Aircraft Scatter - Lentokoneheijastus ja sen doppleri.

Keskustelua antenneista, radioista, yms. radioamatööritekniikasta

Aircraft Scatter Dopplers on RDF Scale - 1.

ViestiKirjoittaja OH7HJ » 24.10.2018 15:36

An example how three aircraft dopplers flying the same route look like on Spectrum Lab Radio Direction Finding (RDF) strip with a crossed 4-el loop array aerial XQ4H on Segezha TV carrier frequency. Their route is close to parallel to Rx - Tx baseline so their dopplers are plotted almost parallel to to the TV carrier for a while.

First pic shows the three dopplers joining TV carrier frequency after the planes pass by Segezha Nadvoitsy TV Tx. Map view is Planefinder.net.

Second screenshots shows their dopplers extracting from the TV carrier as they are bypassing my Rx location. Dividing 'fork doppler' is caused by a strong aircraft doppler signal strength close to Rx making intereference 'mirrors' and 'twins'.

Third image illustrates several simultaneous dopplers of planes plotted on the RDF strip. Colors indicate RDF directions calculated by Spectrum Lab from aerial phase shifts.


- Juha
Liitteet
2018-10-24-1530 FT - RDF XQ4H - Segezha TV - RDF cal 2 CCW - LH715 NH217 and AZ787 dopplers (c) OH7HJ.JPG
Three aircraft dopplers joining Segezha TV carrier frequency after the planes pass by Segezha Nadvoitsy TV Tx.
2018-10-24-1530 FT - RDF XQ4H - Segezha TV - RDF cal 2 CCW - LH715 NH217 and AZ787 dopplers (c) OH7HJ.JPG (272.68 KiB) Katsottu 626 kertaa
2018-10-24-1539 FT - RDF XQ4H - Segezha TV - RDF cal 2 CCW - LH715 NH217 and AZ787 dopplers extracting from TV carrier (c) OH7HJ.JPG
Dopplers extracting from the TV carrier as they are bypassing my Rx location. Dividing 'fork doppler' is caused by a strong aircraft doppler signal strength close to Rx making intereference 'mirrors' and 'twins'.
2018-10-24-1539 FT - RDF XQ4H - Segezha TV - RDF cal 2 CCW - LH715 NH217 and AZ787 dopplers extracting from TV carrier (c) OH7HJ.JPG (293.69 KiB) Katsottu 626 kertaa
2018-10-24-1546 FT - RDF XQ4H - Segezha TV - RDF cal 2 CCW - Dopplers of a rush of planes (c) OH7HJ.JPG
Several simultaneous dopplers of planes plotted on the RDF strip. Colors indicate RDF directions calculated by Spectrum Lab from aerial phase shifts.
2018-10-24-1546 FT - RDF XQ4H - Segezha TV - RDF cal 2 CCW - Dopplers of a rush of planes (c) OH7HJ.JPG (277.53 KiB) Katsottu 626 kertaa
OH7HJ
 
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Aircraft Scatter Dopplers on RDF Scale - 2.

ViestiKirjoittaja OH7HJ » 27.10.2018 18:56

More example SL RDF dopplers of a rush of aircraft. Setup is same as with previous message. Segezha TV carrier is close to zero Hz marker of the Spectrum Lab RDF strip.

Pic 1: Among usual aircraft scatter dopplers there is a smaller sharp 'doppler hook' near the center of the SL strip. This may be created by a natural high sky dividing electric discharge scatter (EDS).

Pic 2: The TV carrier at about -7.5 Hz position of the spectrum strip is Ruskeala TV carrier. Here it has a typical steep rather short aircraft doppler of a plane crossing the Rx-Tx baseline. At the spot marked with cross cursor Spectrum Lab has calculated its RDF direction to be 139.3 degrees from Rx. Ruskeala TV Tx is at abt 140 degrees from my Rx so the RDF calibration seems to be rather good.

Pic 3: Extracting doppler of an aircraft with mirror 'twins' caused by strong doppler scatter signal interference. SL RDF suggests 139.4 degrees as direction of Ruskeala TV Tx at mouse cursor point. RDF directions of faraway TV Tx's vary possibly because multipath effect of surface wave propagation. Above horizon signal source like aircraft doppler RDF directions usually keep rather accurate probably because sky wave propagates directly without need to seek alternative paths like surface wave usually does.

Link to RDF aerial 6m 4+4-el Crossed RDF Loop XQ4H: http://oh7ab.fi/foorumi/viewtopic.php?f ... =200#p2598


- Juha
Liitteet
2018-10-27-1811 FT - RDF XQ4H - Segezha TV - RDF cal 2 CCW - Dopplers of a rush of planes - Sharp doppler hook (c) OH7HJ.JPG
Among usual aircraft scatter dopplers there is a smaller sharp 'doppler hook' near the center of the SL strip. This may be created by a natural high sky dividing electric discharge scatter.
2018-10-27-1811 FT - RDF XQ4H - Segezha TV - RDF cal 2 CCW - Dopplers of a rush of planes - Sharp doppler hook (c) OH7HJ.JPG (287.94 KiB) Katsottu 619 kertaa
2018-10-27-1822 FT - RDF XQ4H - Segezha and Ruskeala TV - RDF cal 2 CCW - Dopplers - Ruskeala TV crossing (c) OH7HJ.JPG
The TV carrier at about -7.5 Hz position of the spectrum strip is Ruskeala TV carrier. Here it has a typical steep rather short aircraft doppler of a plane crossing the Rx-Tx baseline. At the spot marked with cross cursor Spectrum Lab has calculated its RDF direction to be 139.3 degrees from Rx. Ruskeala TV Tx is at abt 140 degrees from my Rx so the RDF calibration seems to be rather good.
2018-10-27-1822 FT - RDF XQ4H - Segezha and Ruskeala TV - RDF cal 2 CCW - Dopplers - Ruskeala TV crossing (c) OH7HJ.JPG (249.21 KiB) Katsottu 619 kertaa
2018-10-27-1835 FT - RDF XQ4H - Segezha and Ruskeala TV - RDF cal 2 CCW - Extracting doppler with mirror twin interferences (c) OH7HJ.JPG
2018-10-27-1835 FT - RDF XQ4H - Segezha and Ruskeala TV - RDF cal 2 CCW - Extracting doppler with mirror twin interferences (c) OH7HJ.JPG (256.7 KiB) Katsottu 619 kertaa
OH7HJ
 
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Experimenting with Directional Filter

ViestiKirjoittaja OH7HJ » 09.11.2018 14:35

Radio Direction Finding (RDF) by two or more aerials allows also many other applications than just direction finding. In principle, any two separate receiving aerials used with a coherent two or multi channel receiver allow assorting signals by their phase shifts. Here are examples of experiments separating desired signals from unwanted noise and interference.

Bare noisy digimode signals are at left with Spectrum Lab RDF screenshots. At right desired signals have been separated by their RDF 'color' which indicates signal phase shift. Because there are yet no directional filter software available, I imitated directional filter effect with Picture Publisher software color picking tool.

The qraphical editing tool of this demonstration is of course too 'hard' making abrupt signal outlines but the pics should give a rough idea about how direction of wave arrival could be used for selecting desired radio signals. Proper practical signal processing software introducing directional filter would work 'softer'.

Example signals were spotted and plotted from 160 m band at 1843 kHz LSB with a coherent pair of FT100D receivers. Aerial was the same 6m band XQ4H crossed loop used for my 50 MHz experiments. Despite that the aerial is in this 160 m case built for 'wrong' band the crossed loop appears to works on other bands, too, providing necessary phase shift for HF directional filtering effect demonstration.


Regards, - Juha
Liitteet
RDF HF 1843 USB - XQ4H (c) OH7HJ - 2018-11-08-2040 - Some noisy signals at left selected with directional filter at right (c) OH7HJ.jpg
RDF HF 1843 USB - XQ4H (c) OH7HJ - 2018-11-08-2040 - Some noisy signals at left selected with directional filter at right (c) OH7HJ.jpg (374.08 KiB) Katsottu 549 kertaa
2018-11-08-1943 FT - HF 2xFT100 XQ4H - RDF cal 0 CW - 160 m 1843 LSB - Some noisy signals at left selected with directional filter at right (c) OH7HJ.jpg
2018-11-08-1943 FT - HF 2xFT100 XQ4H - RDF cal 0 CW - 160 m 1843 LSB - Some noisy signals at left selected with directional filter at right (c) OH7HJ.jpg (378.83 KiB) Katsottu 549 kertaa
OH7HJ
 
Viestit: 442
Liittynyt: 22.02.2009 12:38

Remote Online Plotting of 6m R1 TV Channel Meteor Scatters

ViestiKirjoittaja OH7HJ » 18.11.2018 17:36

The experimental multi-static radar listening to 6m band TV carriers streams almost real time USB audio which is quite good for monitoring meteors scatters and their head echo dopplers (MS HE). Here are instructions to set up your Windows home PC to receive and plot this radar sound stream with MS head and tail echoes on your own computer screen.

1. Load and install Spectrum Lab software by Wolf DL4MH. https://www.qsl.net/dl4yhf/spectra1.html
2. Open two windows of Spectrum Lab.
3. Load the attached archive file "Remote MS monitoring setup files for Spectrum Lab.rar" and extract them to some folder. This archive contains two Spectrum Lab USR setup files for MS plotting from the remote USB sound stream.
4. Then load each of these setup files to one of the Spectrum Lab windows from: File > Load Settings from > browse for these two files. "SL1 MS 40mS-line PK-M 49739-49752.USR" configures Spectrum Lab window for low R1 TV band and "SL2 MS 40mS-line PK-M 49755-49762.USR" for high R1 TV band MS plotting.

5. Download and install some virtual audio cable software you prefer. This software usually installs and works well: https://www.vb-audio.com/Cable/
6. Set this virtual audio cable as Windows default playback device. See the attached screenshot.
7. Set both Spectrum Lab audio input devices for the virtual audio cable: Options > Audio Settings > Input Device / Stream / Driver > Cable Output (VB Audio). See the illustration attached.
8. Set your web browser for https://maanpuolustus.net/pages/tutka/ . Turn its audio volume to maximum. Now the USB sound stream should be flowing to the virtual audio cable. Remark! If your web browser has no volume adjust control visible on the page, try another browser! Internet Explorer usually has a volume control. See the example screenshot below.

Finally apply Spectrum Lab settings. If you got it correct the Spectrum Lab windows should start plotting R1 channel TV from the online streaming radar sound. Then streatch the Spectrum Lab windows proper for you to view them.

Scale with usual OIRT1 channel TV transmitters is on notepad windows above the Spectrum Lab streams that I have put on this thread. Attached are text files of them as archive "Usual R1 TV band transmitters for editing a text file frequency scale (c) OH7HJ.rar".


Regards, - Juha OH7HJ
Liitteet
Usual R1 TV band transmitters for editing a text file frequency scale (c) OH7HJ.rar
(785 Bittiä) 10 kertaa
Remote MS monitoring setup files for Spectrum Lab.rar
(19.88 KiB) 7 kertaa
2018-11-18 Setup for remote online monitoring of 6m R1 TV channel meteor scatters with Spectrum Lab - VB Cable - Internet Explorer with Windows 7 (c) OH7HJ.jpg
2018-11-18 Setup for remote online monitoring of 6m R1 TV channel meteor scatters with Spectrum Lab - VB Cable - Internet Explorer with Windows 7 (c) OH7HJ.jpg (323.16 KiB) Katsottu 462 kertaa
OH7HJ
 
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Meteor Scatter Dopplers on RDF strips - 6.

ViestiKirjoittaja OH7HJ » 23.11.2018 19:35

For automatic capturing of meteor scatter head echoes (MS HE), Timo OH7HMS kindly suggested using a MS capturing script with Spectrum Lab. Knowing that MS HE's are rather difficult to automatically capture by their signal levels because they are much weaker and less frequent than the common high sky spread spectrum electric discharge scatters (EDS), I was dubious about it. However, there were MS capturing scripts accompanied with Spectrum Lab so I tried one created by Simon Dawes.

Right away there appeared a way to use the frequency range setting of the script to help identify long MS head echoes from among usual strong electric scatters. Strongest MS's usually draw their head echo doppler lines up to hundreds of Hz above the beacon tx freq. For them, I set the script to watch only those scatters 100 Hz or higher above the 6m powerful Tx of Moscow TV at 49747.41 kHz that gives nice MS HE's from wide range of sky.

First time trying, Simon's MS script captured overnight 254 screenshots, of which 101 were left after I removed short HE's and EDS bursts and missed ones. A lot of 254 screenshots captured by his MS script is a lot easier to check through than thousands of automatic screenshots saved every half minute or so. It means, that Simon's script works!

Here are some samples of MS HE's selected from among those automatically captured and labeled by the script. Frequency scale is up and time scale at left with SL time stamps as UTC+2h local and script time stamps as UTC. Spectum strip speed is 40 ms/line. The aerial used was the same 2x4-el crossed horizontal loop XQ4H and receivers the coherent pair of FT100D's as with my earlier 6m band RDF experiments. Signals on the spectrum screenshots are colored by Spectrum Lab's radio direction finding (RDF) function by their direction of arrival.


Regards, - Juha OH7HJ


Please click images below to open them.
Liitteet
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-23-043949 - Long.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-23-043949 - Long.jpg (141.38 KiB) Katsottu 372 kertaa
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-23-010130 - Long.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-23-010130 - Long.jpg (140.69 KiB) Katsottu 372 kertaa
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-22-235316 - Long.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-22-235316 - Long.jpg (131.52 KiB) Katsottu 372 kertaa
Viimeksi muokannut OH7HJ päivämäärä 24.11.2018 17:46, muokattu yhteensä 2 kertaa
OH7HJ
 
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Meteor Scatter Dopplers on RDF strips - 7.

ViestiKirjoittaja OH7HJ » 24.11.2018 16:07

Color changing MS HE dopplers:

Spectrum Lab RDF function has made colors of these meteor scatter head echo (MS HE) dopplers change by their direction of arrival.

By my first guess, those MS HE dopplers that change their RDF color are likely to be so close to receiving station (Rx) that while they travel on high sky they make a wide enough angle seen from Rx to change their RDF color on spectrum strip.

Here are some examples of these meteor scatter dopplers that change their RDF color while drawing their ionized tails on sky high above us. A reference SL RDF color circle is at right down corner of each MS HE screenhot. Receiving and capturing setup is the same as with previous report.


Regards, - Juha OH7HJ


Please click screenshots below to expand them.
Liitteet
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-23-135448 - Long changing color maybe close to Rx.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-23-135448 - Long changing color maybe close to Rx.jpg (149.42 KiB) Katsottu 344 kertaa
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-24-075629 - Long spread changing color - Double - Spread.jpg
Meteors sometimes appear to travel together. This color changing meteor doppler is followed by another a couple seconds later.

The meteor has triggered a typical tail scatter with TV side bands visible as vertical lines. Each of these tail scatter lines has a spread spectrum characteristic of high sky natural electric discharges.

Meteor ionized trails seem usually but not always trigger high sky electric discharges. Those meteors that have rather short and very narrow tail scatters without spread spectrum effect apparently have not triggered electric discharge scatters (EDS).
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-24-075629 - Long spread changing color - Double - Spread.jpg (140.3 KiB) Katsottu 344 kertaa
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-24-062604 - Long changing color - Sb twin - Spread tail.jpg
This MS HE is so strong that in addition to its doppler on the strong TV carrier also its short 'twin' is visible on the next strongest side band to the right of the carrier.

This meteor has triggered a spread noise spectrum EDS tail, too.
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-24-062604 - Long changing color - Sb twin - Spread tail.jpg (129.17 KiB) Katsottu 344 kertaa
OH7HJ
 
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Meteor Scatter Dopplers on RDF strips - 8.

ViestiKirjoittaja OH7HJ » 26.11.2018 14:24

Heavenly Meteor Blues:

Those meteor hits that occur near the Rx-Tx baseline are the strongest because of the baseline forward scatter (BFS) effect. The BFS effect increases scatter signal level about 20 dB or so compared to off-baseline scatters. That is why usually most MS HE dopplers plotted appear to come from the direction of transmitting station (Tx), which in this experiment is the Moscow TV on OIRT1 channel at southeast from receiving station (Rx).


However, because this 6m band Moscow TV Tx has a very high ERP power it brings visible also some meteor scatters from away from the Rx-Tx baseline. These are colored by the SL RDF function by their direction. Because Rx-Tx baseline to Moscow points at southeast from my Rx, most usual RDF colors for MS are yellow, green and cyan which represent approximate Moscow TV baseline direction on the Spectrum Lab RDF color circle visible on the low right corner of screenshots.

Most usual ones of the rather weak off-baseline meteor scatters visible on these SL strips are red scatters which represent northeast and blue scatters from south direction of the SL RDF color circle. Here are attached some of those evidently from south of my Rx propagating off-baseline blue or RDF color changing partly blue meteor scatter HE dopplers.


Regards, - Juha OH7HJ


Please click screenshots below to expand them.
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SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-26-043608 - Long color changing.jpg
These example southern blue and color changing while they are moving meteor scatters have a spread noise spectrum tail visible as upright TV side bands with spread noise spectrum indicating that meteor ionized tails appear to have triggered a short time natural high sky electric discharge scatter (EDS).
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-26-043608 - Long color changing.jpg (134.91 KiB) Katsottu 302 kertaa
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-25-031016 - Long blue and red.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-25-031016 - Long blue and red.jpg (137.87 KiB) Katsottu 302 kertaa
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-23-002124 - Long blue.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-23-002124 - Long blue.jpg (139.33 KiB) Katsottu 302 kertaa
OH7HJ
 
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Meteor Scatter Dopplers on RDF strips - 9.

ViestiKirjoittaja OH7HJ » 29.11.2018 22:15

'High Flyers':

Some MS HE dopplers plot interrupted lines on SL spectum strips even if they provide clear strong scatter signal. Because almost all of these dopplers have high dopplers shifts I am using for them a short name of 'high flyers'. These high dopplers are not very usual but there appear a few of them daily on these 6m band TV Tx carriers.


The cause of this kind high interrupted doppler may be either meteor trajectory or bistatic scatter geometry or quick velocity or charge loss or meteor falling apart, to guess a few.

As an example of trajectiories, a meteor 'scratching' upper atmosphere and escaping again might draw this kind interrupted high doppler. Quick velocity loss might make them decelerate below ionizing speed. Lightweight meteors naturally decelerate quicker than heavy ones.

If ionizing is agitated by meteor electric charge then fast charge loss would cause same. If a meteor is suddenly fragmentized by shock of hitting atmosphere it of course is decelerated quickly, too.

Experiment setup is the same as with my previous meteor RDF reports.


Regards, - Juha OH7HJ


Click screenshots below to expand them.
Liitteet
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-29-002311 - High flyer.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-29-002311 - High flyer.jpg (141.78 KiB) Katsottu 234 kertaa
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-27-233942 - High flyer.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-27-233942 - High flyer.jpg (137.77 KiB) Katsottu 234 kertaa
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-26-030727 - Long high flyer - EDS tail.jpg
SL6 RDF XQ4H Moscow TV OH7HJ UTC 2018-11-26-030727 - Long high flyer - EDS tail.jpg (133.38 KiB) Katsottu 234 kertaa
OH7HJ
 
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Geminidien meteorisateen saapumissuunnat - 1.

ViestiKirjoittaja OH7HJ » 08.12.2018 16:38

Jussin OH7TE ystävällisesti Ilkan OH5IY softalla laskemat joulukuun 2018 geminidien meteorisateen saapumissuunnat vuorokaudenajoittain.

14. päivä joulukuuta klo 23 UTC eteenpäin on sateen maksimi, ja radiantti silloin melko etelässä. Näistä näkyy graafisesti, kuinka korkealla meteorisateen säteilypiste on.

Laskettu lokaattorille KP30HV. Kellonajat näkyvät tiedostonimissä ja ovat UTC. Osa 1.


T: - Juha
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GEMINIDS_2018 - 00 UTC.jpg
GEMINIDS_2018 - 00 UTC.jpg (72.46 KiB) Katsottu 116 kertaa
GEMINIDS_2018 - 09 UTC.jpg
GEMINIDS_2018 - 09 UTC.jpg (71.8 KiB) Katsottu 116 kertaa
GEMINIDS_2018 - 16 UTC.jpg
GEMINIDS_2018 - 16 UTC.jpg (71.39 KiB) Katsottu 116 kertaa
Viimeksi muokannut OH7HJ päivämäärä 08.12.2018 16:43, muokattu yhteensä 2 kertaa
OH7HJ
 
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Geminidien meteorisateen saapumissuunnat - 2.

ViestiKirjoittaja OH7HJ » 08.12.2018 16:39

Jatkoa edelliseen, kuvat illalle klo 18 ja 23 UTC.


T: - Juha
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GEMINIDS_2018 - 18 UTC.jpg
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GEMINIDS_2018 - 23 UTC.jpg
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