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

[AV]

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.
>>
>>
>> _______________________________________________
>> CLUSTER mailing list
>> CLUSTER  radio-amador.net
>> http://radio-amador.net/cgi-bin/mailman/listinfo/cluster
>>
>>
> _______________________________________________
> CLUSTER mailing list
> CLUSTER  radio-amador.net
> http://radio-amador.net/cgi-bin/mailman/listinfo/cluster
>
>
-------------- próxima parte ----------
Um anexo em HTML foi limpo...
URL: http://radio-amador.net/pipermail/cluster/attachments/20130905/af5cd219/attachment.html