IEEE Std 4003 pdf download

IEEE Std 4003 pdf download IEEE Standard for Spaceborne Global Navigaton Satellite System-Refectometry (GNSS-R) Data and Metadata Content
3.2 Fundamental observables
The collection of fundamental observables shall include the complete characterization of the following terms: ddm_complex: This feld includes the after-correlation in-phase I (real part) and quadrature Q (imaginary part) components of the scattered signal in raw counts. GNSS-R sensors of the clean-replica c-type as shown in “A Passive Refectometry and Interferometry System (PARIS): Application to Ocean Altimetry,” “The PARIS Ocean Altimeter In-Orbit Demonstrator,” “Tutorial on Remote Sensing Using GNSS Bistatic Radar of Opportunity,” “The CYGNSS Level 1 Calibration Algorithm and Error Analysis Based on On-Orbit Measurements,” and “Design and Performance of a GPS Constellation Power Monitor System for Improved CYGNSS L1B Calibration,” reconstructed-code r-type as mentioned in “Tutorial on Remote Sensing Using GNSS Bistatic Radar of Opportunity,” “Experimental Evaluation of GNSS-Refectometry Altimetric Precision Using the P(Y) and C/A Signals,” and “Direct Signal Enhanced Semicodeless Processing of GNSS Surface-Refected Signals” shall provide two ddm_complex observables, one for the direct and one for the refected signal. GNSS-R sensors of the interferometric i-type as described in “A Passive Refectometry and Interferometry System (PARIS): Application to Ocean Altimetry,” “The PARIS Ocean Altimeter In- Orbit Demonstrator,” and “Tutorial on Remote Sensing Using GNSS Bistatic Radar of Opportunity” and partial interferometric pi-type as illustrated in “Tutorial on Remote Sensing Using GNSS Bistatic Radar of Opportunity” and “Partial Interferometric Processing of Refected GNSS Signals for Ocean Altimetry” only need to produce one ddm_complex observable. The position of the nominal specular point shall be determined using a mean sea surface model over ocean and a digital elevation model (DEM) over land. The reported DDM array dimensions account for the spreading of the DDM in the delay and Doppler domains. For the global positioning system GPS coarse/acquisition C/A code systems, state-of-the-art values are ~4 chips x 5000 Hz as shown in “CYGNSS Handbook” or ~30 chips x 10 000 Hz as shown in “MERRByS Product Manual.” The optimum delay and Doppler bins size shall also be analyzed. The bin size shall be defned considering the scientifc requirements of the mission versus the peak location uncertainty. In other words, the maximum acceptable uncertainty in geophysical parameters retrieval as stated by a mission requirement list shall be used in the defnition of the bin size. Coherent integration time shall be assumed to be a variable.
All information defning the processing approach, including the coherent integration time and the nominal specular point location, shall be included as metadata. Dimension category: matrix.
ddm_complex_compressed: This is the compressed ddm_complex, i.e., the ddm_complex variable compressed to reduce the number of bits required in its representation. The compression approach used, and any uncertainties introduced shall be included in the metadata.
Dimension category: matrix. ddm_complex_cal: This is the calibrated ddm_complex after any corrections are applied for calibration purposes. The calibration method shall be included in the metadata. Dimension category: matrix.
ddm_complex_compressed_cal: This is the calibrated ddm_complex_compressed after any corrections are applied for calibration purposes. The calibration method shall be included in the metadata. Dimension category: matrix. ddm_power: This is the uncalibrated power value in raw counts, that is, the squared modulus of ddm_complex or ddm_complex_compressed.
All information defning the processing approach, including the coherent and the incoherent integration times as well as the location of the nominal specular point corresponding to ddm_ power, shall be included as metadata. The coherent and the incoherent integration times shall be assumed to be variable. Default values of the coherent and the incoherent integration time for land and ocean surfaces shall be specifed for each type of surface and shall be included in the nominal operational mode of the receiver.Dimension category: matrix.