ARLA/CLUSTER: NASA convida radioamadores a transmitir mensagens
para a nave Juno em 28 MHz
João Costa > CT1FBF
ct1fbf gmail.com
Sexta-Feira, 6 de Setembro de 2013 - 17:12:01 WEST
Faço minhas as tuas saudades.
Nunca como naquela epoca gostei tanto de fazer satelite. È capaz de
ter sido pelo "primeiro amor", mas que me deu um grande gozo fazer o
RS12/13 naquelas condições, lá isso deu.
João Costa (Ct1FBF)
2013/9/6 Jose Miguel Fonte <etjfonte ua.pt>:
> 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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