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Description

This Level 1 (L1) dataset contains the Full Delay Doppler Map (DDM) sensor data from the Delay Doppler Mapping Instrument aboard the CYGNSS satellite constellation. The primary CYGNSS instrument, also known as the Delay-Doppler Mapping Instrument (DDMI), measures the incoming radio frequency (RF) streams from three input antenna channels (2 nadir oriented science antennas and one zenith oriented navigation antenna) and processes them in real time into DDMs, which are two-dimensional maps of the signal scattered from the Earth surface as a function of propagation time delay and Doppler frequency shift. DDMs are normally sampled over a restricted range of delay and Doppler values centered on the values at the specular point of reflection. The bit resolution of scattered signal strength is also truncated by a lossy data compression algorithm. Full DDMs are sampled over a wider range of delay and Doppler values and retain their full (lossless) bit resolution. Full DDM data records are typically 10-15 min in duration and are initiated by ground commands to coincide with an overpass by one of the spacecraft of a target area of interest.

Product Summary

Platforms
CYGNSS
Instruments
DDMI
Spatial Extent

N: 40 S: -40 E: 180 W: -180

Spatial Resolution
25000 Meters x 25000 Meters
Location
GLOBAL ,
TROPICS
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2017-08-19 to 2020-11-17
Data Partner
Cyclone Global Navigation Satellite System Mission, NASA Earth Science System Pathfinder, University of Michigan (NASA/ESSP/UMICH/CYGNSS) ,
Physical Oceanography Distributed Active Archive Center, Jet Propulsion Laboratory, NASA (NASA/JPL/PODAAC)
Concept ID
C2036882030-POCLOUD
Data State
ACTIVE
Number of Files/Granules
131
Processing Level
1
Published
Updated
Science Keywords
SENSOR COUNTS

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

CYGNSS. (2020). CYGNSS Level 1 Full Delay Doppler Map Data Record [Data set]. NASA Physical Oceanography Distributed Active Archive Center. https://doi.org/10.5067/CYGNS-L1FDD Date Accessed: 2026-04-15

Documents

USER'S GUIDE

ANOMALIES

DATA CITATION GUIDELINES

GENERAL DOCUMENTATION

PUBLICATIONS

Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor Offset
ddm The netCDF coordinate variable associated with variables that are dimensioned by the 4 DDMI reflectometry channels. It enumerates the zero-justified index range of DDM reflectometry channels. Ranges from 0 to 3. 1 byte N/A N/A 1 N/A
ddm_sample_index The Level 1 netCDF sample index of the corresponding DDM and metadata. Can be utilized together with spacecraft_num and 'source' to look up the corresponding Level 1 DDM data and metadata. 1 int -9999 N/A 1 N/A
ddm_timestamp_utc DDM sample time. The number of seconds since time_coverage_start with nanosecond resolution. Its position relative to the DDM sampling period is determined by ddm_time_type_selector. Some metadata required for DDM calibration are generated relative to pvt_timestamp_utc or att_timestamp_utc. These metadata are interpolated to ddm_timestamp_utc before being used for DDM calibration. Note that the DDM sampling period is not synchronized with the UTC change of second and can occur at any time relative to the UTC change of second. seconds since 2017-08-19 07:48:10.999261715 double N/A N/A 1 N/A
prn_code The PRN code of the GPS signal associated with the DDM. Ranges from 0 to 32. 0 = reflectometry channel idle. 1 through 32 = GPS PRN codes. 1 byte -99 0 to 32 1 N/A
raw_counts 128 x 20 array of DDM bin raw counts These are the uncalibrated power values produced by the DDMI. 1 int -9999 N/A 1 N/A
sample The netCDF coordinate variable associated with the sample dimension, which enumerates the zero-justified index range of the DDM time instants contained in the file. 1 int N/A N/A 1 N/A
spacecraft_id The CCSDS spacecraft identifier: 0xF7 (247): CYGNSS 1 0xF9 (249): CYGNSS 2 0x2B ( 43): CYGNSS 3 0x2C ( 44): CYGNSS 4 0x2F ( 47): CYGNSS 5 0x36 ( 54): CYGNSS 6 0x37 ( 55): CYGNSS 7 0x49 ( 73): CYGNSS 8 0x00 ( 0): end to end simulator 0x0E ( 14): engineering model 0x0D ( 15): default 0xFF (255): unknown 1 short -9999 N/A 1 N/A
spacecraft_num The CYGNSS spacecraft number: Ranges from 1 through 8 and 99. 1 through 8 are on-orbit spacecraft. 99 is the CYGNSS end-to-end simulator. 1 byte -99 N/A 1 N/A
sp_lat Specular point latitude, in degrees North, at ddm_timestamp_utc degrees_north float -9999 N/A 1 N/A
sp_lon Specular point longitude, in degrees East, at ddm_timestamp_utc degrees_east float -9999 N/A 1 N/A
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