ARLA/CLUSTER: NASA convida radioamadores a transmitir mensagens para a nave Juno em 28 MHz

Jose Miguel Fonte etjfonte ua.pt
Sexta-Feira, 6 de Setembro de 2013 - 16:55:01 WEST


Com upload em 21 MHz, o modo K e T... E os footprints enormes... que
saudades do RS12/13 (K) e 10/11 (T).


On Thu, 2013-09-05 at 21:28 +0100, AV wrote:
> Em tempos houve alguns satélites de amador com emissão nos 10m e eram
> bem fáceis de receber.
> 
> Julgo que o problema maior deste caso terá a ver com as
> caracteristicas do receptor.
> 
> 73,
> 
> António Vilela
> 
> CT1JHQ
> 
> 
> 
> On 5 September 2013 17:34, Paulo Faria <pauloafaria  sapo.pt> wrote:
>         Como se isso fosse mais fácil.
>         Fazer passar 28MHz pela ionosfera, é milhares de vezes mais
>         difícil, do que 144MHz. E se houver boa ionização, pior ainda,
>         volta tudo para terra.
>         O sistema detector não é um vfo sensível, nem o sistema será
>         capaz de (ler) os indicativos.
>         Sugere a Nasa, key down durante 30 segundos entre 28.001 e
>         28.450. Só espero que se lembrem dos beacons, e não estraguem
>         o dx a ninguém.
>         Os americanos não têm limites para infracção de regras, mas
>         nós temos.
>         Finalmente, provavelmente os piratas dos camionistas
>         brasileiros, espalhados por todo o espectro, devem cumprir a
>         missão com sucesso, transmitem em AM, durante mais de 30
>         segundos de cada vez, e estão espalhados pela banda de 10
>         metros, entre outras.
>         
>         Cumprimentos
>         Paulo Faria CS8ABA
>         
>         
>         Sent with AquaMail for Android
>         http://www.aqua-mail.com
>         
>         
>         On 5 de Setembro de 2013 15:00:12 Carlos Fonseca wrote:
>         
>         > Aos que se choram de nao conseguirem chamar a iss,
>         > aproveitem esta oportunidade pata depois nao dizerem que nao
>         > avisaram......
>         > 
>         > 73's de CT1GFQ
>         > REP#1406
>         > SKCC#466C
>         > 
>         > Cump.
>         > Carlos Fonseca
>         > 
>         > (Email enviado via plataforma movél).
>         > 
>         > No dia 5 de Set de 2013 13:04, "João Costa &gt; CT1FBF"
>         > <ct1fbf  gmail.com> escreveu:
>         >         Radio hams to say 'HI' to Juno on 10m
>         >         
>         >         NASA's Juno mission is inviting amateur radio
>         >         operators around the
>         >         world to transmit a coordinated message on the 28
>         >         MHz band to the Juno
>         >         spacecraft
>         >         
>         >         NASA's Juno spacecraft will fly past Earth on
>         >         October 9, 2013 to
>         >         receive a gravity assist from our planet, putting it
>         >         on course for
>         >         Jupiter.
>         >         
>         >         To celebrate this event, the Juno mission is
>         >         inviting amateur radio
>         >         operators around the world to say "HI" to Juno in a
>         >         coordinated Morse
>         >         Code message. Juno's radio and plasma wave
>         >         experiment, called Waves,
>         >         should be able to detect the message if enough
>         >         people participate.
>         >         
>         >         Juno will have a better chance of detecting the
>         >         signal from many
>         >         operators if the signal is spread out across the
>         >         spectrum. The Juno
>         >         Waves instrument is a broadband receiver, and the
>         >         detector being used
>         >         for this event has a band width of 1 MHz. It is
>         >         better for detection
>         >         of the signal to have a broadband signal coming in.
>         >         
>         >         For this experiment, we would like to ask those
>         >         participating to
>         >         spread out in frequency across the 10 meter band. We
>         >         have supplied a
>         >         table of suggested frequencies between 28 and 29
>         >         MHz, based on the
>         >         last letter of your call. When the HFR receiver is
>         >         tuned to 28MHz, the
>         >         center frequency is 28.5 MHz. A 50 kHz high pass
>         >         filter limits low
>         >         frequencies hitting the detector, so the frequency
>         >         table excludes 28.5
>         >         MHz ±50 kHz. The natural signals we expect to
>         >         measure at Jupiter will
>         >         consist of a large number of discrete tones, so
>         >         spreading the signals
>         >         out in this manner is a good approximation to the
>         >         signals we expect to
>         >         detect. But at Jupiter, we don't expect to be able
>         >         to decode CW in our
>         >         telemetry!
>         >         
>         >         The 28 MHz band was chosen for this experiment for
>         >         several reasons.
>         >         The Waves instrument is sensitive to radio signals
>         >         in all amateur
>         >         bands below 40 MHz, but experience with the
>         >         University of Iowa
>         >         instruments on the Galileo and Cassini earth flybys
>         >         shows significant
>         >         shielding by the ionosphere at lower frequencies. As
>         >         sad as it sounds,
>         >         we hope for lousy band conditions on October 9, so
>         >         an appreciable
>         >         fraction of the radiated energy escapes the
>         >         ionosphere into space, and
>         >         is not refracted back down to the ground somewhere
>         >         else on the planet.
>         >         
>         >         Juno's antenna consists of a pair of tapered 2.8
>         >         meter long titanium
>         >         tubes, deployed from the bottom deck of the
>         >         spacecraft under the +X
>         >         solar array and magnetometer boom. A high impedance
>         >         radiation
>         >         resistant preamp sits at the base of the antenna and
>         >         buffers the
>         >         signals from 50 Hz to 45 MHz. The elements are
>         >         deployed with an
>         >         opening angle of about 120 degrees. Ten meters is
>         >         above the resonant
>         >         frequency of the antenna and NEC analysis indicates
>         >         a lobe generally
>         >         along the spin axis of the spacecraft. This will be
>         >         good for detection
>         >         on the inbound part of closest approach to Earth.
>         >         
>         >         The Waves instrument uses four receivers to cover
>         >         the frequency range
>         >         of 50 Hz to 41 MHz. Signals up to 3 MHz are bandpass
>         >         filtered, sampled
>         >         by A/D converters and FFT processed into spectra
>         >         using a custom FFT
>         >         processor developed by The University of Iowa under
>         >         a grant from the
>         >         Iowa Space Grant Consortium.
>         >         
>         >         Please join in, and help spread the word to fellow
>         >         amateur radio enthusiasts!
>         >         
>         >         NASA - Say "HI" to Juno!
>         >         http://www.jpl.nasa.gov/hijuno/
>         >         See How do I participate ? for the frequency list.
>         >         
>         >         
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>         >         
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>         
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