Ce mai prindem prin Fm?

[zvartoshu]

Decibel , Watt , Amper , nu o da la intoarsa , zi ca menirea ta a fost ca sa intri in forum sa zici mai intai ca ai nevoie , dupa care sa te lauzi , si pe final ca sa te iei de mine . Las-o ma ca macane . Eu am zis stop abuzurilor si mistourilor , tu vad ca esti cel mai pus cu capsa , evdent pentru nimic , scri total inutil .
Ai tata in telecomunicatie , singur ai colacul de salvare , deci nu mai ai nevoie de forum .
Ai analizor , deci nu mai ai nevoie de filtre , uitate in ochii mei ce iti spun , singur ti-ai dat rapsunsul cu filtrele !
Intelege , nu te cunosc , nu ma cunosti , deci nu vad de unde si pana unde dai cu rdi inainte ? Pe mine ma intereseaza ca am luat un ban din cauza unui penibil ? NU , tre sa iti vezi de treba , sa iei raspunsul de la cel ce stie sa vorbeasca in limbajul tau .
Aici se vorbeste pasareste si pe intelesul nostru . Nu uita in dx nu se vorbeste cu analizor in gura sau cu LC metru in buzunar .

[Necherman]

Mai dane , nu te mai obosi . Este pus de cineva , nu exista om asa de pus cu capsa din prima cum este decibel ! Am fost foarte atent .

Explica te rog cum sta treaba cu scatterele de foarte mare distanta .

[Necherman]

Ne-am luat cu astea si inca o data repet , a fost pe 88,2 ceva si vorbea unul lent .

Am studiat meteor scatter pe net :
Meteor scatter propagation

Meteor scatter occurs when a signal bounces off a meteor's ionized trail.
When a meteor strikes earth's atmosphere, a cylindrical region of free electrons is formed at the height of the E layer. This slender, ionized column is relatively long, and when first formed is sufficiently dense to reflect and scatter television and radio signals, generally observable from 25 MHz upwards through UHF TV, back to earth. Consequently an incident television or radio signal is capable of being reflected up to distances approaching that of conventional Sporadic E propagation, typically about 1500 km. A signal reflected by such meteor ionisation can vary in duration from fractions of a second up to several minutes for intensely ionized trails. The events are classified as overdense and underdense, depending on the electron line-density (related to used frequency) of the trail plasma. The signal from overdense trail has a longer signal decay associated with fading and is a physically a reflection from the ionized cylinder surface, while an underdense trail gives a signals of short duration, which rises fast and decays exponentially and is scatter from individual electrons inside the trail.
Frequencies in the range of 50 to 80 MHz have been found to be optimum for meteor scatter propagation. The 88 – 108 MHz FM broadcast band is also highly suited for meteor scatter experiments. During the major meteor showers, with extremely intense trails, band III 175 – 220 MHz signal reception can occur.
Ionized trails generally reflect lower frequencies for longer periods (and produce stronger signals) compared to higher frequencies. For example, an 8-second burst on 45.25 MHz may only cause a 4-second burst at 90.5 MHz.
The effect of a typical visually seen single meteor (of size 0.5 mm) shows up as a sudden "burst" of signal of short duration at a point not normally reached by the transmitter. The combined effect of several meteors impinging on earth's atmosphere, while perhaps too weak to provide long-term ionisation, is thought to contribute to the existence of the night-time E layer.
The optimum time for receiving RF reflections off sporadic meteors is the early morning period, when the velocity of earth relative to the velocity of the particles is greatest which also increases the number of meteors occurring on the morning-side of the earth, but some sporadic meteor reflections can received at any time of the day, least in the early evening.


Meci mult .