1. Recepia semnalelor de frecvenfoarte joasGabriel Iana

2. Cuprins Originea semnalelor Tipuri de semnale provenite din natur Aplicaii Comunicaii Navigaie Modele de antene

3. Pentru a recepiona semnalele de joasfrecven trebuie s cunoatemsemnalele din natur Semnale electromagnetice provenite dinmediul ambiant Semnale generate de factorul uman

4. Nature RadioIdeea de ascultare a unei emisii care nuprovine de la un operator radio, un modem sau dede la orice dispozitiv, uneori ne surprinde pentru cne asteptm s gsim un zgomot de la o descrcareelectric sau ceva de genul acesta. Dar cnd vomgsi un ton, sau un semnal de tip whistler i multealte suprapuse, precum un cor de voci umane,suntem uimii pentru c nu le-a generat nimeni.Cnd descoperim legturile dintre aceste emisii icmpul magnetic al pmntului, a celor atmosfericeprecum furtunile sau reacii fizice atomice care sepetrec cteva mii de kilometri de Pmnt, rmnemstupefiai.

5. Originea SemnalelorCmpul magnetic terestru

6. Magnetosfera Este la 200km altitudine unde micarea sarcinilorelectrice este controlat de cmpul magnetic alpmntului In interiorul mangetosferei sunt zone mari de radiaiinumite Van Allens Band

7. Descrcrile electrice atmosferice Crusta pmntului esteformat din minerale iap srat (buneconductoare electrice) Potenialul n partea desus a atmosferei estede peste 400000V Intre un nor si pmntse poate ajunge la odiferen de potenialde 2-3milioane de Voli

8. Cmpul biomagnetic

9. Tipuri de semnaleRezonana Shumann Sunt n jur de 2000furtuni la un moment dat Se produc aproximativ 50descrcri electrice pesecund Semnalele se reflectacam de la 100kmnalime Frecvena de baz 7.8Hzi armonice la (15.6,23.4, 31.2 Hz)

10. Fluierturi (The whistlers) Sunt semnale cu frecvene cuprinse ntre 1kHz i 30Khzcu amplitudine maxim ntre 3kHz si 5kHz. Sunt produse de fulgerele crora impulsul magnetictraverseaz ionosfera si apare o dispersie de civa kHz

11. Fluierturi (The whistlers)

12. Fluierturi (The whistlers)

13. Activiti seismice Sunt observatoare seismice care analizeazcmpul magnetic generat de ctre micrilescoarei terestre pentru a le preveni Acestea sunt mprite n 2 benzi de frecven: 0.01Hz i 12Hz 30 i 150Hz

14. Activiti seismice

15. Clasificare benzi radioNume Band FrecvenELF Extremely Low Frequency 3Hz - 30HzSLF Super Low Frequency 30Hz - 300HzULF Ultra Low Frequency 300Hz - 3000HzVLF Very Low Frequency 3 - 30 kHzLF Low Frequency 30 - 300 kHzMF Medium Frequency 300 - 3000kHz (0.3 - 3 MHz)HF High Frequency 3 - 30 MHzVHF Very High Frequency 30 - 300 MHzUHF Ultra High Frequency 300 - 3000 MHz (0.3 - 3GHz)SHF Super High Frequency 3 - 30 GHzEHF Extremely High Frequency 30 - 300 GHz

16. Aplicaii ale semnalelor de joasfrecven n comunicaii Comunicaia ntre sisteme care nu se afl lasuprafa (sub ap, n sol) Sisteme de navigaie pentru submarine, vapoare,sisteme militare, etc. Detecie materiale explozive din incinte ecranateSTATIONS, ITU LICENCES AND SERVICES BELOW 22 kHz50 Hz - 7.04 kHz Range of frequencies to be transmitted by Space Shuttle mission STS-45 in mid March 1992.45 Hz Navy test frequency for submarine communications from US sites 197016.6667 Hz Mains power frequency for railways (Norway). Also referred asindustrial frequency.13 Hz Second Schumann resonance10 Hz Emissions from MIR, INSPIRE Project7 Hz The first Schumann resonance for the earth ionosphere cavity.1 Hz Frequencies in this range may be related to earthquake & seismic events.

17. STATIONS, ITU LICENCES AND SERVICESBELOW 22 kHz1280 Hz Test done at Kaford, Norway in 1979/80. ERP was 29W.1200 Hz MIDAC a system used by cavers to communicate with the surface. CW is useddown to 1200 below ground.1025 Hz Bynary tones on electric mains power, to change accounting rates in homecounters (e.g., used in Switzerland).OOK modulation.983 Hz A ULF beacon available for testing purposes in the USA.874 Hz A frequency mentioned in BREAK-IN in reference to an underground cavingexpedition.470 Hz Bynary tones on electric mains power, to change accounting rates in homecounters, like 1025 Hz76 Hz SANGUINE or Project ELF. A US navy submarine communications network.75 Hz Used during US tests in the 1970s. Replaced by 76Hz. See also 45Hz.70 Hz Submarine communications60 Hz Mains power (N. America and other countries)50 Hz Mains power (Europe)

18. Sisteme de comunicaii la submarine Generarea de cod binar 76Hz pentru U.S. 82Hz pentru Russian system Putere radiat efectiv mic 1-7W Se pot recepiona pe tot globul cu o anten T detip Marconi cu o bucla de 2100 m2

19. Sisteme de comunicaii la submarine

20. Instalaie n bandaELF pentrusubmarine ntreMichigan iWisconsin.Instalaiile sunt la238Km distan isemnalul radioeste generat decurentul dintrecele dou staii.

21. Sisteme de comunicaii

22. Recepie n banda de 82HzA Zevs transmission recorded in Italia by Renato Romero on the 8th of December 2000, at08:40 UTC

23. THE RUSSIAN VLF NAVAID SYSTEM,ALPHA, RSDN-20Segment nr.stationFrequency kHz1 2 3 4 5 6F3p 14.881091 kHzNovosibirsk,Revda, SeydaF3 14.880952 kHz Krasnodar Khabarovsk Novosibirsk Seyda RevdaF2 12.648809 kHz Revda Novosibirsk Khabarovsk Krasnodar SeydaF4 12.090773 kHz RevdaF5 12.044270 kHz SeydaF1 11.904761 kHz Novosibirsk Seyda Krasnodar Khabarovsk RevdaNEW RSDN-20transmission sequenceby frequencyNOVOSIBIRSK 55:45:22.0 N 84:26:52.4 EKRASNODAR 45:24:17.9 N 38:09:29.0 EKHABAROVSK 50:04:23.9 N 136:36:24.1 EREVDA 68:02:07.8 N 34:41:00.0 ESEYDA 39:28:16.0 N 62:43:07.3 E

24. The Russian VLF time-signal stations,Beta

25. Antene de recepie

26. Antena bucl (magnetic)

27. Antene bobinate (magnetice)Number of turns: 96000Wire diameter: 0,16 mm (AWG34)Winding length: 80 cmThick winding: 0,178 cmLength of wire: 13,44 kmWeight of copper wire approximately: 2,5 kgSingle turn area: 0,001225 square meters (3,5x 3,5 cm)1 pT field gives a voltage output of 0,354 mV(+/- 3 dB)1 mV voltage output corresponds to a field of2,82 pT (+/- 3 dB)

28. Preamplificator anten magnetic

29. Concluzii Semnalele de joas frecven reprezint o bazde studiu att pentru cele recepionate din naturdar i cele generate de om Recepia acestora n conjucie cu software-ulradio pot fi analizate i demodulate pn lafrecvena de 24kHz (frecvena maxim a plcii audio de calculator) O provocare n domeniul cercetri cost nrealizarea unei posibile legturi ntre semnalelede joas frecven i percepia celui de-al 6-leasim la animale.

30. Bine ai venit n aceast lumeexotic i distrai-v!