Abstract's details

On-ground processing and performance of the Poseidon-4 altimeter internal calibration: chirp replica and attenuator

Michele Scagliola (Aresys, Italy)


Lisa Recchia (Aresys, Italy); Alessio Izzo (Aresys, Italy); Andrea Recchia (Aresys, Italy); Marco Fornari (RHEA for ESA, the Netherlands); Robert Cullen (ESA, the Netherlands); Luisella Giulicchi (ESA, the Netherlands)

Event: 2022 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Measurement and Retracking

Presentation type: Type Poster

Contribution: PDF file


The main payload of Sentinel-6 Michael Freilich is a dual-band (Ku and C) pulse-width limited radar altimeter, called Poseidon-4, that transmits pulses at a high pulse repetition frequency thus making the received echoes phase coherent and suitable for azimuth processing. Among the different unique characteristic of Poseidon-4, it is worth recalling that digital pulse range compression is performed on-board to transform the received chirp using a matched filter. Thus, a proper calibration approach has been developed, including both an internal and external calibration.
In particular, this abstract presents the long-term monitoring of the internal calibration data for chirp replica and for attenuator that are processed on ground by ad-hoc tools provisioned by Aresys to ESA:
• CAL1 INSTR: This mode measures the internal instrument transfer function in Ku band and in C band. The results of these measures can be taken into account at Digital compression level in the chirp replica(f) to optimize the impulse response of the instrument.
• CAL ATT: Since amplification gain control knowledge directly impacts the σ0 measurements, an attenuation calibration is included in the design. This measures the top of the range impulse response within the full attenuation dynamic range that is then matched to a corresponding value on ground.

The performance of Poseidon-4 altimeter is here presented by analysis of the long-term monitoring of the on-ground processed data from CAL1 INSTR and CAL ATT calibration sequences commanded on board. The analysis of such calibration data allows to verify that the instrument has reached the requirements and that it is maintaining the key performance over its life. Moreover, in-depth analysis of the calibration data revealed how the instrument depends on its temperature and on the orbit of the satellite.


Poster show times:

Room Start Date End Date
Mezzanine Tue, Nov 01 2022,17:15 Tue, Nov 01 2022,18:15
Mezzanine Thu, Nov 03 2022,14:00 Thu, Nov 03 2022,15:45
Michele Scagliola