Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

[OH7HJ]

Nadvoitsy TV Tx near Segezha is told to have ERP power of 13 kW, which is less than 1/10 of St. Petersburg TV Tx power. However, also this medium power R1 channel Tx allows see fairly long off-baseline backscatter aircraft scatter (AS) dopplers of airliners traveling on Far East route through Kainuu waypoint. Here are a couple typical examples of them.

With very low power transmitters (Tx) aircraft doppler scatters are usually visible near baseline between Rx-Tx only because of the baseline forward scatter effect that boosts aircraft scatter as strong or even stronger than the Tx signal at the moment of aircraft crossing Rx-Tx baseline. In such baseline forward scatter cases aircraft scatter doppler crossings have been momentarily observed with VHF transmitters having less than 1 W of transmitting power with receiver 100 km away from transmitter.

With medium strong Tx’s like the Segezha Nadvoitsy AS doppler are visible also away from baseline. Not as far away as with strong transmitters like St Petersburg TV and Moscow TV, which allow observing AS dopplers up to the theoretical common radio horizon of Rx and Tx. With help of baseline forward scatter effect, sometimes even over the horizon (OTH).

These dopplers were observed with an inexpensive RTL dongle receiver and north pointing 6-element 6m band yagi. Softwares used are HDSDR and Spectrum Lab, with FFT set for decimation of about 8 … 16 to allow high resolution and reception sensitivity with good tolerance against noise interference like aurora scatter. Time stamps are Finnish local. Sector of aircraft doppler visibility from doppler appearance to its fadeout is drawn on the pics as lines from Segezha Nadvoitsy TV transmitter (Tx). Aircraft course adjustments are visible as notches in their plotted doppler tracks.

Radar Range and Tx Power Experiments:

East: St Petersburg TV, Äänisjärvi 360 km: openstreetmap - ilmaisia karttoja!
Nyandoma TV, Äänisjärvi 395 km: viewtopic.php?f=21&t=295&start=150#p2370

South: Moskova TV, Tikhvin 469 km: viewtopic.php?f=21&t=295&start=150#p2359
Cherepovets TV, Tikhvin 440 km: viewtopic.php?f=21&t=295&start=110#p1898

West: St Petersburg TV, Ähtäri 300 km: openstreetmap - ilmaisia karttoja!

Low Power: OH5IY lentsikkaheijastukset 0,1 W majakasta OH5ADB 144 MHz: Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

• Juha -
  
  
  
  
  

[OH7HJ]

Continuing with another example of aircraft scatter doppler on Segezha Nadvoitsy TV Tx. First pic show plane location at its doppler appearence on the spectrum strip and the second pic at the fadeout of its doppler from the strip. Next plane doppler is already appearing while the first plane doppler is fading.

Previous pics: AS dopplers from Kainuu - 297 km, part 1 - viewtopic.php?f=21&t=295&start=150#p2379

• Juha -
  
  
  
  
  

[OH7HJ]

Arkhangelsk TV Tx is supposed to have 8 kW of ERP power, so it is lower powered than Segezha Nadvoitsy. However, the Onega Bay of White Sea helps to boost its signal strength so rather long aircraft dopplers are available at it.

Here is an example of flight that despite of its rather low flight level of 10058 m was visible for up to 458 km from receiver. The route of this flight kept close to Rx-Tx baseline, so the baseline forward scatter effect improved its signal strength. The plane was flying almost parallel to Rx-Tx baseline so it plotted a parallel type of doppler close to the Arkhangelsk TV carrier.

Receiving setup is similar to the previous Kainuu experiment, with RTL as Rx 6-element 6m band yagi pointing NEE. Softwares are HDSDR and Spectrum Lab, with FFT set for decimation of about 8 … 16 to allow high resolution and good reception sensitivity. Doppler shift scale is Hz and time ticks are every 10 minutes. Time stamps are Finnish local. Aircraft course adjustments are visible as angles or notches in the doppler. Two pics were saved direct during the flight and one screenshot was created later with Planefinder playback.

Next: Arkhangelsk TV AS dopplers - 426 km, part 2 - viewtopic.php?f=21&t=295&p=2382#p2382

• Juha
  
  
  
  
  
  

[OH7HJ]

Next set of screenshots on Arkhangelsk TV carrier frequency illustrate typical doppler of flight arriving from Far East.

First screenshot is from doppler appear location and next from doppler fadeout location. Sector of doppler visibility is drawn with lines from Arkhangelsk TV Tx.

Date and local time of observation is marked to each file name. Doppler shift scale is Hz and time ticks are every 10 minutes. Receiving setup is the same as in previous experiment.

Previous: Arkhangelsk TV AS dopplers - 458 km, part 1 - Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

• Juha
  
  
  

[OH7HJ]

Two subsequent flight dopplers. Experiment setup as with earlier two reports.

Previous:

Arkhangelsk TV AS dopplers - 458 km, part 1 - Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

Arkhangelsk TV AS dopplers - 426 km, part 2 - posting.php?mode=reply&f=21&t=295#pr2382

• Juha
  
  
  

[OH7HJ]

Here is a series of 4 pics of aircraft dopplers crossing Arkhangelsk TV carrier with transverse to the Rx-Tx baseline flight path.

The transverse crossing is much steeper than the parallel crossings of previous examples so now using narrow spectrum scale. Time ticks are every 5 minutes.

Otherways receiving and file name documenting setup is the same as with previous Arkhangelsk TV AS doppler reports.

Continued in next report: Arkhangelsk TV AS dopplers - transverse crossing 2 - Kerhon kaluston lainausvihko

• Juha -
  
  

[OH7HJ]

AS doppler pics series continued from previous message. Aircraft coming from north is flying lower which makes its doppler weaker.

Previous observation reports:

Arkhangelsk TV AS dopplers - 458 km, part 1 - Aircraft Scatter - Lentokoneheijastus ja sen doppleri.
Arkhangelsk TV AS dopplers - 426 km, part 2 - posting.php?mode=reply&f=21&t=295#pr2382
Arkhangelsk TV AS dopplers - 416 km, part 3 - Kerhon kaluston lainausvihko
Arkhangelsk TV AS dopplers - transverse crossing 1 - Kerhon kaluston lainausvihko

• Juha
  
  

[OH7HJ]

These are aircraft scatter dopplers on Nyandoma TV Tx carrier east of Lake Onega (Äänisjärvi). Nyandoma is supposed to have a medium power TV transmitter with ERP of 46 kW.

There were more similar dopplers in Nyandoma spectrum strips but because many domestic flights do not use locating ADS-B transponders these flights are not visible on online radar servers like PF and FR24 they could not be identified.

Rx aerial is a 6 over 6 element 6m band yagi array (Y12H) pointing at dir 100. Time stamps are Finnish local and time ticks at spectrum strip are 5 minutes apart. Doppler archive with copies of these spectrum strips is arranged by date and local time at: maanpuolustus.net/muut/tutka/kuvat/

Previous: AS dopplers on Nyandoma TV carrier - 395 km- viewtopic.php?f=21&t=295&start=150#p2370

• Juha
  
  
  
  
  

[OH7HJ]

Luonnolliset radioaaltojen hajaspektriheijastukset yläsalamoista saavat joskus hupaisia muotoja. ‘Kovista’ ja ‘kylmistä’ keinotekoisista kohteista, kuten lentokoneista heijastuvat radioaallot näkyvät yhtä kapeina dopplerjuovina, kuin niiden lähetinkin. Luonnollisista sähköisistä ‘kuumista’ ja ‘pehmeistä’ lyhytaikaisia plasma- ja ionipilviä muodostavista sähkönpurkausilmiöistä heijastuvien aaltojen tunnusmerkki on hajaspektri, eli kaiku ‘leviää’ enemmän tai vähemmän. Joskus kohinana, joskus kuvien kaltaisina haarautuvina kiharoina tai ‘dopplerkoukkuina’.

Nämä sähköskatterit on tallennettu Cherepovetsin TV:n kantoaaltotaajuudella n. 49739,583 kHz. Lähekkäisellä taajuudella on myös Arkangelin eli Vienan TV. Nauhoilla näkyy myös näitä kaukaisempien TV-lähetteiden kantoaaltojen tai sivunauhojen heijastuksia. Viistoviivat nauhoilla ovat lentsikkadopplereita Cherepovetsin TV-sivunauhakopioineen.

Otoksissa Spectrum Lab -softan taajuusasteikko yläreunassa on hertseinä, Cherepovetsin TV-kantoaallon kohta likimain nollana, muutaman hertsin ryömintätoleranssin puitteissa. Aikaleimat vasemmalla ovat Suomen aikaa. Radiospektrinauhan liikesuunta on ylhäältä alas. Vastaanotin on tavallinen halpa RTL-SDR-tikku kuuntelemassa 50 MHz 4-el ympärisäteilevää dipolimattoantennia (D4H) radiosoftan HDSDR ja virtuaaliäänikaapelin kautta.

Linkkejä taivasheijastuksiin ja yläsalamiin

Electric Discharge Explanation of Nasa ‘Aurora Arrow’ Photo - viewtopic.php?f=21&t=295&start=150#p2374
Already somewhat known spreading and dividing natural high altitude electric discharges are ‘sprite’ lightnings. Sprite photos by Thomas Ashcraft: heliotown.com/Catalog_Transi … vents.html

“Sprites, Elves and Intense Lightning Discharges”, Nato Science Series II: books.google.fi/books?id=XagIZh … es&f=false
Upper-atmospheric lightning: en.wikipedia.org/wiki/Upper-atm … _lightning
The Manastash Ridge radar: A passive bistatic radar for upper atmospheric radio science - onlinelibrary.wiley.com/doi/10.1 … S02454/pdf

EDS - Yläsalamat aiheuttavat radioheijastuksia: Aircraft Scatter - Lentokoneheijastus ja sen doppleri.
Sähkönpurkausheijastus EDS - Electric Discharge Scatter: Aircraft Scatter - Lentokoneheijastus ja sen doppleri.
Yläsalamapurkauksen synnyttämä ukkos-Es-keli: Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

‘Doppler hooks’ - ‘Dopplerkoukkuja’ ‏Moskovan, Arkangelin ja Pietarin TV-jaksoilla:
Osa 1: viewtopic.php?f=21&t=295&start=100#p1893
Osa 2: Aircraft Scatter - Lentokoneheijastus ja sen doppleri.
Osa 3: viewtopic.php?f=21&t=295&start=110#p1901
Osa 4: viewtopic.php?f=21&t=295&start=110#p1903
Osa 5: Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

Online bistatic radar demo listening to R1 TV channel carriers at maanpuolustus.net/muut/tutka/kuvat/

Briefly in English: High sky radio scatters sometimes plot curious patterns on these R2 TV channel spectrum strips. Here are a few examples of these natural dividing spread spectrum scatters.

[OH7HJ]

Kirkkaana tulipallona maiseman valaiseva tähdenlento havaittiin Lapissa illalla 16.11.2017. Ursan asiantuntijan mukaan tähdenlennon arvioidaan pudottaneen kymmeniä kiloja, jollei jopa satakunta kiloa meteoriittikiviä Inarinjärven etelä- tai kaakkoispuolelle. Tässä 50 MHz bandin monipaikkatutkan tallenteessa näkyy ehdokas tulipallon tutkajäljeksi ympyröitynä, lähinnä sopivan tapahtuma-ajan perusteella.

Jannelta sain tulipallon tarkan alkuajan 18:40:15.241, joka on peräisin Panu Lahtisen Ivalossa olevasta allsky-kamerasta. Kiitos! Tulipallon tarkka syttymisaika näyttäisi sattuvan tutkanauhan lukematarkkuuden puitteissa yhteen tämän tutkatallenteen kanssa. Spectrum Labin hitaalta nauhalta pystyy ajan arvioimaan noin 10 sekunnin tarkkuudella.

Vaikka tutkakaiku näyttää hyvin samanaikaiselta, se voi silti olla jokin tästä tähdenlennosta riippumattomista lukuisista korkean taivaan sähkönpurkausheijastuksista (EDS, Electric Discharge Scatter), joita vastaanotin havaitsee jatkuvasti tällä Arkangelin TV:n taajuudella muutaman minuutin välein. Nauha on tallennettu on pohjoiskoilliseen katsovalta 6-elementtiseltä PA50-6-6 -jagiantennilta HDSDR- ja Spectrum Lab -softilla Arkangelin TV:n kantoaallon taajuutta 49739,586 kHz kuuntelevalta RTL-vastaanottimelta. Nauhan aikaleimat ovat Suomen aikaa.

Liitteet ja linkit:

Video tulipallosta: m.facebook.com/story.php?story_ … cation=ufi

Uutisartikkeleita: mtv.fi/uutiset/kotimaa/arti … gs.JyxwLmQ

Silminnäkijäkomentteja: satakunnankansa.fi/kotimaa/ … 200542207/

Jannen kertoma alkuaika: facebook.com/groups/luonnon … 22R9%22%7D

Ursan Taivaanvahtiin ilmoitetut havaintoajat vaihtelevat n. 18.35 … 18.40 välillä: taivaanvahti.fi/observations … _id/desc/0

Monipaikkatutkan online demonäyttö: maanpuolustus.net/pages/tutka/

Liitekuva tutkanauhasta: LP HDSDR Y6E 030 Arkhangelsk TV © OH7HJ - 2017-11-16-1800 - Bolide in Lapland at 184015 FT - Unknown radar trace at abt 184010 FT.jpg

T: - Juha -

[OH7HJ]

Näihin HDSDR-softaradiolla havaittuihin tyypillisiin spektreihin 6m TV-bandin R1-kanavalta merkkasin ympyröiden ja viivoilla yhdistäen joitakin esimerkkejä samanaikaisista luonnollisista heijastuksista, jotka ovat yhtaikaisia eri TV-lähetinten jaksoilla. Samanaikaiset luonnolliset radioskatterit näkyvät useina erilaisina yhdistelminä eri TV-lähetinten taajuuksilla. Koska radioheijastukset ovat voimakkaimpia lähetinten suunnilla esiintyvistä korkean taivaan kohteista, näiden samanaikaisista yhdistelmistä voi arvioida korkean taivaan heijastusten aiheuttajien summittaista tapahtumissuuntaa TV-lähetinten suuntiin vertaamalla.

Esimerkkiskattereden alussa ei näy meteoriheijastusten tuntomerkkiä, meteorivanan nopean lineaarisen liikkeen head-echo-doppleria, joten ne lienevät tavanomaisia spontaanisti syttyneiden luonnollisten korkean taivaan sähkönpurkausten radioheijastuksia (Electric Discharge Scatter EDS). Tällaisia sähkönpurkausheijastuksia näkyy ala-VHF-bandeilla jokseenkin jatkuvasti, kun taas meteoridopplerit (MS) ovat varsin harvinaisia.

Pitkäaikainen seuraaja saattaisi havaita spontaanien luonnonskattereiden seasta satunnaisia nopeita meteoridopplereita, ja käyttää niiden voimakkuusvertailua meteorivanan tapahtumasuunnan arvioimiseen tunnettujen TV-lähetinten suuntien perusteella. Vielä tarkemmin heijastusten radiosuuntiminen onnistuu tietenkin interferometrialla, jos käytössä on koherentti tuplavastari ja -antenni.

Tunnistetut parhaiten näkyvät TV-lähettimet taajuuksineen, lokaattoreineen ja karttasuuntineen on merkitty spektrikuvan yläreunan asteikolle. Muita etäisiä TV-lähettimiä, joiden luonnollisia heijastuksia nauhoilla myös satunnaisesti näkyy, on toki paljon näitä merkittyjä enemmän. Taajuusasteikko yläspektrin ja vesiputouksen välissä on kilohertseinä (kHz). Aikaleimat vasemmassa reunassa ovat Suomen aikaa, ja päiväys sekä vastaanottosetuppi on merkitty kunkin otoksen tiedostonimeen.

Linkkejä

Oheiset esimerkkiotokset on kopitettu hamssivastarin välitaajuutta kuuntelevalla RTL-SDR-tikulla tällä itään katsovalla jagikaksikolla: viewtopic.php?f=21&t=599&start=30#p1853

Sekä luonnollisia radioheijastuksia, että lentsikkadopplereita voi käyttää myös kaksisuuntaiseen kusoiluun. Tässä yksi softa lentsikkaskatteriyhteyksien harrastajille: AirScout is a Software for Aircraft Scatter Prediction - airscout.eu/

Lentsikkaheijastusten käyttäminen tuntemattomien radiolähetinten suuntimiseen (Aircraft Scatter Direction Finding, ASDF) - Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

Radiosuuntiminen kahden tai useamman antennin ja koherentin vastaanottimen interferometrialla: Simple Interferometer for Radio Direction Finding (RDF) - itr-datanet.com/~pe1itr/sate … ometer.htm

[b]In English:

How to tell the approximate direction of a natural high sky radio scatter? Here is how I estimate the general direction of strong 6m TV band scatters with single aerial and receiver method of known TV transmitters used as radio scatter beacons. [/b]

It is known that the baseline forward scatter effect greatly increases scatter intensity when the scattering target is close to the Rx - Tx baseline. This applies both for natural and artificial radio scatter targets. When scattering target is farther away from Rx - Tx baseline the signal strength of scatter decreases.

With very powerful TV Tx’s as beacons, radio scatters are visible from far away from baseline high sky targets as off-baseline backscatters. With small power TV Tx’s as beacons, only targets close to Rx - Tx baseline create observable scatters because the baseline forward scatter effect boosts their signal intensity.

Direction Estimate of Radio Scatters by TV Tx’s

On the R1 (OIRT1) TV carrier freq of 49750 kHz there are many TV Tx’s a few kHz apart from each other. Looking at the attached R1 TV channel spectrum strips, one can see that some natural scatters appear simultaneously on some of the known TV Tx carrier freqs marked at the scale above the screenshots.

By the directions marked to the TV Tx’s on the scale, one can make a rough estimate about the general direction of each scatter by which Tx freqs they appear on simultaneously.

I have marked and joined with lines some examples of the simultaneous natural high sky electric scatters on the spectrums. There are lots of natural scatter occurring every few seconds on this R1 TV channel so it is rather easy to spot them with modest equipment.

High sky electric discharge scatters seem occur at about similar altitude as Es scatter and be related to them, so their visibility range is comparable to 50 MHz Es ranges. So, Central Europe is not away from R1 TV electroscatter observing range.

73, T: - Juha -

[OH7HJ]

With aerials in low interference station location a long time observer could spot meteor scatter head echo scatters triggering some of these electric discharge scatters. For example, Esko OH2AYP has managed to spot some nice narrow doppler meteor scatter (MS) dopplers preceding spread spectrum electric discharge scatters (EDS).

Attached are a few pics of Esko’s MS dopplers on two TV Tx freqs. The upper one is St. Petersburg TV and the lower one is Moscow TV, both on 6m band R1 TV channel. Freq scale is about the width of receiver SSB filter. Much wider doppler shift indicating very high velocity together with short duration of the doppler distinguishes meteor scatter dopplers from usual aircraft scatter (AS) dopplers.

The actual meteor trail scatter is visible as narrow doppler (head echo). In some of his pics, the meteor trail appears to trigger a typical irregular spread spectrum electric discharge scatter following the actual narrow meteor doppler. In another pics, there is no electric dischage scatter following the meteor doppler. So a meteor trail may usually initiate a natural electric discharge that shows as a spread spectrum scatter.

The electric discharge scatter is usually much stronger and longer lasting than the preceding meteor scatter trace that appears to trigger it. However, usually there is no evidence of any meteor trail doppler preceding the ED scatter. So it appears that meteor trail may initiate a natural atmospheric electricity discharge but not always. There are a lot more natural ED scatters than meteor dopplers so most high sky natural electric discharges seem to be initiated spontaneously.

Spotting MS from among ED scatters - 2: viewtopic.php?f=21&t=295&p=2497#p2497
Spotting MS from among ED scatters - 3: viewtopic.php?f=21&t=295&p=2498#p2498

73, - Juha

[OH7HJ]

A sequence of strong and wide EDS flare or burst natural high altitude scatter occurring on the R1 TV channel. The strength of this flare scatter was strongest on the NEE pointing yagi of my aerials. So I guess this scatter originated from somewhere in North direction. The scatter starts and strengthens quickly and fades gradually in a few minutes which is usual to wide strong flares like this. Momentary spectrum of the flare at top appears to be a symmetric one of an analog TV, with weak center carrier.

The TV Tx of this scatter is unknown and its center frequency of abt 49749.5 kHz is unlisted. Might be some of the Kola dirstrict local TV Tx’s. I added to one of the pics the ‘scale’ of known TV Tx’s. Such wide flares as this occur irregularly from every tens of minutes to every few hours. Sometimes their rate increases before high sky electric activity periods like before aurora borealis spread noise spectrum discharge scatters begin.

These are slow moving monitor strip pics so I can not tell if there were any MS doppler head echo triggering the burst. By shape it is a usual wide TV Tx scatter flare that appears be caused by ionizing high altitude electric discharge. Compared to the Segezha Nadvoitsy TV visible on the same spectrum with sharp side band lines, the wide natural scatter burst has its side band lines merged together. This is a distinctive spread spectrum effect of high sky electric discharge scatters (EDS).

Time stamps at left are UTC + 2 hours. Aerial is a 6-el yagi pointing abt direction 030. Receiver is a RTL dongle working with HDSDR software. The Segezha Nadvoitsy TX is constantly visible with sidebands strong in freezing subzero during night and fading when temperature is rising above 0 C in daytime. An earlier less intense wide EDS flare visible on the strip has occurred less than an hour earlier.

Strong 6m TV High Sky Scatter - Part 2: viewtopic.php?f=21&t=295&p=2421#p2421

• Juha -
  
  
  
  
  
  
  
  

[OH7HJ]

Soon after I had reported about the wide strong natural scatter there appeared an aurora scatter. The aurora was a short burst lasting for a couple hours only. After aurora had stepwise faded out, there appeared one more wide natural burst following it. After this there were no similar strong natural wide bursts for hours.

It might be possible that these wide strong scatters were once again related to high sky electrostatic discharge activity, like accumulating high voltage ionospheric charges that seem to be related to birth of aurora borealis (Northern lights), too?

Solar wind is known to constantly bring positive static high voltage charges to the upper ionosphere. Electrostatic explanation of Northern lights discharge suggests that aurora borealis is a high voltage discharge between polar rims of ionosphere opening (aurora belt) and charged solar wind environment. This model explains easily the curtain shapes of visible aurora discharges in the sky, as well as aurora discharge movements along with night time movement of polar opening of ionospheric layers.

Strong 6m TV High Sky Scatter - Part 1: Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

• Juha -
  
  
  
  
  
  
  
  

[OH7HJ]

Oheiskuvana on leveä tutkanauha aurorapurkauksesta, sekä sitä ennen ja sen jälkeen esiintyneistä leveistä ja voimakkaista korkean taivaan luonnollisista sähkönpurkausheijastuksista (EDS). Nauhan alalaidassa näkyvät edellisen aamuyön aurorapurkausheijastusten pätkät.

Näiden vahvojen sähkönpurkausten luonnetta ei vielä tunneta. Niillä on kuitenkin luonnollisten korkean taivaan sähkönpurkausten moduloimille radioheijastuksille luonteenomainen hajaspektri. Arvauksen mukaan ne saattavat liittyä ylempiin ionosfäärisalamiin.

Revontulipurkausten radioheijastukset (Aurora Scatter) sekä voimakkaat leveät sähkönpurkausheijastukset (Wide EDS) on ympyröity spektrinauhalle. Aikaisempia havaintoraportteja samankaltaisista voimakkaista sähkönpurkausheijastuksista ennen ja jälkeen revontulipurkausten:

Strong 6m TV High Sky Scatter - Part 1 - Kerhon kaluston lainausvihko
Strong 6m TV High Sky Scatter - Part 2 - Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

Vastaanottimena havainnossa on RTL-SDR, softana HDSDR, ja antennina 6-el 50 MHz jagi suunnattuna pohjoiseen.

T: - Juha

[OH7HJ]

Lisää arvoituksellisia leveitä ja voimakkaita korkean taivaan sähkönpurkausheijastuksia tutkanauhoilla.

Näköhavaintoja kaivattaisiin ilmiöiden tunnistamiseksi, mutta niitä on tunnetusti vaikeaa saada täältä pilvien alta…

Nämä näkyivät eilen pohjoisen suuntaa havainnoivalla antennilla. Samankaltaisia näkyy satunnaisesti myös idän suunnalla. Aikaleimat ovat Suomen aikaa.

Strong 6m TV High Sky Scatters:

Part 1 - Kerhon kaluston lainausvihko
Part 2 - Aircraft Scatter - Lentokoneheijastus ja sen doppleri.
Part 3 - viewtopic.php?f=21&t=295&start=170#p2426
Part 4 - viewtopic.php?f=21&t=295&start=170#p2427

Kuva: 2017-12-19-2034 FT - OIRT1 HDSDR SL Y6E 360 Segezha - Three wide EDS bursts © OH7HJ.JPG

T: - Juha

[OH7HJ]

Leveänä nauhana tutkakuvassa näkyvä voimakas sähkönpurkausheijastus osui yksiin tutkassa pystysuuntaisina ‘lieskoina’ näkyvän alkavan revontulipurkauksen tilapäisen taukoamisen kanssa.

Leveän tutkanauhan kuvaa: 2017-12-30-2025 FT - OIRT1 HDSDR Y6H 360 Segezha TV - Wide EDS during pause of aurora discharge © OH7HJ

T: - Juha

[OH7HJ]

Uudenvuodenpäivän iltapäiväinen revontulipurkaus oli varsin voimakas, ja sekaan leimahteli leveitä voimakkaita yläsalamapurkausten radiokaikuja. Tavallisesti aurorapurkausta ja tällaisia voimakkaista leveitä yläsalamaheijastuksia ei näy yhtaikaa, vaan leveät sähkönpurkausheijastukset esiintyvät ennen revontulipurkausta, tai sen jälkeen.

Arvaan purkausten yhtaikaisuuden ja voimakkuuden saattavan merkitä, että aurinkotuulen puhuri on tuonut aimo annoksen taivassähköä. Nyt aurinkotuulen tuomaa sähkövarausta lienee tullut riittävästi purkautumaan samanaikaisesti sekä revontulina, että yläsalamoina…?

Leveät korkean taivaan sähkönpurkausheijastukset näyttävät liittyvän joskus revontulten alkamiseen tai päättymiseen. Niin kävi nytkin. Aurorapurkaus taukosi klo 16.45, minkä jälkeen leimahti revontulitutkan nauhalle yksi voimakas leveä sähkönpurkauskaiku lisää. Revontulikaiut näkyvät tällä leveällä nauhalla pystysuuntaisina ‘lieskoina’. Leveät sähkönpurkausheijastukset puolestaan näkyvät vaakasuuntaisina, yläreunaltaan sahalaitaisina juovina.

Tutkanauhan alemman ikkunan radiospektrinauhan liikesuunta on ylhäältä alaspäin. Aikaleimat nauhan vasemmassa reunassa ovat Suomen aikaa. Päiväys on kuvien tiedostonimessä. Taajuudet näkyvät kilohertseinä taajuusasteikolla spektri-ikkunoiden välissä.

T: - Juha

[OH7HJ]

A simple multi-frequency reception experiment on part of 49750 kHz OIRT1 TV channel spectrum with traditional analog HF communications receiver Plessey PR155 which has filter for 6 kHz wide USB. This is a moderate increase of rx bandwidth which allows receiving two instead of previous one TV tx carrier frequencies at the same time with single aerial and receiver. Here the two freqs are Moscow TV and St Petersburg TV carriers about 3 kHz apart from each other.

First screenshot shows an aurora discharge burst at left on 5.5 kHz wide bandwidth Spectrum Lab display from part of the R1 TV channel spectrum. Moscow TV and St Petersburg at wide spectrum strip left and St Petersburg zoomed as detail at right SL strip. Both were received simultaneously with same receiver and aerial. Scale at top of each strip shows frequency as Hz.

SL2 Y6U PR155 OIRT1 5.5 kHz wide spectrum - Moscow - St Petersburg © OH7HJ - 2018-02-01-0100 - Aurora burst.jpg

Second screenshots shows at left strip Moscow TV and at right strip St Petersburg TV carrier aurora bursts zoomed still wider with simultaneously plotting another example of Spectrum Lab reading the same PR155 receiver through tiny USB audio stick. Sorry for heavy freq drift of the veteran rx and its converter. Neither are near modern stability standards.

The two Spectrum Labs reading receiver sound through an USB audio dongle consume minimal amount of computer power. The same computer reads and plots at the same time sound inputs from two more 50 MHz ham receivers with still one SL example, plus listens to aircraft ADS-B signals with a RTL1090 SDR to plot them on Planeplotter map: maanpuolustus.net/pages/tutka/

This makes a single computer monitor, analyze and save simultaneously 6 spectrum strips and 5 frequencies. Processing power of this pre-Millennium era Fujitsu Scenic desktop running multi analog rx’s and SL windows is about similar to modern Raspberry Pi. Multi frequency and multi spectrum analysis from wide band audio sound feed from single receiver and aerial appears feasible.

SL3 Y6U PR155 OIRT1 - Zoomed from 5.5 kHz wide spectrum - Moscow and St Petersburg © OH7HJ - 2018-02-01-0100 - Aurora burst.jpg

On third screenshot an example of how switching Plessey receiver filters affect monitored bandwidth visible on Spectrum Lab strips.

Filter responses are rather bumpy which is normal for analog receivers like PR155. Modern SDR’s produce nice flat and straight frequency spectrums from their digital filters. I hope that I can get some of the new wide audio SDR’s work in my computers to continue multi frequency experiments with.

2018-02-01-1223 SL3 Y6U PR155 OIRT1 - 5.5 kHz wide USB spectrum - Comparing bandwidths of 0.3 and 3 and 6 kHz rx USB filters © OH7HJ.jpg

Regards,

• Juha -
  
  
  
  
  
  
  
  

[OH7HJ]

Continued from previous message.

Equipment pics: A 50 MHz converter equipped Plessey PR155 HF receiver dating from early 1970’s was used with this experiment because it was my only rx that could listen to rather wide audio USB with its AM filter of about 6 kHz bandwidth and adjustable beat.

Only digitizing device between the PR155 receiver and computer was an inexpensive USB sound stick.

Regards,

• Juha -