bonjour
j'aimerais connaitre la bande de fréquence et ses caractéristiques que peut recevoir le recepteur positionné sur la sonde cassini
. j'ai cherché un peu partout mais je n'ai pas les caractéristiques exactes .
A qui puis- je m'adresser? car j'ai besoin de ces données pour pouvoir faire les calculs et comprendre pourquoi on a dû changer la trajectoire de cassini.
merci
Bonsoir,Envoyé par karla 2
Sur un des sites de la NASA, ce devrait être trouvable.
On a pas dû changer la trajectoire de Cassini, on l'a fait volontairement pour qu'il puisse accomplir les différentes missions qui lui étaient assignées, ce qui n'aurait pas été possible avec une trajectoire unique.
Salut.
Connais toi toi-même (Devise de Socrate inspiré par Thalès)
Est ce que tu a déjà été là :
http://en.wikipedia.org/wiki/Radio_Science_Subsystem
Specifications
* Given a deep space network (DSN) of receivers and/or transmitters.
* A Ka-band traveling wave tube amplifier (K-TWTA) amplifies signals to a transmitting antenna to be received by a distal radio- telescope.
* Ka-band translator (KAT) receives signal from a high-gain antenna and retransmits the signal back to DSN. In this way the phase and phase-shift resulting from signal modification
* Ka-band exciter (KEX) it supplies telemetry data.
* S-band transmitter is used for radio science experiments. The transmitter receives signal from the RFS, amplifies and multiplies the signal, sending a 2290 Mhz signal to the antenna.
* Filter microwave emitter allow only microwaves of a given frequency to be emitted, there is a polarizing element. There are two-bypass filters and a wave-guide. The bypass filters allow different feed polarizations, receiving and transmitting.
Là : http://saturn.jpl.nasa.gov/spacecraf...assini-rss.cfm
Cassini is the only deep space mission to transmit to Earth at three radio wavelengths (approximately 14 cm wavelength, designated S-band; 4 cm, designated X-band; and 1 cm, designated Ka-band) simultaneously.
Ou là : http://saturn.jpl.nasa.gov/mission/nav-uplink.cfm
Uplink is a general term given to radio signals sent "up" from Earth to a spacecraft. The uplink usually sent to Cassini is a highly directional, microwave radio beam in a frequency range called X-band. It's around 7 to 8 billion Hertz (cycles per second), normally at power levels less than 10 kilowatts. The purposes for the uplink to Cassini are for commanding, tracking and radio science. Uplink also refers to the extensive process of planning, designing and sending command sequences.
Likewise, downlink is the general term for the radio signals sent "down" to Earth from a spacecraft. Cassini's normal downlink is in the X-band frequency range. This frequency range is used for tracking, radio science and telemetry.
Cassini can also downlink data in S-band and in Ka-band. The S-band is a lower frequency than X-band, and Ka-band is higher. However, downlinks in the S- and Ka-band are for radio science only.
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a+
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