Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

[OH7HJ]

Aircraft doppler scatters are rather easy to capture on TV carriers. Then, how about Low Earth Orbit (LEO) objects like satellites? There are a few limitations about seeing scatters of those.

First one is that they are rather small and high. Another is that usual TV transmitter aerials are built to beam transmitted power towards horizon or lower. So there are no suitable up towards high sky high radiating TV transmitters for capturing real satellite scatter dopplers.

However, it is rather easy to capture dopplers of active satellite transmitters. Here are some pics and tips about practising satellite Tx doppler spotting.

• Juha
  
  
  
  
  

[OH7HJ]

Example of ‘raw’ images of 145 MHz satellite active transponder passover doppler sections on my HDSDR screen.

[OH7HJ]

The HDSDR allows showing only short strips in its high resolution spectrum graph window. Also its standard passband filters are a couple kHz too narrow to plot a complete frequency shift of a 145 MHz band satellite transmitter passover doppler.

So I cut and pasted together longer HDSDR strips from these ‘raw’ short screenshots. Here are examples of some HDSDR satellite Tx strips combined.

These images are captured with an omnidirectional 2 m collinear vertical X300N aerial 25 m above ground connected to a combination of RTL dongle listening to IF of an FT857 ham receiver as a ‘panadapter’. Time stamps on strips are Finnish local. Nominal frequencies of satellites are approximate.

• Juha
  
  
  
  
  
  
  
  

[OH7HJ]

Voimistuva, jo kaksi päivää vallinnut VHF-tropokeli näkyy R1-TV-kanavan kantoaaltoja seuraavan 6m ‘hamssitutkan’ nauhalla lisääntyvinä TV-sivunauhoina, jotka piirätävä spektriin luonteenomaisia tiheitä pystyviivojaan.

Oheisessa tutkaspektrissä voimakkain asema keskellä on Pietarin TV sivunauhoineen taajuudella 49749,975 kHz. Vahvana tulee myös Itä-Karjalan Sekeen TV n. 8 kHz sen yläpuolella.

Taajuusasteikko on kilohertseinä, ja aikaskaala vasemmassa reunassa on Suomen aikaa. Spektrinauhan liikesuunta on ylhäältä alas.

T: - Juha

[OH7HJ]

An experiment of observing with the 12-el receiving yagi on Moscow TV with a new high resolution Spectrum Lab FFT setup that Wolf DL4YHF kindly advised. This narrow band Spectrum Lab (SL) resolution brought up right away in great detail a lot of dopplers earlier not visible. Most of them proved to be from near the baseline midpoint about on area Tikhvin - Pikalyovo - South Ladoga, high flying ones naturally plotting longest dopplers as they are at the verge of radar horizon. A few of the dopplers were not from planes visible on online radars near this area, however.

While the earlier standard 1 Hz resolution that I used plotted only short dopplers for a few minutes only from a small area near Rx-Tx baseline, the narrow band setup now increased the durations of visible dopplers up to 10 … 15 minutes on Moscow carrier from the same area of indication. Radar range was increased, too. The air route near Tikhvin - Pikalyovo is closest to common radio horizon range from both my receiver and the Moscow TV transmitter so most dopplers appear to plot from there.

Each and every flight of this and other observations was individually identified to its doppler by its baseline crossing time and by its possible turns with help of playbacks of online radars like Planefinder or FR24. Below are three examples of many similar flights. Rx-Tx baseline crossing is again a logical way of identifying to which aircraft each doppler belongs to.

A large A380 aircraft at rather high altitude doppler was visible for up to 469 km away. It looks like the SL narrow band signal processing FFT setup increased sight of this VHF bistatic radar experiment slightly beyond over the horizon (OTH) range…?

Numbers and terms: Receiver (Rx) to transmitter (Tx) baseline distance of this experiment was 892 km. Radar range of a rather high flying A380 airliner was found to be about 469 km from receiver in this example. Transmitter range meaning distance from this aircraft to Moscow TV transmitter was about 443 km. Together these make a bistatic range (Rx-target-Tx) of 911 km.

Links

Online archive doppler strips of the above examples of long range aircraft doppler observations:
maanpuolustus.net/muut/tutka/ku … /23_30.jpg
maanpuolustus.net/muut/tutka/ku … /00_00.jpg
Online multi-static radar archive: maanpuolustus.net/muut/tutka/kuvat/

AS dopplers on Moscow TV carrier - Part 1: oh7ab.fi/foorumi/viewtopic.php?f … =120#p1912
AS dopplers on Moscow TV carrier - Part 2: Facebook OH7AB
Moskovan TV:n lentsikkaheijastuksia: maanpuolustus.net/posts/388598/

Spectrum Lab Manual: qsl.net/dl4yhf/speclab/index.htm
2 x 6 -element 50 MHz yagi array for AS doppler spotting: oh7ab.fi/foorumi/viewtopic.php?f … t=30#p1852
Locator map for measuring distances and baselines: k7fry.com/grid/

• Juha -
  
  
  

[OH7HJ]

Most of these Moscow TV aircraft scatter (AS) dopplers were from near the Rx-Tx baseline midpoint which is within common radio horizon of Rx and Tx for high flying aircraft. However, among these usual dopplers were some very short dopplers that were plotted at too steep angle to be from usual airliners. Steep doppler angle at baseline midpoint would mean aircraft crossing at supersonic speed. It was not likely that there would be many supersonic flight so evidently something else should cause these yet unknown dopplers.

With most cases of the unknown steep dopplers there was no aircraft scatter explanation for them in the usual area of reception of Moscow TV baseline midpoint. Plotted doppler baseline crossing angle is steep close to Rx or Tx, and mild far away from them.

Supersonic flights is not practical explanation so another reason for steep dopplers might be aircraft crossing baseline closer to Rx or Tx. That meant that the unknown dopplers might came from somewhere else than near Moscow TV baseline midpoint that is within or near common radar horizon from both Rx and Moscow TV Tx. The problem about close to Rx or Tx baseline AS crossings is that the aircraft would be far away from the supposed VHF radar range limits of Rx or Tx radio horizons.

Seeking for Steep Doppler Origin

First, I checked 26 of these unknown steep dopplers on Moscow freq from during about 2 days with Planefinder playbacks and found that in 14 cases of 29 unknown steep dopplers there were no planes near the baseline midpoint area of usual visible Moscow crossings. In the cases of aircraft near the area of visible crossing, there usually was usual mild aircraft doppler for it showing separately from the unknown steep doppler.

Antti OH7DI has previously introduced bistatic radar equations showing that strongest bistatic scatters appear with planes near Rx or Tx. In this case planes over Moscow Tx are far out of radio horizons of each other as the Moscow TV Tx is abt 892 km away from Rx. It is also known that aircraft crossing Rx-Tx baseline closer to Tx or Rx plot steeper dopplers than those crossing near midpoint of baseline.

To check if these mystery steep dopplers could somehow propagate over-the-horizon (OTH) from somewhere near Moscow Tx maybe with help of signal boosting baseline forward scatter effect and occasional tropo scatter, I added a check of close to Moscow district to this survey. Not really believing that these crossings could propagate from so far away.

Plane Crossings from Near Moscow…!

The results of plane search appeared suprising. There indeed was a plane on the Rx-Tx baseline in 23 of the 26 cases of these unknown steep dopplers.

The spot was on an almost transverse to baseline air route crossing Rx-Tx baseline near city of Kolakovo about 135 km before Moscow. This crossing point appeared to be close enough to Moscow TV Tx to produce about as steep dopplers as these observed unknown dopplers.

Regarding scientific credibility, the trouble with these findings is that the point of crossings is far beyond receiver radar horizon. It would mean that observed aircraft dopplers propagate from a radar range of about 757 km. That is a clearly over-the-horizon (OTH) observation which has this far been not supposed to regularly happen on VHF…!

Reasons Contributing to OTH Observation

If these really are over the horizon crossings, then we need to explain what would bring so distant low VHF band aircraft dopplers visible. It might be a combination of these favourable factors:

• Very high ERP power of Moscow TV Tx,
• baseline forward scatter effect that increases AS doppler signal level by 20 … up to 30 dB,
• recently configured high resolution Spectrum Lab receiving FFT settings,
• help of occasional tropo scatter, and
• the rather large 12-element receiving yagi array.

I remember having seen a few such steep short dopplers with the previous Moscow TV receiving arrangement but back then with the default wide band receiving Spectrum Lab FFT settings they were not yet sharp and regular enough to catch attention like they now are.

With the powerful 6-over-6 6m receiving yagi array and with the Spectrum Lab FFT settings improved sensitivity of reception the Moscow TV carrier is now visible and plotting practically continuously on its strip. With earlier smaller receiving aerials Moscow TV plotted without visible carrier as a chain of those short and wide electric discharge scatters (EDS) only on its spectrum strip.

Baseline Forward Scatter Effect

The forward scatter effect of baseline crossing is experimentally known to momentarily increase aircraft scatter doppler intensity up to the level of the TV carrier itself, or sometimes even a little stronger than the carrier.

Because the Moscow TV carrier is now practically constantly visible at Rx Spectrum Lab strip, it may be possible that the forward scatter baseline effect boosted crossing are momentarily as strong as the TV carrier, which would bring them visible from over the horizon distance of 757 km from receiver.

Bistatic range of this forward scatter observation is not increased because the crossing occurs right on the 892 km Rx - Moscow TV Tx baseline.

OTH Crossing Screenshots

Below are examples of many of similar crossings near Kolakovo. First attachment illustrates Rx-Tx baseline near receiver (Rx) and near Moscow TV transmitter (Tx) shared to two Planefinder playback maps. Map at left shows that there appear no aircraft near the usual crossing point of baseline midpoint area. Map at right shows aircraft crossing baseline near Kolakovo, abt 757 km from Rx and 135 km from TV Tx in Moscow. Its steep doppler crossing at SL strip shows at right. Pic: 2017-09-28-1554 FT - PF playback - Moscow TV ant Y12H 140 - Steep doppler - No aircraft near baseline midpoint - OK191 near Kolakovo © OH7HJ.JPG

Next attached screenshot shows another example of a plane crossing Moscow carrier near Kolakovo with simultaneous steep doppler. Baseline and range from receiver (Rx) to this crossing point are marked on the map at left: 2017-09-28-2242 FT - PF playback - Map of crossing point on baseline - Moscow TV ant Y12H 140 - Steep doppler - Aircraft near Kolakovo 757 km away © OH7HJ.JPG

Third pic shows Rx - Tx baseline on map with its midpoint near Boksitogorsk and the steep doppler baseline forward scatter crossing point near Kolakovo marked: Moscow TV Rx-Tx baseline length 892 km 145 degr KO85TT Tx from KP42QP Rx - Kolakovo forward scatter crossing point © OH7HJ.JPG

Regards,

• Juha -

Links

Online multi-static radar screenshot archive for doppler originals: maanpuolustus.net/muut/tutka/kuvat/
AS dopplers on Moscow TV carrier - Part 1: oh7ab.fi/foorumi/viewtopic.php?f … =120#p1912
AS dopplers on Moscow TV carrier - Part 2: Facebook OH7AB
AS dopplers on Moscow TV carrier - Part 3, 469 km: viewtopic.php?f=21&t=295&start=150#p2359

Spectrum Lab Manual: qsl.net/dl4yhf/speclab/index.htm
2 x 6 -element 50 MHz yagi array for AS doppler spotting: oh7ab.fi/foorumi/viewtopic.php?f … t=30#p1852
Locator map for measuring distances and baselines: no.nonsense.ee/qth/map.html
Planefinder: planefinder.net/#

Natural Scatters

Radar Aurora Compared to Sodankylä Magnetogram - Part 1. openstreetmap - ilmaisia karttoja!
Radar Aurora Compared to Sodankylä Magnetogram - Part 2. openstreetmap - ilmaisia karttoja!

Electric Discharge Scatter EDS - Yläsalamat aiheuttavat radioheijastuksia viewtopic.php?f=21&t=295&start=100#p1782
TV-lähetteitä aurorassa ja ES-kelissä viewtopic.php?f=21&t=295&start=100#p1892

Natural EDS ‘Doppler Hooks’ may be scatters of spreading high altitude lightnings:
‘Dopplerkoukkuja’ Moskovan TV:n jaksolla - Osa 1. viewtopic.php?f=21&t=295&start=100#p1893
‘Dopplerkoukkuja’ Moskovan TV:n jaksolla - Osa 2. viewtopic.php?f=21&t=295&start=110#p1900
‘Dopplerkoukkuja’ Moskovan TV:n jaksolla - Osa 3. viewtopic.php?f=21&t=295&start=110#p1901
‘Dopplerkoukkuja’ Arkangelin TV:n jaksolla - Osa 4 viewtopic.php?f=21&t=295&start=110#p1903
‘Dopplerkoukkuja’ Pietarin TV:n jaksolla - Osa 5 Facebook OH7AB

Aurora and EDS - Radiorevontulia ja sähkönpurkausheijastuksia 6m bandilla - 1.
viewtopic.php?f=21&t=295&start=140#p2250
Radiorevontulia ja sähkönpurkausheijastuksia 6m bandilla - 2 viewtopic.php?f=21&t=295&start=140#p2289

Tavallisia sähkönpurkausheijastuksia (EDS) viewtopic.php?f=21&t=295&start=140#p2251
Yläsalamapurkauksen synnyttämä ukkos-Es-keli viewtopic.php?f=21&t=295&start=110#p1895

50 MHz Es-keliavauksia viewtopic.php?f=21&t=295&start=140#p2248
50 MHz Es-keliavauksia - osa 2. viewtopic.php?f=21&t=295&start=140#p2249

[OH7HJ]

“LIVE ROCKET LAUNCH - Watch as the European Space Agency (ESA) launches the Sentinel-5P satellite from northern Russia at 5:27 EDT (10:27am BST). The satellite will track global air pollution from orbit.”

The liftoff trajectory of this rocket launch was directed over East Carelia so it appeared possible to plot on the bistatic ‘ham radar’ experiment strips. Checking monitor strip of Arkhangelsk TV carrier, there were signs of a rather faint very fast doppler crossing among usual aircraft doppler traces. The time of the fast doppler trace at 12:27 FT matched with liftoff time told in the video link below.

Range limit for aircraft on high altitude with the VHF bistatic radar experiment is radio horizon about 420 … 450 km away. A high rocket launch has of course longer radio horizon but it has an altitude limit regarding TV transmitter low radiating aerials. Rocket may plot a doppler until about 100 km altitude when flying between receiver and TV transmitter like the Rockot in this case did. Very high flights like satellites above 100 km are above TV transmitter vertical patterns of radiation so they are not visible on these bistatic doppler strips.

No Launch Trajectory Info

It is very uncertain to prepare for spotting dopplers of these rocket launches because there is no advance info available about their initial launch directions, trajectories, altitudes and velocities. This launch information would be needed for proper receiver setups and aerial directions to catch a clear rocket launch doppler. Launches are rare and usually directed to east away from reach of this doppler experiment. This launch had been delayed 6 times so it was not evident that it would be launched now, either. Because of all this it is a matter of good luck to have freqs and aerials oriented correctly for catching a rocket launch doppler from the part of launch trajectory that is within altitude and bearing limits of reception setup.

A couple of common aircraft dopplers are marked on the attached screenshot along with the circled faint tracks that appear Rockot doppler crossing traces on wide and narrow spectrum strips. The strip speeds are set for aircrafts and I was no prepared for very fast objects like a rocket so got only a short and flat doppler trace.

Aerial of this bistatic radar experiment is a 6-element yagi. Receiver is a cheap RTL SDR dongle plotting on laptop screen with HDSDR and Spectrum Lab softwares on Arkhangelsk R1 TV channel carrier frequency. Time stamps on Spectrum Lab strips are UTC + 3 h Finnish local.

Launch Links

Science Video of Rockot-Sentinel liftoff: facebook.com/IFeakingLoveSc … 150278820/

Prior launch info:
Schedule: Oct. 13 Rockot • Sentinel 5p
Launch time: 0927 GMT (5:27 a.m. EDT)
Launch site: Plesetsk Cosmodrome, Russia
A Eurockot Rockot vehicle will launch with the Sentinel 5 Precursor Earth observation satellite for the European Space Agency and the European Commission. Sentinel 5p carries an instrument to measure air quality, ozone, pollution and aerosols in Earth’s atmosphere. Delayed from Oct. 31, early 2017, June, August, Sept. 21 and Oct. 9. [Sept. 21]

spaceflightnow.com/launch-schedule/

earth.esa.int/web/guest/mission … entinel-5P

• Juha -
  
  

[OH7HJ]

The Nyandoma TV plots fairly long dopplers of about 20 minutes from east of Lake Ladoga. Looking for farther range, there is a flight route east of Lake Ääninen about 375 km away from receiver. Aircraft crossing here plot repeatedly doppler tracks of about 5 minutes. Here are examples of them.

Two of the examples are from the North-South route with planes crossing Nyandoma TV carrier abt 375 km away and one from NE route of aircraft crossing at abt 395 km away from the receiver. The funny ‘feathers’ occasionally visible around TV carrier and AS dopplers are curious side bands distinctive to Nyandoma TV Tx.

Receiving aerial is the usual 6 over 6 element 6m band yagi array pointing direction 100. Time stamps are Finnish local, UTC + 3h. Doppler strip archive with originals of these strips is arranged by time and date at: maanpuolustus.net/muut/tutka/kuvat/

The online bi/multistatic radar demo with fresh strips updating every half an hour is here: maanpuolustus.net/pages/tutka/

• Juha -
  
  
  

[OH7HJ]

OIRT-TV-kanavan 2 kuvakantoaalto on nimellistaajuudeltaan 49.750 MHz. Tässä on dopplerohitus Petroskoin (Petrozavodsk) TV:n R2-jaksolla 59249,998 kHz.

Petroskoi on varsin lähellä, joten lentsikoiden lähiohitusten dopplerit näkyvät melko voimakkaina sen kantiksen jaksolla.

Oheiskuvan ohitus on kopitettu 50 MHz jagilla, joka toimii näin etäällä nimellistaajuudestaan lähinnä ympärisäteilevänä dipolina. Dopplereita se näkee silti kohtuullisesti.

Taajuuksia:

Jürgenin kopittamistaan asemista kokoama OIRT-kanavalista tarkkoine taajuuksineen ja tuntomerkkeineen: dx.3sdesign.de/tv_offset_list.htm
Kokonainen OIRT-TV-lista, ilman tarkkoja taajuuksia: vcfm.ru/radio/fais2015_11_1+2ch.php

T: - Juha

[OH7HJ]

Karshevon pienitehoista n. 10 watin paikallislähetintä voisi ehkä merkitä tämä neljän sarja dopplereita, heikolla kantiksella 29 Hz Pietarin kantiksen yläpuolella? Lentsikkasuuntimalla (ASDF) tarkistettaessa, kaikki neljä lentoa osoittivat samaa suuntaa. Ohessa esimerkkikuva lentsikkasuuntimasta spektrinauhalle ympyröityine dopplerohituksineen.

Jakutinon TV on myös samalla suunnalla, mutta niin kaukana, että sen kantiksella pitäisi näkyä EDS-heijastusten helminauhaa. Nyandoman TV:n jokin sivunauha on kolmas vaihtoehto, sekin kun on lähes samalla suunnalla.

Tämä on kopitettu RTL-tikku vastarina suoraan Spectrum Labissa Yaesun välitaajuuden kautta, joten taajuudet näkyvät peilinä, koska en vielä ole löytänyt SL:n asetuksista taajuuden peilausoptiota. Antennina on 6-yli-6 vaakajagi suuntaan 100 astetta.

Linkki lokaattorilaskentasivulle: k7fry.com/grid/

T: - HJ

[OH7HJ]

Looking at natural phenomenon viewpoint, the curious orbital Nasa photo might be from a cloud of high altitude electric discharge. It appears transparent, and either weakly luminous or lighted up by the aurora discharge. The natural 50 MHz scatters on the R1 TV channel usually plot radio scatters dividing to two or three or even more directions. These ‘radio flares’, ‘doppler hooks’ or ‘fork scatters’ may be born by scattering from such dividing streamers of natural high sky electric discharges.

Photo is found with keywords ‘Nasa aurora arrow’ search. Photo link to it is youtu.be/9yCustQ4Zqg

The natural Electric Discharge Scatters (EDS) appear have spread doppler components that may present speed vectors of spread spectrum of accelerated ions and dividing natural discharges in very low pressure air.

After igniting, these discharges spead and create hot enough plasma or cloud of ionized air which is conductive enough to reflect and scatter VHF radio waves. As soon as the high atmosphere electric discharge is over, the temporary semiconducting ionized cloud cools down again fading away their ED radio scatters.

Spectrums Spread by Altitude?

Observing radio scatters of these natural discharges show radio scatters lasting from less than a second to a few minutes. Long lasting EDS usually have wider spread spectrums than short ones. This suggests that air ions or plasma accelerated in the electrostatic field of discharges gets faster and makes wider spread EDS spectrums in lower pressures of higher altitudes. So both duration and spread spectrum width of EDS’s may be related to their altitudes.

One of the highest altitude electric discharges and usually the only visible by eye from here on ground is the Aurora Borealis or Northern Lights, with its distinctive wide spread noise spectrum it causes on radio scatters. The wide spread spectrum aurora scatter is the longest lasting high altitude radio scatter with duration of hours.

There are yet no established words for these high sky electric radio scatters. The curious ionospheric “high-altitude plasma irregularities in the E region” mentioned in this FM bistatic radar paper from 1997 appear same as high lightning discharges that seem to cause the EDS: onlinelibrary.wiley.com/doi/10.1 … S02454/pdf

Articles, Studies and Observations

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/

• Juha -
  
  
  
  

[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.