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 Hackeando Satélites da NASA em casa! 
Open Satellite Project
Motivações
- Telecomunicações espaciais geralmente seguem uma especificação.
- Conteúdo limitado de páginas na internet falando sobre Processamento Digital de Sinais. 
- Software Defined Radios são acessíveis . 
- As imagens dos satélites metereologicos mostram a imensidão do nosso planeta. 
Como um SDR funciona?
Open Source SDRs
RTL-SDR
- Faixa de Frequência: 24 MHz - 1768 MHz
- Resolução de ADC: 8 Bits
- Samples: 3.2 MSPS IQ
Airspy
- Frequência: 24 MHz - 1768 MHz
- Resolução: 12 Bits
- Samples: 10 MSPS R2  e 8 MSPS Mini
- Open Source Firmware
HackRF
- Frequência: 1 MHz - 6 GHz
- Resolução: 8 Bits ADC / 10 bits DAC
- Samples: 20 MSPS IQ
- Half-Duplex Transceiver 
- Open Source Hardware & Software
LimeSDR Mini
- Frequência: 10 MHz - 3.5 GHz
- Resolução: 12 Bits ADC & DAC
- Samples: 30.72 MSPS IQ
- Full-Duplex Tranceiver
- Open Source Firmware & Hardware
Satélites de Orbita Baixa
Recepção
- Polarização RHCP
- Frequência de ~137MHz
- Baixa Resolução (1-4 km)
Especificações:
Equipamentos:
- Antena QFH ou V-Dipole
- Filtro Passa-Banda
- SDR
Roscosmos Meteor M-N2 
- Resolução: 10-bit @ 1km por pixel.
- Modulação: Quadrature Phase Shift Keying
- Canais: Infrared, Near-Infrared e Visible Light.
- Correção de Erro: Viterbi 2/7 & Reed-Solomon
Near-Infrared
Visible Light
Infrared
 Canais LRPT do Meteor M-N2
NOAA-N Prime APT Signal
- Resolução: 4km por pixel.
- Não tem correção de erros.
Geostationary Operational Environmental Satellite
GOES
Hardware de Recepção
- Antena Parabólica de 1.9 m 
- Dois Amplificadores (SPF5189)
- Filtro Passa-Faixa (Bandpass)
- SDR*
Wave Guide Feed (Canantena)
Remember the "old" wardrive times?
Low Noise Amplifier
(LNA4ALL ou SPF5189)
Bandpass Filter
- 1675 MHz Center Frequency
- 150 MHz Bandwidth
- Low Insertion Loss
- 1690 MHz Center Frequency
- 30 MHz Bandwidth
- Chebyshev ~3dB Ripple
- Low Insertion Loss
One LNA4ALL and Lorch Filter
Recepção e Demodulação
L-Band FFT do GOES-16 
BPSK? QPSK??
Binary Phase Shift Keying
Constelations
GNU Radio Companion
BPSK Receiver Constellation
Decodificação
- Usually wireless systems use convolution coded outputs
- Convolution Coded generates parity. The transmitter sends
   only parity data.
- The reverse algorithm to convolution code is Viterbi
- There are few standard parameters for viterbi
- GOES satellites use k=7 , G1 = 0x4F, G2 = 0x6D
- GOES uses Standard CCSDS Sync Word ( 0x1ACFFC1D )
- Easiest way to sync frames: Generate a Encoded Sync Word
   and search for correlation
Syncing using correlation
Viterbi Output
Data Randomization
- Usually wireless transmissions randomize the data send
- First Reason: Avoid sync word collision
- Second Reason: Avoid Line Polarization and Symbol
   Unbalance
- Pseudo-Random Sequence: 1 + x^3 + x^5 + x^7 +x^8
Reed-Solomon Error Correction
- 223 bytes of data for 32 bytes of parity
- Can correct any 16 bytes over the 223 bytes
- Does not change original bitstream, so if SNR is good no need
   for correction
- GOES has 4 RS Blocks (255 bytes each) interleaved by 1 byte.
- Parity is on the end of the packet
--------------------------------------
LRIT Admin Message #011
Start:14-April-2010
End:20-December-2018
Distribution: East and West
Subject: LRIT contact information
--------------------------------------
The LRIT Systems team, in an effort to be more responsive
to the user community, would like for users to have
contact information. In the event that a user notices any
long term trends or anomalies in the LRIT data stream, or
has suggestions or comments. We ask that contact be made
via email to [email protected].

If more immediate matters arise, that the user deems as 
urgent, we advise the use of the following operational 
facility phone number: 301-817-3880.
--------------------------------------
Perguntas?
Links
- https://www.youtube.com/energylabsbr
- http://www.teske.net.br/lucas/
- https://greatscottgadgets.com/hackrf/
- http://www.rtl-sdr.com/
- http://www.github.com/racerxdl
- https://github.com/librtlsdr/librtlsdr
- http://airspy.com
- http://lna4all.blogspot.com
- https://luigifreitas.me/projects
Emails

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