Super typhoon Haiyan makes landfall
Super typhoon Haiyan
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The L band Transmission

While the final modes of operation of the L band transmission are still not yet defined, the technical parameters are already known, following the mission specifications. They provide some compatibility with HRPT stations, up to RF level.

Regional receiving ground stations will have to follow these technical characteristics to set up their installation. Modes of operation will be defined as soons as possible, taking into account the technical capacities of the system and the possible conflicts between requests from users that might impose to establish priorities or schedules for L band transmission on some parts of the orbits (See SPOT4 orbit parameters).

Informations on orbit ephemeris, data format and parameters which are necessary to process raw data will be made available to receiving ground stations.

Telemetry parameters

The onboard transmitting antenna is a low gain cardioid directed toward the Earth center.
Central frequency is 1704.0 MHz with an RF bandwidth of 2MHz. Emission is done in Right Hand Circular Polarization (RHCP).
The EIRP (Electrical Isotropic Radiated Power) is +31dBm at zenith and +33 dBm at 5° elevation angle.
The minimum ground flux is -99dBm/m²; at zenith and -108 dBm/m²; at 5° elevation angle.
The bit rate is 510 kb/s with a symbol rate of 1.02 Mchips (convolutional encoding, R=1/2, k=7). The modulation is a BiPhase Shift Keying (BPSK).

Typical ground station performances

A typical ground station with a 1.8 m diameter antenna should have the following parameters:

G/T > 4dB/K at 5° elevation angle
pointing error < 2° (included total margin)
demodulator losses < 1.5 dB
total margin 3.3dB at 5° elevation angle for a Bit Error Rate of 10**-6