Half-sky auroras, Helsinki, Pukinmäki

In the absence of light frequency observations, I put a radio frequency observation from the last northern lights. That is, it is an observation of radio meteor-scatter equipment from the reflection of a (analog) video carrier on Moscow TV from meteors and northern lights.

The original observational images have been reduced to one-fifth of the original in terms of the time axis and compiled by image processing into seven rows, each with a good hour. Full hours are marked in red on the lanes. Minutes are also displayed (and ten minutes in green, but its color is probably not distinguished from the tapered one). The full hour of the top lane is 9 pm Finnish time on the evening of the 27th.

Displays (EDIT: value corrected) the 1100 Hz radio frequency band with the carrier close to the center and its more accurate location is shown, for example, from a platform with only meteor reflection.

The reflection from the northern lights typically spreads in the frequency band and is often focused on a slightly different frequency. Starts with a reflection at the bottom that is from a different station. There will also be some meteor reflections and the position is unknown. There is also probably (slightly) a Revontuli reflection from two other unknown stations.

The dark area on the second line without visible reflection is probably due to the fact that there is apparently some other strong reflection in the wider radio band, which affects the automatic gain gain of the receiver, attenuating the signal (and noise) over the entire band.

The generation of radio reflection requires a certain geometry for which it is not enough to be visible from both stations. The fact that the Moscow carrier will become a reflection requires a time of the Southern Northern Lights. At one time, when more northern stations were used, for example, Vuokatti and / or northern Scandinavian stations received northern lights reflections much more often, and a printing format was used, which automatically narrowed the observation, for example, a day to one "line".

This description has been automatically translated from Finnish. Click here to see the original text.

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Joni Alavesa - 28.2.2014 at 19.39

Milläkäs taajuudella toi analoogi tv:n pilot carrier tulee?

Esko Lyytinen - 28.2.2014 at 20.44

Tulee taajuudella 49.747 MHz .

Vastaanotin on lukemassa 49.746740 MHz, sen ollessa USB-moodissa ja kantoaallon audiotaajuus on 900 Hz. Heittoa asteikon oikeellisuudessa näillä seuduin lienee muutama sata Hz.

Emma Bruus - 2.3.2014 at 11.40

Muistelen joskus nuorena tyttönä ~2001 katselleeni revontulia ja kuunnelleeni kuinka NMT 450-puhelimen taustakohina elää revontulten tahdissa. Onko tämä mahdollista vai alanko jo dementoitua?

Esko Lyytinen - 2.3.2014 at 11.53

NMT 450 muistaakseni toimi FM-modella.

Revontulet ei itsessään juuri taustakohinaa lisää, mutta kaukaisempien samaan aikaan lähettävien asemien heijastukset voivat tulla lisäkohinana (kohinaisena heijastumana), joko tukiasemaan tai kaukainen tukiasema samalla kanavalla omaan puhelimeen. Itselläni on joskus ollut tuollainen puhelin ja ainakin sen vastaanotin toimi vaan kun puhui jonkun toisen kanssa. Ja jos kuuluvuus toiselta asemalta tukiasemalle tai tukiasemalta omaan puhelimeen on heikon puoleinen niin voisi olla mahdollista että revontulet vaikuttavat kohinaan. Tosin tehot varsinkin itse kännyissä ovat pienen puoleiset joten vaatinee hyvää voimakasta revontulta sopivassa paikassa että tulisi riittävää heijastusta. Siis en pidä tätä mahdottomana mutta vaatii olosuhteilta aika paljon eli tuskin se yleinen ilmiö on ollut.

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Contact information

Half-sky auroras - 27.2.2014 at 21.10 - 28.2.2014 at 03.40 Helsinki, Pukinmäki Observation number 22484