=21&t=295&p=2507&hilit=Spread+Spectrum#p2507

Meteor Scatter 'Head Echo' Dopplers - 4. - viewtopic.php?f=21&t=295&p=2502&hilit=Spread+Spectrum#p2502
Meteor Scatter 'Head Echo' Dopplers - 1. - viewtopic.php?f=21&t=295&p=2499&hilit=Spread+Spectrum#p2499
Spotting MS from among ED scatters - 2. - viewtopic.php?f=21&t=295&p=2497&hilit=Spread+Spectrum#p2497

Spotting MS from among ED scatters - 1. - viewtopic.php?f=21&t=295&p=2401&hilit=Spread+Spectrum#p2401
Strong 6m TV High Sky Scatter - Part 1 - viewtopic.php?f=21&t=295&p=2420&hilit=Spread+Spectrum#p2420
High sky radio scatters sometimes plot curious patterns - viewtopic.php?f=21&t=295&p=2387&hilit=Spread+Spectrum#p2387

Electric Discharge Explanation of Nasa 'Aurora Arrow' Photo - viewtopic.php?f=21&t=295&p=2374&hilit=Spread+Spectrum#p2374


Electrostatic Experimenting with Electric Discharges:

Plasma leiskahtaa kurkkupurkissa - http://guns.connect.fi/innoplaza/energy ... index.html
Himmeli lentää sähköllä - http://guns.connect.fi/innoplaza/energy ... nokki.html


Spread Spectrum Articles in Finnish:

viewtopic.php?f=21&t=295&p=2426&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p2426
viewtopic.php?f=21&t=295&p=2387&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p2387
viewtopic.php?f=21&t=295&p=2251&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p2251

viewtopic.php?f=21&t=295&p=2250&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p2250
viewtopic.php?f=21&t=295&p=1907&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p1907
viewtopic.php?f=21&t=295&p=1900&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p1900

viewtopic.php?f=21&t=295&p=1680&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p1680
viewtopic.php?f=21&t=295&p=1679&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p1679
viewtopic.php?f=21&t=295&p=1676&hilit=hajaspektri&sid=798cfaeb736fe6b6e72de92278b31be1#p1676
Liitteet
RDF MS Syktyvkar TV D4H - Y6H 080 (c) OH7HJ - 2018-04-27 - Long Spread Noise Spectrum ED Scatters.jpg
Rather long and a few short spread noise spectrum scatters on Syktyvkar TV frequency. This TV Tx is 1113 km away from my Rx. Spectrum Lab RDF colors represent different directions of wave arrival.
RDF MS Syktyvkar TV D4H - Y6H 080 (c) OH7HJ - 2018-04-27 - Long Spread Noise Spectrum ED Scatters.jpg (325.58 KiB) Katsottu 51 kertaa
RDF MS Nyandoma TV D4H - Y6H 090 (c) OH7HJ - 2018-04-24-1028 - Long Spread Noise Spectrum ED Scatter.jpg
An example of a long spread noise spectrum ED scatter on Nyandoma TV frequency. This scatter may be combination of two separate scatters because changing RDF colors indicates two directions of arrival for the wave.
RDF MS Nyandoma TV D4H - Y6H 090 (c) OH7HJ - 2018-04-24-1028 - Long Spread Noise Spectrum ED Scatter.jpg (118.56 KiB) Katsottu 64 kertaa
RDF MS Nyandoma TV D4H - Y6H 090 (c) OH7HJ - 2018-04-24-25 - Short Spread Noise Spectrum ED Scatters.jpg
An example of usual short spread noise spectrum natural scatters of TV carrier and side bands on RDF spectrum strips at R1 channel Nyandoma TV Tx frequency. RDF colors indicate radio wave direction of arrival. One may suppose that high atmosphere spread spectrum scatters are created by natural atmosheric electricity discharges. A high voltage discharge in low pressure gas creates ionization or plasma which modulates scattering radio waves by a noise spectrum. Nyandoma Tx is 572 km from Rx.
RDF MS Nyandoma TV D4H - Y6H 090 (c) OH7HJ - 2018-04-24-25 - Short Spread Noise Spectrum ED Scatters.jpg (391.34 KiB) Katsottu 64 kertaa
OH7HJ
 
Viestit: 410
Liittynyt: 22.02.2009 12:38

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