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 > 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.
> >
> >
> > _______________________________________________
> > CLUSTER mailing list
> > CLUSTER radio-amador.net
> > http://radio-amador.net/cgi-bin/mailman/listinfo/cluster
> >
>
>
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