Technical Summary
The antenna system automatically tracks satellites and receives direct broadcast RF transmissions which are focused into the scalar feed horn by the parabolic dish and then fed to the low-noise block downconverter. This amplifies the signal and downconverts it to a lower frequency to minimise cable loss.
The signal is then fed to the RF module in the system interface rack, where it is downconverted to a common frequency (720MHz) and fed to the demodulator.
The demodulator converts the RF signal back to a binary data stream which is then Viterbi decoded, byte-aligned and streamed via a TCP socket to the Polar Orbiter Ingester software running on the ingest PC. This detects the attached synchronisation markers (ASMs) in the data stream and extracts the CCSDS frames (VCDUs) which are then derandomised and Reed-Solomon decoded.
In the case of Terra, Aqua, Suomi NPP and JPSS, the decoded VCDUs are automatically streamed via a TCP socket to the RT-STPS software running on the processing and visualisation PC, which processes them and displays a preview in the Simulcast software. The IPOPP software automatically processes the resulting data sets into level 0, 1 and 2 data and products.
FengYun-3 data is assembled into a file which is automatically transferred via a LAN connection to the FY3L0pp and FY3L1pp software running on the processing and visualisation PC. This automatically produces level 0 and 1 data and products.
Land-based and marine antenna specifications
| Radome | 2m diameter, low-loss composite, hydrophobic coating, white or grey |
|---|---|
| Antenna type | Prime focus parabolic dish, solid spun aluminium, white powder coated |
| Diameter | 1.5m |
| F/D ratio | 0.364 |
| Gain @ 8200MHz | 39.3dBiC including 0.4dB radome loss |
| Feed | Scalar horn |
| Frequency range | 7200–8500MHz |
| Axial ratio | 2dB max |
| Polarisation | RHC/LHC, software controlled |
| Wind speed | 185km/h (100kt) operational 240km/h (130kt) survival |
Demodulator specifications
| Input frequency | X-Band 720MHz, L-Band 140MHz |
|---|---|
| Input dynamic range | –60dBm to 0dBm nominal |
| Modes | BPSK, QPSK, SQPSK |
| Implementation loss | <0.2dB typical @ 1:106 BER |
| Symbol rates | 0.1–100Msps |
| Baseband filter | Root raised cosine (RRC) with variable alpha |
| Convolution decoding | Viterbi, K=7, rates ½ and ¾, single and dual channel, G1=171, G2=133 |
| Monitoring/control | RJ45 Gigabit Ethernet Web interface, OSCP interface |
| Data outputs | RJ45 Gigabit Ethernet Up to 5 simultaneous TCP streams SMA clock and data |
| Supported services | Terra, Aqua, Suomi NPP, JPSS-1/2/3/4, FY-3D/E/F, Metop-SG, NOAA HRPT, Metop AHRPT, DMSP, GOES HRIT, GK-2A LRIT/HRIT |
| Typical system G/T | 19.4dB/K @ 8200MHz |
Low-noise block downconverter (LNB) specifications
| Input frequency | 7750–8400MHz |
|---|---|
| Noise figure | 0.69dB (50K) maximum 0.6dB (43K) typical |
| LO frequency | 6950MHz |
| IF output frequency | 800–1450MHz |
| Gain variation within 30MHz | ±0.4dB maximum |
| Gain variation over band | ±2dB max |
| Conversion gain | 55dB minimum |
| Image rejection | 40dB minimum |
| Local oscillator stability | ±1.5ppm (–40 to +80°C) |
| Local oscillator type | Internal Phase Locked Loop (PLL) locked to Temperature Controlled Crystal Oscillator (TCXO) |
| Phase noise | –90dBc/Hz @ 10kHz typical –100dBc/Hz @ 100kHz typical |
System interface rack RF module specifications
| Input frequency | 800–1450MHz |
|---|---|
| Noise figure | 4dB maximum |
| LO frequency | 1520–2170MHz programmable in 100kHz steps |
| LO stability | ±5ppm |
| Oscillator phase noise | –100dBc/Hz @ 10kHz typical |
| Output frequency | 720MHz |
| Converted bandwidth | 160MHz @ 3dB |
| IF filter | Dielectric |
| IF filter bandwidth | 140MHz @ 1dB 160MHz @ 3dB |
| Conversion gain | 20dB typical |
| Output 1dB compression point | >+19dBm |
| Monitoring/control | 2 × RS-232 serial via USB, software controlled |