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

[Paulo Faria]

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


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On 5 de Setembro de 2013 15:00:12 Carlos Fonseca <ct1gfqgrupos  gmail.com> 
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.
> >
> >
> > _______________________________________________
> > CLUSTER mailing list
> > CLUSTER  radio-amador.net
> > http://radio-amador.net/cgi-bin/mailman/listinfo/cluster
> >
> >
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