Radar Altimeter 2
|Within Vocab||SeaVoX Device Catalogue|
|Preferred Label||Radar Altimeter 2|
|Definition||Radar Altimeter 2 (RA-2) is a dual-frequency, nadir-pointing, pulse-limited active microwave sensor designed to measure the two-way delay of the radar echo from the Earth's surface. RA-2 also measures the power and the shape of the reflected radar pulses. It's design is based on the heritage of ERS-1 Radar Altimeter (RA). RA-2 transmits frequency modulated pulses (chirp) pulses. This frequency modulation is a coding of the signal which spreads the energy of a short pulse over a longer time interval, thus allowing reduced peak power in the pulse. The transmit pulses, which are generated in the chirp generator (by means of SAW RAC) are amplified by either Ku-band or S-Band amplifiers, depending on the selected transmit frequency. The Ku-band HPA uses a traveling wave tube whilst the S-band transmitter applies the solid state technology. The Ku-band front end electronics (KFEE) or the S-band front end electronics (SFEE) feed the signals to be transmitted to the antenna which is designed as a dual-frequency parabolic antenna. RA-2 operates at 13.575 GHz (Ku-band) and 3.2 GHz (S-Band) and at high precision at less than a nanosecond. It measures the power level and time delay of 128 samples of echoes from ocean, ice, and land surfaces. It is optimised to maintain the leading edge of this echo in the range window. Flown on Envisat. https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/envisat/instruments/ra-2|
|Has Current Version||http://vocab.nerc.ac.uk/collection/L22/current/TOOL1047/2/|
|Authored On||2016-11-15 14:35:44|
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