LRO Mini-RF PDS4 Bistatic Derived Data (BSDDR4)

BSDDR4 – PDS4 Bistatic Derived Data

PDS3 Data Set ID: LRO-L-MRFLRO-2/3/5-BISTATIC-V3.0DOI: 10.17189/1520653Citations of DOI: 10.17189/1520653

PDS4 Bundle:urn:nasa:pds:lro_minirf_bistaticDOI: 10.17189/c3ym-tk17

For more information about Bistatic derived data products, see the Mini-RF SAR Bistatic PDS Data Product Software Interface Specification.

The Mini-RF (MRFLRO) Bistatic derived data product (BSDDR) contains the derived data backplanes, Stokes parameters and CPR products, as well as a custom global DEM.

Derived Stokes Parameters and CPR data

From the calibrated data, with complex values for H and V, four pieces of information were derived at each pixel in the data product:

The received power in the horizontal polarization (E_RH), E_RH = HH^*=|H|²
The received power in the vertical polarization (E_RV ),E_RV = VV^*=|V|²
The real portion of the cross product between the two polarization signals (Re HV^*)
The imaginary portion of the cross product between the two polarization signals (Im HV^*)

The first Stokes Parameter, S₁, represents the total power or total intensity of the received field: S₁ = E_RH + E_RV = |H|² + |V|² = HH^*+VV^*

The second Stokes Parameter, S₂, represents the difference between the horizontal and vertical components of the polarized portion of the received field.: S₂ = E_RH - E_RV = |H|²- |V|² = HH^* - VV^*

The third and fourth Stokes parameters represent the cosine and sine of the average phase difference δ between the horizontally and vertically polarized components of the received field:

S₃ = 2Re (HV^*) = 2|H||V|cosδ

S₄ = -2Im (HV^*) = -2|H||V|sinδ

The CPR is a dimensionless parameter calculated by the ratio (S₁ - S₄ )/ (S₁ + S₄). The CPR has been used to potentially evaluate the roughness of the surface and can also be used to detect the presence of thick deposits of frozen volatiles or other changes in materials properties. Each Stokes Parameter and CPR is stored in a separate binary data file as a PDS4 Array_2D_Image. The data is downsampled from the raw data such that the ground sample distance is at 100 m/pixel.

Derived Geometric Backplanes ddr data

Derived geometric backplanes are generated at the same resolution as the Stokes and CPR parameters. They allow the user to lookup various geometric values on a per-pixel basis. The time-varying quantities in each of the backplanes are computed at time of the received pulse that achieves the peak-power in the Mini-RF antenna pattern for each individual pixel. The time backplane provides the value of this time per pixel in the form of an offset in seconds from the start of the collection as defined in each collect’s label file. Each of the Mini-RF derived backplane files is an 11-plane image cube stored as a PDS4 Array_3D_Image object in band-sequential order. Thus, all the data for the latitude 2D plane is written out first, followed by all the data for the longitude 2D plane, and so on. The planes of the cube contain the information detailed in Table 5-2 of the Mini-RF SAR Bistatic PDS Data Product Software Interface Specification., calculated at the center of each pixel.

A custom global DEM (mrf_sar_dem16_v1.img): It is a shape map (radius) of the moon at a resolution of 1.89521 km/pixel. This Digital Elevation Model (DEM) was constructed by resampling the LOLA LDEM256 data product,

which is a DEM at a resolution of 256 pixels/deg down to a resolution consistent with LDEM16 at 16 pixels/deg to preserve the smoothness of the surface even at high latitudes.

MRFLRO BSDDR4 products have the following file names:

Mini-RF Bistatic science data products

lfm_yyyydoyhhmmss_<type>{c}_ppdqqq_Vv.ext (with detached PDS label)

Mini-RF Bistatic calibration and engineering data

lfm_yyyydoyhhmmss_<type>{C}_vV.ext (with detached PDS label)

where:

l = LRO

f= Frequency band

S = S-band

X = X-band

m = operational mode(T=bistatic, ground-based transmitter)

yyyydoyhhmmss = Time of data file start in UTC

yyyy = year

doy = day of year

hh = two digit hour of day

mm = two digit minutes of hour

ss = two digit seconds of minute

<type> = type of data file

For science data products

caln = internal noise calibration

calt = internal tone calibration

calc = internal chirp calibration

bitl = internal transmitter bit leak calibration

eng = 12-bit, unencoded, engineering collection

hskraw = raw, DN-valued housekeeping status telemetry

hskcal = calibrated to engineering units housekeeping status telemetry

For calibration and engineering data

sciraw = unprocessed receiver time series data (raw)

scip = receiver processed into an image (calibrated)

s1 - s4: derived Stokes parameters (derived)

cpr = circular polarization ratio (derived)

ddr= derived geometry and timing data formatted as image backplanes (derived)

{C} = Receiver channel

For science data products This is only for sciraw and scip data types (raw and calibrated science data)

For calibration and engineering dataThis is for all products other than hskraw and hskcal (housekeeping data is not attributed to a specific receiver channel)

h = H-channel

v = V-channel

pp = reference latitude of the map projection to the nearest whole degree. range: 00-90

d = hemisphere of reference latitude. "n" northern hemisphere, "s" southern hemisphere

qqq = reference longitude of the map projection to the nearest whole degree. range: 000-359

v = hardcoded character

V = integer indicating the version of the PDS4 data product. Initial versions start at 1. Version is incremented by 1 for previously delivered products that are redelivered to PDS.

ext = the file extension

dat = binary table files

xml = PDS4 XML labels

img = binary image files

In ODE, BSDDR4 products have the following product ID:

LFM_YYYYDOYHHMMSS_<type>{C}_PPDQQQ_vV for science data products

LFM_YYYYDOYHHMMSS_<type>{C}_vV for calibration and engineering data